Current evidence suggests that yoga may improve back-specific functional status, pain, clinical symptoms and physical and mental quality of life compared to no exercise in adults with chronic non-specific low back pain. Yoga may also reduce pain and improve physical and mental quality of life compared to other exercise. However, yoga may be associated with more adverse events than no exercise (although not in comparison to other exercise). Of note, effect sizes were small to moderate and many did not meet clinical significance. The review had no significant methodological weaknesses. Further, well-designed randomised controlled trials are required to improve confidence in and generate longer-term data for the effects of yoga in the treatment of chronic non-specific low back pain in adults.
Overall summary Low risk of bias in the review
All domains were considered at low concern.
|A. Did the interpretation of findings address all of the concerns identified in Domains 1 to 4?||Probably yes|
|B. Was the relevance of identified studies to the review's research question appropriately considered?||Probably yes|
|C. Did the reviewers avoid emphasizing results on the basis of their statistical significance?||Probably yes|
|Risk of bias in the review||Low|
|Number of studies||12|
|Number of participants||1,080|
|Last search date||11th March 2016|
|Objective||To evaluate the effects of yoga for treating chronic non-specific low back pain compared to no specific treatment, a minimal intervention (education), or another active treatment, with a focus on pain, function and adverse events.|
|Population||Adults (≥18 years of age) with current chronic non-specific low back pain.|
|Interventions||Yoga or yoga plus any intervention at any dose, frequency or duration.
Studies in which interventions based on yoga (stretching exercises based on yoga), but which were not characterised as yoga were excluded.
|Comparator||Any other intervention or no intervention, specifically including: no treatment or a waiting list, a minimal intervention (booklets, lectures, or other educational interventions), usual care (non-exercise controls), active interventions (drugs, manipulation and exercise controls) or interventions alone for combined yoga plus intervention therapies.|
|Outcome||Primary outcomes: back-specific functional status; pain.
Secondary outcomes: clinical improvement; mental or physical quality of life; work disability; adverse events.
|Study design||Randomised controlled trials.
Quasi-randomised trials were excluded.
In terms of back-specific functional status, pooled analysis reported that back-specific functional status (measured using Roland-Morris disability questionnaire) was improved with yoga compared to non-exercise control groups at four to six weeks (standardised mean difference (SMD) = -0.45, 95% confidence interval (CI) -0.71 to - 0.19; 5 studies, n=256 participants), at three to four months (SMD = -0.40, 95% CI -0.66 to -0.14; 7 studies, n=667 participants), at six months (SMD = -0.44, 95% CI -0.66 to -0.22; 6 studies, n=630 participants) and at 12 months (SMD = -0.26, 95% CI -0.46 to -0.05; 2 studies, n=365 participants) in adults with current chronic non-specific low back pain.
Pooled analysis reported no difference in back-specific functional status for yoga compared to exercise at six weeks (SMD = -0.02, 95% CI -0.41 to 0.37; two studies, n=248 participants), at three months (SMD = -0.22, 95% CI -0.65 to 0.20; two studies, n=249 participants) and at six months (SMD = -0.20, 95% CI -0.59 to 0.19; two studies, n=249 participants).
In terms of pain, pooled analysis reported a reduction in pain for yoga at four to six weeks (mean difference (MD) = -10.83, 95% CI -20.85 to -0.81; two studies, n=40 participants), at three to four months (MD = -4.55, 95% CI -7.04 to -2.06; five studies, n=458 participants) and at six months (MD = -7.81, 95% CI -13.37 to -2.25; four studies, n=414 participants) compared to non-exercise controls. At 12 months, pooled analysis reported no difference in pain for yoga compared to non-exercise controls; however, this evidence was very uncertain (MD = -5.40, 95% CI -14.50 to 3.70; 2 studies, n=355 participants).
A single study reported a reduction in pain in participants who practised yoga compared to exercise at four weeks (MD = -15.00, 95% CI -19.90 to -10.10; 1 study, n=54 participants) and at seven months (MD = -20.40, 95% CI -25.48 to -15.32; 1 study, n=54 participants).
In terms of clinical improvement, pooled analysis reported clinical improvement in participants who practised yoga at four to six weeks (risk ratio (RR) = 2.62, 95% CI 1.22 to 5.67; n=141 participants), three to four months (RR=3.18, 95% CI 1.86 to 5.44; three studies, n=168 participants), and at six months (RR=2.53, 95% CI 1.36 to 4.71; one study, n=128 participants) `compared to non-exercise controls.
A single study reported no difference in clinical improvement for yoga compared to exercise at 6 weeks (RR = 1.02, 95% CI 0.67 to 1.57; 1 study, n=164 participants), 3 months (RR 1.30, 95% CI 0.96 to 1.75; 1 study, n=162 participants) or 6 months (RR = 0.99, 95% CI 0.73 to 1.33; 1 study, n=163 participants).
In terms of physical quality of life, pooled analysis reported an improvement in physical quality of life with yoga at three months (SMD=0.22, 95% CI 0.00 to 0.44; 3 studies, n=323 participants) compared to non-exercise controls. Similarly, a single study reported an improvement in physical quality of life with yoga at six months (SMD=0.26, 95% CI 0.01 to 0.50; 1 study, n=259 participants) compared to non-exercise controls.
A single study reported an improvement in physical quality of life for yoga compared to exercise at four weeks (SMD = 1.68, 95% CI 1.06 to 2.31; 1 study, n=54 participants) and at seven months (SMD = 1.34, 95% CI 0.75 to 1.94; 1 study, n=54 participants).
In terms of mental quality of life, a single study reported a decrease in depression at 4 to 6 weeks (SMD = -1.23, 95% CI -2.39 to -0.06; 1 study, n=16 participants), at six months (SMD -0.47, 95% CI -0.89 to -0.05; 1 study, n=90 participants) and at 12 months (SMD -0.50, 95% CI -0.92 to -0.08; 1 study, n=90 participants) compared to non-exercise controls. However, one study reported no difference in depression at 3 months compared to non-exercise controls (SMD = -0.15, 95% CI -0.49 to 0.19; 1 study, n=132 participants).
A single study reported an improvement in mental quality of life for yoga compared to exercise at four weeks (SMD = 0.79, 95% CI 0.24 to 1.35; 1 study, n=54 participants) and at seven months (SMD = 1.33, 95% CI 0.74 to 1.92; 1 study, n=54 participants).
In terms of adverse events, pooled analysis reported an increase in the risk of adverse events for yoga compared to non-exercise controls (risk difference (RD) = 0.05, 95% CI 0.02 to 0.08; 6 studies, n=696 participants).
Pooled analysis reported no difference in the risk of adverse events for yoga compared to exercise (RD 0.01, 95% CI 0.04 to 0.06; 3 studies, n=314 participants).
The eligibility criteria were well described and appeared appropriate to address the review question. No restrictions were reported based on study characteristics or sources of information.
|1.1 Did the review adhere to pre-defined objectives and eligibility criteria?||Probably yes|
|1.2 Were the eligibility criteria appropriate for the review question?||Probably yes|
|1.3 Were eligibility criteria unambiguous?||Probably yes|
|1.4 Were all restrictions in eligibility criteria based on study characteristics appropriate (e.g. date, sample size, study quality, outcomes measured)?||Probably yes|
|1.5 Were any restrictions in eligibility criteria based on sources of information appropriate (e.g. publication status or format, language, availability of data)?||Probably yes|
|Concerns regarding specification of study eligibility criteria||Low|
CENTRAL (which included the Cochrane Back and Neck group trials register (the Cochrane Library, 2016, Issue 2)), MEDLINE (OvidSP, 1946 to March week 1 2016), MEDLINE In-Process & Other Non-Indexed Citations (OvidSP, March 2016), EMBASE (OvidSP, 1980 to 2016 week 10); Cumulative Index to Nursing and Allied Health Literature (CINAHL) (EBSCO, 1981 to March 2016), PsycINFO (OvidSP, 2002 to March week 2 2016), Allied and Complementary Medicine Database (AMED) (OvidSP, 1985 to March 2016), CBN Trials Register (Cochrane Register of Studies), Cochrane Complementary Medicine Field Trials Specialised Register (Cochrane Register of Studies Online), IndMED, PubMed, US National Institutes of Health ClinicalTrials.gov, World Health Organisation (WHO) International Clinical Trials Registry Platform were searched for relevant studies. The reference lists of eligible studies were screened and experts (authors of included studies) in the field were contacted for information on additional trials, which included unpublished or ongoing studies. The full search strategy was provided and found to be appropriate. The searches were not restricted by date, publication format or language. Two review authors were independently involved in the study selection process, and disagreements weere resolved by consensus or by consultation with a third author.
|2.1 Did the search include an appropriate range of databases/electronic sources for published and unpublished reports?||Probably yes|
|2.2 Were methods additional to database searching used to identify relevant reports?||Probably yes|
|2.3 Were the terms and structure of the search strategy likely to retrieve as many eligible studies as possible?||Probably yes|
|2.4 Were restrictions based on date, publication format, or language appropriate?||Yes|
|2.5 Were efforts made to minimise error in selection of studies?||Yes|
|Concerns regarding methods used to identify and/or select studies||Low|
Two review authors were independently involved in the data extraction process. Disagreements between them were resolved by consensus. Sufficient study characteristics appeared to have been extracted to allow interpretation of the results. The study results were appropriately collected for the synthesis. Methodological quality of the included studies was assessed using an adapted version of the Cochrane risk of bias assessment tool; this appeared appropriate. Two review authors were independently involved in the risk of bias assessment, and disagreements were resolved by consensus.
|3.1 Were efforts made to minimise error in data collection?||Yes|
|3.2 Were sufficient study characteristics considered for both review authors and readers to be able to interpret the results?||Probably yes|
|3.3 Were all relevant study results collected for use in the synthesis?||Probably yes|
|3.4 Was risk of bias (or methodological quality) formally assessed using appropriate criteria?||Probably yes|
|3.5 Were efforts made to minimise error in risk of bias assessment?||Yes|
|Concerns regarding methods used to collect data and appraise studies||Low|
The synthesis appeared to include all eligible studies. The method of analysis was explained and appeared appropriate. Heterogeneity was assessed and found to be moderate or substantial for some outcomes. Subgroup analysis was not possible due to limited study numbers. Sensitivity analysis was performed to test the robustness of findings. The quality of individual studies was considered in the synthesis. Assessment of publication bias using funnel plots was not possible since there were insufficient study numbers.
|4.1 Did the synthesis include all studies that it should?||Probably yes|
|4.2 Were all pre-defined analyses reported or departures explained?||Probably yes|
|4.3 Was the synthesis appropriate given the degree of similarity in the research questions, study designs and outcomes across included studies?||Probably yes|
|4.4 Was between-study variation minimal or addressed in the synthesis?||Probably yes|
|4.5 Were the findings robust, e.g. as demonstrated through funnel plot or sensitivity analyses?||Probably yes|
|4.6 Were biases in primary studies minimal or addressed in the synthesis?||Yes|
|Concerns regarding synthesis and findings||Low|
Background: Non-specific low back pain is a common, potentially disabling condition usually treated with self-care and non-prescription medication. For chronic low back pain, current guidelines state that exercise therapy may be beneficial. Yoga is a mind-body exercise sometimes used for non-specific low back pain.Objectives: To assess the effects of yoga for treating chronic non-specific low back pain, compared to no specific treatment, a minimal intervention (e.g. education), or another active treatment, with a focus on pain, function, and adverse events.Search methods: We searched CENTRAL, MEDLINE, Embase, five other databases and four trials registers to 11 March 2016 without restriction of language or publication status. We screened reference lists and contacted experts in the field to identify additional studies.Selection criteria: We included randomized controlled trials of yoga treatment in people with chronic non-specific low back pain. We included studies comparing yoga to any other intervention or to no intervention. We also included studies comparing yoga as an adjunct to other therapies, versus those other therapies alone.Data collection and analysis: Two authors independently screened and selected studies, extracted outcome data, and assessed risk of bias. We contacted study authors to obtain missing or unclear information. We evaluated the overall certainty of evidence using the GRADE approach.Main results: We included 12 trials (1080 participants) carried out in the USA (seven trials), India (three trials), and the UK (two trials). Studies were unfunded (one trial), funded by a yoga institution (one trial), funded by non-profit or government sources (seven trials), or did not report on funding (three trials). Most trials used Iyengar, Hatha, or Viniyoga forms of yoga. The trials compared yoga to no intervention or a non-exercise intervention such as education (seven trials), an exercise intervention (three trials), or both exercise and non-exercise interventions (two trials). All trials were at high risk of performance and detection bias because participants and providers were not blinded to treatment assignment, and outcomes were self-assessed. Therefore, we downgraded all outcomes to 'moderate' certainty evidence because of risk of bias, and when there was additional serious risk of bias, unexplained heterogeneity between studies, or the analyses were imprecise, we downgraded the certainty of the evidence further.For yoga compared to non-exercise controls (9 trials; 810 participants), there was low-certainty evidence that yoga produced small to moderate improvements in back-related function at three to four months (standardized mean difference (SMD) -0.40, 95% confidence interval (CI) -0.66 to -0.14; corresponding to a change in the Roland-Morris Disability Questionnaire of mean difference (MD) -2.18, 95% -3.60 to -0.76), moderate-certainty evidence for small to moderate improvements at six months (SMD -0.44, 95% CI -0.66 to -0.22; corresponding to a change in the Roland-Morris Disability Questionnaire of MD -2.15, 95% -3.23 to -1.08), and low-certainty evidence for small improvements at 12 months (SMD -0.26, 95% CI -0.46 to -0.05; corresponding to a change in the Roland-Morris Disability Questionnaire of MD -1.36, 95% -2.41 to -0.26). On a 0-100 scale there was very low- to moderate-certainty evidence that yoga was slightly better for pain at three to four months (MD -4.55, 95% CI -7.04 to -2.06), six months (MD -7.81, 95% CI -13.37 to -2.25), and 12 months (MD -5.40, 95% CI -14.50 to -3.70), however we pre-defined clinically significant changes in pain as 15 points or greater and this threshold was not met. Based on information from six trials, there was moderate-certainty evidence that the risk of adverse events, primarily increased back pain, was higher in yoga than in non-exercise controls (risk difference (RD) 5%, 95% CI 2% to 8%).For yoga compared to non-yoga exercise controls (4 trials; 394 participants), there was very-low-certainty evidence for little or no difference in back-related funct