Mindfulness for smoking cessation

Sarah Jackson; Jamie Brown; Emma Norris; Jonathan Livingstone-Banks; Emily Hayes; Nicola Lindson

doi:10.1002/14651858.CD013696.pub2

. 2022 Apr 14;2022(4):CD013696. doi: 10.1002/14651858.CD013696.pub2

Mindfulness for smoking cessation

Sarah Jackson ^1,^✉, Jamie Brown ¹, Emma Norris ², Jonathan Livingstone-Banks ³, Emily Hayes ⁴, Nicola Lindson ³

Editor: Cochrane Tobacco Addiction Group

PMCID: PMC9009295 PMID: 35420700

Abstract

Background

Mindfulness‐based smoking cessation interventions may aid smoking cessation by teaching individuals to pay attention to, and work mindfully with, negative affective states, cravings, and other symptoms of nicotine withdrawal. Types of mindfulness‐based interventions include mindfulness training, which involves training in meditation; acceptance and commitment therapy (ACT); distress tolerance training; and yoga.

Objectives

To assess the efficacy of mindfulness‐based interventions for smoking cessation among people who smoke, and whether these interventions have an effect on mental health outcomes.

Search methods

We searched the Cochrane Tobacco Addiction Group's specialised register, CENTRAL, MEDLINE, Embase, PsycINFO, and trial registries to 15 April 2021. We also employed an automated search strategy, developed as part of the Human Behaviour Change Project, using Microsoft Academic.

Selection criteria

We included randomised controlled trials (RCTs) and cluster‐RCTs that compared a mindfulness‐based intervention for smoking cessation with another smoking cessation programme or no treatment, and assessed smoking cessation at six months or longer. We excluded studies that solely recruited pregnant women.

Data collection and analysis

We followed standard Cochrane methods. We measured smoking cessation at the longest time point, using the most rigorous definition available, on an intention‐to‐treat basis. We calculated risk ratios (RRs) and 95% confidence intervals (CIs) for smoking cessation for each study, where possible. We grouped eligible studies according to the type of intervention and type of comparator. We carried out meta‐analyses where appropriate, using Mantel‐Haenszel random‐effects models. We summarised mental health outcomes narratively.

Main results

We included 21 studies, with 8186 participants. Most recruited adults from the community, and the majority (15 studies) were conducted in the USA. We judged four of the studies to be at low risk of bias, nine at unclear risk, and eight at high risk. Mindfulness‐based interventions varied considerably in design and content, as did comparators, therefore, we pooled small groups of relatively comparable studies.

We did not detect a clear benefit or harm of mindfulness training interventions on quit rates compared with intensity‐matched smoking cessation treatment (RR 0.99, 95% CI 0.67 to 1.46; I² = 0%; 3 studies, 542 participants; low‐certainty evidence), less intensive smoking cessation treatment (RR 1.19, 95% CI 0.65 to 2.19; I² = 60%; 5 studies, 813 participants; very low‐certainty evidence), or no treatment (RR 0.81, 95% CI 0.43 to 1.53; 1 study, 325 participants; low‐certainty evidence). In each comparison, the 95% CI encompassed benefit (i.e. higher quit rates), harm (i.e. lower quit rates) and no difference. In one study of mindfulness‐based relapse prevention, we did not detect a clear benefit or harm of the intervention over no treatment (RR 1.43, 95% CI 0.56 to 3.67; 86 participants; very low‐certainty evidence).

We did not detect a clear benefit or harm of ACT on quit rates compared with less intensive behavioural treatments, including nicotine replacement therapy alone (RR 1.27, 95% CI 0.53 to 3.02; 1 study, 102 participants; low‐certainty evidence), brief advice (RR 1.27, 95% CI 0.59 to 2.75; 1 study, 144 participants; very low‐certainty evidence), or less intensive ACT (RR 1.00, 95% CI 0.50 to 2.01; 1 study, 100 participants; low‐certainty evidence). There was a high level of heterogeneity (I² = 82%) across studies comparing ACT with intensity‐matched smoking cessation treatments, meaning it was not appropriate to report a pooled result.

We did not detect a clear benefit or harm of distress tolerance training on quit rates compared with intensity‐matched smoking cessation treatment (RR 0.87, 95% CI 0.26 to 2.98; 1 study, 69 participants; low‐certainty evidence) or less intensive smoking cessation treatment (RR 1.63, 95% CI 0.33 to 8.08; 1 study, 49 participants; low‐certainty evidence).

We did not detect a clear benefit or harm of yoga on quit rates compared with intensity‐matched smoking cessation treatment (RR 1.44, 95% CI 0.40 to 5.16; 1 study, 55 participants; very low‐certainty evidence).

Excluding studies at high risk of bias did not substantially alter the results, nor did using complete case data as opposed to using data from all participants randomised.

Nine studies reported on changes in mental health and well‐being, including depression, anxiety, perceived stress, and negative and positive affect. Variation in measures and methodological differences between studies meant we could not meta‐analyse these data. One study found a greater reduction in perceived stress in participants who received a face‐to‐face mindfulness training programme versus an intensity‐matched programme. However, the remaining eight studies found no clinically meaningful differences in mental health and well‐being between participants who received mindfulness‐based treatments and participants who received another treatment or no treatment (very low‐certainty evidence).

Authors' conclusions

We did not detect a clear benefit of mindfulness‐based smoking cessation interventions for increasing smoking quit rates or changing mental health and well‐being. This was the case when compared with intensity‐matched smoking cessation treatment, less intensive smoking cessation treatment, or no treatment. However, the evidence was of low and very low certainty due to risk of bias, inconsistency, and imprecision, meaning future evidence may very likely change our interpretation of the results. Further RCTs of mindfulness‐based interventions for smoking cessation compared with active comparators are needed. There is also a need for more consistent reporting of mental health and well‐being outcomes in studies of mindfulness‐based interventions for smoking cessation.

Plain language summary

Can mindfulness help people to stop smoking?

Key messages

‐ There is currently no clear evidence that mindfulness‐based treatments help people to stop smoking or improve their mental health and well‐being.

‐ However, our confidence in the evidence is low or very low, and further evidence is likely to change our conclusions.

What is mindfulness?

Mindfulness involves focusing attention on your thoughts and feelings and observing them without judgment as they arise and pass away. Mindfulness is believed to help people better control their thoughts and feelings, rather than be controlled by them. Stopping smoking gives rise to distressing urges to smoke and low mood, so mindfulness‐based treatments could improve people's ability to cope with these.

Types of mindfulness‐based therapies include:

‐ mindfulness training (which involves training in mindfulness‐based meditation);

‐ acceptance and commitment therapy (ACT); which doesn't teach meditation but encourages people to embrace their thoughts and feelings rather than fighting them, while making committed behaviour change);

‐ distress tolerance training (which provides parts of the ACT therapy, as well as presenting people who smoke with situations that make them want to smoke. This allows them to practise the skills that they have learnt through ACT);

‐ yoga (which increases awareness of breathing and encourages a connection between mind and body).

What did we want to find out?

We wanted to find out whether mindfulness‐based stop‐smoking programmes work better than other stop‐smoking programmes or no treatment to help people stop smoking.

We wanted to know:

‐ how many people stopped smoking for at least six months;

‐ whether there were changes in people's mental health and well‐being.

What did we do?

We searched for studies that looked at the use of mindfulness to help people stop smoking.

We compared and summarised the results of the studies and rated our confidence in the evidence, based on factors such as study methods and sizes.

What did we find?

We found 21 studies in 8186 young people and adults who smoked.

The studies tested a range of mindfulness‐based treatments, including mindfulness training (8 studies), ACT (8 studies), yoga (3 studies), and distress tolerance training (2 studies). Studies compared these treatments with:

‐ other stop‐smoking treatments that were equally time‐intensive (such as counselling);

‐ other stop‐smoking treatments that were less intensive (such as brief advice);

‐ no treatment.

Most studies took place in the USA (15 studies). Others took place in Hong Kong (2 studies), Brazil (1 study), Ireland (1 study), and Cyprus (1 study). One study did not report the country it took place in.

Main results

We did not find clear evidence that mindfulness helped people to stop smoking. When we grouped studies by the type of mindfulness‐based intervention people received, we found no evidence that people who received mindfulness training, ACT, distress tolerance training, or yoga were more likely to stop than people who received any other stop‐smoking treatments or no support.

Nine studies looked at whether mindfulness‐based stop‐smoking treatments resulted in positive changes in mental health and well‐being, such as reductions in stress or anxiety or improvements in mood. One of these studies found that people who received a mindfulness training programme reported being less stressed than those who received an alternative stop‐smoking treatment. However, the other 8 did not find evidence of a difference in mental health and well‐being between groups.

What are the limitations of the evidence?

Our confidence in the evidence is low to very low as there were problems with the design of studies, findings of studies were very different from one another, and not enough people took part, making it difficult to tell whether mindfulness helps people to stop smoking or was linked to better mental health and well‐being. We need more studies to draw firmer conclusions.

How up to date is this evidence?

We included evidence published to 15 April 2021.

Summary of findings

Background

Description of the condition

Smoking remains a leading cause of preventable death and disease worldwide (WHO 2019). Stopping smoking can result in substantial health gains, even later in life. The sooner a smoker quits, the more they reduce their risk of developing smoking‐related diseases (Doll 2004). The majority of smokers want to quit and many try to quit each year, but quit rates remain low (WHO 2019).

Description of the intervention

In recent decades, mindfulness has increasingly been recognised as an influence on mood and behaviour (Baer 2003; Keng 2011). It has been adopted as an approach for increasing awareness and responding skilfully to mental processes that contribute to emotional distress and maladaptive behaviour (Baer 2003). In current research contexts, mindfulness is typically defined as the psychological process of bringing non‐judgmental attention to experiences occurring in the present moment (Kabat‐Zinn 2013). There are various definitions of mindfulness used in psychological literature. While no consensus has been reached on how to define mindfulness, a two‐component model proposed by Bishop 2004 is often used in research. This operationalises mindfulness as: (i) maintaining attention on the immediate experience, and (ii) maintaining an attitude of openness, curiosity, and acceptance toward this experience, regardless of its valence or desirability.

Mindfulness approaches are not relaxation or mood management techniques, but rather a form of cognitive training to reduce susceptibility to reactive states of mind that might otherwise induce stress or perpetuate psychopathology (Baer 2003). The practice of mindfulness involves focusing attention on the immediate experience of cognitions, emotions, perceptions, and physical sensations and observing them as they arise and pass away. Mindfulness is nondeliberative: it simply involves paying sustained attention to thoughts and feelings without thinking about or evaluating them. A key tenet of mindfulness is that, by noticing thoughts and feelings in a curious and accepting manner, people develop greater tolerance of these phenomena and are able to recognise that they are transient, so they are less likely to respond impulsively to them (Heppner 2015).

There are a range of different treatments based on the principles of mindfulness. Mindfulness‐based stress reduction (MBSR; Kabat‐Zinn 2013) and mindfulness‐based cognitive therapy (MBCT; Segal 2002) use meditation as the primary method of teaching mindfulness. MBSR was developed to treat chronic stress and pain‐related disorders. It uses three techniques: firstly, sitting meditation, which involves mindful attention on the breath and a state of noncritical awareness of cognitions, feelings, and sensations; secondly, Hatha yoga practice, which involves breathing exercises, simple stretches, and postures; and thirdly, body scan, which involves a gradual sweeping of attention through the entire body from feet to head, while employing nonjudgmental awareness of feelings and sensation in each targeted body region (Kabat‐Zinn 2013). MBCT was developed to prevent relapse in depressive disorders. It integrates aspects of cognitive behavioral therapy (CBT) for depression into the MBSR programme (Segal 2002).

Other treatments that incorporate mindfulness include acceptance and commitment therapy (ACT; Hayes 2016), distress tolerance training, dialectical behaviour therapy (DBT; Linehan 2018), and certain types of yoga (Salmon 2009). ACT focuses on increasing people's willingness to experience physical cravings, emotions, and thoughts, and allowing these to come and go while making committed behaviour changes that are guided by their own values (Hayes 2016). Distress tolerance training combines elements drawn from ACT with exposure‐based treatment, allowing ACT skills to be practised within treatment sessions in response to internal triggers (Brown 2008). DBT also has a strong emphasis on acceptance, incorporating strategies to help the patient accept themselves, their current capabilities, and behavioural functioning (Linehan 2018). Yoga is a key component of MBSR (Kabat‐Zinn 2013), and provides an opportunity to practise mindfulness through movement. Forms of yoga that incorporate breathing exercises and directed meditative focus work to still the mind and focus attention (Bock 2012).

How the intervention might work

Mindfulness‐based interventions may aid smoking cessation by teaching individuals to pay attention to, and work mindfully with, negative affective states, cravings, and other symptoms of nicotine withdrawal as they arise, rather than habitually reacting to these unpleasant states by smoking. Proposed mechanisms of action include attention regulation, body awareness, emotion regulation, and change in self‐perspective (Hölzel 2011).

Withdrawal following smoking cessation is acutely associated with heightened levels of stress and negative affect (Shiffman 2004; West 2017). Once withdrawal symptoms have abated, cessation is generally associated with improved mental health (Taylor 2014; Taylor 2021), but early stage acute stress, negative affect, and depression are predictive of relapse (Correa‐Fernández 2012; Glassman 1990; Shiffman 2004; Shiffman 2005). Therefore, interventions that work to reduce these adverse emotional consequences of stopping smoking may enhance quit rates and ultimately prevent relapse. Mindfulness‐based interventions have shown some efficacy in the treatment of psychiatric disorders relating to or involving these negative affective states (Goyal 2014; Marchand 2013).

Further, by teaching smokers to focus their attention on what is happening in the moment, mindfulness‐based interventions bring habitual behaviours into consciousness. This enables people to understand the associative learning process, and focus on affect and craving as central components of positive and negative reinforcement loops (Brewer 2010). By emphasising the transience of affective states and teaching smokers to ‘sit with’ negative affect and craving, mindfulness interventions target and modify learned responses to smoking cues. This may help smokers to quit and may reduce cigarette consumption among those who do not stop smoking completely.

Thus, it has been suggested that mindfulness‐based treatments “may have the relative advantage of teaching a single technique that may lead to the dampening and eventual dismantling of the complex interrelated associative processes of smoking rather than just removing stimuli that might propagate them” (Brewer 2011).

Why it is important to do this review

If found to be effective, mindfulness‐based interventions could add an innovative intervention option to the range of treatments for smoking cessation. A systematic review, including literature to 2016, did not find evidence of a significant impact of mindfulness meditation interventions on abstinence relative to comparator groups (Maglione 2017). However, the evidence identified was of low certainty due to the high levels of heterogeneity and imprecision detected through meta‐analysis. Therefore, there is a need to update this review to include new evidence, in an effort to increase the certainty of the resulting conclusions. In addition, expanding the search to include other interventions that incorporate mindfulness approaches but do not specifically include an element of meditation (e.g. ACT) can add to our understanding of the potential effectiveness of mindfulness for smoking cessation.

The purpose of the present review is to assess the effect of interventions that incorporate mindfulness approaches for smoking cessation, using the robust methodology of Cochrane and the Cochrane Tobacco Addiction Group. This review also represents part of a separate project to evaluate similarities and differences between the standard methodological processes of the Cochrane Tobacco Addiction Group and a novel, machine‐learning approach developed by the Human Behaviour Change Project (Michie 2013).

Objectives

To assess the efficacy of mindfulness‐based interventions for smoking cessation among people who smoke, and whether these interventions have an effect on mental health outcomes.

Methods

Criteria for considering studies for this review

Types of studies

Randomised controlled trials (RCTs) and cluster‐RCTs that measured smoking cessation at least six months from baseline were eligible for this review. We included studies reported as full text, those published as abstract only, and unpublished data, where available. There were no language or date restrictions.

Types of participants

We included current tobacco smokers of any age who were willing to enrol in a smoking cessation study. We excluded studies that only recruited pregnant women, as their particular needs and circumstances warrant their treatment as a separate population, and these are covered in a separate Cochrane Review (Chamberlain 2017).

Types of interventions

We included interventions targeted at tobacco smoking cessation that were either labelled as mindfulness, or involved a mindfulness‐based approach that could be isolated to investigate effectiveness. There were no restrictions on the minimum duration of the intervention. Where a potentially relevant study intervention was not specifically described as being mindfulness‐based, we discussed as a team (of EN, JLB, NL, SJ) whether it was eligible for inclusion. We intentionally adopted an inclusive approach, including interventions that incorporated mindfulness (e.g. ACT or yoga) in addition to those specifically focused on mindfulness meditation (e.g. MBSR or MBCT) to capture the broadest evidence.

Eligible studies had to include at least one of the following comparison (control) interventions:

no smoking cessation treatment;
another smoking cessation intervention, of any length or intensity (including usual care);
another type of mindfulness intervention (e.g. mindfulness of a lower intensity).

Types of outcome measures

Primary outcomes

Smoking abstinence at longest follow‐up

To be eligible for inclusion, studies must have measured abstinence at least six months from the start of the intervention. Following the Cochrane Tobacco Addiction Group's standard methods, we excluded studies that only measured abstinence at less than six‐months' follow‐up.

In studies with more than one measure of abstinence, we preferred the measure with the strictest criteria, in line with the Russell Standard (West 2005). We used prolonged or continuous abstinence in preference to point prevalence abstinence, and preferred biochemically validated abstinence (e.g. using exhaled carbon monoxide or cotinine measures) over self‐report. We favoured biochemically validated point prevalence abstinence over self‐reported continuous or prolonged abstinence.

Mental health and well‐being

This could provide us with information on potential benefits or harms of the mindfulness‐based interventions. Even if comparisons of mindfulness‐based interventions with other smoking cessation interventions do not find a benefit of mindfulness for smoking cessation, improved mental well‐being could be a reason for choosing this treatment over another. We assessed validated measures of the following relevant constructs:

depression;
anxiety;
quality of life;
positive affect;
negative affect;
stress.

We extracted data on these mental health and well‐being outcomes, measured at the longest follow‐up at which abstinence was reported, or as close to this as possible.

Search methods for identification of studies

Electronic searches

We searched the following databases for studies that referred to mindfulness techniques in the title or abstract, or as keywords:

Cochrane Tobacco Addiction Group Specialised Register via the Cochrane Register of Studies (CRS‐Web)
Cochrane Central Register of Controlled Trials (CENTRAL; 2021, issue 3) via CRS‐Web
MEDLINE Ovid (1946 to 15 April 2021)
Embase Ovid (1974 to 15 April 2021)
PsycINFO Ovid (1806 to 15 April 2021)

We searched all databases from inception through to 15 April 2021. At the time of the search, the Register included the results of searches of MEDLINE (via OVID) to update 20210407; Embase (via OVID) to week 202114; PsycINFO (via OVID) to update 20210329. See the Tobacco Addiction Group website for details of the search strategies for these databases. Search strategies are shown in Appendix 1.

By searching CENTRAL and the Cochrane Tobacco Addiction Group’s register, we were able to identify any ongoing studies registered in the World Health Organization's portal (www.who.int/trialsearch) or ClinicalTrials.gov in the USA, and studies reported in Annual Meeting abstracts for the Society for Research on Nicotine and Tobacco (SRNT). We listed in the Characteristics of ongoing studies table any studies that may be candidates for inclusion (i.e. RCTs of smoking cessation interventions using mindfulness‐based approaches with a minimum follow‐up of six months), but for which results are not yet available.

Searching other resources

We checked reference lists of eligible published papers to identify any other relevant papers that may not have been identified by our search, and consulted experts in the field to identify any relevant forthcoming or unpublished research. We contacted the authors of ongoing studies where necessary.

Alongside these manual search strategies, we employed an automated search strategy developed as part of the Human Behaviour Change Project (Michie 2017), using Microsoft Academic. The Human Behaviour Change Project aims to improve upon the human ability to synthesise, interpret and deliver evidence on behaviour change interventions, using Natural Language Processing and Machine Learning technologies to automate the extraction, synthesis, and interpretation of findings from behaviour change intervention evaluation reports. We added any additional studies identified through this method to those found via the manual search, so that we included all relevant evidence. An evaluation comparing these manual and automated methods of study identification will be reported in a separate paper.

Data collection and analysis

Selection of studies

Two review authors (of EN, JLB, NL, SJ), independently checked the titles and abstracts of retrieved studies for relevance, and acquired full study reports of those that may be candidates for inclusion. The review authors resolved any disagreements by mutual consent, or by recourse to a third review author. Two review authors (of EN, JLB, NL, SJ) then independently assessed the full texts for eligibility, resolving any disagreements through discussion and with involvement of a third review author when necessary. We classified as 'exclude' any studies for which we obtained full reports, but that did not meet the inclusion criteria.

Data extraction and management

Two review authors (of EH, EN, JLB, NL, SJ) independently extracted study data and compared their findings. We resolved any disagreements through discussion, involving a third review author where necessary. Where available, we recorded the following information in the Characteristics of included studies table.

Methods: study design, study name (if applicable), study dates, country, number of study centres, study setting, study recruitment procedure
Participants: number (intervention/control), definition of smoker used, specific demographic characteristics (e.g. mean age, age range, gender, ethnicity, socioeconomic status (SES)), mean cigarettes per day, mean Fagerstrom Test for Nicotine Dependence (FTND), relevant inclusion and exclusion criteria
Interventions: description of intervention(s) (details of behavioural support and any pharmacological treatment provided), description of control (details of behavioural support and any pharmacological treatment provided), what comparisons will be constructed between which groups
Outcomes: relevant primary and secondary outcomes measured, time points reported, biochemical validation, definitions of abstinence, mental health measures used, proportion of participants with follow‐up data
Details of any within‐study analyses of moderators of interest: population type; baseline motivation to quit; baseline mental health
Notes: funding for study, and conflicts of interest statements of study authors (extracted verbatim)

Alongside this data extraction of entities that are typically captured in smoking cessation Cochrane Reviews, we also performed data extraction using entities of the Behaviour Change Intervention Ontology, which is being developed as part of the Human Behaviour Change Project (Michie 2017). The ontology consists of granular entities to specify all aspects of behaviour change interventions, such as:

an intervention’s context (including 'setting' (Norris 2020) and 'population');
content (including 'behaviour change techniques'; (Michie 2013)); and
delivery (including 'mode of delivery': how an intervention is provided to participants (Marques 2021); 'source': who delivers interventions (Norris 2021); and 'schedule': how often an intervention is delivered (Michie 2017)).

An evaluation to compare these methods of data extraction will be reported in a separate paper.

Assessment of risk of bias in included studies

Two review authors (of JLB, NL, SJ) independently assessed the risk of bias for each included study. We used RoB 1, following the guidance as set out in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011).

We assessed the following domains (Higgins 2011):

sequence generation;
allocation concealment,
blinding of outcome assessment;
incomplete outcome data;
selective reporting; and
other sources of bias.

As we were investigating a primarily behavioural intervention, we did not assess the blinding of participants and providers, as it is impossible to blind people to behavioural interventions. This is in accordance with specific guidance from the Cochrane Tobacco Addiction Group.

Each review author recorded information in study reports relevant to each domain and then assessed each domain as either at low, high, or unclear risk of bias. We resolved disagreements by discussion with a third review author. We considered studies to be at high overall risk of bias where we judged at least one domain to be at high risk; at low overall risk of bias where all domains were judged to be at low risk; and at unclear overall risk of bias in all other cases.

Measures of treatment effect

We compared quit rates between intervention and comparator groups for each study. We calculated quit rates on an intention‐to‐treat basis, including all participants originally randomised to a study arm, treating participants lost to follow‐up as relapsed. We calculated a risk ratio (RR) and 95% confidence interval (CI) for each study. We calculated the RR for each study as: (number of participants who reported smoking abstinence in the intervention group/number of participants randomised to the intervention group)/(number of participants who reported smoking abstinence in the control (comparator) group/number of participants randomised to the control (comparator) group).

Due to high levels of variance between studies in interventions and comparators, and in the measurement of mental health and well‐being outcomes, we narratively reported relevant measures of mental health and well‐being.

Unit of analysis issues

The one included cluster‐RCT did not present an analysis adjusting for the clustering effect or report an intracluster correlation coefficient (ICC). Therefore, we used unadjusted data for the primary analysis and performed a sensitivity analysis where we estimated the ICC (0.03), based on the ICC reported in other smoking cessation studies (Fanshawe 2017), and adjusted the analysis on this basis.

In the case of studies with multiple intervention arms, we analysed individual arms separately.

Dealing with missing data

For smoking abstinence, we assumed participants lost to follow‐up to be smoking, as is standard in the field (West 2005). However, we conducted a sensitivity analysis, excluding numbers lost to follow‐up from the denominator.

Assessment of heterogeneity

In order to assess whether it was appropriate to pool studies and conduct meta‐analyses, we assessed the characteristics of included studies to identify any clinical or methodological variance between studies. If we deemed the studies to be homogeneous enough to be combined meaningfully and we could conduct meta‐analyses, we assessed statistical heterogeneity using the I² statistic (Higgins 2003). We considered an I² statistic over 50% to indicate moderate to substantial heterogeneity (Deeks 2021). Where the I² statistic was 80% or more, the direction of individual study effects differed, and heterogeneity was not fully explained by subgroup and sensitivity analyses, we do not report a pooled estimate because it could be misleading. We conducted the subgroup and sensitivity analyses described below to investigate any potential causes of observed heterogeneity.

Assessment of reporting biases

It was not appropriate to assess reporting bias using funnel plots as none of our analyses pooled 10 or more studies.

Data synthesis

We provided a narrative summary of the included studies and, where appropriate, conducted meta‐analyses.

The primary outcome of abstinence provides dichotomous data, therefore, as per the Cochrane Tobacco Addiction Group's standard methods, we combined RRs from individual studies using random‐effects, Mantel‐Haenszel methods, to calculate pooled overall RRs with 95% CIs.

Meaures of our mental health and well‐being outcome typically provided continuous data. Data were too heterogeneous to carry out meta‐analyses, so we tabulated the existing information and summarised narratively.

We also narratively reported the results of any within‐study analyses that have investigated the following moderators of effectiveness at at least six months' follow‐up:

population type;
baseline motivation to quit;
baseline mental health.

Subgroup analysis and investigation of heterogeneity

We carried out subgroup analyses, categorising studies by the type/intensity of control treatment received and mode of intervention delivery. We compared pooled summary statistics across groups and ran statistical tests for subgroup differences.

Sensitivity analysis

For smoking abstinence, we tested the impact of excluding studies deemed to be at overall high risk of bias and compared abstinence rates calculated assuming 'missing equals smoking' with abstinence rates calculated through complete‐case analysis. We also carried out the sensitivity analysis reported above, using an assumed ICC to adjust for potential clustering effects in a cluster‐RCT.

Summary of findings and assessment of the certainty of the evidence

Following standard Cochrane methodology (Schünemann 2021), we created summary of findings tables for smoking abstinence, and mental health and well‐being outcomes, detailing different intervention types in separate tables (mindfulness training; ACT; distress tolerance training; yoga). Also following standard Cochrane methodology (Schünemann 2021), we used the five GRADE considerations (risk of bias, inconsistency, imprecision, indirectness, and publication bias) to assess the certainty of the body of evidence for each outcome, within each comparison, and to draw conclusions about the certainty of evidence within the text of the review.

Results

Description of studies

Results of the search

Our bibliographic database searches and automated search process identified 2900 non‐duplicate records (Figure 1). We screened all records and retrieved the full‐text papers of 166 potentially relevant articles. After screening and checking the full texts, we identified 57 reports relating to 27 studies. Of these, 21 were completed studies (see Characteristics of included studies table) and six were ongoing studies (see Characteristics of ongoing studies table). We were unable to classify one study because the follow‐up period was unclear (see Characteristics of studies awaiting classification table).

Included studies

In total, we included 21 completed studies (Bloom 2020; Bock 2012; Bock 2019; Bricker 2014a; Bricker 2018; Bricker 2020; Brown 2013; Davis 2014a; Davis 2014b; de Souza 2020; Garrison 2020; Gaskins 2015; Gifford 2003; Mak 2020; McClure 2020; O'Connor 2020; Pbert 2020; Savvides 2014; Singh 2014; Vidrine 2016; Weng 2021). Key features of the included studies are summarised below.

Context and participants

Studies were conducted in the USA (15 studies), Hong Kong (2 studies), Brazil (1 study), Ireland (1 study), and Cyprus (1 study). One study (Singh 2014) did not report its location. Participants were recruited from the community (12 studies), online (3 studies), from healthcare centres (2 studies), high schools and universities (2 studies), tobacco treatment services (1 study), and workplaces (1 study). One study was a cluster‐RCT (Pbert 2020), which randomised high schools to different conditions. All other studies were randomised at the individual level.

The total number of participants across studies was 8186. The median sample size was 146 but ranged from 38 to 2637 participants. Two studies deliberately targeted young adults (Pbert 2020; Savvides 2014), two studies low SES smokers (Davis 2014a; Davis 2014b), one study uninsured smokers (Bricker 2014a), one study smokers with a history of early lapse (never able to remain abstinent for more than 72 hours; Brown 2013), and one study adults with mild intellectual disability (Singh 2014). Most studies had similar proportions of men and women or slightly more women than men. The exceptions were Bloom 2020, Bock 2012 and Weng 2021, which targeted only women; Gaskins 2015, which targeted only men; Singh 2014, which recruited 82% men with mild intellectual disability; and Mak 2020, which was conducted in Hong Kong where smoking prevalence among women is low and recruited 71% men.

Studies typically recruited people who smoked at least five cigarettes a day. Although some studies included lighter smokers as well, the average number smoked was over 15 a day in most studies, ranging from five a day in Pbert 2020's sample of high school students to 22 a day in Brown 2013's community sample.

Intervention programmes

Mindfulness training

Eight studies used mindfulness training (which, for the purpose of this review, we define as specific training in mindfulness and mindfulness‐based meditation techniques).

Five studies tested the effectiveness of mindfulness training delivered face‐to‐face. Davis 2014b compared seven weeks of group mindfulness training and meditation practice with an alternative, intensity‐matched, behavioural support programme. Similarly, Vidrine 2016 compared mindfulness‐based addiction treatment (8 x 2‐hour sessions) with an intensity‐matched CBT programme. In the latter study, there was also a second, less intensive comparator arm, in which participants received briefer support intended to represent the intervention a smoker might typically receive if they asked a healthcare provider for help (4 x 5‐ to 10‐minute sessions). All participants received self‐help materials. The other three studies compared mindfulness training with less intensive comparators. Davis 2014a compared an eight‐week mindfulness and meditation training programme with quitline support. Singh 2014 compared mindfulness and meditation training for adults with mild intellectual disability with treatment as usual, which varied between participants and encompassed a range of treatments such as behaviour therapies, nicotine replacement therapy (NRT), and other medications. Weng 2021 provided women in workplaces with self‐help materials and compared the effectiveness of additional mindfulness and meditation training (2 x 2‐hour sessions), with brief advice to follow the advice of the self‐help materials. Provision of pharmacotherapy varied between studies: three studies (Davis 2014a; Davis 2014b; Vidrine 2016), provided participants in both arms with a course of nicotine patches, one study provided no pharmacotherapy (Weng 2021), and one study (Singh 2014), did not specifically provide pharmacotherapy to participants in either arm, although for some comparator arm participants it was part of their usual treatment.

Two studies tested the effectiveness of mindfulness training delivered via smartphone apps. Garrison 2020 was conducted online. It compared a mobile mindfulness training app plus experience sampling (which asked participants to check in 6 times a day for 22 days) with experience sampling only. Pbert 2020 was a cluster‐RCT conducted in high schools. It tested the effectiveness of a mindfulness smartphone app designed for teens against two comparators: firstly, an alternative (non‐mindfulness) smoking cessation app designed for teens and secondly, self‐help materials. Participants in each of the three arms met with the school nurse weekly for four weeks. No pharmacotherapy was provided in either study.

de Souza 2020 was the only study to focus on mindfulness for relapse prevention. All participants received CBT over two phases: a smoking cessation phase (weekly sessions over 4 weeks) and a maintenance phase (6 sessions between weeks 6 and 48). The intervention arm also received eight mindfulness‐based relapse prevention sessions during the maintenance phase. Participants were offered the choice of NRT or bupropion.

Behaviour‐change techniques (BCTs) varied across studies. The most commonly used techniques included body changes (7 studies), problem solving (4 studies), self‐monitoring of behaviour (4 studies), pharmacological support (4 studies), and goal setting (3 studies), with no clear patterning in the number or type of BCTs used across mode of delivery.

Acceptance and commitment therapy (ACT)

Eight studies used ACT.

Three studies tested the effectiveness of ACT delivered exclusively face‐to‐face. McClure 2020 compared a five‐week, group ACT programme with a five‐week, group CBT programme. The two arms were matched for the number and duration of sessions. Participants in both arms were provided with eight weeks of nicotine patches. Gifford 2003 compared a seven‐week programme of individual and group ACT sessions (with no pharmacotherapy) with a lower‐intensity comparator group that received a seven‐week course of nicotine patches. O'Connor 2020 compared six weeks of face‐to‐face, group ACT sessions with six weeks of face‐to‐face, group behavioural support, matched in intensity to the six‐week, face‐to‐face ACT programme. No pharmacotherapy was provided.

One study tested the effectiveness of ACT delivered through a combination of face‐to‐face sessions and a smartphone app. In addition to the face‐to‐face‐only intervention arm, O'Connor 2020 included a second intervention arm in which ACT was delivered via two modalities: the six‐week, face‐to‐face ACT programme and an ACT‐based smartphone app. This combined ACT intervention was compared with a less intensive ACT arm (i.e. 6 weeks of face‐to‐face ACT without the app).

One study tested the effectiveness of ACT delivered exclusively via smartphone app. Bricker 2020 compared an ACT smartphone app with a smoking cessation app based on national clinical practice guidelines. No pharmacotherapy was provided.

One study tested the effectiveness of ACT delivered through a combination of face‐to‐face sessions and telephone calls. Mak 2020 compared ACT delivered in one face‐to‐face session and two follow‐up telephone calls with brief advice (5 minutes). Participants in both arms were also provided with self‐help materials. No pharmacotherapy was provided.

One study tested the effectiveness of ACT delivered exclusively via telephone. Bricker 2014a compared an ACT programme delivered over five telephone calls with standard quitline CBT. The arms were matched for the number and duration of telephone calls. Participants were provided with two weeks of nicotine patches or gum.

Two studies tested the effectiveness of ACT delivered via websites. Bricker 2018 compared an online ACT programme with a national standard online quit programme, with both arms receiving daily messages prompting them to log in. Savvides 2014 compared an avatar‐led, internet‐based ACT programme with a waitlist control. Neither study provided participants with pharmacotherapy.

BCTs varied across studies. The most commonly used techniques included problem solving (6 studies), body changes (5 studies), goal setting (4 studies), and action planning (4 studies), with no clear patterning in the number or type of BCTs used across mode of delivery.

Distress tolerance training

Two studies used distress tolerance training. Distress tolerance training interventions combined elements drawn from ACT with exposure‐based treatment. Exposure included periods of scheduled abstinence prior to sessions and exposure to cues within sessions, allowing ACT skills to be practised within the sessions in response to internal triggers.

Bloom 2020 targeted women who were concerned about post‐cessation weight gain. The intervention was nine weeks of CBT plus distress tolerance training ‐ a face‐to‐face and telephone programme that targeted the fear of anticipated post‐cessation weight gain and facilitated initiation of abstinence, and appetite awareness and mindful eating skills to reduce post‐cessation emotional eating. The comparator was nine weeks of CBT plus smoking health education, which mentioned diet and exercise as strategies for health promotion but did not specifically recommend changing diet or increasing physical activity to prevent post‐cessation weight gain.

Brown 2013 targeted smokers who had previously tried to quit but had never been able to remain abstinent for more than 72 hours. The intervention was eight weeks of face‐to‐face distress tolerance treatment and the comparator was six weeks of standard treatment.

Both studies also provided NRT (8 weeks of nicotine patches) to all participants in the intervention and comparator arms.

BCTs varied across studies: while both used pharmacological support, Brown 2013 used reduce prompts/cues and Bloom 2020 used problem solving, self‐monitoring of behaviour, social support, information about health consequences, and anticipated regret.

Yoga

Three studies used yoga involving a mindfulness‐based approach.

Two studies used Vinyasa yoga (Bock 2012; Gaskins 2015), and one used Iyengar yoga (Bock 2019). In each study, participants in the intervention arm were provided with eight CBT classes and 16 yoga classes over eight weeks. Participants in the comparator arm received CBT and wellness classes over eight weeks. In Bock 2012 and Bock 2019, the comparator was matched to the intervention in terms of the number and duration of wellness classes (16 x 1‐hour classes). However, in Gaskins 2015 the comparator was less intensive than the intervention: the intervention arm received 16 yoga classes over the eight weeks, each lasting 60 to 90 minutes, while the comparator arm received eight brief wellness discussions following the CBT sessions.

None of the studies provided participants with pharmacotherapy, but two studies (Bock 2012; Bock 2019), noted that participants were permitted to use NRT or other medications alongside the programme if they wanted to.

BCTs were similar across studies: all three studies used goal setting, problem solving, and social support. Bock 2012 and Gaskins 2015 also used self‐monitoring of behaviour and body changes, and Gaskins 2015 also used reduce negative emotions.

Outcomes

Smoking abstinence

The included studies provided a range of smoking abstinence outcome measures. Two studies reported the strictest outcome as biochemically verified continuous abstinence (Bock 2019; Davis 2014a), 12 studies defined abstinence as biochemically verified, seven‐day point prevalence (Bloom 2020; Bock 2012; Brown 2013; Davis 2014b; Garrison 2020; Gaskins 2015; Gifford 2003; Mak 2020; O'Connor 2020; Pbert 2020; Vidrine 2016; Weng 2021), one study as biochemically verified, 30‐day point prevalence (McClure 2020), and one study as carbon monoxide less than 10 parts per million (de Souza 2020).

Four additional studies reported self‐reported continuous abstinence (Bricker 2020), self‐reported seven‐day point prevalence (Singh 2014), or self‐reported 30‐day point prevalence (Bricker 2014a; Bricker 2018), without biochemical verification.

Most studies had a maximum follow‐up duration of six months, but six studies collected their final follow‐up data at 12 months (Bricker 2018; Bricker 2020; Gifford 2003; Mak 2020; McClure 2020; Singh 2014). Savvides 2014 reported collecting data on seven‐day and 30‐day point prevalence abstinence at six and 12 months but at the time this report was published data collection was ongoing and the only smoking abstinence outcomes reported are from immediately post‐treatment; we have not been able to find long‐term outcome data reported elsewhere.

Mental health

Ten of the included studies reported collecting data on mental health and well‐being (Bloom 2020; Bock 2012; Brown 2013; Davis 2014a; Davis 2014b; de Souza 2020; Gaskins 2015; Gifford 2003; O'Connor 2020; Vidrine 2016), of which nine analysed and reported on changes in these outcomes. Mental health outcomes included depression, anxiety, perceived stress, and negative and positive affect. The constructs assessed, measures used, and follow‐up durations varied across studies.

Excluded studies

Figure 1 shows the most common reasons for exclusion of studies during full‐text screening, which included: a follow‐up period of less than six months; ineligible study design (not an RCT); conference proceedings with no relevant studies; and an intervention where it was not possible to isolate the effects of the mindfulness element.

In the Characteristics of excluded studies table, we list exclusion reasons for 47 studies. This list is not comprehensive, only containing studies that a reader might plausibly expect to be included.

Risk of bias in included studies

Overall, we judged four of the 21 completed studies to be at low risk of bias, nine studies to be at unclear risk, and the remaining eight studies at high risk of bias.

Details of risk of bias judgments for each domain of each included study can be found in the Characteristics of included studies table. Figure 2 illustrates judgments for each included study.

Allocation

Random sequence generation

We judged one study (Singh 2014), to be at high risk of selection bias for sequence generation, because randomisation was via alternate placement in the experimental and control groups. We judged eight studies at low risk of bias (Bock 2019; Bricker 2014a; Bricker 2018; Bricker 2020; Gifford 2003; Mak 2020; O'Connor 2020; Savvides 2014). The risk of bias for the remaining studies was unclear.

Allocation concealment

We judged six studies (Bricker 2014a; Bricker 2018; Bricker 2020; Mak 2020; O'Connor 2020; Weng 2021), to be at low risk of selection bias for allocation concealment, and the remainder to be at unclear risk as there was insufficient information with which to judge.

Blinding

Blinding of participants and personnel (performance bias)

Blinding of outcome assessment (detection bias)

We rated three studies (Mak 2020; Savvides 2014; Singh 2014), at high risk for detection bias. These studies did not use blinding, they provided different levels of support, and outcomes were self‐reported. This meant we thought there was a high risk of bias being introduced. We judged the remaining studies to be at low risk for detection bias.

Incomplete outcome data

We judged most studies (13 out of 21) to be at low risk of attrition bias. We rated four studies with substantial (> 50%) loss to follow‐up and one study with more than a 20% difference in follow‐up rates between arms at high risk of attrition bias (Davis 2014a; Davis 2014b; de Souza 2020; Gaskins 2015; Mak 2020). The remaining three studies (Bock 2012; Savvides 2014; Singh 2014), did not provide sufficient data on which to judge, and hence we judged them to be at unclear risk.

Selective reporting

Of the 21 studies, we considered 13 to be at low risk of reporting bias, as they reported all prespecified or expected outcomes. We rated two studies (Bock 2012; de Souza 2020), at high risk, as they did not present data as specified in the original protocols. We judged the rest (Bloom 2020; Brown 2013; Gifford 2003; Mak 2020; Savvides 2014; Singh 2014), to be at unclear risk, as we were unable to identify a protocol.

Other potential sources of bias

We judged one study (Savvides 2014), to be at high risk of other bias because it used a waitlist control. This design risks participants in the control arm delaying quitting, knowing that they would be receiving an intervention at a later date. This has the potential to inflate the reported effect of the intervention. We did not find any other studies to be at risk of other bias.

Effects of interventions

See: Table 1; Table 2; Table 3; Table 4

Summary of findings 1. Mindfulness training compared with control for smoking cessation.

Mindfulness training compared with control for smoking cessation
Patient or population: people who smoke Setting: community; online; tobacco treatment services; high schools; workplaces (USA; Brazil; Hong Kong)  Intervention: mindfulness training; mindfulness‐based relapse prevention Comparisons: matched‐intensity smoking cessation treatment; less intensive smoking cessation treatment; no treatment
Outcomes	*Anticipated absolute effects^ (95% CI)**		Relative effect (95% CI)	№ of participants (studies)	Certainty of the evidence (GRADE)	Comments
	Risk with control	Risk with mindfulness training
Mindfulness training vs matched‐intensity smoking cessation treatment: smoking cessation (≥ 6‐month follow‐up)	Study population		RR 0.99 (0.67 to 1.46)	542 (3 RCTs)	⊕⊕⊝⊝ Low^a,b
	16 per 100	16 per 100 (11 to 24)
Mindfulness training vs less intensive smoking cessation treatment: smoking cessation (≥ 6‐month follow‐up)	Study population		RR 1.19 (0.65 to 2.19)	813 (5 RCTs)	⊕⊝⊝⊝ Very low^c,d,e
	11 per 100	14 per 100 (7 to 25)
Mindfulness training vs no treatment: smoking cessation (≥ 6‐month follow‐up)	Study population		RR 0.81 (0.43 to 1.53)	325 (1 RCT)	⊕⊕⊝⊝ Low^f
	12 per 100	10 per 100 (5 to 18)
Mindfulness‐based relapse prevention vs no treatment: smoking cessation (≥ 6‐month follow‐up)	Study population		RR 1.43 (0.56 to 3.67)	86 (1 RCT)	⊕⊝⊝⊝ Very low^g,h
	14 per 100	20 per 100 (8 to 52)
Mental health and well‐being	Studies investigated a range of outcomes: anxiety, depression, negative affect, positive affect, stress. Although 1 study found a statistically significantly greater reduction in perceived stress in people who received mindfulness training compared with those who received a matched‐intensity smoking cessation treatment at 6‐month follow‐up, the other 2 studies found no clinically meaningful between‐group differences in change in mental health and well‐being measures.			633 (3 RCTs)	⊕⊝⊝⊝ Very low^i,j	We were unable to meta‐analyse these outcomes and therefore summarised them narratively.
*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).  CI: confidence interval; RCT: randomised controlled trial; RR: risk ratio
GRADE Working Group grades of evidence High certainty: we are very confident that the true effect lies close to that of the estimate of the effect. Moderate certainty: we are moderately confident in the effect estimate: the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low certainty: our confidence in the effect estimate is limited: the true effect may be substantially different from the estimate of the effect. Very low certainty: we have very little confidence in the effect estimate: the true effect is likely to be substantially different from the estimate of effect.

Acceptance and commitment therapy (ACT) compared with control for smoking cessation
Patient or population: people who smoke Setting: community; online; primary care; high schools and universities (USA; Cyprus; Hong Kong; Ireland) Intervention: Acceptance and commitment therapy (ACT) Comparisons: matched‐intensity smoking cessation treatment; NRT; brief advice; less intensive ACT
Outcomes	*Anticipated absolute effects^ (95% CI)**		Relative effect (95% CI)	№ of participants (studies)	Certainty of the evidence (GRADE)	Comments
	Risk with control	Risk with ACT
ACT vs matched‐intensity smoking cessation treatment: smoking cessation (≥ 6‐month follow‐up)	It was not appropriate to pool data across these studies because there was a high level of heterogeneity (I² = 82%) and the result may be misleading.			5723 (5 RCTs)	⊕⊝⊝⊝ Very low^a,b,c
ACT vs NRT: smoking cessation (≥ 6‐month follow‐up)	Study population		RR 1.27 (0.53 to 3.02)	102 (1 RCT)	⊕⊕⊝⊝ Low^d
	15 per 100	19 per 100 (8 to 45)
ACT vs brief advice: smoking cessation (≥ 6‐month follow‐up)	Study population		RR 1.27 (0.59 to 2.75)	144 (1 RCT)	⊕⊝⊝⊝ Very low^d,e
	14 per 100	17 per 100 (8 to 37)
ACT vs less intensive ACT: smoking cessation (≥ 6‐month follow‐up)	Study population		RR 1.00 (0.50 to 2.01)	100 (1 RCT)	⊕⊕⊝⊝ Low^d
	24 per 100	24 per 100 (12 to 48)
Mental health and well‐being	One study that compared ACT with NRT found no clinically meaningful difference in negative affect across conditions at all follow‐ups to 12 months. Another study that compared ACT with a matched‐intensity smoking cessation treatment and a less intensive ACT intervention found no clinically meaningful difference in positive mental health across conditions up to 6‐month follow‐up.			252 (2 RCTs)	⊕⊝⊝⊝ Very low^f,g	We were unable to meta‐analyse this outcome and therefore summarised narratively.
*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).  ACT: Acceptance and commitment therapy; CI: confidence interval; NRT: nicotine replacement therapy; RCT: randomised controlled trial; RR: risk ratio
GRADE Working Group grades of evidence High certainty: we are very confident that the true effect lies close to that of the estimate of the effect. Moderate certainty: we are moderately confident in the effect estimate: the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low certainty: our confidence in the effect estimate is limited: the true effect may be substantially different from the estimate of the effect. Very low certainty: we have very little confidence in the effect estimate: the true effect is likely to be substantially different from the estimate of effect.

Distress tolerance training compared with control for smoking cessation
Patient or population: people who smoke Setting: community (USA) Intervention: distress tolerance training Comparisons: matched‐intensity smoking cessation treatment; less intensive smoking cessation treatment
Outcomes	*Anticipated absolute effects^ (95% CI)**		Relative effect (95% CI)	№ of participants (studies)	Certainty of the evidence (GRADE)	Comments
	Risk with control	Risk with distress tolerance training
Distress tolerance training vs matched‐intensity smoking cessation treatment: smoking cessation (≥ 6‐month follow‐up)	Study population		RR 0.87 (0.26 to 2.98)	69 (1 RCT)	⊕⊕⊝⊝ Low^a
	14 per 100	12 per 100 (4 to 41)
Distress tolerance training vs less intensive smoking cessation treatment: smoking cessation (≥ 6‐month follow‐up)	Study population		RR 1.63 (0.33 to 8.08)	49 (1 RCT)	⊕⊕⊝⊝ Low^a
	9 per 100	15 per 100 (3 to 73)
Mental health and well‐being	One study that compared distress tolerance training with less intensive smoking cessation treatment found no clinically meaningful difference in negative affect at 4 weeks post‐quit.			49 (1 RCT)	⊕⊕⊝⊝ Low^b	We were unable to meta‐analyse this outcome and therefore summarised narratively.
*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).  CI: confidence interval; RCT: randomised controlled trial; RR: risk ratio
GRADE Working Group grades of evidence High certainty: we are very confident that the true effect lies close to that of the estimate of the effect. Moderate certainty: we are moderately confident in the effect estimate: the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low certainty: our confidence in the effect estimate is limited: the true effect may be substantially different from the estimate of the effect. Very low certainty: we have very little confidence in the effect estimate: the true effect is likely to be substantially different from the estimate of effect.

Yoga compared with control for smoking cessation
Patient or population: people who smoke Setting: community (USA) Intervention: yoga Comparison: matched‐intensity smoking cessation treatment; less intensive smoking cessation treatment
Outcomes	*Anticipated absolute effects^ (95% CI)**		Relative effect (95% CI)	№ of participants (studies)	Certainty of the evidence (GRADE)	Comments
	Risk with control	Risk with yoga
Yoga vs matched‐intensity smoking cessation treatment: smoking cessation (≥ 6‐month follow‐up)	Study population		RR 1.44 (0.40 to 5.16)	55 (1 RCT)	⊕⊝⊝⊝ Very low^a,b
	13 per 100	19 per 100 (5 to 67)
Mental health and well‐being	One study compared yoga with matched‐intensity smoking cessation treatment and found no clinically meaningful difference in depression, anxiety, or general well‐being scores between conditions at 8‐week follow‐up after controlling for baseline scores. Another study compared yoga with less intensive smoking cessation treatment and found no clinically meaningful differences in the change in depression or anxiety scores by group up to 6‐month follow‐up.			93 (2 RCTs)	⊕⊝⊝⊝ Very low^c,d	We were unable to meta‐analyse this outcome and therefore summarised narratively.
*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).  CI: confidence interval; RCT: randomised controlled trial; RR: risk ratio
GRADE Working Group grades of evidence High certainty: we are very confident that the true effect lies close to that of the estimate of the effect. Moderate certainty: we are moderately confident in the effect estimate: the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low certainty: our confidence in the effect estimate is limited: the true effect may be substantially different from the estimate of the effect. Very low certainty: we have very little confidence in the effect estimate: the true effect is likely to be substantially different from the estimate of effect.

Mental health outcomes
Study	Depression	Anxiety	Quality of life	Stress	Negative affect	Other
Davis 2014a	Not assessed	Not assessed	Not assessed	Not assessed	Depression, Anxiety and Stress Scales (DASS): assessed at 1 month post‐baseline, data only reported for intervention arm	Not assessed
Davis 2014b	Not assessed	Not assessed	Not assessed	Perceived Stress Scale (PSS): assessed at 6 months post‐quit. Significantly greater reduction in intervention than control arm (P = 0.03) Intervention arm scored 16.2 at baseline and 13.0 at 6 months post‐quit (−3.2); comparator arm scored 17.5 at baseline and 16.9 at 6 months post‐quit (−0.6). This difference was not significant when analysed as intention to treat	Not assessed	Not assessed
de Souza 2020	Hospital Anxiety and Depression Scale (HAD): assessed at 4 and 12 weeks. No difference across conditions in the change between 4 weeks and 12 weeks (F (3.421) = 17.549; P = 0.074). Intervention arm scored 6.4 at 4 weeks and 6.9 at 12 weeks (+0.5); comparator arm scored 7.6 at 4 weeks and 6.0 at 12 weeks (−1.6)	HAD: assessed at 4 and 12 weeks. No difference across conditions in the change between 4 weeks and 12 weeks (F (0.352) = 1.668; P = 0.558). Intervention arm scored 10.4 at 4 weeks and 8.9 at 12 weeks (−1.4); comparator arm scored 9.5 at 4 weeks and 8.7 at 12 weeks (−0.8)	Not assessed	Not assessed	Positive and Negative Affect Scale (PANAS): assessed at 4 and 12 weeks. No difference across conditions in the change between 4 weeks and 12 weeks (F (0.015) = 0.278; P = 0.903). Intervention arm scored 20.3 at 4 weeks and 19.1 at 12 weeks (−1.2); comparator arm scored 19.2 at 4 weeks and 17.7 at 12 weeks (−1.4)	Positive affect ‐ PANAS: assessed at 4 and 12 weeks. No difference across conditions in the change between 4 weeks and 12 weeks (F (0.904) = 14.395; P = 0.350). Intervention arm scored 25.9 at 4 weeks and 27.2 at 12 weeks (+1.2); comparator arm scored 25.3 at 4 weeks and 24.6 at 12 weeks (−0.7)
Vidrine 2016	Center for Epidemiologic Studies ‐ Depression Scale (CES‐D): assessed 6 times between quit date and 6 months post‐quit. No significant difference in the change between quit date and 6 months post‐quit between intervention arm and either control arm (CBT: β 0.03, 95% CI −0.16 to 0.22, P = 0.762; usual care: β −0.18, 95% CI −0.40 to 0.03, P = 0.099)	Not assessed	Not assessed	4‐item Perceived Stress Scale ‐ Short Form (PSS‐SF): assessed 6 times between quit date and 6 months post‐quit. No significant difference in the change between quit date and 6 months post‐quit between intervention arm and either control arm (CBT: β 0.09, 95% CI −0.10 to 0.28, P = 0.362; usual care: β −0.16, 95% CI −0.38 to 0.05, P = 0.141)	PANAS: assessed 6 times between quit date and 6 months post‐quit. No significant difference in the change between quit date and 6 months post‐quit between intervention arm and either control arm (CBT: β 0.08, 95% CI ‐0.11 to 0.27, p = 0.403; usual care: β ‐0.19, 95% CI ‐0.40 to 0.03, p = 0.086)	Positive affect ‐ PANAS: assessed 6 times between quit date and 6 months post‐quit. No significant difference in the change between quit date and 6 months post‐quit between intervention arm and either control arm (CBT: β ‐0.09, 95% CI ‐0.29 to 0.10, p = 0.337; usual care: β 0.09, 95% CI ‐0.13 to 0.30, p = 0.444)

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1.1 Mindfulness training vs matched‐intensity smoking cessation treatment	3	542	Risk Ratio (M‐H, Random, 95% CI)	0.99 [0.67, 1.46]
1.1.1 Face‐to‐face	2	444	Risk Ratio (M‐H, Random, 95% CI)	1.05 [0.64, 1.72]
1.1.2 Smartphone app	1	98	Risk Ratio (M‐H, Random, 95% CI)	0.78 [0.29, 2.08]
1.2 Mindfulness training vs less intensive smoking cessation treatment	5	813	Risk Ratio (M‐H, Random, 95% CI)	1.19 [0.65, 2.19]
1.2.1 vs. less intensive behavioural support	2	453	Risk Ratio (M‐H, Random, 95% CI)	1.31 [0.75, 2.30]
1.2.2 vs. brief advice	1	213	Risk Ratio (M‐H, Random, 95% CI)	0.47 [0.18, 1.23]
1.2.3 vs. self‐help materials	1	96	Risk Ratio (M‐H, Random, 95% CI)	0.75 [0.28, 2.00]
1.2.4 vs. mixed treatment	1	51	Risk Ratio (M‐H, Random, 95% CI)	2.77 [1.30, 5.94]
1.3 Mindfulness training vs no treatment	1	325	Risk Ratio (M‐H, Random, 95% CI)	0.81 [0.43, 1.53]
1.4 Mindfulness‐based relapse prevention vs no treatment	1	86	Risk Ratio (M‐H, Random, 95% CI)	1.43 [0.56, 3.67]
1.5 Mental health outcomes	4		Other data	No numeric data

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
2.1 ACT vs matched‐intensity smoking cessation treatment	5		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
2.1.1 Face‐to‐face	2	550	Risk Ratio (M‐H, Random, 95% CI)	0.76 [0.32, 1.78]
2.1.2 Telephone	1	121	Risk Ratio (M‐H, Random, 95% CI)	1.35 [0.74, 2.46]
2.1.3 Website	1	2637	Risk Ratio (M‐H, Random, 95% CI)	0.91 [0.79, 1.05]
2.1.4 Smartphone app	1	2415	Risk Ratio (M‐H, Random, 95% CI)	1.77 [1.32, 2.37]
2.2 ACT vs NRT	1	102	Risk Ratio (M‐H, Random, 95% CI)	1.27 [0.53, 3.02]
2.3 ACT vs brief advice	1	144	Risk Ratio (M‐H, Random, 95% CI)	1.27 [0.59, 2.75]
2.4 ACT vs less intensive ACT	1	100	Risk Ratio (M‐H, Random, 95% CI)	1.00 [0.50, 2.01]
2.5 Mental health outcomes	2		Other data	No numeric data

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
3.1 Distress tolerance vs matched‐intensity smoking cessation treatment	1	69	Risk Ratio (M‐H, Random, 95% CI)	0.87 [0.26, 2.98]
3.2 Distress tolerance vs less intensive smoking cessation treatment	1	49	Risk Ratio (M‐H, Random, 95% CI)	1.63 [0.33, 8.08]
3.3 Mental health outcomes	2		Other data	No numeric data

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
4.1 Yoga vs matched‐intensity smoking cessation treatment	1	55	Risk Ratio (M‐H, Random, 95% CI)	1.44 [0.40, 5.16]
4.2 Mental health outcomes	2		Other data	No numeric data

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
5.1 Mindfulness training vs matched‐intensity smoking cessation treatment	2	407	Risk Ratio (M‐H, Random, 95% CI)	0.82 [0.51, 1.33]
5.2 Mindfulness training vs less intensive smoking cessation treatment	3	566	Risk Ratio (M‐H, Random, 95% CI)	0.81 [0.50, 1.33]
5.2.1 vs. less intensive behavioural support	1	257	Risk Ratio (M‐H, Random, 95% CI)	1.11 [0.57, 2.18]
5.2.2 vs. brief advice	1	213	Risk Ratio (M‐H, Random, 95% CI)	0.47 [0.18, 1.23]
5.2.3 vs. self‐help materials	1	96	Risk Ratio (M‐H, Random, 95% CI)	0.75 [0.28, 2.00]

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
6.1 Mindfulness training vs matched‐intensity smoking cessation treatment	3	356	Risk Ratio (M‐H, Random, 95% CI)	1.05 [0.69, 1.59]
6.2 Mindfulness training vs less intensive smoking cessation treatment	4	479	Risk Ratio (M‐H, Random, 95% CI)	1.08 [0.53, 2.16]
6.2.1 vs. less intensive behavioural support	2	224	Risk Ratio (M‐H, Random, 95% CI)	1.72 [0.62, 4.80]
6.2.2 vs. brief advice	1	165	Risk Ratio (M‐H, Random, 95% CI)	0.50 [0.19, 1.29]
6.2.3 vs. self‐help materials	1	90	Risk Ratio (M‐H, Random, 95% CI)	0.78 [0.30, 2.08]
6.3 Mindfulness training vs no treatment	1	247	Risk Ratio (M‐H, Random, 95% CI)	0.77 [0.41, 1.43]
6.4 Mindfulness‐based relapse prevention vs no treatment	1	20	Risk Ratio (M‐H, Random, 95% CI)	1.23 [0.72, 2.10]
6.5 ACT vs matched‐intensity smoking cessation treatment	5	4537	Risk Ratio (M‐H, Random, 95% CI)	1.05 [0.70, 1.57]
6.5.1 Face‐to‐face	2	437	Risk Ratio (M‐H, Random, 95% CI)	0.71 [0.35, 1.44]
6.5.2 Telephone	1	81	Risk Ratio (M‐H, Random, 95% CI)	1.14 [0.66, 1.96]
6.5.3 Website	1	2309	Risk Ratio (M‐H, Random, 95% CI)	0.93 [0.81, 1.07]
6.5.4 Smartphone app	1	1710	Risk Ratio (M‐H, Random, 95% CI)	1.85 [1.39, 2.47]
6.6 ACT vs NRT	1	71	Risk Ratio (M‐H, Random, 95% CI)	1.63 [0.71, 3.72]
6.7 ACT vs brief advice	1	66	Risk Ratio (M‐H, Random, 95% CI)	1.06 [0.54, 2.11]
6.8 ACT vs less intensive ACT	1	91	Risk Ratio (M‐H, Random, 95% CI)	0.94 [0.47, 1.86]
6.9 Distress tolerance vs matched‐intensity smoking cessation treatment	1	54	Risk Ratio (M‐H, Random, 95% CI)	0.86 [0.26, 2.86]
6.10 Distress tolerance vs less intensive smoking cessation treatment	1	46	Risk Ratio (M‐H, Random, 95% CI)	1.68 [0.34, 8.28]

*Study characteristics*
Methods	Study design: RCT Location: USA Setting: community Recruitment: uninsured callers to the South Carolina State Quitline Study dates: 2012‐13
Participants	N = 121 Specialist population?: uninsured Definition of smoker used: ≥ 10 cpd for at least the past 12 months Participant characteristics: 69% female; average age: 39 years; 73% white; 55% high school education or less; nicotine dependence: 71% HSI score ≥ 4; 39% positive depression screen
Interventions	Comparator: standard CBT‐based counselling intervention offered through the South Carolina State Quitline Mode of delivery: telephone Intensity: 5 calls (1 x 30 min, 4 x 15 min) Pharmacotherapy: 2 weeks of nicotine patch or gum (participant’s choice) Type of therapist/provider: bachelor's‐ or master's‐level providers with ≥ 3 years of general counselling experience and > 100 h of training BCTs: 1.2 Problem solving, 1.4 Action planning, 3.1 Social support (unspecified), 11.1: Pharmacological support, 12.4 Distraction Intervention: ACT programme The acceptance components taught skills in increasing willingness to experience urges that cue smoking changing the function of smoking urges responding differently to smoking urges (e.g. noticing and not acting on urges). The commitment components focused on helping individuals articulate the values guiding quitting and taking actions to quit guided by those values Mode of delivery: telephone Intensity: 5 calls (1 x 30 min, 4 x 15 min) Pharmacotherapy: 2 weeks of nicotine patch or gum (participant’s choice) Type of therapist/provider: bachelor's‐ or master's‐level providers with ≥ 3 years of general counselling experience and > 100 h of training BCTs: 1.4 Action planning, 3.1 Social support (unspecified), 11.1: Pharmacological support
Outcomes	Definition of abstinence: 30‐day point prevalence Longest follow‐up: 6 months Biochemical verification: none Other relevant outcomes reported: none
Notes	Relevant comparisons: ACT (telephone) + NRT vs CBT (quitline) + NRT Funding source: National Institute on Drug Abuse (R21DA030646) Author conflicts of interest: “In 2011 Dr. Heffner served as a consultant for Pfizer.”
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomised by automated algorithm
Allocation concealment (selection bias)	Low risk	Quote: “Randomized study arm assignments were computer generated and concealed from participants after eligibility was determined and consent for participation was obtained. Neither research staff nor participants had access to upcoming randomized study arm assignments”
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Abstinence self‐reported but no face‐to‐face contact so no difference in intensity; differential report unlikely
Incomplete outcome data (attrition bias) All outcomes	Low risk	At 6‐month follow‐up 27.1% (16/59) were lost to follow‐up in the intervention group and 38.7% (24/62) in the control group
Selective reporting (reporting bias)	Low risk	Prespecified outcomes reported

*Study characteristics*
Methods	Study design: RCT Location: USA Setting: online Recruitment: targeted Facebook adverts, an online survey panel, search engine results, friends/family referral, Google ads, and earned media Study dates: 2014‐19
Participants	N = 2637 Specialist population?: no Definition of smoker used: ≥ 5 cpd for the last year Participant characteristics: 79% female; average age: 46 years; 73% white; 28% high school education or less; nicotine dependence: average FTND 5.6; 56% current depressive symptoms; 34% current anxiety symptoms; 48% current panic disorder symptoms; 53% current PTSD symptoms; 30% current social anxiety symptoms
Interventions	Comparator: Smokefree online quit programme available for 12 months Intensity: up to 4 daily messages (via text or email) designed to encourage logging in for 28 days after randomisation, unless they opted out Mode of delivery: website Pharmacotherapy: none Type of therapist/provider: N/A BCTs: 1.2 Problem solving, 1.4 Action planning, 5.1 Information about health consequences Intervention: WebQuit online ACT programme with attached online forum available for 12 months Intensity: up to 4 daily messages (via text or email) designed to encourage logging in for 28 days after randomisation, unless they opted out Mode of delivery: website Pharmacotherapy: none Type of therapist/provider: N/A BCTs: 1.4 Action planning, 2.3 Self‐monitoring of behaviour
Outcomes	Definition of abstinence: 30‐day point prevalence Longest follow‐up: 12 months Biochemical verification: none Other relevant outcomes reported: none
Notes	Relevant comparisons: ACT online programme (WebQuit) vs Smokefree online programme Funding source: National Cancer Institute (R01 CA166646; R01CA192849); National Institute on Drug Abuse (R01 DA038411) Author conflicts of interest: “In July 2016, Dr. Jonathan Bricker was a consultant to Glaxo Smith Kline, the makers of a nicotine replacement therapy. He now serves on the Scientific Advisory Board of Chrono Therapeutics, the makers of a nicotine replacement therapy device. Other authors have no declarations.”
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: “Using randomly permuted block randomization, stratified by daily smoking frequency (≤20 vs. ≥21), education (≤ high school vs. ≥ some college), and gender (male vs. female).”
Allocation concealment (selection bias)	Low risk	Quote: “Random assignments were concealed from participants until after study eligibility, consent, and baseline data was obtained. Neither research staff nor study participants had access to upcoming randomized study arm assignments.”
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Abstinence self‐reported but no face‐to‐face contact so no difference in intensity; differential report unlikely
Incomplete outcome data (attrition bias) All outcomes	Low risk	At 12‐month follow‐up 13.5% (178/1319) were lost to follow‐up in the intervention group and 11.4% (150/1318) in the control group
Selective reporting (reporting bias)	Low risk	Prespecified outcomes reported

*Study characteristics*
Methods	Study design: RCT Location: USA Setting: online Recruitment: nationally via Facebook ads, a survey sampling company, search engine results, and referral from friends and family Study dates: 2017‐19
Participants	N = 2415 Specialist population?: no Definition of smoker used: ≥ 5 cpd for at least the past year Participant characteristics: 70% female; average age: 38 years; 69% white; 41% high school education or less; nicotine dependence: average FTND 5.9; 48.5% positive depression screen
Interventions	Comparator: QuitGuide smartphone app including content on motivations to quit, preparing to quit (including quit plan, triggers, social support, and advice on pharmacotherapy), avoiding cravings, and remaining abstinent Mode of delivery: smartphone app Pharmacotherapy: none BCTs: 1.1 Goal setting (behaviour), 1.2 Problem solving, 3.1 Social support (unspecified), 5.1 Information about health consequences, 8.2 Behaviour substitution Intervention: iCanQuit smartphone app; ACT programme teaching skills for coping with urges, staying motivated and preventing relapse, and including advice on pharmacotherapy Mode of delivery: smartphone app Pharmacotherapy: none BCTs: 1.1 Goal setting (behaviour), 1.2 Problem solving, 2.3 Self‐monitoring of behaviour, 4.1 Instruction on how to perform behaviour (where to and what NRTs)
Outcomes	Definition of abstinence: prolonged Longest follow‐up: 12 months Biochemical verification: none Other relevant outcomes reported: none
Notes	Relevant comparisons: ACT app (iCanQuit) vs QuitGuide app Funding source: National Cancer Institute (R01CA192849) Author conflicts of interest: “Dr Bricker reported receiving grants from the National Cancer Institute during the conduct of the study; serving on the scientific advisory board for and receiving personal fees from Chrono Therapeutics outside the submitted work; and reported that the Fred Hutchinson Cancer Research Center has applied for a US patent that pertains to the content of the iCanQuit application. 2Morrow, Inc, a Kirkland, Washington–based software company, has licensed this technology from the Fred Hutchinson Cancer Research Center. Dr Bricker had no personal financial relationships with this patent application, the licensing agreement, or 2Morrow, Inc. Ms Mull reported receiving grants from the National Institutes of Health/National Cancer Institute during the conduct of the study. Dr Heffner reported receiving nonfinancial support from Pfizer outside the submitted work. None of the authors has a financial relationship with the iCanQuit application and thus will not receive any compensation when it becomes publicly available. No other disclosures were reported.”
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: “The random allocation sequence was generated by a database manager and implemented automatically by the study website.”
Allocation concealment (selection bias)	Low risk	Quote: “Random assignments were concealed from participants throughout the trial. The random allocation sequence was generated by a database manager and implemented automatically by the study website. Neither research staff nor study participants had access to upcoming randomized study group assignments.”
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Abstinence self‐reported but no face‐to‐face contact so no difference in intensity; differential report unlikely
Incomplete outcome data (attrition bias) All outcomes	Low risk	At 12‐month follow‐up 30.9% (375/1214) were lost to follow‐up in the intervention group and 27.5% (330/1201) in the control group
Selective reporting (reporting bias)	Low risk	Prespecified outcomes reported

*Study characteristics*
Methods	Study design: RCT Location: USA Setting: unclear, recruitment from community Recruitment: newspaper and radio advertisements targeting smokers who had “previous difficulty quitting for even short periods of time” Study dates: not reported
Participants	N = 49 Specialist population?: smokers with a history of early lapse (< 72 h post‐quit) Definition of smoker used: ≥ 15 cpd for at least the past 3 years Participant characteristics: 49% female; average age: 48 years; 90% white; 33% high school education or less; average cpd: 22; nicotine dependence: average FTND 6.3; 29% one or more depressive episodes
Interventions	Comparator: standard treatment covering self‐monitoring, identifying triggers, developing self‐management strategies for coping with triggers, and relapse prevention skills Mode of delivery: face‐to‐face (group), telephone Intensity: 6 face‐to‐face group sessions (x 90 min) and 1 phone call (20 min) over 6 weeks Pharmacotherapy: 8 weeks of nicotine patches from quit date (4 weeks x 21 mg, 2 x 14 mg, 2 x 7 mg) Type of therapist/provider: doctoral‐level psychologists or trainees (trained by senior investigators) BCTs: 1.2 Problem solving, 2.3 Self‐monitoring of behaviour, 8.2 Behaviour substitution; 11.1 Pharmacological support Intervention: distress tolerance treatment. This included exercises aimed at increasing participants’ tolerance of distress while maintaining a focus on the valued life goals associated with quitting smoking Mode of delivery: face‐to‐face (individual and group) Intensity: 6 individual sessions (x 50 min) and 9 group sessions (x 2 h) over 8 weeks Pharmacotherapy: 8 weeks of nicotine patches from quit date (4 weeks x 21 mg, 2 x 14 mg, 2 x 7 mg) Type of therapist/provider: doctoral‐level psychologists or trainees (trained by senior investigators) BCTs: 7.3 Reduce prompts/cues: 'nicotine fading', 11.1 pharmacological support
Outcomes	Definition of abstinence: 7‐day point prevalence Longest follow‐up: 6 months Biochemical verification: CO ≤ 5 ppm and cotinine ≤ 10 ng/mL Other relevant outcomes reported: negative affect
Notes	Relevant comparisons: distress tolerance training + NRT vs standard treatment + NRT Funding source: National Institute on Drug Abuse (DA017332) Author conflicts of interest: “None declared”
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Method not reported
Allocation concealment (selection bias)	Unclear risk	Concealment not reported
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Abstinence biochemically verified
Incomplete outcome data (attrition bias) All outcomes	Low risk	At 6‐month follow‐up 7.4% (2/27) were lost to follow‐up in the intervention group and 4.8% (1/21) in the control group
Selective reporting (reporting bias)	Unclear risk	No protocol available

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
7.1 Mindfulness training vs matched‐intensity smoking cessation treatment	3	501	Risk Ratio (M‐H, Random, 95% CI)	1.01 [0.68, 1.50]
7.1.1 Face‐to‐face	2	444	Risk Ratio (M‐H, Random, 95% CI)	1.05 [0.64, 1.72]
7.1.2 Smartphone app	1	57	Risk Ratio (M‐H, Random, 95% CI)	0.83 [0.25, 2.77]
7.2 Mindfulness training vs less intensive smoking cessation treatment	5	773	Risk Ratio (M‐H, Random, 95% CI)	1.22 [0.66, 2.26]
7.2.1 vs. less intensive behavioural support	2	453	Risk Ratio (M‐H, Random, 95% CI)	1.31 [0.75, 2.30]
7.2.2 vs. brief advice	1	213	Risk Ratio (M‐H, Random, 95% CI)	0.47 [0.18, 1.23]
7.2.3 vs. self‐help materials	1	56	Risk Ratio (M‐H, Random, 95% CI)	0.80 [0.24, 2.67]
7.2.4 vs. mixed treatment	1	51	Risk Ratio (M‐H, Random, 95% CI)	2.77 [1.30, 5.94]

*Study characteristics*
Methods	Study design: RCT Location: Brazil Setting: outpatient public health tobacco treatment service Recruitment: by phone from a waiting list of an outpatient public health tobacco treatment service Study dates: 2012‐16
Participants	N = 86 Specialist population?: no Definition of smoker used: ≥ 10 cpd Participant characteristics: 80% female; average age: 50 years; 85% high school education or less; 33.7% average cpd ≥ 20
Interventions	Comparator: standard treatment (CBT + maintenance sessions) Mode of delivery: unclear Intensity: smoking cessation phase: 4 weekly CBT sessions (x 90 min; smoking cessation phase) maintenance phase: 6 CBT sessions between weeks 6 and 48 Pharmacotherapy: choice of NRT or bupropion Type of therapist/provider: physician with experience treating smoking and with training in the standard treatment approach BCTs: 5.1 Information about health consequences, 11.1 Pharmacological support Intervention: standard treatment (CBT + maintenance sessions) + mindfulness‐based relapse prevention (MBRP) Mode of delivery: group sessions, audio CD Intensity: smoking cessation phase: 4 weekly CBT sessions (x 90 min; smoking cessation phase) maintenance phase: 6 CBT sessions between weeks 6 and 48 + 8 weekly group MBRP sessions (x 2 h) Pharmacotherapy: choice of NRT or bupropion Type of therapist/provider: certified MBRP instructor who had received MBRP training; physician with experience treating smoking and with training in the standard treatment approach BCTs: 1.2 Problem solving, 2.3 Self‐monitoring (behaviour), 5.1 Information about health consequences, 11.1 Pharmacological support, 12.6 Body changes
Outcomes	Definition of abstinence: CO < 10 ppm Longest follow‐up: 6 months Biochemical verification: CO < 10 ppm Other relevant outcomes reported: depression, anxiety, positive and negative affect
Notes	Relevant comparisons: mindfulness‐based relapse prevention + CBT + NRT/bupropion vs CBT + NRT/bupropion Funding source: Fundação de Amparo à Pesquisa do Estado de São Paulo (2013/02316‐5), Conselho Nacional de Desenvolvimento Científico e Tecnológico (870470/1997‐3), Fundação de Amparo à Pesquisa do Estado de Minas Gerais (APQ‐04279‐10) and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (552452/2011) Author conflicts of interest: “None declared.”
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Method not reported
Allocation concealment (selection bias)	Unclear risk	Concealment not reported
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Abstinence biochemically verified
Incomplete outcome data (attrition bias) All outcomes	High risk	Attrition was high in both groups: at 24‐week follow‐up 75.0% (33/44) were lost to follow‐up in the intervention group and 78.6% (33/42) in the control group
Selective reporting (reporting bias)	High risk	Some prespecified outcomes not reported (dependence, maintenance of abstinence at 12 months, change in smoking urges)

*Study characteristics*
Methods	Study design: RCT Location: Hong Kong Setting: primary care Recruitment: from 6 primary healthcare centres Study dates: 2012‐15
Participants	N = 144 Specialist population?: no Definition of smoker used: ≥ 1 cpd in the past 30 days Participant characteristics: 29% female; average age: 46 years; 22% primary education or less; 18% unemployed; 16% household income ≤ HKD 9999; 17% average cpd > 20; 38% high nicotine dependence
Interventions	Comparator: brief advice + self‐help materials Mode of delivery: face‐to‐face, written materials Intensity: brief 5 minute talk Pharmacotherapy: none Type of therapist/provider: not reported BCTs: 1.2 Problem solving, 4.1 Instruction on how to perform the behaviour, 5.1 Information about health consequences Intervention: ACT + self‐help materials Mode of delivery: face‐to‐face, telephone, written materials Intensity: 1 face‐to‐face ACT session and 2 telephone follow‐up sessions (each 15‐20 min) Pharmacotherapy: none Type of therapist/provider: experienced health counsellor trained in the principles of ACT applied in smoking cessation BCTs: 1.2 Problem solving, 4.1 instruction on how to perform the behaviour, 5.3 Information about social and environmental consequences, 12.6 Body changes
Outcomes	Definition of abstinence: 7‐day point prevalence Longest follow‐up: 12 months Biochemical verification: CO < 6 ppm was measured but validated quit rates are not reported Other relevant outcomes reported: none
Notes	Relevant comparisons: ACT + self‐help vs brief advice + self‐help Funding source: Health and Medical Research Fund of the Food and Health Bureau of the Hong Kong SAR Government (10111861) Author conflicts of interest: “The authors declare that they have no competing interests.”
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: “The process of randomization was based on computer‐generated, block randomization with random block sizes, which were placed in sealed opaque envelopes."
Allocation concealment (selection bias)	Low risk	Quote: “The process of randomization was based on computer‐generated, block randomization with random block sizes, which were placed in sealed opaque envelopes."
Blinding of outcome assessment (detection bias) All outcomes	High risk	Although abstinence was biochemically verified, only unverified quit rates are reported and we were unable to obtain verified rates from the study authors.
Incomplete outcome data (attrition bias) All outcomes	High risk	Attrition was high: at 12‐month follow‐up 50.0% (35/70) were lost to follow‐up in the intervention group and 58.1% (43/74) in the control group
Selective reporting (reporting bias)	Unclear risk	Abstinence was defined as prespecified, although 12 month follow‐up was not prespecified. 6 month rates are not reported so unclear whether the reporting of 12‐month rates is an example of selective reporting

*Study characteristics*
Methods	Study design: RCT Location: Ireland Setting: community Recruitment: from the community by self‐selection Study dates: 2016‐18
Participants	N = 150 Specialist population?: no Definition of smoker used: ≥ 10 cpd for the past 12 months Participant characteristics: 53% female; average age: 36 years; average years in education: 16.7; 75% employed; average cpd: 17; nicotine dependence: average FTND 4.7
Interventions	Comparator: behavioural support programme based on motivational interviewing Mode of delivery: face‐to‐face (group) Intensity: 6 sessions (x 90 min) over 6 weeks Pharmacotherapy: none Type of therapist/provider: a doctoral‐level and a bachelor’s‐level staff member who had undergone training in smoking cessation from the National Centre for Smoking Cessation and Training (NCSCT) BCTs: 1.2 Problem solving, 1.4 Action planning, 5.1 Information about health consequences Intervention 1: ACT Mode of delivery: face‐to‐face (group) Intensity: 6 sessions (x 90 min) over 6 weeks Pharmacotherapy: none Type of therapist/provider: psychology doctoral student with training in ACT and a doctoral‐level peer‐reviewed ACT trainer BCTs: 1.4 Action planning, 12.6 Body changes Intervention 2: ACT + SmartQuit smartphone app Mode of delivery: face‐to‐face (group), smartphone app Intensity: 6 sessions (x 90 min) over 6 weeks Pharmacotherapy: none Type of therapist/provider: psychology doctoral student with training in ACT and a doctoral‐level peer‐reviewed ACT trainer BCTs: 1.2 Problem solving, 1.4 Action planning, 12.6 Body changes
Outcomes	Definition of abstinence: 7‐day point prevalence Longest follow‐up: 6 months Biochemical verification: CO < 10 ppm Other relevant outcomes reported: positive mental health
Notes	Relevant comparisons: ACT (face‐to‐face + app) vs ACT (face‐to‐face) ACT (face‐to‐face) vs behavioural support Funding source: Irish Research Council Government of Ireland Postgraduate Scholarship Author conflicts of interest: “The authors declare that there are no conflicts of interest.”
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: “the allocation sequence was generated with random block sizes of 3, 6 and 9 by a researcher with no clinical involvement in the trial using an online randomization tool”
Allocation concealment (selection bias)	Low risk	Quote: “allocation sequence was concealed from the researcher (MOC) enrolling participants in sequentially numbered, opaque, sealed envelopes”
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Abstinence biochemically verified
Incomplete outcome data (attrition bias) All outcomes	Low risk	At 6‐month follow‐up 12.0% (6/50) were lost to follow‐up in the combined ACT + app group, 6.0% (3/50) in the ACT group, and 18.0% (9/50) in the control group
Selective reporting (reporting bias)	Low risk	Prespecified outcomes reported

*Study characteristics*
Methods	Study design: cluster‐RCT Location: USA Setting: high schools Recruitment: parents of all 9‐12 grade students were sent letters allowing them to opt out of their adolescent participating in the study Study dates: 2014‐16
Participants	N = 146 (across 9 schools) Specialist population?: high school students Definition of smoker used: average of ≥ 5 cpd for the past 7 days Participant characteristics: 56% female; average age: 17 years; 90% white; 69% in reduced or free lunch programme; average cpd: 5; 23% high level of nicotine dependence; 43% elevated depressive symptoms
Interventions	All participants had weekly visits with the school nurse for 4 weeks, plus written self‐help materials or 1 of 2 smartphone apps Comparator 1: written self‐help materials (pamphlets) Mode of delivery: written materials, face‐to‐face Intensity: weekly visits with the school nurse over 4 weeks Pharmacotherapy: none Type of therapist/provider: school nurse BCTs: 1.2 Problem solving, 4.1 Instruction on how to perform behaviour Comparator 2: National Cancer Institute QuitSTART App, a free smartphone app developed as a smoking cessation resource for teens Mode of delivery: smartphone app, face‐to‐face Intensity: app intensity unclear, weekly visits with the school nurse over 4 weeks Pharmacotherapy: none Type of therapist/provider: school nurse, smartphone app BCTs: 1.1 Goal setting (behaviour), 1.2 Problem solving, 2.3 Self‐monitoring of behaviour, 15.4 Self‐talk Intervention: craving to quit (C2Q) app adapted for teens, based on core elements of mindfulness training for smoking Mode of delivery: smartphone app, face‐to‐face Intensity: 22 training modules plus 4 bonus modules (5‐15 min/module), weekly visits with the school nurse over 4 weeks Pharmacotherapy: none Type of therapist/provider: school nurse, smartphone app BCTs: 1.1 Goal setting (behaviour), 1.2 Problem solving, 2.3 Self‐monitoring of behaviour
Outcomes	Definition of abstinence: 7‐day point prevalence Longest follow‐up: 6 months Biochemical verification: salivary cotinine < 11.4 ng/mL Other relevant outcomes reported: none
Notes	Relevant comparisons: mindfulness training app (C2Q) + school nurse vs QuitSTART app + school nurse mindfulness training app (C2Q) + school nurse vs self‐help materials + school nurse Funding source: National Institute on Drug Abuse (R34 DA037886) Author conflicts of interest: "JB owns stock in Claritas MindSciences, the company that developed the Craving to Quit app. The other authors declare that they have no competing interest."
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Method not reported
Allocation concealment (selection bias)	Unclear risk	Concealment not reported
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Abstinence biochemically verified
Incomplete outcome data (attrition bias) All outcomes	Low risk	At 6‐month follow‐up 8.3% (4/48) were lost to follow‐up in the intervention (C2Q) group, 2.0% (1/50) in the QuitSTART group, and 4.2% (2/48) in the materials group
Selective reporting (reporting bias)	Low risk	Prespecified outcomes reported

*Study characteristics*
Methods	Study design: RCT Location: Cyprus Setting: high schools and universities Recruitment: from the cafeterias and psychology classes of the universities and through the Ministry of Education and head teachers of the schools Study dates: not reported
Participants	N = 165 Specialist population?: young adults Definition of smoker used: ≥ 1 cpd Participant characteristics: 65% female; average age: 22 years; 32% weekly allowance/income < EUR 50; average cpd: 9; average FTND score: 3.1
Interventions	Comparator: waitlist Intensity: none Pharmacotherapy: none Intervention: avatar‐led, internet‐based, ACT Mode of delivery: online Intensity: 6 sessions (x 25 min) spaced out over a minimum of 3 days between each session Pharmacotherapy: none BCTs: 1.1 Goal setting (behaviour), 1.2 Problem solving, 1.5 Review behavioural goals, 1.9 Commitment, 10.3 Non‐specific reward, 11.2 Reducing negative emotions, 12.3 Avoidance/Reducing exposure to cues for the behaviour, 12.6 Body changes, 13.4 Valued self‐identity
Outcomes	Definition of abstinence: 30‐day point prevalence Longest follow‐up: 12 months Biochemical verification: none Other relevant outcomes reported: none
Notes	Notes: quitting outcomes were collected but not reported Funding source: not reported Author conflicts of interest: not reported
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Group assignment was done using an online random number generator"
Allocation concealment (selection bias)	Unclear risk	Quote: "Group assignment was done using an online random number generator" However, it is unclear if this was sufficient to conceal allocation.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Biochemical validation not used and unequal levels of contact between study arms
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Attrition at 12‐month follow‐up not reported
Selective reporting (reporting bias)	Unclear risk	No protocol available
Other bias	High risk	Waitlist control ‐ participants in the control arm may have delayed quitting, knowing that they would be receiving an intervention at a later date. This has the potential to inflate the reported effect of the intervention.

*Study characteristics*
Methods	Study design: RCT Location: not reported Setting: community Recruitment: by referrals from families, supported living and group home supervisors, and primary care physicians Study dates: not reported
Participants	N = 51 Specialist population?: adults with mild intellectual disability Definition of smoker used: unclear Participant characteristics: 18% female; average age: 34 years; average cpd: 12; average years smoking: 16
Interventions	Comparator: treatment as usual, including motivational therapies, behaviour therapies, NRTs, non‐nicotine medicines, or a combination of the above Mode of delivery: not reported Intensity: unclear, varied across participants Pharmacotherapy: none specifically provided, although for some usual care included NRT Type of therapist/provider: community therapists BCTs: 2.3 Self‐monitoring (behaviour), 11.1 Pharmacological support Intervention: training in the use of mindfulness and meditation techniques Mode of delivery: face‐to‐face (individual or small groups) or via Skype Intensity: 2 training sessions (1 x 1 h, 1 x 45 min), 10 supervised practice sessions (x 30 min over 5 days), weekly contact with trainer Pharmacotherapy: none Type of therapist/provider: trainer with a 35‐year history of service provision to people with intellectual and developmental disabilities and long‐standing personal meditation practice, clinical expertise, and experience in mindful service delivery to individuals at all levels of intellectual functioning BCTs: 1.9 Commitment, 2.3 Self‐monitoring of behaviour, 12.4 Distraction, 12.6 Body changes
Outcomes	Definition of abstinence: 7‐day point prevalence Longest follow‐up: 12 months Biochemical verification: none Other relevant outcomes reported: none
Notes	Relevant comparisons: mindfulness and meditation training vs treatment as usual Funding source: not reported Author conflicts of interest: not reported
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Randomisation was via alternate placement in the experimental and control groups
Allocation concealment (selection bias)	Unclear risk	Concealment not reported
Blinding of outcome assessment (detection bias) All outcomes	High risk	Abstinence self‐reported, differing levels of face‐to‐face contact between arms
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Only reported attrition during treatment
Selective reporting (reporting bias)	Unclear risk	No protocol available

Study	Reason for exclusion
Aggarwal 2017	Ineligible follow‐up period
Arcari 1997	Ineligible follow‐up period
Arora 2013	Not possible to isolate the mindfulness element
Baruffi 2014	Ineligible patient population
Bloom 2017	Ineligible study design
Bowen 2009	Ineligible follow‐up period
Brewer 2011	Ineligible follow‐up period
Bricker 2014b	Ineligible follow‐up period
Chirikos 2004	Ineligible patient population
Cropley 2007	Ineligible follow‐up period
Davis 2013	Ineligible follow‐up period
Davoudi 2017	Ineligible follow‐up period
Elibero 2011	Ineligible follow‐up period
Elwafi 2013	Ineligible follow‐up period
Gifford 2011	Not possible to isolate the mindfulness element
Heffner 2013	Ineligible follow‐up period
Hemenway 2021	Ineligible follow‐up period
Hernandez‐Lopez 2009	Ineligible study design
Janes 2019	Ineligible follow‐up period
Jang 2019	Ineligible intervention
Jones 2015	Ineligible follow‐up period
Jones 2017	Not possible to isolate the mindfulness element
Karelka 2020	Ineligible follow‐up period
Kochupillai 2005	Ineligible study design
Luberto 2016	Ineligible follow‐up period
Luk 2019	Not possible to isolate the mindfulness element
Luo 2018	Ineligible follow‐up period
Minami 2018	Ineligible follow‐up period
Mineyama 2019	Ineligible study design
Mujcic 2018	Not possible to isolate the mindfulness element
NCT01314378	Ineligible follow‐up period
NCT04038255	Ineligible follow‐up period
Otto 2020	Ineligible follow‐up period
Pakhale 2014	Ineligible study design
Rogojanski 2011a	Ineligible follow‐up period
Rogojanski 2011b	Ineligible follow‐up period
Ruscio 2016	Ineligible follow‐up period
Sarkar 2017	Not possible to isolate the mindfulness element
Schuman‐Olivier 2014	Ineligible follow‐up period
Shahab 2013	Ineligible follow‐up period
Sharma 2013	Ineligible study design
Sidhu 2016	Ineligible study design
Spears 2019	Ineligible follow‐up period
Sussman 2004	Not possible to isolate the mindfulness element
Tang 2013	Ineligible outcomes
Ussher 2009	Ineligible follow‐up period
Zeng 2016	Ineligible study design

Study name	Yoga as a complementary intervention for tobacco cessation: a PROBE trial
Methods	Study design: RCT Location: India Setting: Centre of Integrative Medicine and Research, All India Institute of Medical Sciences Recruitment: not reported Study dates: 2020‐23 (estimated)
Participants	Target N = 200 Specialist population?: no Definition of smoker used: ≥ 5 cpd for at least the past year
Interventions	Comparator: exercise + wellness programme Mode of delivery: face‐to‐face, video, audio recordings and written materials Intensity: 4 supervised sessions in the first week followed by 1 weekly session for 7 weeks Pharmacotherapy: Type of therapist/provider: institutionally certified yoga therapist + study wellness counsellor or other healthcare professional (e.g. psychologist) Intervention: yoga + wellness programme Mode of delivery: face‐to‐face, video and telephone Intensity: 4 supervised sessions in the first week followed by weekly sessions for 7 weeks Pharmacotherapy: none Type of therapist/provider: institutionally certified yoga therapist + study wellness counsellor or other healthcare professional (e.g. psychologist) BCTs: 4.1 Instruction on how to perform behaviour, 5.1 Information about health consequences, 8.6 Generalisation of a target behaviour, 12.6 Body changes
Outcomes	Definition of abstinence: unclear Longest follow‐up: 6 months Biochemical verification: salivary cotinine and CO (threshold not reported) Other relevant outcomes: depression, anxiety, quality of life
Starting date	2020
Contact information	Gautam Sharma, All India Institute of Medical Sciences (AIIMS)
Notes	Contacted PI for update: no update to report Funding source: Centre for Integrative Medicine and Research (CIMR) Institute Name: All India Institute of Medical Sciences (AIIMS), New Delhi Author conflicts of interest: not reported

Study name	Smoking cessation treatment for head & neck cancer patients
Methods	Study design: RCT Location: USA Setting: cancer centre Recruitment: from patients planning to or currently undergoing treatment, or in follow‐up care Study dates: 2010‐2021 (estimated)
Participants	Specialist population?: current or history of head and neck, lung, breast, gastrointestinal, or genitourinary cancer Definition of smoker used: ≥ 1 cpd
Interventions	Comparator: motivational and behavioural counselling Mode of delivery: not reported Intensity: 6 counselling sessions (x 1 h) delivered over a 5‐week period Pharmacotherapy: varenicline (2 mg daily for 12 weeks) Type of therapist/provider: not reported BCTs: 3.1 Social support (unspecified), 11.1 Pharmacological support Intervention: ACT Mode of delivery: not reported Intensity: 6 counselling sessions (x 1 h) delivered over a 5‐week period Pharmacotherapy: varenicline (2 mg daily for 12 weeks) Type of therapist/provider: not reported BCTs: 1.9 Commitment, 3.1 Social support (unspecified): counselling, 11.1 Pharmacological support
Outcomes	Definition of abstinence: unclear Longest follow‐up: 26 weeks after target quit date Biochemical verification: unclear Other relevant outcomes: none
Starting date	2010
Contact information	Jan Blalock, PhD M.D. Anderson Cancer Center
Notes	Contacted PI for update: no update to report Funding source: not reported Author conflicts of interest: not reported

PERMALINK

Mindfulness for smoking cessation

Sarah Jackson

Jamie Brown

Emma Norris

Jonathan Livingstone-Banks

Emily Hayes

Nicola Lindson

Abstract

Background

Objectives

Search methods

Selection criteria

Data collection and analysis

Main results

Authors' conclusions

Plain language summary

Summary of findings

Background

Description of the condition

Description of the intervention

How the intervention might work

Why it is important to do this review

Objectives

Methods

Criteria for considering studies for this review

Types of studies

Types of participants

Types of interventions

Types of outcome measures

Primary outcomes

Smoking abstinence at longest follow‐up

Mental health and well‐being

Search methods for identification of studies

Electronic searches

Searching other resources

Data collection and analysis

Selection of studies

Data extraction and management

Assessment of risk of bias in included studies

Measures of treatment effect

Unit of analysis issues

Dealing with missing data

Assessment of heterogeneity

Assessment of reporting biases

Data synthesis

Subgroup analysis and investigation of heterogeneity

Sensitivity analysis

Summary of findings and assessment of the certainty of the evidence

Results

Description of studies

Results of the search

1.

Included studies

Context and participants

Intervention programmes

Mindfulness training

Acceptance and commitment therapy (ACT)

Distress tolerance training

Yoga

Outcomes

Smoking abstinence

Mental health

Excluded studies

Risk of bias in included studies

2.

Allocation

Random sequence generation

Allocation concealment

Blinding

Blinding of participants and personnel (performance bias)

Blinding of outcome assessment (detection bias)

Incomplete outcome data

Selective reporting

Other potential sources of bias

Effects of interventions

Summary of findings 1. Mindfulness training compared with control for smoking cessation.

Summary of findings 2. Acceptance and commitment therapy (ACT) compared with control for smoking cessation.

Summary of findings 3. Distress tolerance training compared with control for smoking cessation.

Summary of findings 4. Yoga compared with control for smoking cessation.

Study name	A mindfulness based application for smoking cessation (MBSC)
Methods	Study design: RCT Location: USA Setting: community Recruitment: not reported Study dates: 2013‐18
Participants	N = 5 Specialist population?: no Definition of smoker used: ≥ 5 cpd
Interventions	Comparator: behavioural smoking cessation (NCI Quit Pal app) Mode of delivery: smartphone app Intensity: not reported Pharmacotherapy: none Type of therapist/provider: n/a BCTs: unclear Intervention: mindfulness‐based therapy (Craving to Quit app) Mode of delivery: smartphone app Intensity: not reported Pharmacotherapy: none Type of therapist/provider: n/a BCTs: 12.6 Body changes
Outcomes	Definition of abstinence: unclear Longest follow‐up: 6 months Biochemical verification: CO (threshold not reported) Other relevant outcomes: none
Starting date	2013
Contact information	Jennifer K Penberthy, PhD University of Virginia
Notes	Contacted PI for update: no response Funding source: not reported Author conflicts of interest: not reported

Study name	Mobile mindfulness training for smoking cessation
Methods	Study design: RCT Location: USA Setting: not reported Recruitment: not reported Study dates: 2015‐17
Participants	N = 1251 Specialist population?: no Definition of smoker used: ≥ 5 cpd with < 3 months' abstinence in the past year
Interventions	Comparator: standard smartphone app to support smokers to quit Mode of delivery: smartphone app Intensity: not reported Pharmacotherapy: none Type of therapist/provider: n/a BCTs: 1.1 Goal setting (behaviour), 1.3 Goal setting (outcome), 2.3 Self‐monitoring (behaviour), 3.1 Social support (unspecified) Intervention: smartphone app that provides training in mindfulness for smoking cessation Mode of delivery: smartphone app Intensity: 22 modules (x 10‐15 minutes each) + 5 bonus modules available upon completion of earlier modules Pharmacotherapy: none Type of therapist/provider: n/a BCTs: 1.1 Goal setting (behaviour), 1.2 Problem solving, 1.3 Goal setting (outcome), 2.3 Self‐monitoring (behaviour), 12.6 Body changes
Outcomes	Definition of abstinence: 7‐day point prevalence Longest follow‐up: 6 months Biochemical verification: not reported Other relevant outcomes: none
Starting date	2015
Contact information	Judson Brewer, MD PhD University of Massachusetts, Worcester
Notes	Contacted PI for update: data were never analysed Funding source: not reported Author conflicts of interest: not reported

Study name	Telephone‐delivered interventions for smoking cessation (TALK)
Methods	Study design: RCT Location: USA Setting: not reported Recruitment: not reported Study dates: 2015‐19
Participants	N = 1275 Specialist population?: no Definition of smoker used: ≥ 10 cpd for at least the past 12 months
Interventions	Comparator: CBT Mode of delivery: telephone Intensity: 5 weekly sessions Pharmacotherapy: NRT Type of therapist/provider: not reported BCTs: 3.1 Social support Intervention: Acceptance and Commitment Therapy (ACT) Mode of delivery: telephone Intensity: 5 weekly sessions Pharmacotherapy: NRT Type of therapist/provider: not reported BCTs: 3.1 Social support (note: full details of therapy not provided)
Outcomes	Definition of abstinence: 30‐day point prevalence Longest follow‐up: 12 months Biochemical verification: not reported Other relevant outcomes: none
Starting date	2015
Contact information	Jonathan B Bricker, Ph.D. Fred Hutchinson Cancer Research Center
Notes	Contacted PI for update: no update to report Funding source: not reported Author conflicts of interest: not reported

Study name	Individual acceptance and commitment therapy (ACT) for smoking cessation for schizophrenic patients
Methods	Study design: RCT Location: Hong Kong Setting: not reported Recruitment: not reported Study dates: 2014‐18 (estimated)
Participants	N = 160 (target) Specialist population?: diagnosed schizophrenia Definition of smoker used: ≥ 1 cpd
Interventions	All participants are given a brief educational talk on encouraging quitting smoking (about 5 min) and a self‐help leaflet on smoking cessation Comparator: ACT + brief advice + self‐help materials Mode of delivery: face‐to‐face, written materials Intensity: 10 sessions (x 20‐30 min) Pharmacotherapy: none Type of therapist/provider: n/a BCTs: 1.9 Commitment, 4.1 Instruction on how to perform the behaviour Intervention: social support + brief advice + self‐help materials Mode of delivery: face‐to‐face, written materials Intensity: 10 sessions (x 5 min) Pharmacotherapy: none Type of therapist/provider: n/a BCTs: 3.1 Social support (unspecified), 4.1 Instruction on how to perform the behaviour
Outcomes	Definition of abstinence: 7‐day point prevalence Longest follow‐up: 6 months Biochemical verification: CO (threshold not reported), urinary cotinine (threshold not reported) Other relevant outcomes: none
Starting date	2014
Contact information	Dr. Yim Wah Mak, Assistant Professor, The Hong Kong Polytechnic University
Notes	Contacted PI for update: no response Funding source: not reported Author conflicts of interest: not reported