Table 1. Characteristics of included studies (n = 9).

Author, year, country (Ref)	Study design	Participants	Intervention	Comparison (control)	Outcome measures	Measurement time point
Astin et al. 2003, USA [34]	RCT	128 participants, mean age 48 yrs., 98.4% women in intervention and 100% in control group	n = 64, mindfulness meditation/ qigong movement therapy	n = 64, education-support group	Pain; MOS SF-36, BDI	Baseline, end of treatment (8 weeks), and at follow-up (4 months + 6 months)
Cash et al. 2015, USA [41]	RCT	91 participants, mean age 48 yrs., 100% women	n = 51, mindfulness-based stress reduction	n = 40, wait-list	Pain; VAS, SSQ, The Fatigue Symptom Inventory	Baseline, end of treatment (8 weeks) and at follow-up (2 months)
Grossman et al. 2007, Switzerland [35]	Quasi-RCT	58 participants, mean age 52 yrs., 100% women	n = 38, mindfulness-based stress reduction	n = 13, education-support group	Pain; VAS, HADS, QoL*	Baseline and at end of treatment (8 weeks)
Luciano et al. 2014, Spain [36]	RCT	156 participants, mean age 48 yrs., 96% women in both groups	n = 51, acceptance and commitment therapy	n = 52, recommended pharmacological treatment + n = 53, wait-list	HADS, Pain; VAS, EQ-5D	Baseline, end of treatment (8 weeks) and follow-up (6 months)
Parra-Delgado et al. 2013, Spain [37]	RCT	33 participants, mean age 53 yrs., 100% women	n = 17, mindfulness-based cognitive therapy	n = 16, treatment as usual	BDI, Pain; VAS**	Baseline, end of treatment (8 weeks) and follow-up (3 months)
Schmidt et al. 2011, Germany [38]	RCT	177 participants, mean age 53 yrs., 100% women	n = 59, mindfulness-based stress reduction	n = 59, education-support group + n = 59, wait-list	HRQoL (PLC), CES-D, STAI, PSQI, PPS***, FMI	Baseline, end of treatment (8 weeks) and follow-up (2 months)
Septhon et al. 2007, USA [39]	RCT	91 participants, mean age 48 yrs., 100% women	n = 51, mindfulness-based stress reduction	n = 40, wait-list	BDI	Baseline, end of treatment (8 weeks) and at follow-up (2 months)
Simister et al. 2018, Canada [42]	RCT	67 participants, mean age 40 yrs., 95% women	n = 33, acceptance and commitment therapy	n = 34, treatment as usual	CES-D, SF-MPQ, PSQI, FFMQ	Baseline, end of treatment (12-weeks) and follow-up (3 months)
Wicksell et al. 2012, Sweden [40]	RCT	40 participants, mean age 45 yrs., 100% women	n = 23, acceptance and commitment therapy	n = 17, wait-list	PDI, SF-36****, BDI, STAI	Baseline, end of treatment (12-weeks) and follow-up (3–4 months)

RCT = Randomized Controlled Trial

BDI = Beck Depression Inventory; 21-question multiple-choice self-report inventory. Each question had a set of at least four possible responses, ranging in intensity

MOS SF-36 = Medical Outcome Study Shortform-36 Scores range from 0–100, Lower scores = more disability, higher scores = less disability

VAS = Visual Analogue Scale for pain intensity, 0–100, “no pain” (score of 0) and “pain as bad as it could be” or “worst imaginable pain” (score of 100)

SSQ = Stanford Sleep Questionnaire; 7-point scale with scale rating from 1 "feeling active, vital, alert, or awake" to 7 "No longer fighting sleep, sleep onset soon; having dream-like thoughts"

The Fatigue Symptom Inventory = scale composed of 14 items (one of which is not scored) designed to evaluate multiple aspects of fatigue, including its perceived severity, frequency, and interference with daily functioning

HRQoL (PLC) = The Quality of life Profile for the Chronically Ill; Questionnaire composed of 40 Likert-scaled items (scale 0–4) with 0 representing minimum and 4 representing maximum satisfaction. The items measure physical, psychological and social capacity of performance and well-being

HADS = Hospital Anxiety and Depression Scale; fourteen item scale that generates ordinal data. Seven of the items relate to anxiety and seven relate to depression

PPS = The Pain Perception Scale; 24-item scale that evaluates pain perception

EQ-5D = Visual analogue scale of EuroQol; EQ-5D self-reported questionnaire includes a visual analog scale (VAS), which records the respondent's self-rated health status on a graduated (0–100) scale, with higher scores for higher HRQoL. It also includes the EQ-5D descriptive system, which comprises 5 dimensions of health

CES-D = Center for Epidemiological Studies depression inventory; 20-item, self-report measure designed to measure symptoms of depression over the past week

STAI = State-Trait-Anxiety-Inventory; 20 items for assessing trait anxiety and 20 for state anxiety. All items are rated on a 4-point scale from 'not at all' to 'very much so'. Higher scores indicate greater anxiety

PSQI = Pittsburgh Sleep Quality Index; 19 individual items, creating 7 components producing one global score

FMI = Freiburg Mindfulness Inventory; a 14-item short form measuring Mindfulness

PDI = Pain Disability Index; a self-report tool used for measuring the degree of pain a patient is experiencing. Participants use a 0 (no disability) to 10 (total disability) numeric rating scale

PIPS = Psychological Inflexibility in Pain Scale; 16-item scale used to assess psychological inflexibility. Respondents are asked to rate items on a 7-point scale ranging from 1 (never true) to 7 (always true). Higher scores indicate greater levels of psychological inflexibility

SF-MPQ = Short form McGill Pain Questionnaire; 15 items asking participants to rank their typical pain experience on a 4-point Likert scale, from 0 (no pain) to 3 (severe), and maximum total score of 45

FFMQ = Five Facet Mindfulness Questionnaire; 39-items questionnaire measuring 5 facets of mindfulness

SF-36 = Short form-36 Healthy Survey, 36-item measure assessing health-related quality of life. Higher scores indicate better functioning

*The Quality of life Profile for the Chronically Ill was reported as six dimensions and therefore not included in this review

**The Visual Analogue Scale for pain intensity was measured on seven different parts of the body and not included in this review

***The Pain Perception Scale was divided into affective and sensory and only sensory was included in this review

****The short form-36 Healthy Survey provided summary for two subscales and not included in this review.