ORIGINAL ARTICLE

Qigong versus exercise therapy for chronic low back pain in adults – A randomized controlled non-inferiority trial S. Blödt1*, D. Pach1*, T. Kaster1, R. Lüdtke2, K. Icke1, A. Reisshauer3, C.M. Witt1,4 1 2 3 4

Institute for Social Medicine, Epidemiology and Health Economics, Charité – Universitätsmedizin Berlin, Germany Karl and Veronica Carstens Foundation, Essen, Germany Clinic for Physical Medicine and Rehabilitation, Charité – Universitätsmedizin Berlin, Germany Institute for Complementary and Integrative Medicine, University Hospital Zurich, Switzerland

Correspondence Claudia Witt E-mail: [email protected] *Both authors contributed equally. Prof. Dr. Claudia Witt had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Funding sources The trial is supported by the grant for the chair for complementary medicine research of the Karl and Veronica Carstens Foundation. Conflicts of interest None declared. Trial Registration: ClinicalTrials.gov-ID: NCT00993980 http://clinicaltrials.gov/ct2/show/ NCT00993980?term=qeba&rank=1 Accepted for publication 6 April 2014 doi:10.1002/ejp.529

Abstract Background: The value of qigong in the treatment of chronic low back pain is unclear. In a randomized controlled trial, we evaluated whether qigong is non-inferior to exercise therapy in patients with chronic low back pain. Methods: German outpatients (aged 46.7 ± 10.4) with chronic low back pain [mean visual analogue scale (VAS), 53.9 ± 12.5 mm] were enrolled and randomly allocated in a 1:1 ratio to receive either qigong (64 patients, 12 sessions with 1 × 90 min/week over 3 months) or exercise therapy (63 patients, 12 sessions 1 × 60 min/week). The primary outcome measure was the average pain intensity over the last 7 days on a VAS (0–100 mm, 0 = no pain, 100 = worst imaginable pain, non-inferiority margin = 5 mm) after 3 months. Follow-up was measured after 6 and 12 months. Results: The mean adjusted low back pain intensity after 3 months was 34.8 mm [95% confidence interval (CI) 29.5; 40.2] in the qigong group and 33.1 mm (95% CI 27.7; 38.4) in the exercise group. Non-inferiority of the qigong group compared with the exercise group failed to show statistical significance (p = 0.204). In both groups, 10 patients reported suspected adverse reactions (e.g., muscle soreness, dizziness, pain) the total number was comparable in both groups (qigong n = 40, exercise n = 44). Conclusions: Qigong was not proven to be non-inferior to exercise therapy in the treatment of chronic low back pain. Its role in the prevention of chronic low back pain might be addressed in further studies.

1. Introduction Low back pain is a highly prevalent condition in industrialized countries with estimated lifetime prevalence of up to 84% (Airaksinen et al., 2004). In a systematic analysis for the Global Disease Study 2010, low back pain was identified as the leading cause of global years lived with disability in all developed countries (Vos et al., 2012). Low back pain affects quality of life and productivity, and has a high economic impact. In the United Kingdom, low back pain accounts for 13% of absences from work. © 2014 European Pain Federation - EFIC®

Up to 7% of patients develop chronic pain with pain duration of at least 3 months. Chronic low back pain is the predominant cause of chronic musculoskeletal pain (Morlion, 2013). Consensus guidelines agree to apply a multimodal approach including education and self-care, exercise, behavioural therapy, and physiotherapy (Koes et al., 2006; Chenot et al., 2007; Savigny et al., 2009). However, long-term effects are difficult to achieve (Koes et al., 2006). The majority of nonpharmacological treatments have shown little to no effect (Chou et al., 2007). For exercise, small to modEur J Pain 19 (2015) 123–131

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What is already known? • Low back pain (LBP) is highly prevalent and has a high economic impact. • Exercise is recommended as a therapeutic option for chronic LBP. • Qigong is used for the treatment of pain conditions. • It is unknown whether qigong is as effective as exercise for the treatment of chronic LBP. What does the study add? • Non-inferiority of qigong compared with exercise therapy in the treatment of chronic LBP could not be proven.

erate effect size was observed (Hayden et al., 2005; Ferreira et al., 2010), and it is recommended for chronic low back pain (Smidt et al., 2005; Koes et al., 2006; Chenot et al., 2007; Savigny et al., 2009). In patients with chronic low back pain, exercise reduces disability and pain severity while improving fitness and occupational status. The German National Disease Management Guideline for low back pain considers physical activity as part of standard care (Bundesärztekammer et al., 2010). The use of complementary and alternative medicine is growing (Härtel and Volger, 2004; Su and Li, 2011; Okoro et al., 2013) and in Germany, Qigong is increasingly used (Chu, 2004). Qigong, which is part of Chinese medicine, follows the principle of regulating the ‘qi’, which is described as harmonizing mind and body and activating self-healing capacities. Literally translated, ‘qi’ means breath, steam or mist (Reuther and Aldridge, 1998; Sancier and Holman, 2004; Guo et al., 2008). Two main categories of qigong exist, the ‘Internal Qigong’ using slow body movements as an aerobic exercise, and controlled breathing to achieve relaxation (Ernst et al., 2008), and the ‘External Qigong’ for healing others by sending one’s qi to them usually done by a therapist. In usual care, qigong has been used for the prevention and the treatment of pain conditions, but the number of studies evaluating its effectiveness is very limited (Lee et al., 2007, 2009). In patients with chronic neck pain, qigong was more effective than waiting list control group (Rendant et al., 2011). Our choice of a non-inferiority trial design was based on the hypothesis that qigong is not inferior to exercise therapy for treating low back pain and might therefore be an additional treatment option. Most randomized controlled trials aim to determine whether one intervention is superior than 124 Eur J Pain 19 (2015) 123–131

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another. Failure to show a difference does not mean they are equivalent (Piaggio et al., 2006). A noninferiority trial seeks to determine whether a new treatment is not relevantly worse than a reference treatment. For the statistical analysis of the primary outcome, a so called non-inferiority margin has to be predefined to define the area that represents non-inferiority. The aim of the trial presented here was to investigate whether qigong is non-inferior (5 mm noninferiority margin on the VAS) to exercise therapy for low back pain reduction measured on a VAS in patients with chronic low back pain. That means, if the lower limit of the one-sided confidence interval for the group difference on the VAS is below −5 mm noninferiority cannot be confirmed.

2. Methods 2.1 Design The study is a two-armed randomized controlled trial, investigating the non-inferiority of qigong in comparison with exercise therapy in patients with chronic low back pain. Intervention duration was 3 months. All participants received supervised training once a week and were encouraged to do home practice and to continue with their therapy after they had finished the 12 weeks course. The total follow-up length was 12 months, with measurements after 6 and 12 months. This study followed the common guidelines for clinical trials (Declaration of Helsinki, The International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use and Good Clinical Practice (ICH-GCP) revised version, Somerset West (SA) 1996) and was approved by the Ethics Committee of the Charité – Universitätsmedizin Berlin (Approval No. EA 1/210/09). All patients gave written informed consent.

2.2 Participants Patients were eligible for the trial if they fulfilled the following inclusion criteria: age 20–65 years, low back pain for at least 3 months (clinical diagnosis of chronic low back pain), but not longer than 5 years, low back pain more prominent than pain in other spine areas, average pain intensity in the previous 7 days ≥ 40 mm measured on a VAS (0–100 mm), and informed consent. Exclusion criteria were: low back pain as a consequence of an accident or malignant disease, inflammatory arthropathy, history of spine surgery, prolapsed vertebral disc or spondylolisthesis with radicular symptoms, planned start of physiotherapy and other therapies (e.g., acupuncture, massage, spinal manipulation, neuroflexotherapy, feldenkrais) against low back pain, taking up new activities that have a positive

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influence on low back pain during the study participation such as swimming, yoga, Pilates, tai chi, kung fu, tai bo, gymnastics, regular (> once a week) intake of analgesics, pregnancy or planned pregnancy within the treatment period, severe acute or chronic disorders (physical or mental), any other mental or physical limitation that does not allow study participation, substance or alcohol abuse, current participation in any qigong/or exercise therapy or participation in the previous 12 months, participation in another trial during the last 6 months, or a history of participation in any qigong/or exercise therapy/low back pain study. Patients were recruited in Berlin, Germany using informational material (brochures, handouts), intranet platforms of the university and other companies (reaching more than 20,000 employees). Patients were pre-screened according to the main eligibility criteria by telephone interviews and then invited to our outpatient clinic for a screening visit that included a clinical examination. In the recruitment and patients’ information, both interventions were described as similar useful and plausible for treating low back pain. Patients were informed that the aim of the study was to compare the effectiveness of both interventions.

2.3 Randomization If patients met all inclusion criteria and no exclusion, they were randomized to either the qigong or exercise therapy group using a block randomization (with a fixed block length of 10) with an allocation ratio of 1:1 that is 60:60 participants. The randomization list was compiled by a statistician from the ‘ranuni’ random number generator of the SAS/ STAT software (version 9.2. SAS Inc., Cary, NC, USA) and transferred into a generated Microsoft Office Access 2003® (Microsoft Corporation, Redmond, WA, USA) secured database, where it was hidden in the background, which was not accessible to anyone involved in the randomization or treatment. Patients who fulfilled the eligibility criteria and provided informed consent were registered in the preface of the database and randomized using a button. The result was provided to the patient. Patients could not be changed or deleted in the database, which ensured consecutive order.

2.4 Interventions 2.4.1 Qigong Qigong classes were performed by three qualified therapists certified by the German qigong society, who had at least 15 years of experience (mean: 19.0, range 15–21 years). Qigong was based on Neiyanggong (Yafei, 2008), an inner nourishing medical qigong, and was chosen based on a consensus procedure with the three therapists. The system of Neiyanggong contains static/still (Jing Gong) and moving (Dong Gong) exercises. Patients randomized to the qigong group participated in weekly sessions of 90 min over a period of 3 months. Qigong lessons started with 14 movement exercises

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for the spine and legs out of the basic level and was followed by seven exercises out of the intermediate level ‘Change muscles and tendons and move the qi’. A home practice manual was provided.

2.4.2 Exercise therapy Exercise therapy was developed by the Department for Physical Medicine and Rehabilitation at the Charité – Universitätsmedizin Berlin and was carried out by five qualified physiotherapists with professional experience of at least 15 years (mean: 24.8, range 15–36 years). Patients in the exercise group participated in 12 sessions over 3 months. Each weekly session of exercise therapy lasted about 60 min and started with a warm-up programme using a dynamic gym ball and was followed by strengthening exercises. It ended with stretching exercises and relaxation. Special attention was paid to ensure that the individual pain level was not exceeded. A home practice manual was provided. Patients in both groups were allowed to take pain medication for acute pain and it was recommended that they take the same medication as in the previous 6 months before the study began. Prohibited were any complementary and alternative medicine treatments (e.g., massage, acupuncture, spinal manipulation), physiotherapy or manual therapy. Participants in both groups received the study therapy free of charge and were not paid for their participation.

2.5 Outcome measurements Outcome measurements were assessed at baseline (before randomization) after 3, 6 and 12 months using standardized questionnaires that were completed by the patients. The primary outcome measure was the average low back pain intensity of the previous 7 days measured on a VAS (Huskisson, 1974) (0–100 mm, 0 = no pain, 100 = worst pain imaginable) 3 months after the start of the therapy. Secondary outcome measures included the Roland Morris Questionnaire (Wiesinger et al., 1999), health-related quality of life [Short Form-36 questionnaire (Bullinger and Kirchberger, 1998) ], perceived self-efficacy measured by the self-efficacy scale (Schützler and Witt, 2010). Quality of sleep was assessed by asking ‘How well did you sleep?’ and sleep satisfaction by asking ‘How satisfied were you with your sleep?’ [mean of the last week measured by a rating scale very good = 0, very bad = 10, and very (satisfied) = 0, not at all = 10, respectively]. Moreover, compliance (qigong/ exercise frequency) and satisfaction with the therapy were evaluated. In addition, patients were asked after 3, 6 and 12 months to report suspected adverse reactions during the previous 3 months and 6 months, respectively. After each qigong/exercise therapy session the therapists documented suspected adverse reactions and serious adverse events. Causality of the serious adverse events was evaluated by physicians of the study office. At baseline, socio-demographic data, the clinical characteristics, including the physical examination, were assessed,

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317 interested patients

150 attended the admission interview 23 excluded based on eligibility criteria

Enrolment

145 did not meet inclusion criteria 22 not interested

59 followed up at 3 months 3 refused further participation in the study 2 withdrew from treatment

58 follow-up at 3 months 3 refused further participation in the study 2 without giving reasons

57 followed up at 6 months 2 withdrew from treatment

57 follow-up at 6 months 1 withdrew from treatment

64 used for primary endpoint analysis based on ITT

63 used for primary endpoint analysis based on ITT

and for the usage as a covariate the presumed therapy’s effectiveness [as applied in previous studies (Pach et al., 2011, 2013) by a Lickert scale ‘very effective’, ‘effective’, ‘small effect’ and ‘no effect’].

2.6 Statistical analysis The trial was powered for assessing non-inferiority of qigong compared with exercise. On the basis of our previous studies on qigong as a treatment for pain, we assumed that the true advantage of qigong after 3 months compared with exercise would be > 5 mm on the VAS. With a sample size of 53 patients in each group, a onesided t-test and a 2.5% significance level, the study would have a power of 80% to detect non-inferiority with a predefined non-inferiority margin of d = 5 mm on a 100-mm VAS [standard deviation (SD) 20 mm]. Assuming a dropout rate of around 10%, we sought to include 120 patients. The analysis of the primary endpoint was performed with a generalized estimating equations based on analysis of covariance model using the PROC GENMOD procedure in SAS 9.2 software (SAS Inc.). The model included treatment group, baseline pain (VAS, linear covariate), patient’s expectations for the outcome to the treatment at baseline (linear covariate) and time point. The non-inferiority margin was set at 5 mm. Testing for group differences was one-sided with significance level 0.025, based on the intention-to-treat population (including patients with baseline assessment who

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Follow-Up

64 allocated to exercise therapy 1 withdrew consent before receiving the intervention

Primary Analysis

64 allocated to qigong

Allocation

128 randomized

Figure 1 Trial flow chart. ITT, intention-totreat.

had at least one treatment session). For the VAS at 6 and 12 months, the same model was used as for the primary endpoint. All other analyses (other endpoints, other time points, etc.) were performed within similar models, but two-sided with a significance level of 0.05, and considered explorative. The analysis was based on available data (full analysis set based on intention-to-treat). Missing data were not imputed.

3. Results 3.1 Participants The study was conducted between October 2009 and February 2011. From 317 interested patients, 150 were assessed for eligibility (see Fig. 1); 128 were randomized into two groups (qigong n = 64, exercise therapy n = 64). One participant withdrew his consent directly after randomization, because of this 127 patients were included in the intention-to-treat analysis. All baseline characteristics are presented in Table 1. The mean age was 46.7 ± 10.4 and the majority of participants were female (80.3%). Three-quarters of participants (74%) had already consulted a physician and 63% an orthopaedist because of their low back pain. Half of them (49.6%) reported concomitant diseases; the most frequent were cardiovascular diseases © 2014 European Pain Federation - EFIC®

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Qigong versus exercise therapy for chronic low back pain

Table 1 Baseline demographic and clinical characteristics of trial groups. Socio-demographic characteristics

Qigong (n = 64)

Exercise therapy (n = 63)

Age (years; mean ± SD) Gender Female (%) Male (%) BMI (kg/m2; mean ± SD) >10 years of school (%) Family status (%) Living in partnership Living alone Size of household Single-person Multi-person Duration of low back pain (years; mean ± SD) Concomitant diseases (%) Cardiovascular disease Endocrine, nutritional and metabolic Diseases Respiratory disease Medication intake because of low back pain (%) Consultation because of low back pain (%) Sports and activity (%) Dancing Fitness Yoga Tai qi/qigong Swimming Muscle building training Others Average low back pain (VAS; mean ± SD) Low back pain/disability (RMD; mean ± SD) Physical health (SF-36; mean ± SD) Mental health (SF-36; mean ± SD) Self-efficacy (Schützler & Witt; mean ± SD) Quality of sleep (mean ± SD) Sleep satisfaction (mean ± SD) Expected effectiveness of qigong (%) Very effective Effective Less effective Ineffective Expected effectiveness of exercise therapy (%) Very effective Effective Less effective Ineffective

45.7 ± 10.0

47.7 ± 10.8

90.6 9.4 24.2 ± 4.3 67.2

69.8 30.2 25.0 ± 3.9 55.6

64.1 34.4

79.4 20.6

39.1 60.9 2.7 ± 1.4

22.2 77.8 3.2 ± 1.5

14.1 18.8

27.0 17.5

4.7 37.5 73.4

12.7 44.4 74.6

3.1 1.6 0.0 1.6 3.1 1.6 20.3 55.6 ± 14.2 6.2 ± 3.4 41.8 ± 8.5 46.3 ± 10.8 19.4 ± 3.6 4.7 ± 2.7 4.9 ± 2.9

6.3 9.5 0.0 0.0 6.3 3.2 34.9 52.1 ± 10.5 5.7 ± 3.4 42.6 ± 7.5 49.2 ± 10.1 19.3 ± 3.5 4.7 ± 2.4 5.1 ± 2.5

21.9 67.2 10.9 0.0

15.9 68.3 15.9 0.0

21.9 68.8 9.4 0.0

31.7 58.7 9.5 0.0

BMI, body mass index; RMD, Roland–Morris disability; SD, standard deviation; SF-36, Medical Outcomes Study (MOS) 36-item short-form quality-of-life questionnaire; VAS, visual analogue scale for assessing the average low back pain intensity.

(qigong: 14.1%, exercise therapy: 27.0%) and endocrine, nutritional and metabolic disease (qigong: 18.8%; exercise therapy 17.5%). At baseline, two differences between both groups with possible relevance occurred (Table 1): more women were randomized in the qigong group (90.6% vs. 69.8%) and participants in the qigong group had higher school education (>10 © 2014 European Pain Federation - EFIC®

years 67.2% vs. 56.6%). Furthermore, participants in the qigong group reported a shorter duration of low back pain (qigong mean 2.7, SD 1.4; exercise 3.2 SD 1.5) The majority of patients expected that either qigong or exercise therapy would be effective. Attendance at classes was higher in the qigong class compared with the exercise group (67.2% of Eur J Pain 19 (2015) 123–131

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Table 2 Primary and secondary outcomes at 3, 6 and 12 months. At 3 months

Average low back pain (VASa) Low back pain/disability (RMDa) Self-efficacy (Schützler & Wittb) Quality of sleep Sleep satisfaction SF-36 quality of life (SF-36b) Bodily pain Physical component score Mental component score

Qigong mean (95% CI)

Exercise therapy mean (95% CI)

Difference exercise therapy versus qigong (95% CI)

p

p (non-inferiority)

34.8 (29.5; 40.2) 4.3 (3.6; 5.0) 19.7 (18.8; 20.6) 4.5 (3.8; 5.1) 4.8 (4.1; 5.5)

33.1 (27.7; 38.4) 3.8 (3.1; 4.6) 20.1 (19.5; 20.8) 4.3 (3.7; 4.9) 4.7 (4.1; 5.3)

–1.8 (–9.4; 5.8) –0.5 (–1.5; 0.5) 0.5 (–0.6; 1.6) –0.2 (–1.0; 0.7) –0.1 (–1.0; 0.8)

0.646 0.353 0.413 0.720 0.850

0.204

41.2 (39.4; 43.0) 44.3 (42.6; 46.1) 44.9 (42.3; 47.5)

42.2 (40.1; 44.3) 45.5 (43.8; 47.3) 45.7 (43.3; 48.1)

1.0 (–1.7; 3.8) 1.2 (–1.3; 3.7) 0.8 (–2.7; 4.4)

0.475 0.346 0.654

At 6 months

a

Average low back pain (VAS ) Low back pain/disability (RMDa) Self-efficacy (Schützler & Wittb) Quality of sleep Sleep satisfaction SF-36 quality of life (SF-36b) Bodily pain Physical component score Mental component score

Qigong mean (95% CI)

Exercise therapy mean (95% CI)

Difference exercise therapy versus qigong (95% CI)

p

p (non-inferiority)

35.1 (30.0; 40.3) 4.1 (3.3; 4.8) 19.0 (18.2; 19.9) 4.6 (3.9; 5.2) 5.0 (4.4; 5.7)

27.4 (22.8; 32.1) 3.1 (2.4; 3.8) 19.5 (18.8; 20.2) 4.5 (3.9; 5.2) 4.8 (4.2; 5.4)

–7.7 (–14.7; –0.7) –0.9 (–2.0; 0.1) 0.5 (–0.6; 1.6) –0.0 (–1.0; 0.9) –0.3 (–1.1; 0.6)

0.031 0.076 0.418 0.916 0.561

0.776

43.0 (41.2; 44.8) 45.8 (43.9; 47.7) 45.4 (42.7; 48.1)

44.6 (42.6; 46.5) 46.6 (44.7; 48.4) 46.6 (44.3; 49.0)

1.5 (–1.2; 4.2) 0.8 (–1.9; 3.4) 1.2 (–2.4; 4.9)

0.262 0.563 0.501

At 12 months

a

Average low back pain (VAS ) Low back pain/disability (RMDa) Self-efficacy (Schützler & Wittb) Quality of sleep Sleep satisfaction SF-36 quality of life (SF-36b) Bodily pain Physical component score Mental component score

Qigong mean (95% CI)

Exercise therapy mean (95% CI)

Difference exercise therapy versus qigong (95% CI)

p

p (non-inferiority)

35.9 (29.8; 42.1) 4.3 (3.4; 5.2) 19.0 (18.1; 19.8) 4.5 (4.0; 5.1) 5.1 (4.5; 5.7)

28.8 (23.5; 34.1) 3.1 (2.5; 3.8) 18.9 (17.9; 19.9) 4.7 (4.1; 54.3) 5.1 (4.5; 5.7)

–7.1 (–15.2; 1.0) –1.2 (–2,3; –0.1) –0.1 (–1.4; 1.3) 0.2 (–0.7; 1.0) 0.1 (–0.8; 0.9)

0.086 0.031 0.910 0.683 0.865

0.695

41.4 (39.1; 43.7) 44.8 (42.5; 47.0) 45.0 (41.9; 48.2)

43.4 (40.9; 45.9) 46.5 (44.4; 48.7) 45.5 (42.9; 48.1)

2.0 (–1.4; 5.4) 1.8 (–1.3; 4.9) 0.5 (–3.6; 4.6)

0.243 0.268 0.815

CI, confidence interval; RMD, Roland–Morris disability; SF-36, Medical Outcomes Study (MOS) 36-item short-form quality-of-life questionnaire; VAS, visual analogue scale for assessing the average low back pain intensity. a Lower values indicate better status. b Higher values indicate better status.

the qigong participants attended at least eight classes vs. 50.8% in the exercise group). Home practice was also performed more often in the qigong group (72.0% compared with 61.9% the exercise group).

3.2 Outcomes For the primary outcome measured on the VAS, no relevant differences were observed between qigong and exercise in the mean change in pain intensity after 128 Eur J Pain 19 (2015) 123–131

three months [qigong: 34.8 95% confidence interval (CI) 29.5–40.2; exercise 33.1 95% CI 27.7–38.4; Table 2]. The non-inferiority (margin of 5 mm) of qigong compared with exercise could not be proven (group difference −1.8 mm 95% CI: –9.4 to 5.8, onesided pnon-inferiority = 0.204). For the secondary outcomes, only a significant difference between qigong and exercise was found in pain intensity over the last 7 days after 6 months [Δ –7.7 mm (–14.7 to –0.7), p = 0.031] and for the Roland–Morris disability after 12 months [Δ –1.2 (–2.3 © 2014 European Pain Federation - EFIC®

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to –0.1 p = 0.031) ]. No significant differences between qigong and exercise were found in pain intensity over the last 7 days after 12 months [Δ –7.1 (–15.2 to 1.0), p = 0.086]. Furthermore, we did not find any difference for the other secondary outcome parameters (disability after 3 and 6 months, quality of life, sleep quality and satisfaction with sleep) after 3, 6 and 12 months (Table 2). Most patients were content with their therapy, recommended their therapy and would use the therapy for other indications.

3.3 Safety data One patient in the exercise therapy group was diagnosed with a lymphoma after the study had started and received radiation, and another patient in this group had an elective colon surgery. Both events were not classified as likely to be associated with the intervention. In both groups, 10 patients reported suspected adverse reactions (more than one per patient possible). Qigong group: muscle soreness (n = 10), muscle tenseness (n = 7), dizziness (n = 12), mood fluctuation (n = 2), neck blockage (n = 1), other pain (n = 3), back pain (n = 3), increased pain (n = 2); exercise group: muscle soreness (n = 19), muscle tenseness (n = 14), dizziness (n = 3), mood fluctuation (n = 1), strain on the back (n = 2), other pain (n = 4), low back pain (n = 1).

4. Discussion Patients with low back pain experienced pain relief in both groups that maintained up to 12 months. Although the mean for the group difference of the primary outcome was within the predefined margin of 5 mm the lower CI was below the margin. Therefore, non-inferiority of qigong in comparison with exercise therapy was not confirmed. Both interventions were relatively safe having only minor side effects. The strengths of this trial are the randomized study design, the relatively large sample size for a trial on qigong, and high compliance and follow-up rates. The non-inferiority approach reflects the real-world situation: Is qigong as effective as an established intervention for low back pain such as exercise? In our study, therapists were highly qualified with long-term experience. The main limitation is that patients and therapists were not blinded, which is difficult to achieve with this kind of intervention. We adjusted for the patients’ expectation in our statistical analysis. However, bias © 2014 European Pain Federation - EFIC®

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might have occurred and even the patient–therapist interaction might have influenced the outcome (Di Blasi et al., 2001). To reflect a more usual care setting, we did not apply more sophisticated diagnostic procedures. Additionally, our recruitment process resulted in a sample of study participants, which were mostly female, well educated and very motivated to do something about their back pain. The VAS on pain as the primary outcome measure is a validated and sensitive tool that is widely used to measure pain (Chapman et al., 2011). Moreover, its application is easy and fast. However, the VAS on pain limits the scope to pain. Other dimensions such as body function or activities of daily living have not been included in the primary outcome. Usually, patients choose a therapy that suits their needs and preferences. In our study, 47% in the exercise group would have preferred qigong and 12.5% in the qigong group would have preferred exercise therapy. Patients’ preferences were not dealt with in the randomization process of our study and the effect of patients’ preferences on treatment outcomes remain uncertain (McPherson et al., 1997). Trial designs that take patient preferences into account are more complex and also have their limitations (Prady et al., 2013). Our study was designed to compare two different complex therapies. However, chronic low back pain should be treated with a multimodal approach, which usually includes not only exercise, but also medication and cognitive behavioural therapy as recommended in the German National Disease Management Guideline for low back pain (Bundesärztekammer (BÄK) et al., 2010). Therefore, exercise and qigong would have been part of such a multi-component intervention. However, because the evidence on qigong for low back pain was scarce, we decided to evaluate first its effectiveness before evaluating it as part of a whole treatment package. In a review (n = 7 studies) on qigong for pain, the authors concluded that the evidence is not sufficient to suggest that qigong is an effective modality for pain management (Lee et al., 2009). In a randomized controlled trial about tai chi, another Chinese complex and multi-component intervention, which combines meditation and movement, the results supported a beneficial effect for tai chi compared with usual care alone on pain symptoms, pain intensity, function and disability after 10 weeks of a weekly tai chi class for patients with persistent low back pain. Treatment effects on all outcomes were comparable with those reported for exercise (Hall et al., 2011), but noninferiority was not investigated. The results of the current study are in accordance with a previous trial of Eur J Pain 19 (2015) 123–131

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our group investigating qigong versus exercise versus no therapy for patients aged 20–60 years with chronic neck pain (Rendant et al., 2011). Although neck pain improved significantly more in the qigong group compared with the no-therapy group after 3 and 6 months, and the mean in both intervention groups was very similar, the non-inferiority of qigong versus exercise could not be proven. The main effect in pain intensity reduction already occurred after 3 months for qigong, whereas exercise continued to improve the pain reduction for up to 6 months. Pain intensity after 6 months and disability after 12 months was statistically significantly lower in the exercise group compared with the qigong group. These effects support the hypotheses that exercise might be better to reduce pain and disability in patients with chronic low back pain. Hours of back exercise and self-efficacy were most beneficial in mediating the effects of yoga on back dysfunction (Sherman et al., 2013). However, in our study, no significant differences could be found between exercise and qigong for the secondary outcomes. Furthermore, there was no change in selfefficacy and quality of life from baseline to follow-up in both groups. It might be that mind-body interventions such as qigong might have a greater influence on pain acceptance and body awareness, which have not been measured. Furthermore, qigong might have rehabilitative and preventative benefits that take place over years and increase over time as practitioners’ skills improve, as has been reported for tai chi (Irwin et al., 2003; Wayne and Kaptchuk, 2008). And it has been suggested that qigong might have a role in the prevention of low back pain (Zauner-Dungl, 2004; Posadzki, 2011), but studies have not been conducted so far. To conclude, qigong was not proven to be noninferior to exercise therapy in the treatment of chronic low back pain. Its role in the prevention of chronic low back pain might be addressed in further studies. Author contributions T.K., K.I., A.R. and C.M.W. conceived and designed the study. Data analysis and interpretation were done by S.B., D.P., K.I. and C.M.W. Statistics were done by R.L. and C.M.W. S.B. and D.P. wrote the first draft of the paper. All authors discussed the results, commented on the paper and approved the final paper.

Acknowledgements We thank Beatrice Eden and Iris Bartsch for data acquisition, and all patients for their participation in this study.

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Supporting Information Additional Supporting Information may be found in the online version of this article at the publisher’s web-site: Protocol S1. Trial protocol. Checklist S1. CONSORT checklist.

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