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Complementary Therapies in Clinical Practice 16 (2010) 187e193

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Complementary Therapies in Clinical Practice

journal homepage: www.elsevier .com/locate/ctnm

A randomised controlled trial of yoga for the treatment of chronic low backpain: Results of a pilot studyq

Helen Cox a,*, Helen Tilbrook a, John Aplin b, Anna Semlyen c, David Torgerson a, Alison Trewhela d,Ian Watt a

aDepartment of Health Sciences, SRB Area 4, University of York, York YO10 5DD, United KingdombDivision of Human Development, St Mary’s Hospital, Manchester, United KingdomcBritish Wheel of Yoga Teacher, Friends Meeting House, Friargate, York, United Kingdomd Iyengar Yoga Teacher, ZedShed, Jubilee Wharf, Penryn, United Kingdom

Keywords:Pilot studyFeasibilityRCTYogaLow back painPrimary care

q This study was funded by York Trials Unit, DepUniversity of York.* Corresponding author. Tel.: þ44 01904 321614; fa

E-mail address: hc18@york.ac.uk (H. Cox).

1744-3881/$ e see front matter � 2010 Elsevier Ltd.doi:10.1016/j.ctcp.2010.05.007

a b s t r a c t

Objective: To conduct a pilot trial of yoga for the treatment of chronic low back pain (LBP) to inform thefeasibility and practicality of conducting a full-scale trial in the UK; and to assess the efficacy of yoga forthe treatment of chronic low back pain.Design: A pragmatic randomised controlled trial was undertaken comparing yoga to usual care.Participants: Twenty participants who had presented to their GP with chronic low back pain in theprevious 18 months were recruited via GP records from one practice in York, UK.Interventions: Twenty patients were randomised to either 12 weekly 75-min sessions of specialised yogaplus written advice, or usual care plus written advice. Allocation was 50/50.Main outcome measures: Recruitment rate, levels of intervention attendance, and loss to follow-up werethe main non-clinical outcomes. Change as measured by the Roland and Morris disability questionnairewas the primary clinical outcome. Changes in the Aberdeen back pain scale, SF-12, EQ-5D, and pain self-efficacy were secondary clinical outcomes. Data were collected via postal questionnaire at baseline, 4weeks, and 12 weeks follow-up.Results: Of the 286 patients identified from the GP database, 52 (18%) consented and returned theeligibility questionnaire, out of these 20 (6.9%) were eligible and randomised. The total percentage ofpatients randomised from the GP practice population was 0.28%. Ten patients were randomised to yoga,receiving an average of 1.7 sessions (range 0e5), and 10 were randomised to usual care. At 12 weeksfollow-up data was received from 60% of patients in the yoga group and 90% of patients in the usual caregroup (75% overall). No significant differences were seen between groups in clinical outcomes apart fromon the Aberdeen back pain scale at four weeks follow-up where the yoga group reported significantlyless pain.Conclusion: This pilot study provided useful data and information to inform the design and developmentof a full-scale trial of yoga for CLBP in the UK. A key finding is the calculation of GP practice total list sizerequired for patient recruitment in a full-scale trial, and the need to implement methods to increase classattendance.

� 2010 Elsevier Ltd. All rights reserved.

1. Introduction

Most people will experience at least one episode of low backpain (LBP) during their life and in developed countries the reported

artment of Health Sciences,

x: þ44 01904 321387.

All rights reserved.

lifetime prevalence varies from 49% to 70% with point prevalencesfrom 12% to 30%.1,2 In 1998 the UK Department of Health (DoH)presented results prepared by the Government Statistical Serviceon the prevalence of LBP in the UK and reported that 40% of adultssaid they had suffered from LBP lasting more than one day in theprevious 12 months, with 15% of LBP sufferers reporting chronicpain throughout the year. Nearly 40% of LBP sufferers consulteda GP for help; 10% visited a practitioner of complementarymedicine(osteopaths, chiropractors and acupuncturists); and 5% of LBPsufferers aged 16e64 in employment had taken time off work

H. Cox et al. / Complementary Therapies in Clinical Practice 16 (2010) 187e193188

during the previous month because of LBP.3 More than 1000randomised controlled trials (RCTs) have been published evaluatingall types of conservative, complementary, or surgical treatments forLBP. Current evidence based guidelines for the management of LBPsuggest that exercise and keeping mobile is helpful.4 However,evidence from RCTs are mixed and many have shown that exercisetreatment, though widely used and recommended, has shown onlya small and short-term effect on LBP.5,6 Unfortunately manycommonly used interventions for LBP lack sufficient evidence forclinically relevant long-term effects,7,8 and patients are generallyunsatisfied with current levels of care, hence the need for furtherrigorous research to seek alternative methods of reducing LBP andincreasing mobility in those with back problems.

Yoga is an increasingly popular therapy which offers a combi-nation of physical exercise with mental focus that may make ita suitable therapy for the treatment of LBP. The practice of yogafocuses on the control of muscle functions using a sequence ofpostures. Progression through the sequence and meditation isintended to challenge muscle strength, joint flexibility and balance.Yoga is potentially a very cost effective treatment as it can bedelivered in group sessions. The potential for yoga to have a longerterm influence is more likely than, for example, manipulation andexercise therapy, as yoga participants will be encouraged to prac-tice the technique at home, between classes, and to continue withhome practice after the classes have been completed. A systematicreview of the literature revealed four full-scale RCTs9e12 and threepilot RCTs13e15 of yoga for LBP. Although results weremixed, all fourof the full-scale trials showed statistically significant effects on LBPthat favoured the yoga group. For example, Sherman et al.9 repor-ted differences in disability at 3 months and 6 months follow-up,Williams et al.10 reported reductions in pain, functional disabilityand medication use at 3 months follow-up, Williams et al.11

reported a reduction in disability, pain and depression at 6months follow-up, and Tekur et al.12 reported a reduction indisability post-intervention. However these trials were limited inthat theywere small, in some cases interventions were delivered byonly one teacher resulting in lack of generalisibility, the clinicalsignificance of the some of the studies is questionable, and durationof follow-up was short resulting in a lack of information regardingthe possible longer term benefits of yoga. Of the three pilot trialstwo reported a significant improvements in the yoga group. Saperet al.14 reported a reduction in pain and medication use, andWilliams et al.15 reported a reduction in functional disability andpain. The results from the above trials are promising, however all ofthe studies above were conducted outside of the United Kingdom(UK), mainly in the USA, follow-up did not exceed 6 months, andpatients were recruited by self-referral. The health care system inthe UK differs greatly to that of the USA and, as far as we are aware,a study of this kind has not been conducted in the UK. For thesereasons further research into designing and executing a large RCTofyoga for LBP in the UK is warranted.

The primary objective of this pilot study was to focus onestablishing key design features, practicality and feasibility toinform a larger multicentre trial of the effectiveness of yoga forCLBP. This study was not powered to reach statistical or clinicalsignificance. In particular we aimed to establish the potentialrecruitment rate, questionnaire design, levels of interventionattendance, and loss to follow-up.

2. Methods

2.1. Study design and setting

This pilot RCT compared a 12 week course of specialised yogaback classes with usual care alone and was undertaken between

June and September 2007. The yoga group continued with theirusual care and both groups received written information on how tomanage their LBP in the form of a small booklet called The BackBook.16 Participants were recruited and randomised from onegeneral practice in York, UK.

2.2. Recruitment and participants

The practice manager searched their database using Read Codesto identify patients who had presented to their GP with LBP once ormore within the previous 18 months. The GP practice excludedpregnant patients and patients under 18 or over 65 years of age.Identified patients were mailed out a recruitment pack from the GPpractice containing an information sheet, consent forms, anda screening questionnaire. Patients who were interested inparticipating completed the pre-randomisation screening ques-tionnaire and consent form and returned them to the University ofYork where their eligibility was assessed.

The inclusion criteria were: aged 18e65 years; a score of 4 ormore on the Roland and Morris Disability Scale (RDQ); had pre-sented to their GP in the previous 18 months with LBP; can attendyoga classes (times and dates), and; sufficiently physically mobile(i.e. can get up off the floor unaided, and can walk up and downstairs). The exclusion criteria were: pregnant women; psychosis orrecent substance abuse; already participating in yoga; already ina trial for their LBP; not currently suffering an episode of LBP;previous spinal surgery, and; clinical indications of serious spinal orneurological pathology as indicated by four ‘red flags’ (1) difficultypassing or controlling urine, (2) numbness around back passage orinner thighs, (3) numbness, pins and needles or weakness in bothlegs, and (4) unsteadiness on feet. All of this data was collected viathe initial screening questionnaire. The details of those patientswho were eligible to participate were then sent to their GP whosecond checked their eligibility against the patient’s records.Patients were then randomised using computer generated randomnumbers by an independent data manager to either 12 weeklyclasses of yoga or usual care. York Local Research Ethics Committeeapproved the study.

2.3. Interventions

The yoga intervention consisted of 12 weekly 75-min classesand was devised by an Iyengar Yoga teacher (IYAUK) and LBP yogaspecialist, in collaboration with a British Wheel of Yoga teacher(BWY), who delivered the intervention. The structure was based onthat previously used in the US Karen Sherman yoga trial,9 whilstensuring that a common ground was found between the twoassociations of IYAUK and BWY. Other influences included Geetaand B.K.S. Iyengar, who has taught yoga for over 70 years and hasapplied therapeutic variations of classical poses to many healthproblems including LBP.17

The yoga programme was introduced in a gentle graded wayover the 12 weeks. Class 1 focused on relaxation and pain-relievingpostures. Classes 2e6 taught the CORE practice sequences, whichincluded settling/pacifying poses, standing poses to teach goodposture, improve flexibility in the upper back and shoulders, thenchair-seated posture-strengthening poses. These were followed bysimple supine and prone floor poses, to give strength, mobility andfurther postural understanding and to allow the students to learna good grounding in the fundamental starting points of themajority of yoga pose types. Classes 7e12 built upon the COREPractices poses, by introducing the PROGRESSIVE Practicesequences and included further standing poses, often using wallsand chairs, plus more variations of abdominal, supine and proneposes, and simple breathing awareness. Modifications of poses

Table 1Yoga class themes.

1. Sukkha e relaxation and comfort2. Sthita/dharana e steadiness of body mind and breath3. Asana e posture and symmetry4. Svadhyaya and sarira prajna e self observation and self knowledge5. Karmayoga e movement and mobility6. Rajas/akash e height, space and lift7. Prana prajna e intelligence and life8. Moksa/freedom e space and stretch9. Stira e strengthen the body and mind

10. Sauch/sarva e holistically healthy11. Ananda e positivity and joy12. Saddhana and tapas e practice and passion.13. Savasana e relaxation was an important part of every class and of the

students’ home practice.

H. Cox et al. / Complementary Therapies in Clinical Practice 16 (2010) 187e193 189

were available for people who needed them. Table 1 describes the12 weekly class themes, which encouraged patients to aim to takeon board some of the useful elements of yoga philosophy.

As part of the pilot study, and with the aim of continuing toa larger scale trial, we developed a manual for yoga practitionersand their students. The manual described an agreed series of yogatechniques that could be readily used by yoga teachers’, andsimplified for ease and understanding so it could be practiced athome by LBP patients receiving yoga. Yoga students were eachgiven a yoga manual and yoga mat, weekly practice handouts andencouraged to practice yoga at home, as well as taught to havebetter awareness of posture, movement and correct breathing. Aslearning yoga relaxationwas a key element of the yoga interventionin this pilot trial it was agreed that a Relaxation CD would bedeveloped and given to participants in any full-scale trial.

Patients returned forms and a

for eligibility

n = 52

Total number of patients rand

n = 20

Randomised to Yoga n = 10

Attended no classes n = 5 Attended two classes n = 2 Attended four classes n = 2 Attended five classes n = 1

Returned baseline data

n = 6 (60%)

Followed up at 4 weeks

n = 5 (50%)

Followed up at 12 weeks

n = 6 (60%)

Withdrawn

n = 1

Patients identified by databas

n = 286

Fig. 1. Patients’ progres

Participants in both the yoga and control groups were givenwritten advice on the management of LBP16 and both groupscontinued with their usual care.

2.4. Outcomes

Clinical outcome measures were collected via postal question-naires at baseline, four weeks and twelve weeks post-random-isation follow-up. The primary outcome measure was functionallimitations as measured by the RDQ.18 The RDQ consists of a 24point scale asking questions relating to the patients LBP anddysfunction on that day. The higher the score the greater thedisability. The minimum clinically significant difference on the RDQhas been estimated to range between 2 and 3 points.19e21 This scalehas been found to be sensitive to change, reliable and valid.19,20,22

Secondary outcome measures included: Clinical status asmeasured by the Aberdeen Back Pain Scale (ABPS) 23, where higherscores indicate more clinical problems; General health statusmeasured using the SF-1224 where higher scores indicate bettergeneral health status; The EQ-5D health index; Pain self-efficacy asmeasured by the Pain Self-Efficacy Questionnaire (PSEQ)25 wherehigher scores represent greater self-efficacy, and; simple quanti-fyingmeasures of the number of days (i) spent in bed due to LBP, (ii)with restricted activity attributed to LBP, and (iii) whether medi-cation was used for LBP over the previous four weeks.

2.5. Data analysis

The outcome data were analysed using SPSS Windows, version15. Analysis of primary outcome data was intention to treat and

ssessed

omised

Excluded

Ineligible n= 32

Randomised to Usual Care n = 10

Returned baseline data

n = 9 (90%)

Followed up at 4 weeks

n = 8 (80%)

Followed up at 12 weeks

n = 9 (90%)

Withdrawn

n = 0

e search

s through the trial.

Table 2Baseline characteristics of participants at randomisation.

Variable Yoga Usual care Total

N¼ 10 N¼ 10 N¼ 20Age (years) 39 51 45

Gender (%) N¼ 10 N¼ 10 N¼ 20Male 2 (20) 5 (50) 7 (35)Female 8 (80) 5 (50) 13 (65)

Employment status (%) N¼ 5 N¼ 9 N¼ 14Part-time 0 (0) 1 (11) 1 (7)Full-time 3 (60) 6 (67) 9 (64)Housewife 0 (0) 1 (11) 1 (7)Self-employed 2 (40) 1 (11) 3 (22)

Age left education (%) N¼ 6 N¼ 9 N¼ 1516 or below 3 (50) 6 (67) 9 (60)17e19 0 (0) 2 (22) 2 (13)20 or over 2 (33) 1 (11) 3 (20)Still in full-time education 1 (17) 0 (0) 1 (7)

N¼ 10 N¼ 10 N¼ 20Total duration of LBP (months) (range) 107.2 (10e430) 165.7 (8e486) 136.5 (8e486)

N¼ 9 N¼ 10 N¼ 19Duration of current episode (days) (range) 56.0 (7e168) 71.0 (2e245) 63.5 (2e245)

N¼ 10 N¼ 10 N¼ 20Roland & Morris disability questionnaire (0e24 points) (SD) 9.9 (4.5) 8.7 (4.0) 9.3 (4.2)

N¼ 6 N¼ 9 N¼ 15Aberdeen back pain scale (0e100 points) (SD) 33.5 (9.7) 29.6 (12.8) 31.2 (11.5)

SF-12 (SD) N¼ 6 N¼ 9 N¼ 15Physical component score 42.6 (4.2) 38.5 (9.95) 40.1 (8.2)Mental component score 41.8 (13.0) 48.5 (9.1) 45.8 (10.9)

N¼ 6 N¼ 9 N¼ 15EQ-5D (0e1 points) (SD) 0.71 (0.06) 0.59 (0.26) 0.64 (0.21)

N¼ 6 N¼ 9 N¼ 15Self-efficacy (0e60 points) (SD) 42.7 (8.5) 44.8 (13.1) 43.9 (11.2)

N¼ 10 N¼ 9 N¼ 19Mean (range) days of usual activities missed past 4 weeks 1.0 (0e14) 2.9 (0e10) 1.9 (0e14)

Mean no. (range) past 3 months N¼ 5 N¼ 9 N¼ 15GP visits 0.17 (0e1) 1.33 (0e5) 0.87 (0e5)Practice nurse visits 0.0 (0) 0.11 (0e1) 0.07 (0e1)Physiotherapist visits 0.0 (0) 0.0 (0) 0.0 (0)

No. (%) patients used medication in past 4 weeks N¼ 10 N¼ 10 N¼ 20Yes 7.0 (70) 6.0 (60) 13.0 (65)No 3.0 (30) 4.0 (40) 7.0 (35)

Patient preference (%) N¼ 10 N¼ 10 N¼ 20No. preferred yoga 6 (60) 6 (60) 12 (60)No. preferred usual care 1 (10) 0 (0) 1 (5)No. no preference 3 (30) 4 (40) 7(35)

H. Cox et al. / Complementary Therapies in Clinical Practice 16 (2010) 187e193190

conducted blind to treatment allocation. We estimated the effectsof treatment on the outcomemeasures using analysis of covariance,with the change scores as the dependant variable and adjustmentbeing made for baseline scores.

3. Results

3.1. Recruitment and follow-up

The participating GP practice list size was 7040. The practiceidentified and mailed recruitment packs to 286 patients (4% ofpractice population) who had presented with LBP one or moretimes during the period of 1st November 2005 to 30 April 2007. Outof those 286 identified patients, 52 (18%) returned their screeningforms and a total of 20 (6.9%) were eligible and randomised. Thetotal percentage of patients randomised from the GP practicepopulation was 0.28%.

Ineligible patients indicated any one or more of the following:less than 4 on RDQ (n¼ 14); could not attend classes (n¼ 1); notphysically mobile (n¼ 4); one or more red flag (n¼ 14), indicatedby (i) difficulty passing urine, (ii) numbness around rectum/geni-tals, (iii) numbness, pins & needles in legs, (iv) unsteadiness on feet;already taking part in yoga (n¼ 1); In another trial for LBP (n¼ 1);no current LBP episode (n¼ 17), and; previous spinal surgery(n¼ 5).

Follow-up data were received in total from 15 (75%) patients atbaseline, 13 (65%) at four weeks follow-up and, 15 (78%) patients atfinal 12 weeks follow-up from randomisation. When split bytreatment, in the yoga group follow-up data were received from 6(60%) patients at baseline, 5 (50%) at four weeks and 6 (60%) attwelve weeks, and in the usual care group data were received from9 (90%) patients at baseline, 8 (80%) at four weeks follow-up and 9(90%) at 12 weeks follow-up (Fig. 1). The missing data at baselinewas because we screened the patients prior to randomisation, then

H. Cox et al. / Complementary Therapies in Clinical Practice 16 (2010) 187e193 191

sent out the baseline questionnaires to eligible patients whom wehad randomised. As such this resulted in missing baseline data, andpossible bias as participants knew their allocation whencompleting the baseline questionnaire. A full-scale trial wouldrequire us to merge the screening and baseline data into onequestionnaire administrated prior to randomisation.

3.2. Baseline characteristics

Table 2 shows the clinical and demographic characteristics ofthe patients at randomisation. The patients in the usual care groupwere on average 12 years older and had a greater duration of LBPand a greater duration of current episode of LBP. The majority of thepatients (65%) were female, and the majority of patients were infull-time employment (60%). The mean total duration of patients’LBP was 136.5 months, with a range of 8e486 months. The meanduration of patients’ current episode of LBP was 63.5 days, witha range of 2e245 days. Most patients when asked (60%) would havepreferred to be allocated to the yoga classes.

3.3. Treatment retention

Of the ten patients allocated to receive yoga, five (50%) did notattend any one session. Three of these could not be contacted, onewithdrew immediately post-randomisation due moving to

Table 3Changes in outcome measures from baseline values in intervention and control groups a

Yoga [N]

4 Weeks follow-upRoland & Morris disability questionnaire (0e24 points) �4.16 [5]Aberdeen back pain scale (0e100 points) �10.39 [5]

SF-12 N¼ 5Physical component score 7.35Mental component score �2.49

EQ-5D (0e1 points) 0.16 [5]Self-Efficacy (0e60 points) 8.81 [5]Mean (range) days of usual activities missed past 4 weeks 0.00

No. (%) patients used medication in past 4 weeks N¼ 5Yes 3 (60)No 2 (40)

Current LBP (%) N¼ 5Yes 3 (60)No 5 (40)

12 Weeks follow-upRoland & Morris disability questionnaire (0e24 points) �1.76 [6]Aberdeen back pain scale (0e100 points) �7.72 [4]

SF-12 N¼ 4Physical component score 1.20Mental component score 3.40

EQ-5D (0e1 points) 0.06 [4]Self-efficacy (0e60 points) 8.26 [4]

N¼ 5Mean (range) days of usual activities missed past 4 weeks 1.20 (0e6)

Mean no. (range) past 3 months N¼ 5GP visits 0.60 (0e2)Practice nurse visits 0.00 (0)Physiotherapist visits 0.00 (0)

No. (%) patients used medication in past 4 weeks N¼ 5Yes 4 (80)No 1 (20)

Current LBP (%) N¼ 5Yes 4 (80)No 1 (20)

a different area, and one was working away and then on holiday.Two patients attended two sessions, two patients attended foursessions and one patient attended five sessions. The main reasonsestablished for non-attendance was holidays, other reasonsincluded childcare problems and illness. No patients allocated tothe control group took part in the yoga classes. We found a rela-tionship between those participants who were randomised toreceive yoga and did not attend any classes and those patients whofailed to return follow-up data and this is reflected in the imbalancein return rates between the control and intervention groups. Of thefive participants who attended no classes, one returned baselinedata, none returned 4-week data, and two returned 12-week data.Of the five participants who attended one or more class, allreturned baseline data, all returned 4-week data, and four returned12-week data. It is clear that there is a need to implement strategiesto improve compliance for a full-scale trial. This could includea choice of times and dates of classes in each area, as in this pilottrial there was only one weekly class available.

3.4. Outcomes

Table 3 shows the mean change scores in outcome measuresfrom eligibility to four weeks follow-up and twelve weeks follow-up. After adjustment for baseline scores, at four weeks follow-upthe yoga intervention group reported greater mean decreases in

t 1 month and 3 months follow-up.

Usual care [N] Mean difference (95% CI) P value

�2.28 [8] 1.88 (�3.18 to 6.94) 0.43�2.00 [8] 8.39 (1.18e15.60) 0.03

N¼ 86.60 �0.75 (�8.38 to 6.89) 0.832.22 4.71 (�5.98 to 15.39) 0.35

0.10 [8] 0.06 (�0.19 to 0.08) 0.352.74 [8] �6.07 (�14.6 to 2.53) 0.150.00

N¼ 85 (62.5)3 (37.5)

N¼ 86 (75)2 (25)

�2.94 [9] �1.18 (�8.09 to 5.74) 0.72�5.16 [9] 2.56 (�13.4 to 18.5) 0.73

N¼ 96.88 5.68 (�6.44 to 17.81) 0.320.59 �2.81 (�16.33 to 10.7) 0.65

0.04 [8] �0.02 (�0.39 to 0.35) 0.891.22 [9] �7.04 (�20.7 to 6.66) 0.28

N¼ 91.44 (0e10) 0.24 (�3.8 to 4.07) 0.89

N¼ 91.33 (0e4) 0.73 (�1.03 to 2.49) 0.380.11 (0e1) 0.11 (�0.21 to 0.44) 0.490.33 (0 to 3) 0.33 (�0.66 to 1.33) 0.49

N¼ 96 (66.6)3 (33.3)

N¼ 98 (89)1 (11)

H. Cox et al. / Complementary Therapies in Clinical Practice 16 (2010) 187e193192

disability as measured by the RDQ, and pain as measured by theABPS. Although only the latter was statistically significant(P¼ 0.03). All other variables at four weeks were not significantlydifferent. At four weeks follow-up 80% of the yoga group hadimproved by at least two points on the RDQ, compared to 37.5% ofthe usual care group.

At twelve weeks follow-up the usual care group reporteda greater mean decrease in disability, and the yoga interventiongroup reported a greater mean decrease in pain, neither of whichwere significantly different. All other variables at twelve weekswere not significantly different. At twelve weeks follow-up 66.6% ofthe yoga group had improved by at least two points on the RDQ,compared to 55.6% of the usual care group. At both follow-up pointswe have observed a non-significant trend in the yoga groupshowing a substantial improvement in pain self-efficacy over theusual care group.

4. Discussion

This pilot study provided useful data and information to informthe design of a full-scale trial of yoga for LBP. A key finding was that18% of potentially eligible patients on the GP database consented toparticipate in the trial and 6.9% were deemed eligible according tothe inclusion and exclusion criteria, equating to 0.28% of the totalpractice list size randomised. Based on this recruitment rate, themethod of retrospective GP database recruitment will enablea large sample to be recruited to a full-scale trial relatively quicklyin comparison to prospective recruitment methods of incidentcases.26 The proposed sample size for a full-scale trial would be 280participants and this could be met by a participating list size ofapproximately 100,000.

Class attendance was low in this pilot trial with only 50% of trialparticipants randomised to receive yoga attending one or more ofthe classes (range 2e5). The Sherman trial9 reported a mean classattendance of 9 out of 12 classes offered which is substantiallyhigher. The main reason for non-attendance was reported to beholidays. A likely explanation for this is that the classes were runthrough the six weeks of school summer holidays, as such thetiming of classes should be considered carefully so as to avoid thesummer break. It is usual practice for general yoga classes to takea class break at Easter, half-terms and Christmas so that partici-pants do not have to miss class. Despite this, the fact that half ofthose randomised to yoga did not attend a class suggests it wouldbe prudent to incorporatemeasures such as a ‘run-in’ period duringwhich participants would attend screening visits to identify thosewho are unlikely to show up for future interventions, and/or toover-recruit in a full-scale trial to allow for such treatment reten-tion issues. Another suggestion for a larger trial would be to runseveral yoga classes in the same area on different days of the weekto allow participants the choice of a class more convenient to them,providing just one weekly class has more than likely contributed tolow attendance rates.

We also found differential response rates between the yoga andcontrol group with only 60% of patients randomised to yogareturning 12-week follow-up data, compared to 90% of the controlgroup. This is worrying as differential attrition can introduceselection bias. Secondary analysis revealed that those participantsrandomised to yoga and attended no classes were less likely toreturn follow-up questionnaires. Therefore in future trials stepsshould be taken to screen out participants who are not likely toattend yoga classes and therefore are less likely to return follow-updata if they are randomised to receive yoga. This might be achievedby ensuring that everyone who has consented to participate is fullyaware of the trial conditions pre-randomisation. Additionally,telephone reminders, emails, and/or text message reminders could

be used to try to increase response rate. The datasets for thoseparticipants who did return their questionnaires were completeindicating that the questionnaires were appropriate and relevant tothe participants . However psychological outcome measures werenot collected and should be incorporated in any future trial as thereis evidence of potentially beneficial effects of yoga interventions ondepressive disorders.27

Clinical outcomes revealed very few statistically significantdifferences between groups and at twelve weeks follow-up bothgroups had improved to a similar degree in all clinical outcomes.However emphasis should not be placed on this outcome data asa larger sample would be needed to detect significant changes inoutcomes. In view of the low attendance and differential responserate its hard to fully interpret the clinical outcome data for sucha small sample.

The pragmatic design of the trial was considered appropriate,and overall in terms of generalisability the broad inclusion criteriafor recruiting patients made it more likely that the patients enteredinto the trial were fairly representative of those typically presentingin primary care with LBP. It should be noted that the trial recruitedparticipants from the York area which is a predominantly a white,middle class population and therefore the recruitment figuresmight be different in other geographical and demographic areas ofthe country. The database recruitment process used in this pilotstudy can be considered as successful. Patients were identified andrecruited simply and in a short space of time.

This study did not find evidence for the clinical effectiveness ofyoga for CLBP due to inadequate power. However the study did notprimarily set out to establish the efficacy of yoga for CLBP as itsmain aim; rather it was to establish methodological issues thatmight present in a full-scale trial. As such the results of this pilothave provided information of importance for future research in thisarea as well as useful data and key features to inform the devel-opment of a future full-scale trial.

Finally, since we conducted this pilot study funding has beenawarded for a full-scale multicentre RCT from Arthritis Research UK(formerly Arthritis Research Campaign). We have addressed manyof the methodological flaws discussed in this paper, and imple-mented many of the considerations. Although the outcome resultsare not yet available in the public domain, we can state that in theyoga intervention, on average nine out of the twelve classes wereattended, which is comparable to the Sherman trial.9

Acknowledgements

We thank the GP practice Dr. Kemp & Partners and Dr. RebeccaField who participated in this study. This study was funded by YorkTrials Unit, University of York.

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