Abstract
Background
Cough both protects and clears the airway. Cough has three phases: breathing in (inspiration), closure of the glottis, and a forced expiratory effort. Chronic cough has a negative, far‐reaching impact on quality of life. Few effective medical treatments for individuals with unexplained (idiopathic/refractory) chronic cough (UCC) are known. For this group, current guidelines advocate the use of gabapentin. Speech and language therapy (SLT) has been considered as a non‐pharmacological option for managing UCC without the risks and side effects associated with pharmacological agents, and this review considers the evidence from randomised controlled trials (RCTs) evaluating the effectiveness of SLT in this context.
Objectives
To evaluate the effectiveness of speech and language therapy for treatment of people with unexplained (idiopathic/refractory) chronic cough.
Search methods
We searched the Cochrane Airways Trials Register, CENTRAL, MEDLINE, Embase, CINAHL, trials registries, and reference lists of included studies. Our most recent search was 8 February 2019.
Selection criteria
We included RCTs in which participants had a diagnosis of UCC having undergone a full diagnostic workup to exclude an underlying cause, as per published guidelines or local protocols, and where the intervention included speech and language therapy techniques for UCC.
Data collection and analysis
Two review authors independently screened the titles and abstracts of 94 records. Two clinical trials, represented in 10 study reports, met our predefined inclusion criteria. Two review authors independently assessed risk of bias for each study and extracted outcome data. We analysed dichotomous data as odds ratios (ORs), and continuous data as mean differences (MDs) or geometric mean differences. We used standard methods recommended by Cochrane. Our primary outcomes were health‐related quality of life (HRQoL) and serious adverse events (SAEs).
Main results
We found two studies involving 162 adults that met our inclusion criteria. Neither of the two studies included children. The duration of treatment and length of sessions varied between studies from four sessions delivered weekly, to four sessions over two months. Similarly, length of sessions varied slightly from one 60‐minute session and three 45‐minute sessions to four 30‐minute sessions. The control interventions were healthy lifestyle advice in both studies.
One study contributed HRQoL data, using the Leicester Cough Questionnaire (LCQ), and we judged the quality of the evidence to be low using the GRADE approach. Data were reported as between‐group difference from baseline to four weeks (MD 1.53, 95% confidence interval (CI) 0.21 to 2.85; participants = 71), revealing a statistically significant benefit for people receiving a physiotherapy and speech and language therapy intervention (PSALTI) versus control. However, the difference between PSALTI and control was not observed between week four and three months. The same study provided information on SAEs, and there were no SAEs in either the PSALTI or control arms. Using the GRADE approach we judged the quality of evidence for this outcome to be low.
Data were also available for our prespecified secondary outcomes. In each case data were provided by only one study, therefore there were no opportunities for aggregation; we judged the quality of this evidence to be low for each outcome. A significant difference favouring therapy was demonstrated for: objective cough counts (ratio for mean coughs per hour on treatment was 59% (95% CI 37% to 95%) relative to control; participants = 71); symptom score (MD 9.80, 95% CI 4.50 to 15.10; participants = 87); and clinical improvement as defined by trialists (OR 48.13, 95% CI 13.53 to 171.25; participants = 87). There was no significant difference between therapy and control regarding subjective measures of cough (MD on visual analogue scale of cough severity: −9.72, 95% CI −20.80 to 1.36; participants = 71) and cough reflex sensitivity (capsaicin concentration to induce five coughs: 1.11 (95% CI 0.80 to 1.54; participants = 49) times higher on treatment than on control). One study reported data on adverse events, and there were no adverse events reported in either the therapy or control arms of the study.
Authors' conclusions
The paucity of data in this review highlights the need for more controlled trial data examining the efficacy of SLT interventions in the management of UCC. Although a large number of studies were found in the initial search as per protocol, we could include only two studies in the review. In addition, this review highlights that endpoints vary between published studies. The improvements in HRQoL (LCQ) and reduction in 24‐hour cough frequency seen with the PSALTI intervention were statistically significant but short‐lived, with the between‐group difference lasting up to four weeks only. Further studies are required to replicate these findings and to investigate the effects of SLT interventions over time. It is clear that SLT interventions vary between studies. Further research is needed to understand which aspects of SLT interventions are most effective in reducing cough (both objective cough frequency and subjective measures of cough) and improving HRQoL. We consider these endpoints to be clinically important. It is also important for future studies to report information on adverse events.
Because of the paucity of data, we can draw no robust conclusions regarding the efficacy of SLT interventions for improving outcomes in unexplained chronic cough. Our review identifies the need for further high‐quality research, with comparable endpoints to inform robust conclusions.
Plain language summary
Speech and language therapy for chronic cough
Background to the question
People normally cough to protect and clear the airways. For example, when we have a chest infection, we cough to eject bacteria. Or when we breathe in dust, we cough to eject the dust. Some people have chronic, or long‐term cough, due to a disease such as asthma, chronic obstructive pulmonary disease (COPD), or gastro‐oesophageal reflux disease. However, some people have chronic cough for no obvious reason. This is known as unexplained (idiopathic/refractory) chronic cough (UCC). Coughing over months and years is unpleasant, causing a reduction in quality of life.
Current guidelines recommend the use of gabapentin (a drug usually used to control seizures and reduce nerve pain) to try to stop people with UCC from coughing. However, this drug has side effects including drowsiness.
Speech and language therapy (SLT) has been suggested as a non‐drug‐based option for managing UCC. Speech and language therapy would avoid the risks and side effects of medication.
Speech and language therapy aims to teach people to control their cough. The person is taught methods to help them suppress the urge to cough. Education is given with the intention to help people understand how the technique works and hopefully get them to stick with it. People also receive vocal hygiene information. Vocal hygiene involves techniques to reduce the trigger to cough. For example, vocal hygiene may involve helping someone breathe through their nose rather than their mouth and avoiding drinking alcohol and caffeine, which can worsen cough. They may also be given psychoeducational counselling to help them learn they have the means to control their cough.
This review assessed the latest evidence regarding the effectiveness of SLT in the management of UCC.
Study characteristics
We found two relevant studies to include in the review. Both studies were randomised controlled trials (a type of study in which participants are assigned to one of two or more treatment groups using a random method) in which participants had a diagnosis of UCC. Participants received either an intervention including SLT techniques or 'healthy lifestyle advice' as a control group. We chose to use health‐related quality of life and serious adverse events to judge whether SLT is a useful intervention.
Main results
Only one of the studies comparing SLT to usual care reported data about quality of life (using a questionnaire). After four weeks, participants in the study who were receiving the SLT treatment, physiotherapy and speech and language therapy intervention (PSALTI), had on average an improvement in their quality of life compared to people in the control group. However, this benefit compared to control was short‐lived and disappeared after four weeks. This means that although the treatment appeared to work in the shorter term, it may not improve quality of life in the longer term compared to usual care.
We also looked for information about side effects or harms of the treatment. The same study reported that no one experienced serious side effects or harms during the study.
Other ways of measuring the impact of SLT were also considered, and in each case relevant data were only provided by one study. An improvement in objective cough counts (using a cough monitor), symptoms (using symptom scores), and clinical improvement was shown with SLT compared to controls. The included trials reported no difference for other secondary outcomes such as subjective measures of cough or cough reflex sensitivity (measured in the laboratory using airway irritants).
Quality of the evidence
The small number of high‐quality, relevant studies found in this review means that we cannot be sure of the overall benefits of SLT in the management of UCC. Improvements in health‐related quality of life were associated with the PSALTI intervention over a short period in one study, but further research is required to replicate this finding. Overall, more controlled trials are required to fully examine the potential of SLT for the management of UCC.
Summary of findings
Summary of findings for the main comparison. Speech and language therapy compared with healthy lifestyle advice for chronic cough.
| Speech and language therapy compared with control for chronic cough | ||||||
|
Patient or population: participants with chronic cough Settings: hospital Intervention: speech and language therapy Comparison: Healthy lifestyle advice | ||||||
| Outcomes | Illustrative comparative risks* (95% CI) | Relative effect (95% CI) | No. of participants (RCTs) | Quality of the evidence (GRADE) | Comments | |
| Assumed risk | Corresponding risk | |||||
| Placebo programme | Speech and language therapy | |||||
| Health‐related quality of life Follow‐up: 4 weeks |
Source data not available in trial report | MD 1.53 (0.21 to 2.85) | 71 (1) | ⊕⊕⊝⊝ Low1,2 |
The statistically significant difference for PSALTI versus control was not maintained between 4 weeks and 3‐month follow‐up. | |
| Serious adverse events Follow‐up: 4 weeks |
0/41 | 0/34 | Not estimable | 75 (1) | ⊕⊕⊝⊝ Low1,2 |
|
| Objective cough counts (over 24‐hour period) Follow‐up: 4 weeks |
Source data not available in trial report | Ratio for mean coughs per hour on treatment was0.59 (0.37 to 0.95) | 71 (1) | ⊕⊕⊝⊝ Low1,2 |
This statistically significant difference was not maintained for PSALTI versus control between 4 weeks and 3‐month follow‐up (Chamberlain Mitchell 2017). | |
| Symptoms Follow‐up: 2 months |
The mean improvement in symptoms in the control group was 2.9. | MD 9.80 better (4.50 to 15.10) | ‐ | 87 (1) | ⊕⊕⊝⊝ Low1,2 |
The data were skewed and were analysed with non‐parametric methods by Vertigan 2006, which also gave a significant result favouring speech and language therapy. |
| Clinical improvement (as defined by trialists) Follow‐up: 2 months |
6/44 demonstrated successful improvement | 38/43 demonstrated successful improvement | OR 48.13 (13.53 to 171.25) | 87 (1) | ⊕⊝⊝⊝ Very low1,2,3 |
|
| Subjective measures of cough (e.g. VAS/numerical cough scale score) Follow‐up: 4 weeks |
Source data not available in trial report | MD −9.72 (−20.80 to 1.36) | 71 (1) | ⊕⊕⊝⊝ Low1,2 |
Similarly, there was no difference for PSALTI versus control between 4 weeks and 3‐month follow‐up. | |
| Cough reflex sensitivity (as measured by cough challenge: capsaicin concentration required to provoke 5 coughs) Follow‐up: 4 weeks |
Source data not available in trial report | Capsaicin concentration 1.11 (0.80 to 1.54) times higher in intervention group | 49 (1) | ⊕⊕⊝⊝ Low1,2 |
There was no significant difference for PSALTI versus control in the capsaicin cough challenge either in terms of the 2 or 5 cough thresholds (Chamberlain Mitchell 2017). | |
| Adverse events Follow‐up: 4 weeks |
0/41 | 0/34 | Not estimable | 75 (1) | ⊕⊕⊝⊝ Low1,2 |
|
| *The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (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; IV: inverse variance; MD: mean difference; OR: odds ratio; PSALTI: physiotherapy and speech and language therapy intervention; RCT: randomised controlled trial; VAS: visual analogue scale | ||||||
| GRADE Working Group grades of evidence High quality: Further research is very unlikely to change our confidence in the estimate of effect. Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. Very low quality: We are very uncertain about the estimate. | ||||||
1A point was deducted to reflect the study question precluding the opportunity to double‐blind. 2A point was deducted to reflect imprecision (data from a single study with modest sample size). 3A point was deducted to reflect judgement being made of outcome as defined by trialists.
Background
Description of the condition
Cough is a reflex action to clear the airways of mucus and irritants such as smoke. Cough is a sequence comprising an inspiratory, glottic (vocal fold) closure, then a forced expiratory effort initially against the closed glottis (Fontana 2008). The duration of cough can be acute (less than three weeks), subacute (between three and eight weeks), or chronic (longer than eight weeks) (Irwin 2006). Details regarding the theory and treatment of cough can be found in several different clinical fields, including otolaryngology, respiratory medicine, speech and language therapy, respiratory physiology, and physiotherapy (Vertigan 2016a).
Unexplained (idiopathic/refractory) chronic cough (UCC) is a cough that persists after common causes have been evaluated and ruled out and medical management options have not offered any convincing relief from symptoms. This condition is a diagnosis of exclusion following a careful diagnostic workup to exclude other causes of cough such as underlying lung/airways disease, gastro‐oesophageal reflux, drugs (such as angiotensin‐converting enzyme inhibitors (ACEis)), and rhinosinusitis (Gibson 2016a; Morice 2006; Morice 2007; Morice 2007a; Vertigan 2016a).
Evidence suggests that UCC may be caused by neural hyper‐responsiveness. The observation that lower concentrations of tussive agents are required to induce cough in participants with UCC compared with healthy controls illustrates an increase in sensitivity of the cough reflex (Prudon 2005). Symptomatically, patients with this condition describe an 'irritation' or 'tickle' within the throat and a heightened urge or need to cough (Hilton 2015). Functional magnetic resonance imaging (fMRI) studies have demonstrated a clear role of the central nervous system in the sensation or urge to cough (Farrell 2014; Leech 2013; Mazzone 2007; Mazzone 2011), as well as a failure of descending inhibition of cough (Ando 2016). It is known that vagal afferent bronchopulmonary C‐fibres as well as A‐delta fibres are important in cough (Belvisi 2003; Canning 2014). Novel drugs targeting C‐fibre receptors have been recently trialed in humans. An oral transient receptor potential vanilloid subtype 1 (TRPV1) antagonist had no effect on cough frequency but did reduce cough reflex sensitivity in participants with UCC (Khalid 2014). Another, more potent, TRPV1 antagonist showed similar results in a more recent randomised controlled trial (RCT) (Belvisi 2017). In contrast, targeting the P2X3 receptor demonstrated a 75% reduction in daytime cough frequency in participants with UCC using a novel P2X3 antagonist (Abdulqawi 2015), supporting the hypothesis of a neural mechanism in UCC.
Furthermore, an overlap has been postulated between chronic cough and other laryngeal dysfunction presentations, such as inducible laryngeal obstruction (ILO), extra‐thoracic responsiveness, globus pharyngeus, hyperfunctional muscle tension, muscle tension dysphonia, voice disorders, and dysphagia symptoms (Altman 2002; Irwin 2010; Morrison 1999; Ryan 2009; Song 2014; Vertigan 2006; Vertigan 2012; Vertigan 2013; Vertigan 2016a; Vertigan 2019). Inducible laryngeal obstruction, previously known as vocal cord dysfunction (VCD) or paradoxical vocal form movement (PVFM), is an "inappropriate, transient, reversible narrowing of the larynx in response to external triggers" (Halvorsen 2017), leading to symptoms of shortness of breath, dysphonia, and cough (Vertigan 2016a). Symptoms of ILO are localised to the larynx (Benninger 2011). It has been suggested that these symptoms may represent different manifestations of an underlying hypersensitive and hyper‐responsive upper airway (Morrison 1999; Vertigan 2007a; Vertigan 2010; Vertigan 2016a).
Description of the intervention
Speech and language therapy (SLT) offers a non‐pharmacological intervention for people with UCC who may have exhausted medical treatment for their condition, or who wish to pursue a non‐pharmacological treatment option (Haines 2015; Ryan 2010; Ryan 2014; Vertigan 2006; Vertigan 2016a). Speech and language therapy has been incorporated into the Treatment of unexplained chronic cough: CHEST guideline and expert panel report (Gibson 2016a), which details treatment of UCC, and the Australian cough guidelines summary statement (Gibson 2010). The goal of SLT is to reduce laryngeal irritation that can trigger an individual's urge to cough, and to increase voluntary control of cough by interrupting or preventing coughing episodes, as well as to address symptoms associated with dysphonia and ILO (Vertigan 2016a; Vertigan 2019).
Speech and language therapists are appropriately trained to manage chronic cough via a combination of detailed knowledge of anatomy and physiology of the upper airway, experience in education and training on respiratory physiology and clinical voice disorders, and knowledge of interventions to modify laryngeal behaviour (Altman 2000; Stemple 2009). As there is a hypothesised and clinically recognised overlap between cough and other upper airway and laryngeal disorders, such as ILO, globus pharyngeus, muscle tension dysphonia, and dysphagic symptoms, SLT professionals have the skills required to identify, assess, and manage these overlapping conditions effectively by applying techniques traditionally used to treat muscle tension voice disorders (Blager 1998; Blager 2000; Carney 1997; Chhetri 2014; Dunn 2015; Estill 2009; Estill 2009a; Ryan 2010; TitzeI 2006; Vertigan 2007a). Speech and language therapy assessment can also investigate patient‐reported symptoms of dysphagia to identify clinical signs of aspiration that may warrant further investigation (Vertigan 2013; Vertigan 2016a; Irwin 2010).
Given the overlap between chronic cough and other upper airway and laryngeal disorders, videolaryngoscopy may assist differential diagnosis and consequent targeted therapy (Forrest 2012; Vertigan 2016a). Furthermore, the trained SLT professional can provide biovisual feedback with videolaryngoscopy. This has been found to be useful for assisting patients in applying techniques and in helping to monitor response to SLT in other related conditions such as clinical voice disorders and ILO (Balkissoon 2012; Belafsky 2001; Christopher 2010; Hull 2016; Olin 2017).
The urge to cough and indicators suggestive of ILO can be evaluated through the use of scales (e.g. Davenport 2002) (Ryan 2014; Traister 2014). Hyperfunction in the larynx during voicing can signify laryngeal dysfunction and can serve as a contributory factor to cough reflex sensitivity. Voicing is often cited as a trigger for coughing episodes. A clinical voice assessment can use recognised descriptive rating scales of perceptual voice characteristics, such as rough, breathy, and strained vocal qualities (Hirano 1981; Omori 2011; Ryan 2014; Vertigan 2007a).
The SLT professional can also assess voice production instrumentally (Ryan 2010; Zelcer 2002), for example by using an acoustic voice analysis programme or visualising the larynx via videolaryngoscopy during voice use according to a recognised protocol (RCSLT 2008). Manual assessment of tension in the extrinsic laryngeal musculature is a useful tool for assessing hyperfunction, which can be detected in muscle tension voice disorders (Rubin 2000; Vertigan 2016a).
Vertigan 2012 and Vertigan 2016a outlined a multidimensional SLT intervention for chronic cough management consisting of the following elements.
Education
Education focusses on encouraging adherence, with the aim of acceptance that patients can control their cough and take steps at the first sign of the urge to cough to implement cough suppression strategies such as cough suppression swallow, controlled breathing, relaxed throat breathing, and ILO release breathing (Vertigan 2016). Patients are provided with information on the importance of sustained application of cough suppression techniques (Vertigan 2012), as well as reassurance that their cough is not necessary or beneficial to them.
Education is provided on the perpetuating nature of the cough, and how this can potentially lead to an increased laryngeal sensitivity, laryngeal trauma, and laryngeal tension. Specific goals for therapy are planned with the patient. The ultimate goal of SLT is for the patient to control the cough, even in the presence of the sensation or urge to cough.
Symptom control techniques
The aim of symptom control strategies is to enable the patient to prevent, stop, or interrupt the cough despite having the triggering sensation or urge. The patient is taught to substitute the cough with a competing response (e.g. distraction, cough suppression swallow, relaxed throat breathing, a sip of fluids, laryngeal deconstriction) (Estill 2009; Vertigan 2007a). Laryngeal control techniques for any coexisting inducible laryngeal obstruction can also be included in the therapy intervention (Blager 2000; Boone 1993; Chhetri 2014; Kotby 1993).
A hierarchy for applying control techniques can be devised with the patient; this can include graded exposure to desensitise the patient to particular triggers, and facilitate automaticity of techniques when symptomatic (Vertigan 2016).
Reducing laryngeal irritation via vocal hygiene
Vocal hygiene advice is routinely used in the SLT approach to clinical voice disorders (Blager 1988), and it may be beneficial in the treatment of UCC (Vertigan 2012). Vocal hygiene consists of advice on reducing irritation and trauma to the upper airway, for example the potential harmful effects of smoking, mouth breathing, caffeine, and alcohol on laryngeal mucosa. Easy voicing and adequate hydration are emphasised and demonstrated to reduce the risk of phonotrauma (Boone 1993; Kotby 1993; Murry 2004; Solomon 2014; Vertigan 2007a). Information on diet and behavioural management of gastro‐oesophageal and laryngopharyngeal reflux is provided (Koufman 2011; Vertigan 2019).
Psychoeducational counselling
The therapist can assess readiness to engage in SLT, as this may impact the efficacy of therapy (Prochaska 1982). Acceptance that the patient can control the cough (internal locus of control), self‐efficacy (Bandura 1986), and the effort required of the patient are made explicit, with emphasis on treatment being 'hard work'. Realistic, targeted goal setting helps the therapist to direct interventions and monitor progress (Murry 2004; Ryan 2010; Vertigan 2012).
Overall goals of speech and language therapy interventions can be summarised as follows (Gibson 2015a).
Reduce the sensitivity of the cough reflex.
Encourage improvement in voluntary control of cough.
Reduce irritation of the larynx.
How the intervention might work
Speech and language therapy interventions aim to improve a person's control over cough and symptoms associated with any overlapping dysphonia and ILO (Vertigan 2016a), but the mechanism(s) by which multimodal SLT interventions may reduce cough severity and frequency, leading to improvement in health‐related quality of life, is poorly understood. However, it is postulated that SLT management of UCC can help break the cycle of reciprocal irritation of cough receptors by increasing voluntary cognitive control of the urge to cough, reducing cough reflex sensitivity, reducing laryngeal irritation and laryngeal muscle tension, and also treating any coexisting paradoxical vocal fold movement (Ryan 2010; Vertigan 2016; Vertigan 2019).
Speech and language therapy interventions have been shown to reduce cough sensitivity in participants with UCC (Ryan 2009; Smith 2005; Vertigan 2006; Vertigan 2016). However, a multicentre RCT demonstrated no differences between intervention and control groups with capsaicin cough challenge (Chamberlain Mitchell 2017). The psychoeducational and control strategies component may support subjective improvement in chronic cough management techniques and may reduce upper airway muscle tension (Canning 2006; Gibson 2009). Improved laryngeal hygiene attained via hydration and education on reduction of laryngeal injury may support lower phonation threshold pressure, thereby reducing stimulation of cough receptors (Casper 2003; Solomon 2014).
Vertigan 2019 details that the overall mechanism for improvement in cough symptoms following multimodal SLT intervention is unknown. However, it could represent both a central action in improved function of the neural cough suppression networks and laryngeal control, and a peripheral action demonstrated by a reduction in laryngeal hypersensitivity.
Why it is important to do this review
Cough is one of the most common reasons why patients seek medical advice (Morice 2006). The reported prevalence of chronic cough in the population varies in the most recent studies from 4%, Colak 2017, to 9.6% (Song 2015). Cough presents a considerable financial burden, with acute cough costing approximately GBP 979 million in the UK, including GBP 875 million in loss of productivity and GBP 104 million in healthcare costs (Morice 2006). The cost of chronic cough to the economy remains unclear.
The impact of chronic cough on quality of life is far reaching and can include negative physical, psychological, and social consequences (Decalmer 2007; French 1998; McGarvey 2013). Patient‐reported impact has been reported to be comparable to the impact of stroke or Parkinson's disease (Song 2013). Reported psychological and physical morbidities include vomiting, social embarrassment, headaches, low mood, and sleep disturbance (Chamberlain 2013). Urinary incontinence associated with chronic cough is a particularly distressing symptom (Hrisanfow 2013).
Few effective medical treatments for individuals with UCC are known. Current guidelines advocate the use of gabapentin (Gibson 2016a), following improvements in quality of life reported in an RCT of gabapentin in UCC (Ryan 2012). One study demonstrated a reduction in subjective cough scores in response to slow‐release morphine sulphate (Morice 2007a). Another study examined amitriptyline in participants with postviral vagal neuropathy and cough, but guidelines do not currently recommend this treatment (Jeyakumar 2006).
Speech and language therapy has been advocated as an attractive non‐pharmacological option for managing UCC without the risks and side effects associated with pharmacological agents and is advocated in guidelines (Gibson 2016a). Speech and language therapy was the focus of this review.
Objectives
To evaluate the effectiveness of speech and language therapy for treatment of people with unexplained (idiopathic/refractory) chronic cough.
Methods
Criteria for considering studies for this review
Types of studies
We included randomised controlled trials (RCTs). We included studies reported in full text, those published as an abstract only, and unpublished data. We planned to include cluster trials and first‐period data from cross‐over trials if these were available, however all of the included studies were of conventional parallel‐group design.
Types of participants
We included participants with a diagnosis of unexplained chronic (idiopathic/refractory) cough (UCC) who had undergone a full diagnostic workup to exclude an underlying cause, as per published guidelines or local protocols. Had we identified eligible studies in children (17 years of age and younger), we would have analysed them separately from adult studies, however all of the included studies focused on adult participants.
Types of interventions
We included studies that used recognised speech and language therapy (SLT) techniques for UCC, such as the multidimensional SLT intervention described in the Background section (education, symptom control or vocal hygiene, psychoeducational counselling) and/or other recognised SLT laryngeal control techniques as defined by trialists.
We planned to include other co‐interventions, provided they were not part of the randomised treatment.
We included studies comparing SLT and usual care versus usual care, such as reassurance, lifestyle advice, and background medications. We also planned to include studies comparing SLT versus an 'active' control such as non‐prescribed/over‐the‐counter cough products (e.g. lozenges). We included trials that delivered a number of sessions and planned to investigate in subgroup analyses the number of sessions provided wherever possible (Ryan 2010).
Types of outcome measures
Primary outcomes
Health‐related quality of life (assessed via a validated measure)
Serious adverse events
Secondary outcomes
Objective cough counts (e.g. using the Leicester Cough Monitor (LCM))
Symptoms (preferentially assessed on validated symptom scales)
Clinical improvement (as defined by trialists)
Subjective measures of cough (e.g. visual analogue scale (VAS)/numerical cough scale score)
Cough reflex sensitivity (as measured by cough challenge)
Adverse events/side effects
Reporting in the study of one or more of the outcomes listed was not an inclusion criterion for this review.
Search methods for identification of studies
Electronic searches
The Cochrane Airways Group Information Specialist conducted systematic searches in the following sources:
Cochrane Airways Trials Register via the Cochrane Register of Studies (CRS‐Web), searched on 8 February 2019;
Cochrane Central Register of Controlled Trials (CENTRAL), via the Cochrane Register of Studies (CRS‐Web), searched on 8 February 2019;
MEDLINE Ovid SP from 1946 to 8 February 2019;
Embase Ovid SP from 1974 to 8 February 2019;
CINAHL EBSCO (Cumulative Index to Nursing and Allied Health Literature) from 1937 to 8 February 2019;
US National Institutes of Health Ongoing Trials Register ClinicalTrials.gov (www.clinicaltrials.gov/). searched on 8 February 2019;
World Health Organization International Clinical Trials Registry Platform (WHO ICTRP) (apps.who.int/trialsearch/) searched on 8 February 2019
Search strategies are provided in Appendix 1.
We searched all sources from inception to the present, with no restriction on language of publication.
Searching other resources
We checked the reference lists of all primary studies and review articles for additional references. We searched for errata or retractions from included studies published in full text on PubMed (www.ncbi.nlm.nih.gov/pubmed) and reported within the review the date this was done (February 2019).
Data collection and analysis
Selection of studies
Two review authors (CS and PM) independently screened the titles and abstracts of studies identified by the search and coded them as 'retrieve' (eligible or potentially eligible/unclear) or 'do not retrieve'. We retrieved the full‐text study reports of all potentially eligible studies, and two review authors (CS and PM) independently screened them for inclusion, while recording reasons for exclusion of ineligible studies. We planned to resolve any disagreements through discussion, consulting a third person/review author (AV) if necessary, however this was not required. We identified and excluded duplicates and collated multiple reports of the same study so that each study, rather than each report, was the unit of interest in the review. We recorded the selection process in sufficient detail to complete a PRISMA flow diagram and 'Characteristics of excluded studies' tables (Moher 2009).
Data extraction and management
We used a data collection form that had been piloted on at least one study in the review to record study characteristics and outcome data. Two review authors (SJM and JM) extracted the following study characteristics from the included studies.
Methods: study design, total duration of study, details of any 'run‐in' period, number of study centres and locations, study setting, withdrawals, and dates of study.
Participants: N, mean age, age range, gender, severity of condition, diagnostic criteria, baseline lung function, smoking history, inclusion criteria, and exclusion criteria.
Interventions: intervention, comparison, concomitant medications, and excluded medications.
Outcomes: primary and secondary outcomes specified and collected, and time points reported.
Notes: funding for studies and notable conflicts of interest of trial authors.
Two review authors (SJM and JM) independently extracted outcome data from the included studies. We noted in the 'Characteristics of included studies' table if outcome data were not reported in a manner precluding them from being entered into the Review Manager 5 file (RevMan 2014). We planned to resolve any disagreements by consensus, consulting a third person/review author (PM) if necessary, however this was not required. One review author (SJM) transferred data into the Review Manager 5 file (RevMan 2014). A second review author (CS) double‐checked that study characteristics and data had been entered correctly by comparing the data presented in the systematic review against that in the study reports.
Assessment of risk of bias in included studies
Two review authors independently (SJM and JM) assessed risk of bias for each study using the criteria outlined in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). We planned to resolve any disagreements by discussion, consulting another review author (PM) if necessary, however this was not required. We assessed risk of bias according to the following domains.
Random sequence generation.
Allocation concealment.
Blinding of participants and personnel.
Blinding of outcome assessment.
Incomplete outcome data.
Selective outcome reporting.
Other bias.
We judged each potential source of bias as high, low, or unclear and provided a quote from the study report together with a justification for our judgement in the 'Risk of bias' table. We summarised 'Risk of bias' judgements across different studies for each of the domains listed. We considered blinding separately for different key outcomes when necessary (e.g. for unblinded outcome assessment, risk of bias for all‐cause mortality may be very different than for use of a patient‐reported pain scale). When information on risk of bias related to unpublished data or correspondence with a trialist, we noted this in the 'Risk of bias' table.
When considering treatment effects, we took into account risk of bias for studies that contribute to that outcome.
Assessment of bias in conducting the systematic review
We conducted the review according to our published protocol and planned to justify any deviations from it in the Differences between protocol and review section. There was no need to deviate from the protocol (Slinger 2018).
Measures of treatment effect
We analysed dichotomous data as odds ratios (ORs) and continuous data as mean differences (MDs) or geometric MDs. We planned that if data from rating scales were combined in a meta‐analysis, we would ensure that they were entered with a consistent direction of effect (e.g. lower scores always indicate improvement). The paucity of data meeting our inclusion criteria precluded further consideration of this issue.
We planned to conduct meta‐analyses only when meaningful, that is when treatments, participants, and the underlying clinical question were similar enough for pooling to make sense. Unfortunately, there was no opportunity for aggregation.
We planned to describe skewed data narratively (e.g. as medians and interquartile ranges for each group).
Had multiple trial arms been reported in a single study, we would have included only the relevant arms. All of the trials meeting our inclusion criteria were two‐arm studies. In the protocol for this review we stated that "If two comparisons (e.g. intervention A vs usual care and intervention B vs usual care) are combined in the same meta‐analysis, we will either combine the active arms or halve the control group to avoid double‐counting"; however, this was not an issue with the available data.
Where adjusted analyses were available (analysis of variance (ANOVA) or analysis of covariance (ANCOVA)), we used these as a preference in our meta‐analyses. Where both change from baseline and endpoint scores were available for continuous data, we used change from baseline. We planned to avoid doing so in the event of low correlation between measurements in individuals, and there was no apparent indication of this issue. We planned that where a study reported outcomes at multiple time points, we would use change in baseline and endpoint scores.
When both per‐protocol/completer and intention‐to‐treat (ITT) analyses were provided in a single report, we used the latter.
Unit of analysis issues
For dichotomous outcomes, we used participants, rather than events, as the unit of analysis (e.g. number of people experiencing an adverse event, rather than number of adverse events per person). However, we planned that if rate ratios had been reported in a study, we would analyse them accordingly; this was not an issue with the included studies. We planned to meta‐analyse data from cluster‐RCTs only if available data had been adjusted (or could be adjusted) to account for the clustering. Again, this was not an issue with our included studies.
Dealing with missing data
We contacted the investigators of the included studies to verify key study characteristics and for additional clarifications.
Assessment of heterogeneity
We planned to use the I² statistic to measure heterogeneity among the studies in each analysis. Had we identified substantial heterogeneity, we would have reported this and explored possible causes by performing prespecified subgroup analysis. However, there was no opportunity for aggregation.
Assessment of reporting biases
We planned that if we had been able to pool more than 10 studies, we would create and examine a funnel plot to explore possible small‐study and publication biases. However, there were insufficient studies meeting our inclusion criteria to pursue this aim.
Data synthesis
We used a random‐effects model and planned to perform a sensitivity analysis with a fixed‐effect model if necessary.
'Summary of findings' table
We created a 'Summary of findings' table using the following outcomes.
Primary outcomes
Health‐related quality of life (assessed with a validated measure)
Serious adverse events
Secondary outcomes
Symptoms
Clinical improvement (as defined by trialists)
Subjective measures of cough (e.g. VAS/numerical cough score)
Cough reflex sensitivity (as measured by cough challenge)
Objective cough counts
Adverse events/side effects
Reporting in the study of one or more of the outcomes listed here was not an inclusion criterion for the review.
We used the five GRADE considerations (risk of bias, consistency of effect, imprecision, indirectness, and publication bias) to assess the quality of a body of evidence as it relates to studies that contribute data for the prespecified outcomes. We used the methods and recommendations described in Section 8.5 and Chapter 12 of the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011), employing GRADEpro software (GRADEpro GDT). We justified all decisions to downgrade the quality of studies using footnotes, and included comments to aid the reader's understanding of the review when necessary.
Subgroup analysis and investigation of heterogeneity
We planned to carry out the following subgroup analyses on our two primary outcomes (health‐related quality of life and serious adverse events). However, this was not possible due to the paucity of data.
Number of sessions of SLT (one to three sessions versus four to six sessions versus seven or more sessions).
Speech and language therapist‐delivered intervention versus intervention delivered by other healthcare professionals.
We planned to use the formal test for subgroup interactions in Review Manager 5 (RevMan 2014).
Sensitivity analysis
We planned to conduct sensitivity analyses by removing studies when the method of randomisation was judged as unclear or high in the 'Risk of bias' assessment. We also planned to conduct sensitivity analyses by removing studies with an active control arm. Furthermore, we planned to compare the results from a fixed‐effect model with those from the random‐effects model. However, this was not possible due to the paucity of data.
Results
Description of studies
Results of the search
We retrieved 141 references from the literature searches conducted on 9 July 2018. We assessed 94 references after removal of duplicate records (see study flow diagram in Figure 1).
1.
Study flow diagram.
On 8 February 2019 we identified a further six references, with no duplicates. In total we therefore assessed 100 references (see Figure 1).
Included studies
We included two trials with a total of 162 randomised participants. One study was conducted across multiple sites in the UK (Chamberlain Mitchell 2017), and another in Newcastle, Australia (Vertigan 2006). Further clarification on the included studies was requested and received from authors.
Populations
In Vertigan 2006, participants were eligible if cough was persistent for more than two months following medical treatment including treatment for asthma, postnasal drip syndrome, gastro‐oesophageal reflux, and withdrawal of angiotensin‐converting enzyme inhibitors. The participants underwent thorough respiratory history, hypertonic saline challenge, and induced sputum analysis before inclusion in the study. The study included a total 87 participants, randomised to placebo group (n = 44) and treatment group (n = 43).
The eligibility criteria in Chamberlain Mitchell 2017 included chronic cough (duration of more than two months) with normal chest x‐ray, minimal sputum production, and negative and/or failed treatments for asthma, gastro‐oesophageal reflux disease, and rhinitis. Patients were excluded if they had vocal cord nodules, evidence of aspiration or malignancy. There were 75 eligible participants who were randomised to control group (n = 41) and physiotherapy and speech and language therapy intervention (PSALTI) group (n = 34).
Interventions
The intervention therapies used in the two included studies had differing titles: Speech Pathology Evaluation and Intervention for CHronic Cough (SPEICH‐C) in Vertigan 2006 and PSALTI in Chamberlain Mitchell 2017. However, the content was very similar, comprising four one‐to‐one sessions of laryngeal hygiene and hydration, cough suppression techniques, and psychoeducational counselling around volitional control and the concept of the idiopathic nature of cough. Both studies used healthy lifestyle advice as a control therapy with a focus on exercise, physical activity, diet and nutritional advice, and stress management.
In one study, both the intervention and control therapies were delivered purely by a speech and language therapist (Vertigan 2006). The other study delivered intervention therapy by either a physiotherapist or speech and language therapist, and the control therapy by a physiotherapist, speech and language therapist, or nurse (Chamberlain Mitchell 2017).
The duration of treatment and length of sessions varied between studies, from four sessions delivered weekly in Chamberlain Mitchell 2017 to four sessions over two months in Vertigan 2006. Similarly, length of sessions varied slightly, from one 1‐hour session and three 45‐minute sessions in Chamberlain Mitchell 2017 to four 30‐minute sessions in Vertigan 2006.
Excluded studies
We excluded 90 records, with reasons given in the Characteristics of excluded studies tables. A study flow diagram is shown in Figure 1. The primary reason for exclusion was: 59 (65%) were not relevant to people with a diagnosis of UCC; 13 (14%) were reviews; eight (9%) were not randomised studies; one (1%) did not include an SLT intervention; one (1%) was an editorial; and one (1%) was a comparison between pregabalin in addition to speech pathology versus speech pathology alone. An additional trial considered the benefit of adding video recordings of speech therapy techniques, demonstrated by a speech pathologist, to support participants' development of the technique for chronic refractory cough (1%).
Risk of bias in included studies
A full 'Risk of bias' assessment for each study can be found in the Characteristics of included studies tables, and a summary of our judgements in Figure 2.
2.
Risk of bias summary: review authors' judgements about each risk of bias item for each included study.
Allocation
We assessed Chamberlain Mitchell 2017 and Vertigan 2006 as at low risk of bias for random sequence generation and allocation concealment.
Blinding
We judged Chamberlain Mitchell 2017 and Vertigan 2006 as at unclear risk of performance bias. We assessed Chamberlain Mitchell 2017 as at low risk and Vertigan 2006 as at unclear risk of detection bias. Our judgments of unclear risk of bias reflect our uncertainty in relation to reporting.
Incomplete outcome data
We assessed Chamberlain Mitchell 2017 and Vertigan 2006 as at low risk of attrition bias.
Selective reporting
We judged Chamberlain Mitchell 2017 and Vertigan 2006 as at unclear risk of reporting bias. As in the assessments of blinding, our judgments of unclear risk of bias reflect our uncertainty in relation to reporting, as we did not have access to trial protocols.
Effects of interventions
See: Table 1
Primary outcomes
Health‐related quality of life (HRQoL)
Only one study contributed data to this outcome, and using the GRADE approach we judged the quality of evidence to be low (Table 1). Health‐related quality of life was assessed by Chamberlain Mitchell 2017 with the Leicester Cough Questionnaire (LCQ). Data were analysed using ANCOVA and reported as between‐group difference from baseline to four weeks (mean difference (MD) 1.53, 95% confidence interval (CI) 0.21 to 2.85; participants = 71; studies = 1; Analysis 1.1), revealing a statistically significant benefit for PSALTI versus control. This difference is also clinically significant as it exceeds the minimum clinically important difference (MCID) of 1.3 in chronic cough (Raj 2009). Our analysis focused on the 71 ITT population participants (of the total 75 entering the study). This statistically significant difference for PSALTI versus control was not maintained between four weeks and three‐month follow‐up.
1.1. Analysis.
Comparison 1 Speech and language therapy versus healthy lifestyle advice, Outcome 1 Health‐related quality of life (Leicester Cough Questionnaire).
There were no differences between the two groups from baseline to four weeks on general health and mood assessments, that is the 36‐item Short Form Health Survey (SF‐36) and Hospital Anxiety and Depression Scale (HADS) scores.
We did not attempt subgroup analyses due to the paucity of the data.
Serious adverse events
Vertigan 2006 did not report serious adverse events. Chamberlain Mitchell 2017 reported that there were no serious adverse events in either the PSALTI or control arms of the study (Analysis 1.2). We judged the quality of the evidence to be low using the GRADE approach (Table 1).
1.2. Analysis.
Comparison 1 Speech and language therapy versus healthy lifestyle advice, Outcome 2 Serious adverse events.
Secondary outcomes
Objective cough counts
Cough frequency per hour over a 24‐hour period was measured by Chamberlain Mitchell 2017. This was analysed as geometric means, which compare the ratio of mean cough counts per hour on treatment to control. The Leicester Cough Monitor (LCM) is a validated, objective, semi‐automated, and ambulatory cough‐monitoring device that was used in this study to assess objective cough frequency (Birring 2008). The device was worn by participants for 24 hours at baseline, at 4 weeks (after the fourth treatment session), and at 3‐month follow‐up; in each of these sessions the device recorded the number of coughs per hour. The effect estimate favoured PSALTI (versus control), which was associated with a ratio of cough counts per hour of 59% (95% CI 37% to 95%; participants = 71; studies = 1; Analysis 1.3) of cough counts per hour on control. We judged the quality of this evidence to be low using the GRADE approach (Table 1). This statistically significant difference for PSALTI versus control was not maintained between four weeks and three‐month follow‐up.
1.3. Analysis.
Comparison 1 Speech and language therapy versus healthy lifestyle advice, Outcome 3 Objective cough counts (e.g. using the Leicester Cough Monitor).
Symptoms
Vertigan 2006 reported a significant benefit for the SLT intervention (SPEICH‐C) versus control for change in total symptoms scores over the four treatment sessions (MD 9.80, 95% CI 4.50 to 15.10; participants = 87; studies = 1; Analysis 1.4). We are aware that these data are skewed, and were analysed with non‐parametric methods by Vertigan 2006. In the non‐parametric analysis there was a significant difference between groups, favouring SPEICH‐C versus control. We judged the quality of the evidence to be low using the GRADE approach (Table 1).
1.4. Analysis.
Comparison 1 Speech and language therapy versus healthy lifestyle advice, Outcome 4 Symptoms.
Clinical improvement (as defined by trialists)
Vertigan 2006 demonstrated a significant improvement following SPEICH‐C versus control for change in symptoms scores of breathing, cough, voice, upper airway, and limitation over the four treatment sessions (odds ratio (OR) 48.13, 95% CI 13.53 to 171.25; participants = 87; studies = 1; Analysis 1.5). Each participant’s outcome was categorised by a speech and language therapist as successful, unsuccessful, or partially successful. The assessment was based on the participant’s informal reports of the effectiveness of the intervention together with the speech and language therapist's clinical judgement of the participant’s understanding and implementation of the intervention. Thirty‐eight out 43 participants in the SPEICH‐C group were regarded as having a successful outcome in relation to these criteria, whereas only six out of 44 participants in the control group were judged to have a successful outcome. Using the GRADE criteria, we judged the quality of this evidence as very low (Table 1).
1.5. Analysis.
Comparison 1 Speech and language therapy versus healthy lifestyle advice, Outcome 5 Clinical improvement (as defined by trialists).
Chamberlain Mitchell 2017 found no differences between groups with respect to a vocal performance questionnaire from baseline to four weeks.
Subjective measures of cough (e.g. visual analogue scale (VAS)/numerical cough scale score)
Only one study contributed data to this outcome, and we judged the quality of the evidence as low using the GRADE approach (Table 1). Cough severity, measured on a VAS (ranging from 0 to 100 mm, with higher scores denoting higher severity) (Boulet 2015), was reported by Chamberlain Mitchell 2017 (MD −9.72, 95% CI −20.80 to 1.36; participants = 71; studies = 1; Analysis 1.6). The mean difference favoured the intervention, but the result is uncertain as the confidence interval includes the possibility of no difference between groups. Similarly, there was no difference for PSALTI versus control between four weeks and three‐month follow‐up.
1.6. Analysis.
Comparison 1 Speech and language therapy versus healthy lifestyle advice, Outcome 6 Subjective measures of cough (e.g. visual analogue scale/numerical cough scale score).
Cough reflex sensitivity (as measured by cough challenge)
There was no significant difference between PSALTI and control in the capsaicin cough challenge for either the two or five cough thresholds (capsaicin concentration to induce five coughs: 1.11 (95% CI 0.80 to 1.54) times higher on treatment than on control; participants = 49; studies = 1; Analysis 1.7) (Chamberlain Mitchell 2017). We judged the quality of the evidence to be low using the GRADE approach (Table 1).
1.7. Analysis.
Comparison 1 Speech and language therapy versus healthy lifestyle advice, Outcome 7 Capsaicin cough challenge (to induce 5 coughs).
Adverse events/side effects
Adverse events were not reported by Vertigan 2006. Chamberlain Mitchell 2017 reported no adverse events in either the PSALTI or control conditions (Analysis 1.8). We judged the quality of this evidence as low using the GRADE approach (Table 1).
1.8. Analysis.
Comparison 1 Speech and language therapy versus healthy lifestyle advice, Outcome 8 Adverse events/side effects.
Discussion
Summary of main results
Overall there was a paucity of controlled trial data. We found only two randomised trials that met our inclusion criteria (Chamberlain Mitchell 2017; Vertigan 2006). Both were undertaken in adults with UCC and examined the effect of an intervention versus healthy lifestyle advice. Chamberlain Mitchell 2017 (conducted in the UK) examined the effect of a physiotherapy and speech and language therapy intervention (PSALTI) on HRQoL and measures of cough. Vertigan 2006 (conducted in Australia) studied the effect of a speech therapy intervention (SPEICH‐C) on symptom scores.
There was a significant improvement in HRQoL (LCQ) scores at four weeks, but not between four weeks and three months; however, these data were from one study only (Chamberlain Mitchell 2017), as this outcome was not included in Vertigan 2006. No serious adverse events were reported, however information on this outcome was not specifically stated in one of the trials (Vertigan 2006).
We found statistically significant improvements in 24‐hour cough frequency at four weeks when comparing PSALTI to control, but this difference was not maintained between four weeks and three months. The effect of PSALTI on subjective measures of cough was uncertain with no statistically significant difference in cough severity measured on a VAS, although the mean difference favoured the intervention. These data were from only one study (Chamberlain Mitchell 2017).
We found statistically significant improvements in symptom scores following the SLT intervention in Vertigan 2006..
Overall completeness and applicability of evidence
Due to the absence of common outcomes in the two studies, opportunities for statistical aggregation did not arise, and consequently, whilst the results are encouraging, the paucity of evidence precludes us from drawing robust conclusions to guide clinical practice.
Only two studies with modest sample sizes met our inclusion criteria. They were both conducted in high‐income settings, therefore the global applicability of the evidence is limited. Moreover, the two studies used different outcomes, precluding direct statistical aggregation. The interventions were based either on SLT, Vertigan 2006, or SLT and physiotherapy combined (Chamberlain Mitchell 2017). Both studies appeared to employ similar treatment approaches, as first described by Vertigan 2006. In Chamberlain Mitchell 2017, the Active Cycle of Breathing Technique (ACBT) was introduced if the participant's sputum production was close to the limit of sputum exclusion criteria, and nasal douche for nasal mucus hypersecretion. The benefit of physiotherapy techniques in addition to SLT techniques was not investigated in Chamberlain Mitchell 2017, hence it is not possible to draw conclusions on the relative positive contribution of discipline‐specific interventions (Smith 2017).
Quality of the evidence
The overall quality of the evidence presented in this review is low for seven of the eight outcomes included in the GRADE assessment; the quality of the evidence from the remaining outcome 'clinical improvement (as defined by trialists)' was judged as very low when assessed by the GRADE criteria. However, only two studies met our inclusion criteria. Both studies described methods of randomisation, and these were similar. The control and intervention arms for the two studies were comparable and clearly defined, although one study had a two‐month intervention arm with no long‐term outcome data (Vertigan 2006), and the other study had a four‐week intervention arm with four‐week and three‐month postintervention outcome data (Chamberlain Mitchell 2017). One study used the treating speech therapist's judgement on clinical outcome and symptom scores (Vertigan 2006), whilst the other study used a validated questionnaire, interval cough monitoring, and VAS to assess the effect of the intervention (Chamberlain Mitchell 2017). The latter study also undertook general health and mood assessments using the SF‐36 and HADS. The two studies also used different primary and secondary endpoints. The variance in data collection and analysis meant it was not possible to statistically combine the two studies for any outcome. The quality of the evidence was limited critically by the lack of studies meeting our inclusion criteria, and of those that did meet our inclusion criteria, by the lack of consistency in data collection methodology, duration of follow‐up, and primary and secondary endpoints analysed.
The two included studies by Vertigan 2006 and Chamberlain Mitchell 2017 were single‐blinded, and symptom ratings were blinded. It was not possible to blind the treating therapist, and there is inevitably the possibility of unconscious bias having been conveyed to the participants; this is not a criticism of these well‐conducted studies, but a feature of the interventions, introducing concomitant uncertainty in this regard.
In our GRADE assessment we deducted one point to reflect the study question, which precluded the opportunity to double‐blind, and an additional point to reflect imprecision (data from a single study with modest sample size); this was applied to all outcomes considered in the Table 1. We deducted a further point for the outcome 'clinical improvement (as defined by trialists)' to reflect that the judgement of efficacy on this outcome was made against criteria defined by the trialists.
Potential biases in the review process
We recognise that there is the possibility of publication bias, which could influence our understanding of the effects of the interventions reported in this review. Studies demonstrating an absent or negative effect of the proposed intervention are less likely to have been presented or accepted for publication. Subsequently, data that are made available for review could, as a result, be biased. Due to the small number of trials included in the review, it was not possible to assess the significance of publication bias formally. However, potentially eligible studies were identified using a robust, systematic search process conducted by experienced specialists using multiple sources including journals, conference publications, electronic databases, reference and citation lists of included studies, and trial registries. It is possible that some studies may have been inaccurately classified as not eligible for inclusion in the review. Due to the small number of studies included, we did not perform a sensitivity analysis to explore the impact of excluding studies that did not meet agreed criteria. Any studies excluded from analysis were done so on the basis of agreed and consistent criteria. There is the potential for errors to occur in data entry for some full‐text reports; however, we took measures to double‐check all data in an attempt to avoid this during data extraction. All papers included in the review process were independently assessed by two review authors, with data corroborated by a third review author. Owing to the variability in outcomes reported across the included studies, we were unable to statistically combine the overall findings. However, we contacted the chief authors of the included studies, and both were willing and able to provide further clarity on their methodology and interpretation of data. We therefore feel that we have taken thorough measures to minimise risk of bias in this review, and are confident in the merit of outcomes individually reported in the included studies.
Agreements and disagreements with other studies or reviews
We are aware of reviews of chronic cough in the literature that assess diagnosis and management, but they differ in primary objectives and methodologies used. Vertigan 2007 reviews behaviour modification therapies in chronic cough using systematic reviews and case studies to explain the main constructs required to deliver effective non‐pharmacological therapies to treat chronic cough. The components of cough suppression therapy are further reviewed by Chamberlain 2013. Each of the four therapy components are reviewed individually and the evidence base considered to provide a structure for the speech and language therapist/respiratory physiotherapist to use to support patient outcome. Ryan 2014 reviewed the treatment of refractory chronic cough with speech and language therapy and gabapentin via RCTs, systematic reviews, and case reports in English publications eight years prior to their paper, concluding that behavioural treatment and pharmacological neuromodulation have a role. Chronic cough can arise due to known respiratory as well as non‐respiratory pathology. Molassiotis 2010 undertook a systematic review in adults including RCTs and controlled trials to evaluate the effectiveness of pharmacological and non‐pharmacological interventions in the relief of chronic cough excluding malignant disease. Guidelines for the diagnosis and treatment of chronic cough were published in Chest (Gibson 2016), using the best available evidence from RCTs and systematic reviews. Eleven RCTs were included, but only one looked at non‐pharmacological intervention as the major component of the study. The Chamberlain Mitchell 2017 RCT postdated all these review articles, and its impact on UCC is not assessed. A further review included all studies examining non‐pharmacological treatments in UCC focusing on potential mechanisms and the effects of treatment (Chamberlain Mitchell 2019).
There is a paucity of evidence in this area with regard to outcomes of speech and language therapy in the management of chronic cough. The RCTs that do exist use similar methodologies of treatment, but interstudy data analysis is not possible due to the absence of common outcome measures.
It is important to note that Vertigan 2016, although not meeting the inclusion criteria for this review, found that SLT, when combined with the neuromodulator pregabalin, led to a significantly greater improvement in participants' perceived cough severity and cough‐related quality of life, when compared to SLT alone. This combination of SLT and pregabalin was also found to improve cough sensitivity. This benefit was sustained after treatment withdrawal. However, due to observed adverse effects of pregabalin, the authors state that this multimodal treatment should be reserved for those with more severe end spectrum cough symptoms. Further studies to help understand who may benefit from combined pharmacological and non‐pharmacological approaches, and the timing of each component, may help inform clinical practice further. This study is of clinical interest to professionals working with people with UCC, although data from this single trial would need to be confirmed in subsequent research to provide us with robust evidence to guide clinical practice.
Authors' conclusions
Implications for practice.
We found only two trials meeting our inclusion criteria, which included a combined total of 162 randomised adult participants. Neither of the studies included children.
We identified positive effects in one study of speech and language therapy (SLT)‐based approaches, in combination with physiotherapy, for our predefined primary outcome of health‐related quality of life (HRQoL). No adverse events were reported (Chamberlain Mitchell 2017).
However, the between‐group benefits of the intervention with regard to HRQoL in Chamberlain Mitchell 2017 were found to be short‐lived, and this finding needs to be interpreted with caution when applying it to clinical practice. Vertigan 2006 did not report data on HRQoL.
Further high‐quality studies with comparable endpoints are needed to inform robust conclusions and guide clinical practice.
Implications for research.
The paucity of data in this review highlights the need for more randomised controlled trial data examining the efficacy of SLT in the management of UCC. This review highlights that endpoints vary between the included studies.
The improvements in HRQoL (Leicester Cough Questionnaire) and reduction in 24‐hour cough frequency seen with the physiotherapy and speech and language therapy intervention (PSALTI) were statistically significant but short‐lived, with the effect lasting up to 4 weeks only between PSALTI and control groups. Further studies examining SLT intervention in UCC are required to replicate these findings and to investigate the effects of the interventions over time. It is clear that SLT interventions vary between studies. Further research is needed to understand which aspects of the SLT intervention are most effective in reducing cough (both objective cough frequency and subjective measures of cough) and improving HRQoL. We consider these endpoints to be important clinically. It is also important for studies to report any adverse events that occur. Further studies could be designed to understand the essential components of the intervention (Smith 2017).
Further research is needed to investigate whether the results of this review are applicable across cultures and along the age spectrum.
Acknowledgements
Rebecca Fortescue was the Editor for this review and commented critically on the review.
We are especially grateful to Emma Dennett, Liz Stovold, and Emma Jackson of Cochrane Airways, and to Rebecca Normansell and Chris Cates (Cochrane Airways Co‐ordinating Editors) for the additional guidance provided. We are also particularly grateful to Anne Vertigan and Sarah Chamberlain‐Mitchell for their invaluable assistance in providing additional clarification on their studies and confirming that they know of no additional studies that would meet our inclusion criteria.
We are grateful also to Richard Slinger for draft and proof reading of this review.
The Background and Methods sections of this protocol are based on a standard template used by Cochrane Airways.
This project was supported by the National Institute for Health Research (NIHR) via Cochrane Infrastructure funding to Cochrane Airways. The views and opinions expressed therein are those of the review authors and do not necessarily reflect those of the Systematic Reviews Programme, NIHR, NHS, or the Department of Health.
Appendices
Appendix 1. Database search strategies
CENTRAL (Cochrane Register of Studies)
#1 MESH DESCRIPTOR Cough EXPLODE ALL #2 cough*:ti,ab,kw #3 #2 OR #1 #4 MESH DESCRIPTOR Rehabilitation of Speech and Language Disorders EXPLODE ALL #5 ((speech* or language*) NEAR5 (therap* or treatment* or interven* or program* or train* or exercise* or rehabilit*)) #6 SLT:ti,ab #7 #4 OR #5 OR #6 #8 #7 AND #3
Cochrane Airways Register of Trials (Cochrane Register of Studies)
#1 MESH DESCRIPTOR Cough EXPLODE ALL #2 cough*:ti,ab,kw #3 #2 OR #1 #4 MESH DESCRIPTOR Rehabilitation of Speech and Language Disorders EXPLODE ALL #5 ((speech* or language*) NEAR5 (therap* or treatment* or interven* or program* or train* or exercise* or rehabilit*)) #6 SLT:ti,ab #7 #4 OR #5 OR #6 #8 #7 AND #3
MEDLINE (Ovid)
1. Cough/ 2. cough$.tw. 3. 1 or 2 4. exp "rehabilitation of speech and language disorders"/ 5. ((speech$ or language$) adj5 (therap$ or treatment$ or interven$ or program$ or train$ or exercise$ or rehabilit$)).tw. 6. SLT.ti,ab. 7. or/4‐6 8. 3 and 7 9. (controlled clinical trial or randomized controlled trial).pt. 10. (randomized or randomised).ab,ti. 11. placebo.ab,ti. 12. dt.fs. 13. randomly.ab,ti. 14. trial.ab,ti. 15. groups.ab,ti. 16. or/9‐15 17. Animals/ 18. Humans/ 19. 17 not (17 and 18) 20. 16 not 19 21. 8 and 20
Embase (Ovid)
1. exp coughing/ 2. cough$.tw. 3. 1 or 2 4. exp "speech and language rehabilitation"/ 5. ((speech$ or language$) adj5 (therap$ or treatment$ or interven$ or program$ or train$ or exercise$ or rehabilit$)).tw. 6. SLT.ti,ab. 7. or/4‐6 8. 3 and 7 9. Randomized Controlled Trial/ 10. randomization/ 11. controlled clinical trial/ 12. Double Blind Procedure/ 13. Single Blind Procedure/ 14. Crossover Procedure/ 15. (clinica$ adj3 trial$).tw. 16. ((singl$ or doubl$ or trebl$ or tripl$) adj3 (mask$ or blind$ or method$)).tw. 17. exp Placebo/ 18. placebo$.ti,ab. 19. random$.ti,ab. 20. ((control$ or prospectiv$) adj3 (trial$ or method$ or stud$)).tw. 21. (crossover$ or cross‐over$).ti,ab. 22. or/9‐21 23. exp animals/ or exp invertebrate/ or animal experiment/ or animal model/ or animal tissue/ or animal cell/ or nonhuman/ 24. human/ or normal human/ or human cell/ 25. 23 and 24 26. 23 not 25 27. 22 not 26 28. 8 and 27
CINAHL (EBSCO)
S1 (MH "Cough") S2 cough* S3 S1 OR S2 S4 (MH "Rehabilitation, Speech and Language+") S5 ((speech* OR language*) n5 (therap* OR treatment* OR interven* OR program* OR train* OR exercise* OR rehabilit*)) S6 SLT S7 S4 OR S5 OR S6 S8 S3 AND S7 S9 (MH "Clinical Trials+") S10 randomized or randomised S11 placebo* S12 randomly S13 clinical* n3 (trial* or study or studies) S14 (single* or double* or triple*) n3 blind* S15 S9 OR S10 OR S11 OR S12 OR S13 OR S14 S16 S8 AND S15
ClinicalTrials.gov
| Search field | Search terms |
| condition | cough |
| intervention | speech or language |
| Study type | interventional |
WHO ICTRP
| Search field | Search terms |
| condition | Cough |
| Intervention | Speech OR language |
Data and analyses
Comparison 1. Speech and language therapy versus healthy lifestyle advice.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 1 Health‐related quality of life (Leicester Cough Questionnaire) | 1 | Mean Difference (Fixed, 95% CI) | Subtotals only | |
| 2 Serious adverse events | 1 | 75 | Odds Ratio (M‐H, Fixed, 95% CI) | 0.0 [0.0, 0.0] |
| 3 Objective cough counts (e.g. using the Leicester Cough Monitor) | 1 | Geometric Mean (Fixed, 95% CI) | Subtotals only | |
| 4 Symptoms | 1 | Mean Difference (IV, Random, 95% CI) | Totals not selected | |
| 5 Clinical improvement (as defined by trialists) | 1 | Odds Ratio (M‐H, Random, 95% CI) | Totals not selected | |
| 6 Subjective measures of cough (e.g. visual analogue scale/numerical cough scale score) | 1 | Mean Difference (Fixed, 95% CI) | Subtotals only | |
| 7 Capsaicin cough challenge (to induce 5 coughs) | 1 | Geometric Mean (Fixed, 95% CI) | Subtotals only | |
| 8 Adverse events/side effects | 1 | 75 | Odds Ratio (M‐H, Fixed, 95% CI) | 0.0 [0.0, 0.0] |
Characteristics of studies
Characteristics of included studies [ordered by study ID]
Chamberlain Mitchell 2017.
| Methods | Multicentre, single‐blinded randomised controlled trial | |
| Participants | Treatment (PSALTI) group n = 34 (8 did not receive allocated intervention) Control group n = 41 (4 did not receive allocated intervention)
Trial report notes the groups were well matched at baseline, with the exception of SF‐36 PCS (higher in the control group). Inclusion criteria: Reported as: adults with chronic cough (defined as duration > 2 months), with normal chest X‐ray, minimal sputum production (< 10 mL sputum a day) with negative investigations and/or failed treatment trials for asthma, gastro‐oesophageal reflux disease, and rhinitis, as per British Thoracic Society guidelines Exclusion criteria: Reported as: patients were excluded if they had had an upper respiratory tract infection in the past 4 weeks, were taking ACE inhibitors, were current smokers, or had a known respiratory disease (such as lung cancer, pneumonia, pulmonary fibrosis, sarcoidosis, pleural effusion, bronchiectasis). Patients were also excluded if they had vocal cord nodules, malignancy, or evidence of active aspiration. |
|
| Interventions | PSALTI consisted of education, laryngeal hygiene and hydration, cough suppression techniques, breathing exercises, and psychoeducational counselling. Participants attended weekly sessions and received 1‐to‐1 treatment from a healthcare professional (physiotherapist or speech and language therapist) over 4 weeks. Session durations were the same as for the control group. Participants in the control group attended weekly sessions and received 1‐to‐1 standardised healthy lifestyle advice from a healthcare professional (nurse, physiotherapist, or speech and language therapist) over 4 weeks. The control intervention was based on that used in the trial reported by Vertigan 2006. The initial session covered general advice on exercise and physical activity; the second session dietary and nutritional advice; the third session stress management; and the fourth session relaxation. The material covered in each session was based on healthy lifestyle advised by the UK Department of Health and National Health Service. |
|
| Outcomes | Primary outcome(s):
Secondary outcomes:
Secondary endpoints were assessed at baseline, 4 weeks, and 3 months. Capsaicin cough challenge was assessed in a subset of the participants (King's College Hospital Foundation Trust and Northumbria Healthcare NHS Foundation Trust) to measure participants' cough reflex sensitivity at baseline and at 4 weeks (after fourth treatment session). |
|
| Notes | Study conducted across 3 hospitals in the UK (King's College Hospital NHS Foundation Trust, Lancashire Teaching Hospitals NHS Foundation Trust, and Northumbria Healthcare NHS Foundation Trust). 2 further sites, Royal Brompton & Harefield NHS Foundation Trust and Guy's and St Thomas' NHS Foundation Trust, were recruitment‐only sites, and participants were referred to King's College Hospital to receive the intervention. The study was undertaken between December 2011 and April 2014. Funded by: Chartered Society of Physiotherapy Charitable Trust, UK (Award PRF 10/4). Additional funding was obtained from NIHR‐CRN; King's College Hospital NHS Foundation Trust; London National Institute for Health Research (NIHR)/Wellcome Trust; King's Clinical Research Facility and the NIHR Biomedical Research Centre and Dementia Unit at South London and Maudsley NHS Foundation Trust and King's College London; National Institute for Health Research Biomedical Research Centre at Guy's and St Thomas' National Health Service (NHS) Foundation Trust and King's College London; NIHR Collaboration for Leadership in Applied Health Research and Care South London (CLAHRC South London). |
|
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Reported as: Participants were block‐randomised, stratified by age (above and below 50 years old) and gender by the King's Clinical Trials Unit, King's College London. |
| Allocation concealment (selection bias) | Low risk | Reported as: Participants were registered into the randomisation service provided by the King's Clinical Trials Unit, King's College London. This prevented foreknowledge of treatment assignment for the study researchers. Group allocation was concealed from participants until they had completed the study and all postintervention assessments. |
| Blinding of participants and personnel (performance bias) All outcomes | Unclear risk | Reported as: The study was single‐blinded. It was not possible to blind the treating therapist to the intervention the participant received. |
| Blinding of outcome assessment (detection bias) All outcomes | Low risk | Reported as: Potential bias was minimised by asking participants to complete their primary outcome measures independently from the treating therapist, and participants remained blinded until after completion of the final postintervention outcome measures. |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | Reported as: 75 participants were randomised and had baseline assessments. 1 additional participant was randomised to the PSALTI group but did not attend baseline assessments. 4 participants did not receive any treatment (PSALTI group (n = 3): myocardial infarction prior to treatment, unable to travel to hospital, and insufficient time for the study; control group (n = 1): undisclosed illness prior to start of treatment). |
| Selective reporting (reporting bias) | Unclear risk | No apparent indication of selective reporting, but we did not have access to trial protocols |
Vertigan 2006.
| Methods | Single‐blinded randomised controlled trial | |
| Participants | Treatment (SPEICH‐C) group n = 43 Control group n = 44
Trial report notes the groups were well balanced with respect to age, sex, reflux, ACE inhibitor use, allergies, asthma, postnasal drip syndrome, and smoking status. Inclusion criteria: Reported as: chronic cough was defined as the presence of chronic coughing that persisted for 2 months following medical treatment based on the approach recommended by Irwin 1998. The severity of the cough was sufficient for patients to seek medical attention from both general practitioner and respiratory physician. Patients had undergone respiratory case history, hypertonic saline challenge, and induced sputum analysis before inclusion in the study. Significant symptoms identified during the case history were subsequently investigated and treated. A minimum age of 18 years and ability to travel to John Hunter Hospital. Exclusion criteria: Reported as: recent upper respiratory tract infection, untreated allergy, PNDS, asthma, GER, eosinophilic bronchitis, lung pathology, abnormality on the chest radiograph, COPD, and neurological voice disorder. |
|
| Interventions | In the intervention group, participants received Speech Pathology Evaluation and Intervention for CHronic Cough (SPEICH‐C). The SPEICH‐C comprises 4 components including education about the nature of chronic cough, strategies to control the cough, psychoeducational counselling, and vocal hygiene education to reduce laryngeal irritation. These techniques were designed to improve the efficiency of voicing by reducing the load on the larynx while promoting adequate breath support and oral resonance. The education component emphasised the futility and negative side effects of repeated coughing, the benefits of cough suppression, and the capacity of individuals to develop voluntary control over cough. The cough suppression component required participants to anticipate when a cough was about to occur and then implement a strategy to suppress or replace the cough. The vocal hygiene component included strategies to reduce laryngeal irritation and maximise hydration in order to reduce stimulation of cough receptors. Relaxed throat breathing exercises were also provided for those participants with inspiratory dyspnoea. The psychological component was designed to facilitate internalisation of control over their cough and view the cough as something individuals do in response to irritating stimuli rather than a phenomenon outside the participant's control. In the control group, participants received an equivalent course of healthy lifestyle education. Participants in both groups attended 4 individual 30‐minute intervention sessions scheduled over a 2‐month period. |
|
| Outcomes | Outcomes:
A division between primary and secondary outcomes was not explicitly made in the trial report. |
|
| Notes | Study conducted at the John Hunter Hospital, New South Wales, Australia between April 2003 and October 2004. Funded by: The Hunter Medical Research Institute |
|
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Study randomised by random number generation. |
| Allocation concealment (selection bias) | Low risk | Reported as: The treating speech pathologist was not involved in the randomisation process; however, once the treatment group was allocated, the speech pathologist knew the participant's group allocation. Group allocation was concealed from participants until the postintervention symptom rating and clinical judgement of outcome had been recorded. |
| Blinding of participants and personnel (performance bias) All outcomes | Unclear risk | Reported as: Because of the single‐blinded design of this study and the nature of the intervention programmes, it was not possible to blind the treating speech pathologist to the type of intervention. |
| Blinding of outcome assessment (detection bias) All outcomes | Unclear risk | As above |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | Reported as: 1 participant in the treatment group and 4 in the placebo group did not commence their respective intervention programmes because of unexpected family responsibilities and spontaneous resolution of symptoms before treatment commenced. 3 participants in the treatment group and 2 in the placebo group discontinued intervention through failure to contact or attend appointments. |
| Selective reporting (reporting bias) | Unclear risk | No apparent indication of selective reporting, but we did not have access to trial protocols |
ACE: angiotensin‐converting‐enzyme; COPD: chronic obstructive pulmonary disease; GER: gastro‐oesophageal reflux; IQR: interquartile range; PNDS: postnasal drip syndrome; PSALTI: physiotherapy and speech and language therapy intervention; SD: standard deviation; SF‐36 PCS: the SF‐36 is a generic (rather than disease‐specific) 36‐item, patient‐reported health‐related quality of life scale; 'PCS' refers to the physical component score from the instrument (and excludes data from the mental component score); VAS: visual analogue scale
Characteristics of excluded studies [ordered by study ID]
| Study | Reason for exclusion |
|---|---|
| Ackerstaff 1995 | Not cough patients. No speech and language therapy intervention (comparison: heat and moisture exchangers intervention and no placebo) |
| Al‐Riyami 2001 | Cross‐sectional study using a questionnaire. Non‐randomised study. Non‐interventional. Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. |
| Bemanin 2015 | Cross‐sectional questionnaire study. Not a randomised trial. Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. |
| Benninger 2011 | Review. Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. |
| Birring 2017 | Review |
| Biswas 2015 | Retrospective (non‐randomised) study. Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. |
| Brady 2018 | Non‐randomised study. Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. |
| Cacciari 2017 | Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. Interventions do not include speech and language therapy techniques (non‐interventional study). |
| Carmel 2016 | Literature review. Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough and no speech and language therapy intervention. |
| Chamberlain 2013 | Review |
| Cholera 2016 | Review. Does not relate to a diagnosis of chronic unexplained (idiopathic/refractory) cough |
| Dart 2003 | Review. Does not relate to a diagnosis of chronic unexplained (idiopathic/refractory) cough |
| Faria 2014 | Retrospective case control study. Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. No speech and language therapy intervention and no randomisation |
| Fernandez 2015 | Non‐randomised study. Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. |
| Finck 2006 | Review. Not a randomised trial. Focus not on a diagnosis of chronic unexplained (idiopathic/refractory) cough |
| Gibson 2014 | Editorial |
| Gibson 2015 | Review |
| Gibson 2016 | Review |
| Goldstein 2007 | Case report. Not a randomised trial |
| Good 2018 | Not a randomised controlled trial |
| Harvey 2018 | Participant did not have a diagnosis of chronic cough. Single case report. Not a randomised trial |
| Hertegard 2002 | Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. No speech and language therapy intervention for chronic unexplained (idiopathic/refractory) cough (comparison: hylan B gel with no placebo arm) |
| Hilgers 1996 | Not a randomised study. Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. |
| Hilgers 2003 | Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. No speech and language therapy (comparison: reusable, multi‐magnet automatic speaking valve with no placebo arm) |
| Hull 2005 | Retrospective case review not relating to chronic unexplained (idiopathic/refractory) cough |
| Hunter 2011 | Non‐randomised study. Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. |
| Ihalainen 2015 | Non‐randomised study. Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. |
| Irons 2010 | Systematic review. Does not relate to participants with a diagnosis of chronic unexplained (idiopathic/refractory) cough |
| Irwin 2010 | Review. Not a randomised trial |
| Jensen 2013 | Non‐randomised study. No intervention. Not in participants with a diagnosis of chronic unexplained (idiopathic/refractory) cough |
| Kapela 2019 | Participants were randomised to receive either a standard speech pathology intervention or standard speech pathology intervention + supplemental pre‐recorded videos to support practice at home. The comparison was therefore not speech pathology intervention versus no intervention to evaluate the effectiveness of speech and language therapy for treatment of chronic cough. |
| Kew 2017 | Systematic review. Non‐randomised trial. Not in participants with a diagnosis of chronic unexplained (idiopathic/refractory) cough |
| Killoran 2012 | Review |
| Kyriakou 2018 | Participants did not have a diagnosis of chronic cough, and the study was not a randomised controlled trial. |
| Lukrafka 2010 | Cross‐sectional study. Not a randomised trial. Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. |
| Marques 2015 | Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. Interventions do not include speech and language therapy techniques. Intervention is pelvic floor/hip strengthening. |
| McGarvey 2013 | Review. Not specifically examining intervention of speech and language therapy in participants with a diagnosis of chronic unexplained (idiopathic/refractory) cough |
| Mellor 1998 | Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. No speech and language therapy intervention (comparison: bupivacaine versus ketorolac) |
| Mesia 2010 | Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. No speech and language therapy intervention (comparison: cetuximab platinum‐fluorouracil versus platinum‐fluorouracil) |
| Michaudet 2017 | Review |
| Molassiotis 2010 | Systematic review. Non‐randomised. Not specifically examining effect of speech and language therapy in chronic unexplained (idiopathic/refractory) cough. |
| Morice 2017 | Review. Focus is not on a diagnosis of chronic unexplained (idiopathic/refractory) cough in patients who have undergone a full diagnostic workup to exclude an underlying cause, as per published guidelines or local protocols. |
| NCT03457610 | Not a randomised trial |
| Oner 2013 | Not a randomised trial |
| Oskam 2013 | Non‐randomised trial. Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. |
| Park 2017 | Not a randomised study. Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. |
| Patterson 2007 | Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. No speech and language therapy intervention (comparison: miglustat versus usual care) |
| Perez 2011 | Non‐randomised study. Not in participants with a diagnosis of chronic unexplained (idiopathic/refractory) cough |
| Perez 2012 | Non‐randomised study. Not in participants with a diagnosis of chronic unexplained (idiopathic/refractory) cough |
| Plowman 2016 | Not in participants with a diagnosis of chronic unexplained (idiopathic/refractory) cough who have undergone a full diagnostic workup to exclude an underlying cause, as per published guidelines or local protocols. Interventions do not include speech and language therapy techniques (intervention is inspiratory‐expiratory exercise in amyotrophic lateral sclerosis). |
| Pohl 2012 | Review. Focus not on a diagnosis of chronic unexplained (idiopathic/refractory) cough. No speech and language therapy intervention |
| Raggi 2016 | Non‐randomised study. Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. Speech and language therapy intervention is on swallow rather than cough. |
| Reverberi 2019 | Participant did not have a diagnosis of chronic cough. Single case report. Not a randomised trial |
| Ryan 2009 | Non‐randomised study. No intervention. Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. |
| Ryan 2010 | Study not randomised |
| Ryan 2014 | Review |
| Ryan 2016 | Retrospective review of effect of amitriptyline on chronic unexplained (idiopathic/refractory) cough. No speech and language therapy intervention. Not a randomised trial |
| Sauni 2013 | Systematic review. Does not include participants with chronic unexplained (idiopathic/refractory) cough. No speech and language therapy intervention |
| Selby 2017 | Non‐randomised study |
| Shem 2012 | Cross‐sectional study. Not a randomised trial. Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. |
| Sitoh 2000 | Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. |
| Smithard 1998 | Not a randomised trial. Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. |
| Soria 2013 | Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. Interventions do not include speech and language therapy techniques (interventions were aimed at dysphagia). |
| Soria 2013a | Non‐randomised study. Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. |
| Suiter 2014 | Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. |
| Tong 2016 | Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. Interventions do not include speech and language therapy techniques (comparison: Impact of expiratory muscle strength training versus sham). |
| Vertigan 2007 | Review |
| Vertigan 2011 | Study not randomised |
| Vertigan 2012 | Review. Not a randomised trial |
| Vertigan 2014 | Non‐randomised study. Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. |
| Vertigan 2016 | Trial compares pregabalin in addition to speech pathology versus speech pathology alone and therefore does not meet our inclusion criteria. |
| Vertigan 2018 | Cross‐sectional non‐randomised study |
| Videnovic 2013 | Non‐randomised study. Review in Huntington’s disease (not chronic unexplained (idiopathic/refractory) cough). No speech and language therapy intervention |
| Weinberger 2010 | Review. Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. |
| Weinhardt 2008 | Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. Interventions do not include speech and language therapy techniques; no specific interventions; examines agreement between nurses and speech and language therapists in swallow assessments. |
| Wright 2012 | Not a randomised study. Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. |
| Wu 2017 | Case report. Not a randomised trial. Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. |
| Young 2008 | Case report. Not a randomised trial. Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. |
| Zhu 2013 | Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. |
| Zimmels 2015 | Not a randomised trial. Participants do not have a diagnosis of chronic unexplained (idiopathic/refractory) cough. |
| Zobeiri 2011 | Cross‐sectional questionnaire study. Not a randomised trial |
Contributions of authors
CS contributed to the Background and Methods sections; screened the titles and abstracts of the studies identified by the search and the full‐text study reports of all potentially eligible studies; and spot‐checked study characteristics entered into Review Manager 5 for accuracy against the study report. She also contributed to the Discussion, Authors' conclusions, and Abstract.
SBM contributed to the Background, Discussion, and Abstract.
SJM contributed to the Background and Methods sections; extracted study characteristics from included studies; independently extracted outcome data from included studies and entered the data into Review Manager 5; and independently assessed risk of bias for each study using the criteria outlined in the Cochrane Handbook for Systematic Reviews of Interventions. He also contributed to the Discussion, Authors' conclusions, and Abstract. In addition, he contributed to the 'Characteristics of included studies' and 'Characteristics of excluded studies' tables, the 'Summary of findings' table, and Figures.
SD contributed to the Background and Methods sections. He also contributed to the 'Characteristics of excluded studies' tables and Plain language summary.
JM contributed to the Background and Methods sections; extracted study characteristics from included studies, independently extracted outcome data from included studies and independently assessed risk of bias for each study using the criteria outlined in the Cochrane Handbook for Systematic Reviews of Interventions . She also contributed to the Discussion and Abstract.
AV contributed to the Background and Methods sections. He also contributed to the Discussion and Abstract.
PM contributed to the Background and Methods sections and screened the titles and abstracts of the studies identified by the search and the full‐text study reports of all potentially eligible studies. He also contributed to the Discussion, Authors' conclusions, and Abstract.
Contributions of editorial team
Rebecca Fortescue (Co‐ordinating Editor): edited the review; advised on methodology, interpretation, and content; approved the final review prior to publication. Chris Cates (Co‐ordinating Editor) checked the data entry prior to the full write‐up of the review. Emma Dennett (Managing Editor): co‐ordinated the editorial process; advised on interpretation and content; edited the review. Emma Jackson (Assistant Managing Editor): conducted peer review; edited the Plain language summary and References sections of the protocol and the review. Elizabeth Stovold (Information Specialist): designed the search strategy; ran the searches; edited the Search methods section.
Sources of support
Internal sources
The authors declare that no such funding was received for this systematic review, Other.
External sources
The authors declare that no such funding was received for this systematic review, Other.
Declarations of interest
CS: A donation, with no further requirement was provided by Breas Medical for a separate study to look at purchasing a dedicated laryngoscopy equipment to visualise the larynx during application of a cough assist device. This is to look at patterns of laryngeal behaviour when using the device, and so may help participants who initially do not tolerate it, and may help quality of life for participants with bulbar symptoms who then go onto have weak, ineffectual cough, but cannot tolerate mechanical insufflation‐exsufflation. I have received honoraria payments for study days undertaken in my own time unrelated to this project, looking at laryngeal patterns and upper airways dysfunction for long‐term tracheostomy weaning.
SBM: None known.
SJM: None known.
SD: None known.
JM: None known.
AV: I have had support to attend International meetings and the Winter national British Thoracic Society meeting from various Pharma groups. I have had direct payments to support GP education in asthma predominantly discussing effective assessment and inhaler therapy. These payments are unrelated to the review.
PM: Paul has accepted lecture fees and conference accommodation/fees, but these are unrelated to the current review.
New
References
References to studies included in this review
Chamberlain Mitchell 2017 {published data only}
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