OA11.03. Mediators of the effects of yoga and stretching on chronic low back pain (cLBP) outcomes: results from the YES RCT

Yoga for chronic non-specific low back pain

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 recommend exercise therapy. Yoga is a mind-body exercise sometimes used for non-specific low back pain.

OBJECTIVES

To evaluate the benefits and harms of yoga for treating chronic non-specific low back pain in adults compared to sham yoga, no specific treatment, a minimal intervention (e.g. education), or another active treatment, focusing on pain, function, quality of life, and adverse events.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search date was 31 August 2021 without language or publication status restrictions.

SELECTION CRITERIA

We included randomized controlled trials of yoga compared to sham yoga, no intervention, any other intervention and yoga added to other therapies.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methods. Our major outcomes were 1. back-specific function, 2. pain, 3. clinical improvement, 4. mental and physical quality of life, 5. depression, and 6.

ADVERSE EVENTS

Our minor outcome was 1. work disability. We used GRADE to assess certainty of evidence for the major outcomes.

MAIN RESULTS

We included 21 trials (2223 participants) from the USA, India, the UK, Croatia, Germany, Sweden, and Turkey. Participants were recruited from both clinical and community settings. Most were women in their 40s or 50s. Most trials used iyengar, hatha, or viniyoga yoga. Trials compared yoga to a non-exercise control including waiting list, usual care, or education (10 trials); back-focused exercise such as physical therapy (five trials); both exercise and non-exercise controls (four trials); both non-exercise and another mind-body exercise (qigong) (one trial); and yoga plus exercise to exercise alone (one trial). One trial comparing yoga to exercise was an intensive residential one-week program, and we analyzed this trial separately. All trials were at high risk of performance and detection bias because participants and providers were not blinded to treatment, and outcomes were self-assessed. We found no trials comparing yoga to sham yoga. Low-certainty evidence from 11 trials showed that there may be a small clinically unimportant improvement in back-specific function with yoga (mean difference [MD] -1.69, 95% confidence interval [CI] -2.73 to -0.65 on the 0- to 24-point Roland-Morris Disability Questionnaire [RMDQ], lower = better, minimal clinically important difference [MCID] 5 points; 1155 participants) and moderate-certainty evidence from nine trials showed a clinically unimportant improvement in pain (MD -4.53, 95% CI -6.61 to -2.46 on a 0 to 100 scale, 0 no pain, MCID 15 points; 946 participants) compared to no exercise at three months. Low-certainty evidence from four trials showed that there may be a clinical improvement with yoga (risk ratio [RR] 2.33, 95% CI 1.46 to 3.71; assessed as participant rating that back pain was improved or resolved; 353 participants). Moderate-certainty evidence from six trials showed that there is probably a small improvement in physical and mental quality of life (physical: MD 1.80, 95% CI 0.27 to 3.33 on the 36-item Short Form [SF-36] physical health scale, higher = better; mental: MD 2.38, 95% CI 0.60 to 4.17 on the SF-36 mental health scale, higher = better; both 686 participants). Low-certainty evidence from three trials showed little to no improvement in depression (MD -1.25, 95% CI -2.90 to 0.46 on the Beck Depression Inventory, lower = better; 241 participants). There was low-certainty evidence from eight trials that yoga increased the risk of adverse events, primarily increased back pain, at six to 12 months (RR 4.76, 95% CI 2.08 to 10.89; 43/1000 with yoga and 9/1000 with no exercise; 1037 participants). For yoga compared to back-focused exercise controls (8 trials, 912 participants) at three months, we found moderate-certainty evidence from four trials for little or no difference in back-specific function (MD -0.38, 95% CI -1.33 to 0.62 on the RMDQ, lower = better; 575 participants) and very low-certainty evidence from two trials for little or no difference in pain (MD 2.68, 95% CI -2.01 to 7.36 on a 0 to 100 scale, lower = better; 326 participants). We found very low-certainty evidence from three trials for no difference in clinical improvement assessed as participant rating that back pain was improved or resolved (RR 0.97, 95% CI 0.72 to 1.31; 433 participants) and very low-certainty evidence from one trial for little or no difference in physical and mental quality of life (physical: MD 1.30, 95% CI -0.95 to 3.55 on the SF-36 physical health scale, higher = better; mental: MD 1.90, 95% CI -1.17 to 4.97 on the SF-36 mental health scale, higher = better; both 237 participants). No studies reported depression. Low-certainty evidence from five trials showed that there was little or no difference between yoga and exercise in the risk of adverse events at six to 12 months (RR 0.93, 95% CI 0.56 to 1.53; 84/1000 with yoga and 91/1000 with non-yoga exercise; 640 participants).

AUTHORS' CONCLUSIONS

There is low- to moderate-certainty evidence that yoga compared to no exercise results in small and clinically unimportant improvements in back-related function and pain. There is probably little or no difference between yoga and other back-related exercise for back-related function at three months, although it remains uncertain whether there is any difference between yoga and other exercise for pain and quality of life. Yoga is associated with more adverse events than no exercise, but may have the same risk of adverse events as other exercise. In light of these results, decisions to use yoga instead of no exercise or another exercise may depend on availability, cost, and participant or provider preference. Since all studies were unblinded and at high risk of performance and detection bias, it is unlikely that blinded comparisons would find a clinically important benefit.

Yoga treatment for chronic non-specific low back pain

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 function at three months (SMD -0.22, 95% CI -0.65 to 0.20; corresponding to a change in the Roland-Morris Disability Questionnaire of MD -0.99, 95% -2.87 to 0.90) and six months (SMD -0.20, 95% CI -0.59 to 0.19; corresponding to a change in the Roland-Morris Disability Questionnaire of MD -0.90, 95% -2.61 to 0.81), and no information on back-related function after six months. There was very low-certainty evidence for lower pain on a 0-100 scale at seven months (MD -20.40, 95% CI -25.48 to -15.32), and no information on pain at three months or after seven months. Based on information from three trials, there was low-certainty evidence for no difference in the risk of adverse events between yoga and non-yoga exercise controls (RD 1%, 95% CI -4% to 6%).For yoga added to exercise compared to exercise alone (1 trial; 24 participants), there was very-low-certainty evidence for little or no difference at 10 weeks in back-related function (SMD -0.60, 95% CI -1.42 to 0.22; corresponding to a change in the Oswestry Disability Index of MD -17.05, 95% -22.96 to 11.14) or pain on a 0-100 scale (MD -3.20, 95% CI -13.76 to 7.36). There was no information on outcomes at other time points. There was no information on adverse events.Studies provided limited evidence on risk of clinical improvement, measures of quality of life, and depression. There was no evidence on work-related disability.

AUTHORS' CONCLUSIONS

There is low- to moderate-certainty evidence that yoga compared to non-exercise controls results in small to moderate improvements in back-related function at three and six months. Yoga may also be slightly more effective for pain at three and six months, however the effect size did not meet predefined levels of minimum clinical importance. It is uncertain whether there is any difference between yoga and other exercise for back-related function or pain, or whether yoga added to exercise is more effective than exercise alone. Yoga is associated with more adverse events than non-exercise controls, but may have the same risk of adverse events as other back-focused exercise. Yoga is not associated with serious adverse events. There is a need for additional high-quality research to improve confidence in estimates of effect, to evaluate long-term outcomes, and to provide additional information on comparisons between yoga and other exercise for chronic non-specific low back pain.