An evidence map of yoga for low back pain

Complementary Therapies in Medicine 25 (2016) 170–177

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Complementary Therapies in Medicine journal homepage: www.elsevierhealth.com/journals/ctim

An evidence map of yoga for low back pain Adam P. Goode a,b,∗ , Remy R. Coeytaux b , Jennifer McDuffie c,d , Wei Duan-Porter c,d , Poonam Sharma d , Hillary Mennella e , Avishek Nagi c , John W. Williams Jr. c,d a

Department of Orthopedic Surgery, Duke University Medical Center, 2200 West Main Street, Durham, NC 27705, United States Duke Clinical Research Institute, Duke University Medical Center, 2400 Pratt Street, Durham, NC 27705, United States Durham Center for Health Services Research in Primary Care and Evidence Synthesis Program, Durham VA Medical Center, 508 Fulton Street, Durham, NC 27705, United States d Division of General Internal Medicine, Department of Medicine, Duke University Medical Center, 411 West Chapel Hill Street, Suite 500, Durham, NC 27701, United States e Duke University School of Nursing, 307 Trent Drive, Durham, NC 27710, United States b c

a r t i c l e

i n f o

Article history: Received 2 April 2015 Received in revised form 21 December 2015 Accepted 26 February 2016 Available online 3 March 2016 Keywords: Yoga Low back pain Evidence mapping

a b s t r a c t Objective: Yoga is being increasingly studied as a treatment strategy for a variety of different clinical conditions, including low back pain (LBP). We set out to conduct an evidence map of yoga for the treatment, prevention and recurrence of acute or chronic low back pain (cLBP). Methods: We searched Medline, Cochrane Database of Systematic Reviews, EMBASE, Allied and Complementary Medicine Database and ClinicalTrials.gov for randomized controlled trials (RCT), systematic reviews or planned studies on the treatment or prevention of acute back pain or cLBP. Two independent reviewers screened papers for inclusion, extracted data and assessed the quality of included studies. Results: Three eligible systematic reviews were identified that included 10 RCTs (n = 956) that evaluated yoga for non-specific cLBP. We did not identify additional RCTs beyond those included in the systematic reviews. Our search of ClinicalTrials.gov identified one small (n = 10) unpublished trial and one large (n = 320) planned clinical trial. The most recent good quality systematic review indicated significant effects for short- and long-term pain reduction (n = 6 trials; standardized mean difference [SMD] −0.48; 95% CI, −0.65 to −0.31; I2 = 0% and n = 5; SMD −0.33; 95% CI, −0.59 to −0.07; I2 = 48%, respectively). Longterm effects for back specific disability were also identified (n = 5; SMD −0.35; 95% CI, −0.55 to −0.15; I2 = 20%). No studies were identified evaluating yoga for prevention or treatment of acute LBP. Conclusion: Evidence suggests benefit of yoga in midlife adults with non-specific cLBP for short- and long-term pain and back-specific disability, but the effects of yoga for health-related quality of life, wellbeing and acute LBP are uncertain. Without additional studies, further systematic reviews are unlikely to be informative. © 2016 Elsevier Ltd. All rights reserved.

Contents 1. 2.

3.

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 2.1. Data sources and search . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 2.2. Inclusion/exclusion criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 2.3. Data abstraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 2.4. Quality assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 2.5. Data synthesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172

∗ Corresponding author. Fax: +1 919 684 1846. E-mail addresses: [email protected] (A.P. Goode), [email protected] (R.R. Coeytaux), [email protected] (J. McDuffie), [email protected] (W. Duan-Porter), [email protected] (P. Sharma), [email protected] (H. Mennella), [email protected] (A. Nagi), [email protected] (J.W. Williams Jr.). http://dx.doi.org/10.1016/j.ctim.2016.02.016 0965-2299/© 2016 Elsevier Ltd. All rights reserved.

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4. 5.

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Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176 Conflicts of interest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176 Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176 Appendix A. Supplementary data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176

1. Introduction Chronic pain affects an estimated 100 million adults in the United States, resulting in annual costs of approximately $635 billion, including direct medical expenditures and work loss productivity.1 Low back pain (LBP) is a common cause for chronic symptoms with a lifetime prevalence of 39%.2 Although many patients undergo procedures to treat or correct pathoanatomy for low back pain, many continue to have chronic symptoms, which in turn may be due to multiple biologic and behavioral etiologies.3 As such, chronic low back pain (cLBP) is commonly referred to as a multidimensional condition with components of physical, psychological and social factors.4 Further, cLBP can progress beyond chronic symptoms to a state that includes persistent anatomic and functional changes in the central nervous system.5 Yoga is a term used to describe a collection of spiritual and physical practices originating in ancient India and used to cultivate deep meditative states in order to achieve greater union with the divine or true self.6 The key elements of yoga include breathing exercise (pranayama), postures (asanas) and meditation (dhyana).7 Protocols for trials of yoga applied to chronic pain management tend to incorporate Hatha yoga for relaxation and gentle postures, including Iyengar yoga for physical postures and breathing techniques.8,9 When reported, the adverse events for yoga to treat musculoskeletal conditions have been minimal and not serious.10 Evidence mapping is an emerging approach that uses descriptive epidemiology to characterize information for a broad area of medicine and identify gaps in the research.11–13 The aim of evidence mapping is to systematically examine the extent and range of research activity within scientific studies and may include many different study designs and reviews of the literature.14 Evidence mapping has been successfully conducted in complementary and alternative medicines since the early 2000’s. There is no shortage of the possible interventions for cLBP. These may include surgical, physical, behavioral and pharmaceutical approaches. However, these interventions as monotherapies have small effect sizes with limited support for long-term reduction in pain and increased function. Yoga has received considerable attention as a treatment approach for cLBP since it combines a treatment approach of both mental and physical factors. In this study, we present the results of our evidence map for yoga for the treatment, prevention and recurrence of acute or cLBP. 2. Methods This current review is part of a larger report for the Veterans Health Administration’s Evidence Synthesis Program to investigate existing evidence on yoga for common clinical conditions in the general population and among Veterans. The full report, which investigates several high impact conditions and provides greater detail regarding the methods, is available elsewhere.6 This review will focus on yoga and low back pain. 2.1. Data sources and search We conducted a librarian-assisted computerized search of PubMed, the Cochrane Database of Systematic Reviews, Embase,

and the Allied and Complementary Medicine Database (AMED) for systematic reviews and recent randomized controlled trials (RCTs) of yoga for low back pain. We used Medical Subject Headings (MeSH) terms and selected free-text terms for yoga, systematic reviews, randomized controlled trials and low back pain. The search strategies for this review are available in Appendix A. We also searched ClinicalTrials.gov for completed and ongoing clinical trials on yoga for low back pain. Searches were completed in July 2014. All results were tracked in both DistillerSR (Evidence Partners Inc.) and EndNote® (version X7, Thompson Reuters). 2.2. Inclusion/exclusion criteria We included systematic reviews published from 2008 forward that evaluated yoga for LBP. Our goal was to identify current systematic reviews, as prior studies have shown that reviews can become rapidly outdated.14 We also included RCTs (sample size ≥100 subjects) published since January 2011. The goal was to identify recent large RCTs that may not have been identified or published since the search date of published systematic reviews. To be included, participants must be adults with LBP (acute or chronic). There are numerous styles or lineages of yoga that were drawn from the traditions of the yoga sutras or Hatha yoga, and many of these have emerged in the past century. For the purposes of this review, we accepted any form of yoga as the active intervention, as identified by the authors of the primary studies. We excluded studies that did not have a specific focus on yoga or when yoga was only one of many interventions evaluated and the isolated effect of yoga was not demonstrated. Studies could have any inactive control (waitlist, attention, or information control; or unenhanced usual care) or active comparator. Health outcomes including symptom severity, health-related quality of life, global measures of well-being, and adverse effects were of interest. For systematic reviews, we accepted the outcome timing specified in the review’s eligibility criteria. 2.3. Data abstraction Data elements were abstracted into a customized Excel spreadsheet by one investigator and verified by a second. Disagreements were resolved by consensus or by obtaining a third investigator’s opinion when consensus could not be reached. Data elements included study characteristics (e.g., search date, eligibility criteria, or assessment for publication bias), synthesis methods (e.g., metaanalysis, sensitivity analyses), results (e.g., number and design of included primary studies, sample characteristics, intervention characteristics, treatment effects, or risk of bias assessments), funding source, conflict of interest, and authors’ conclusions. 2.4. Quality assessment We used the following key quality criteria adapted from the Quality of Reporting of Meta-analyses15 and Assessment of Multiple Systematic Reviews16 instruments to categorize each systematic review as good, fair, or poor quality based upon established criteria (Appendix B). Briefly, “good” quality indicates that none of the limitations are thought to decrease the validity of the review’s

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Table 1 Characteristics of systematic reviews evaluating yoga for low back pain. Characteristic

Cramer et al.10

Holtzman and Beggs21

Posadzki and Ernst22

Condition(s) Search date Databases searched

CLBP January 2012 PubMed Embase Cochrane Library CAMbase

CLBP November 2011 CINAHL MEDLINE Global health Cochrane central register of controlled trials Embase PsycINFO

CLBP March 2011 PubMed Cochrane central register of controlled trials Clinical trial registry of Indian council Embase CINAHL AMED PsycINFO

Study designs included Studies included Meta-analysis performed? Systematic review quality

RCTs 10 Yes Good

RCTs 8 Yes Good

RCTs 7 No Good

Abbreviation: RCTs = randomized controlled trials.

conclusions, “fair” quality denotes that there is some uncertainty about the validity, and “poor” quality is reserved for when there is serious uncertainty about the validity of conclusions. Quality assessment was conducted by one reviewer and verified by a second reviewer. Disagreements were resolved between the 2 investigators by discussion. We did not formally assess the quality of the primary literature; instead we relied on quality assessments as reported by the authors of the systematic reviews.

2.5. Data synthesis We used systematic reviews, prioritizing the most recent goodquality review, to qualitatively describe the number of studies, study designs, patient populations, intervention characteristics, and treatment effects together with any other RCTs identified. When systematic reviews conducted meta-analyses, they reported treatment effects as standardized mean differences (SMDs). SMDs of 0.2 can be considered small treatment effects; 0.5, moderate effects; and ≥0.8, large effects.17 Authors sometimes also reported Cochran’s Q and I2 statistics, which are measures of heterogeneity, or variability, in treatment effect. The I2 statistic describes the percentage of total variation across studies due to heterogeneity rather than to chance. We used the following scaling to determine the amount of I2 statistic identified heterogeneity. Studies with 0–40%: heterogeneity might not be important; 30–60%: may represent moderate heterogeneity; 50–90%: may represent substantial heterogeneity; and 75–100%: considerable heterogeneity.18 We created summary tables to describe the number of RCTs, study characteristics, and estimates of treatment effect across conditions. We used these data to make judgments about possible next steps: if no RCTs or only a few good-quality RCTs identified: consider RCTs. If >3 RCTs and no good-quality systematic review identified: consider a systematic review. If a good-quality systematic review along with subsequently published RCTs identified: consider using formal methods19,20 to determine the need for an updated review. If a good-quality systematic review, but no additional RCTs identified: consider surveillance of the primary literature to identify the need for an updated review.

3. Results Two hundred and ninety-six studies were identified through database searches. Ninety-seven unique titles and abstracts then were assessed for eligibility for inclusion, resulting in three appropriate systematic reviews.10,21,22 The process of study selection and the number of studies excluded at each stage, with reasons for exclusion is available in Fig. 1.

Table 2 Characteristics of RCTs evaluating yoga for low back pain included in Cramer et al.10 Characteristic

Studies (n = 10)

Condition Low back pain <3 months Low back pain ≥3 months Low back pain ≥6 months Low back pain ≥3 months plus a physical functional deficit

1 6 1 2

Population age Adults

10

Geographical region North America Europe Asia

6 2 2

Sample size 25–50 >50–100 >100

4 3 3

Yoga style Iyengar Hatha Viniyoga Other

3 2 2 3

Treatment duration ≤4 weeks 5–12 weeks >12 weeks

2 6 2

Treatment intensity <10 h 10–20 h

1 9

Timing of outcome assessmenta ≤3 months >3–6 months >6 months

3 6 5

Abbreviation: RCTs = randomized controlled trials. a Some studies assessed outcomes at multiple time points.

All 3 systematic reviews included only RCTs and were judged to be good quality. Details of the responses to each item of the quality assessment are available in Appendix C. Details of the included reviews are provided in Table 1. Each systematic review conducted a thorough search of the literature with relevant databases. Two of the 3 reviews conducted formal meta-analysis of included literature. The Cramer et al. review contained 10 RCTs and encompassed all of the RCTs included in the Holtzman and Beggs21 (n = 9) and Posadzki and Ernst22 (n = 7) reviews. We focus our results on the most recent, good-quality review by Cramer et al.10 that included 956 randomized patients with low back pain (Table 2). This review searched 5 computerized databases and the gray literature for eligible RCTs published through January

Identification

A.P. Goode et al. / Complementary Therapies in Medicine 25 (2016) 170–177

Records idenfied through Medline (n = 58), EMBASE (n=32), Cochrane (n=11), AMED (n=195)

173

Addional records idenfied through search of primary RCT’s (n = 0 )

Eligibility

Screening

Records aer duplicates removed (n = 97 )

Records screened (n =97 )

Full-text arcles assessed for eligibility (n = 27 )

Included

Studies included in qualitave synthesis (n = 3)

Records excluded (n =70 )

Full-text arcles excluded, with reasons (n = 24 ) -Published prior to 2008 (3) -Ineligible study design (3) -non English/original (10) -not condion of interest (1) -Not outcome of interest (2) -Intervenon not yoga (2) -RCTs <100 subjects (3)

Studies included in quantave synthesis (meta-analysis) (n = 0 ) Fig 1. Flow of study selection for included studies.

2012. The review included 10 RCTs that evaluated yoga compared with active or inactive controls in adult patients with a clinical diagnosis of low back pain of a nonspecific origin. Studies were published between 2004 and 2011 with 5 of the 10 studies being published in the past 5 years. Sample sizes for individual trials ranged from 12 to 313 with only 3 of the 10 studies having over 100 included subjects. The systematic review authors judged 8 RCTs to be at low risk of bias, and 2 to be at high risk of bias. Compliance with the intervention was found to be unclear or unacceptable in 4 of the 10 studies. Eligibility criteria allowed a range of symptom duration, pain intensity, and functional deficits. The review included trials of yoga interventions of any tradition, intensity, style, or duration. Other treatments (e.g., medications) concurrent with yoga were allowed in all trials. Studies were included if they reported one of the following patient-centered outcomes: pain, back-specific disability, quality of life, generic disability (e.g., activities of daily living, work absenteeism), and global improvement. Detailed study characteristics for the 10 RCTs are presented in Table 3. Most trials enrolled midlife adults (median age 48.0), and all focused specifically on cLBP. More women (median proportion 69.3%) than men were enrolled. Yoga was conducted by certified or experienced yoga teachers in 9 trials; the instructors’ qualifications were not clearly reported in one trial. The median number of hours planned for the yoga intervention was 15 (range 3–72), delivered in programs that ranged from 1 to 24 weeks (median 11 weeks). Eight studies reported a co-intervention with yoga. Cointerventions consisted of usual or routine care (n = 3), education (n = 3), and lifestyle and diet changes (n = 2). Most of the included studies used a 2-arm study design (n = 8); 2 studies used a 3-arm

design. In the 2-arm studies, yoga was compared with wait-list control (n = 3) plus routine care or education; standard care (n = 1); education (n = 1); lifestyle change (n = 1); or physical therapy and exercise (n = 1). In both 3-arm studies, yoga was compared with exercise in one arm and an educational intervention in the other. Three RCTs used exercise as a comparator. Short- and long-term outcomes were assessed at a median of 12 weeks (range 1 week to 6 months) for short-term outcomes (n = 10) and at a median of 28 weeks (range 26 weeks to 1 year) for long-term outcomes. In 9 of the 10 RCTs, the authors specified that certified or experienced teachers served as instructors. Cramer et al. computed summary estimates of treatment effects from 8 of the included studies (2 were excluded from meta-analysis due to insufficient data reporting) using a random-effects metaanalysis with RevMan 5.1 software.23 Statistical methods to assess publication bias were not used because there were too few studies in the final analyses. Meta-analysis showed consistent evidence for short-term benefits of yoga on pain (n = 6; SMD −0.48; 95% CI, −0.65 to −0.31; I2 = 0%). Long-term effects of yoga revealed evidence for reduction in pain (n = 5; SMD −0.33; 95% CI, −0.59 to −0.07; I2 = 48%) and back-specific disability (n = 5; SMD −0.35; 95% CI, -0.55 to −0.15; I2 = 20%). Yoga also improved short-term backspecific disability (n = 8; SMD −0.59; 95% CI, −0.87 to −0.30), but with moderate heterogeneity in treatment effects (I2 = 59%). No short-term (n = 4; SMD 0.41; 95% CI, −0.11 to 0.93) or long-term effect (n = 2; SMD 0.18; 95% CI, −0.05 to 0.41) was found for healthrelated quality of life. The review by Cramer et al. included separate analyses for both short- and long-term effects of yoga in comparison to usual care,

174

Table 3 Individual study characteristics of included systematic reviews. Country

N

Condition

Yoga style

Yoga elements

Yoga duration; yoga hours per week

Comparator

Age (SD); sex

Included in meta-analysis?

Cox et al.47

UK

20

LBP at least 3 months; RMDQ > 4; no spinal surgery

Specialized Iyengar for back pain (relaxation, postures)

Meditation, breathing, postures

WLC + booklet “the back book” + usual care for 12 week

45 65% female

Yes, short-term pain, back-specific disability and HRQOL

Galantino et al.8

USA

22

WLC; usual care allowed for 6 week

30–65 77.3% female

Yes, short-term back-specific disability

India

12

Hatha yoga (stretching postures, asanas, breathing, relaxation, meditation) Asanas, prayer, chanting, pranayama

Meditation, breathing, postures

Pushpika Attanayake et al.48

Meditation, breathing, postures

3 week, 60 min/week + lifestyle and dietary changes

Lifestyle and dietary changes (exercise, prayer, chanting); 3 week

30–49 NR

No, excluded due to high bias

Saper et al.24

USA

30

Hatha yoga (breathing, asanas, relaxation)

Meditation, breathing, postures

12 week, 75 min/week

WLC, routine care allowed + book for 12 week

44(13) 83% female

Yes, long- and short-term pain, back-specific disability, and HRQOL

Sherman et al.40

USA

101

LBP at least 6 months; min of 2 conservative treatments without long term relief LBP at least 3 week; no specific causes, no neurological symptoms; no major concomitant illness Muscular LBP at least 12 week; pain intensity 2 week before >4 (0–10 NRS); no back surgery within last 3 year Muscular LBP at least 12 week

12 week, 75 min weekly, homework regular practice + booklet “the back book” + usual care 6 week, 60 min 2×/week

Viniyoga (breathing, postures, relaxation)

Breathing, postures

12 week, 75 min/week

44(12) 66% female

No

Sherman et al.25

USA

228

Muscular LBP at least 12 week; bothersome >3 (0–10 NRS)

Viniyoga (breathing, postures, relaxation)

Breathing, postures

12 week 75 min/week

48.1 (9.8) NR

Yes, short- and long-term pain and back-specific disability

Tekur et al.28 andTekur et al.29

India

80

Yoga (meditation, chanting, physical practice, lectures)

Meditation, breathing, postures

1 week, daily practice + vegetarian diet

49 (3.6) 45% female

Tilbrook et al.26

UK

313

LBP at least 3 months; inpatients in a healthcare center; no radiating pain to the leg or organic pathology LBP at least 3 months RMDQ >4, no spine surgery

1. Exercise (education, aerobics and strengthen-ing) 12 week, 75 min/week 2. Book (exercise, fitness, lifestyle advice) for home use 12 week 1. Exercise (education, aerobic and strengthen-ing) 12 week, 75 min/week 2. Book (exercise, fitness, lifestyle advice) for home use 12 week PT exercise 1 week, daily practice + vegetarian diet

Meditation, breathing, postures

12 week, 75 min/week

WLC + back pain education book 12 week

46.3 (1.5) 70.3% female

Williams et al.27

USA

60

LBP at least 3 months, no organic origin

Yoga (asanas, pranaya-mas, relaxation, mental focus, philosophy Iyengar yoga

Postures

Education control; weekly newsletters on back care, 2 × 60-min lectures, handouts on PT for 16 week

48 (2) 68.2% female

Williams et al.49

USA

90

LBP at least 3 months. No organic origin

Iyengar yoga

Postures

16 week, 90 min/week; 30 min practice 5 days/week + weekly newsletters on back care and 2 × 60-min lectures with handouts 24 week, 90 min 2×/week; homework 30 min daily

Yes, short-term back-specific disability and HRQOL. Results from Tekur et al.28 and Tekur et al.29 combined. Yes, long- and short-term pain, back-specific disability and HRQOL Yes, short- and long-term pain and back-specific disability

Self-directed SMC 24 week

48 (11.1) 76.7% female

Yes, short- and long-term pain and back-specific disability

N = sample size, SD = standard deviation, UK = United Kingdom, LBP = low back pain, WK = week, RMDQ = Roland Morris Disability Questionnaire, WLC = wait list control, HRQOL = health related quality of life, USA = United States of America, NR = not reported, NRS = numeric pain rating scale, Min = minutes.

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education, or exercise. Yoga showed short-term benefit for low back pain, back-specific disability, and health-related quality of life compared with education. For the other comparators, there was not a consistent pattern of benefit for pain, disability and healthrelated quality of life. Over the longer term, yoga was beneficial for low back pain compared with education. In the review of cLBP by Cramer et al.,10 3 studies reported 26 adverse effects among 248 included participants.24–26 Most adverse effects were mild to moderate, while 3 were severe. Severe adverse effects consisted of a worsening of back pain,24 a new diagnosis of herniated disc,27 and 2 subjects discontinuing the study due to respiratory tract infections.28,29 The conclusions of all 3 systematic reviews were similar. Cramer et al. concluded: “This systematic review found strong evidence for short-term effectiveness and moderate evidence for long-term effectiveness of yoga for cLBP in the most important patientcentered outcomes. Given the low number of adverse events, yoga can be recommended as an additional therapy to patients who do not improve with education on self-care options.” The other 2 systematic reviews21,22 evaluated the same question and similar literature as Cramer et al., but did not add important additional information about the effect of yoga on cLBP. The review by Holtzman and Beggs concluded that “the results of the present study indicate that yoga may be an efficacious adjunctive treatment for cLBP.” Similar results for short- and long-term pain and backspecific function were found in Holtzman and Beggs compared with Cramer et al.; however, the review by Holtzman and Beggs did not assess short- or long-term effects of yoga on health-related quality of life among patients with cLBP. The review by Posadzki and Ernst concluded that “the evidence that yoga alleviates chronic [low back pain] in the majority of studies is positive.” Although we rated the review by Cramer et al.10 as good quality, there were some limitations. The subgroup analyses were conducted on small groups of studies—groups that fall below, by some sources, the recommended minimal threshold for these analyses.30 Decreased intervention compliance and dropout rates were found to be unclear or not acceptable in 4 out of 10 studies. Although a sensitivity analysis was conducted with a composite risk of bias score, no sensitivity analysis was conducted to specifically determine if attrition might have had a significant influence on pooled study estimates. Further, the subgroup analyses did not specify a level of significance for testing differences between the groups. These subgroup analyses should be considered exploratory, and the observed variability in treatment effects was not adequately explained. Additional RCTs with n ≥ 100 were not identified outside those included in the systematic reviews; 3 RCTs with n < 100 were identified, but are not considered here because they did not meet eligibility criteria.32–34 Our search of ClinicalTrials.gov identified one small (n = 10) completed but unpublished trial (NCT01963871) and one large (n = 320) planned active but not recruiting clinical trial (NCT01343927).

4. Discussion We conducted an evidence-mapping approach to search and describe published systematic reviews and RCTs for yoga in the treatment, prevention or recurrence of acute or chronic low back pain. Our search revealed 3 recent systematic reviews on yoga as an intervention for cLBP. All 3 of these reviews included only RCTs and were judged to be of good quality. A wide variety of different types of yoga were used and the focus of these studies was on the treatment of cLBP. Meta-analysis effect sizes for 2 of the 3 systematic reviews indicated a significant improvement in pain and function for the short term. We did not identify any additional completed RCTs that met our inclusion criteria. Nor did we identify any stud-

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ies that used yoga for the treatment or prevention of acute low back pain or cLBP. However, we did identify 2 unpublished clinical trials for yoga as a treatment approach for cLBP, one that has been completed and one that is ongoing s. Adverse events were rarely reported and when reported the majority presented were not serious. Evidence mapping originated out of identifying, synthesizing and reporting on complementary and alternative medicine in the early 2000’s.35 Since evidence mapping is in a relatively new phase of development, there is no consensus on the methodology. General principles have been articulated such as including involvement of experts in the field, methods for searching and appraising the evidence to inform decisions.35 We utilized an evidence mapping approach to a broad intervention topic, which can lead to substantial heterogeneity in a traditional systematic review approach. To involve experts in the field, our internal and external study team consisted of numerous researchers and instructors of yoga and our external review team consisted of experts on yoga as an intervention for cLBP. The internal and external study team, as well as key stakeholders, were involved in key question development, protocol development, final report drafting and dissemination. Our search employed multiple specific databases as well as a clinical trial registry. We also utilized a duplicate process of screening and inclusion of literature as well as with quality assessment to improve the reliability. To appraise the evidence we relied on the authors of individual reviews assessment of the primary literature but conducted quality assessment of the review itself using a well established quality criteria. Chronic low back pain has a substantial impact on physical function, psychosocial well-being and healthcare costs. As such, interventions to mitigate pain and decreased physical function are greatly needed. Exercise is a safe and moderately beneficial intervention for the treatment of cLBP.36 The majority of included RCTs in this mapping exercise utilized a type of yoga that incorporated a physical posture component, a specific type of exercise, for adults with chronic non-specific lower back pain. The evidence to support exercise in the treatment of cLBP is increasing. However, there are limitations in understanding the types and duration of exercises that are more beneficial than others.37 In two of the included systematic reviews, meta-analysis was conducted demonstrating significant improvements for both short-term pain and low back specific disability with effect sizes stronger than most currently utilized isolated interventions. There has been a recent increased interest in interventions that cut across multiple domains which may be due to a wider acceptance of the biopsychosocial model.38 There is also good evidence to support treatment strategies the involve a multimodal approach.39 Yoga is a term used to describe a collection of spiritual and physical practices originating in ancient India and used to cultivate deep meditative states in order to achieve greater union with the divine or true self. As such, yoga is especially appealing for the treatment of cLBP because it combines exercise as well as a mental and relaxation components.36 However, it remains unclear how yoga’s mental and physical components together may contribute to treatment effectiveness. In particular, there is mixed evidence on whether he mental effect of meditation and breathing exercises is important for treatment outcomes, above and beyond the impact of physical postures. For example, Sherman et al.40 reported that the effect of physical activity involving stretching regardless of yoga or conventional stretching classes has moderate benefits on cLBP, suggesting that the benefits of yoga are largely attributed to the physical rather than mental components. In contrast, in a small (n = 80) RCT, Tekur et al.34 found that a short-term, seven day, intensive residential program of yoga significantly reduced anxiety and depression scores. Further, there is evidence that yoga is more effective than aerobic exercise as a treatment approach for depression and depressive

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symptoms, a common comorbidity found among cLBP patients.6 It is important to also note that the Sherman et al.40 trial was conducted in the US while the Tekur et al.34 trial was conducted in India. This may also explain these differences since trials originating out of India tend to have stronger effects favoring yoga.41 A greater understanding of the impact yoga may have on the psychological and behavioral aspects of treatment are needed given the importance of these two domains for outcomes in cLBP. Adverse events reported in clinical trias of yoga for LBP are similar to those found for exercise for LBP in general. Given the small sample sizes of most RCTs included in the systematic reviews, it is possible that infrequent adverse effects may have been missed. The most common adverse event reported was an exacerbation of existing low back symptoms. The most severe adverse event, which occurred in one case, was a herniated lumbar intervertebral disc. Yoga, like general stretching and strengthening exercise, is considered a relatively safe intervention approach for cLBP.36,40 There have been numerous RCTs on yoga for cLBP, however there are several gaps and needed areas of research. The majority of clinical studies to this point have been in mid-life adults, generally presenting with chronic, non-specific low back pain. We did not identify any studies specifically addressing yoga for acute low back pain. This may be because the duration of acute low back pain is typically limited and most individuals do not seek care, or when they do seek care, they are not typically referred for physical treatments.42,43 Therefore, there may not be a strong indication for an intervention such as yoga for acute low back pain. We also did not find any literature on yoga for the prevention of cLBP. There is limited support in the literature on general physical interventions in the prevention of cLBP44 although there is some support for psychosocial education.45 This is also true of recurrent acute LBP where up to 33% of individuals with an acute episode of low back pain with have a recurrence within a 1-year period.46 Despite the lack of existing research on yoga- for the prevention of cLBP or recurrence of acute low back pain, interest in this area is generally increasing, particularly as we seek to better understand the transitions from acute to cLBP. We identified several different outcome measures used through these studies, which, in one meta-analyses, lead to the use of standardized effect measures. Future studies should follow a standardized outcome and LBP measuring approach, such as that suggested by the NIH Task Force on Research Standards for cLBP.3 5. Conclusion Overall, we conclude that the existing evidence suggests potential benefit of yoga in midlife adults with chronic nonspecific low back pain for short- and long-term pain and back-specific disability, but the effectiveness of yoga for short- and long-term healthrelated quality of life are uncertain. The effects of yoga for acute low back pain or for the prevention of low back pain are also uncertain, as we did not identify eligible systematic reviews or RCTs that evaluated yoga for these stages of low back pain. For cLBP, yoga appears to be a reasonable treatment option; however, given the multidimensional nature of cLBP, yoga as a monotherapy may not be sufficient. There were few studies addressing long-term outcomes; therefore, larger, good-quality RCTs with longer-term outcomes that include functional status and health-related quality of life should be considered. There were several ongoing and funded clinical trials in specific subgroups of patients with cLBP. Emerging evidence may result in changes to these conclusions and without additional studies, further systematic reviews are not needed. Conflicts of interest None.

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