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Objectives To illustrate the pitfalls of using meta-analysis to combine estimates of effect in trials that are highly varied and have a high potential for bias.Methods We used a random-effects meta-analysis to pool the results of 51 sham-controlled acupuncture trials of chronic pain published in English before 2008 and explored the heterogeneity using meta-regression. We repeated the process on a subset of these trials that used a visually credible non-penetrating sham device as control (N?=?12).Results In both analyses there were high levels of heterogeneity and many studies were at risk from potential bias. The heterogeneity was not explained by meta-regression.Conclusions Trials of interventions that have high potential for bias, such as many in the acupuncture literature, do not meet the assumptions of the statistical procedure that underlie random-effects meta-analysis. Even in the absence of bias, heterogeneity in meta-analyses is not accounted for by the CIs around the pooled estimate.

Background In trials, ‘therapist intensive’ complex interventions are typically delivered over time, during which a relationship between the practitioner and participant may develop. Such relationships are sometimes criticised as obscuring any ‘true’ treatment effect. Limiting interactions is one strategy that might be used to try to control for the effect of a therapeutic relationship.Objectives We conducted systematic review into the rationale, methods and effects of constraining relationships in controlled trials and cohort studies of acupuncture, including studies published before 2008 with an update citation search in 2010.Methods We searched six databases without keyword restrictions. Meta-analysis and meta-regression were used to explore the effect of relationship constraint on pain outcomes.Results Eighty-one of 785 (10.3%) trials reported constraining relationships. Most did not state the reason for constraint, describe the nature of the limitation, provide information on how the constrained relationship was monitored or note protocol adherence. Where a reason was reported, this was primarily to maintain participant blinding, rarely was it stated that the constraint was to control the therapeutic relationship. We found no evidence of an effect of constraint on pain outcomes (percentage heterogeneity explained, p=0.89). These results were robust to variation in trial quality and design.Conclusions Acupuncture trials appear to be constrained mostly to try to prevent participant unblinding to their allocated treatment, not to control the therapeutic relationship. The apparent lack of monitoring and negligible effects on pain outcomes of the included trials indicate the need for more high-quality randomised controlled trials investigating the effect of constraint.

Introduction There is growing evidence about the effectiveness of acupuncture in the short term treatment of chronic low back pain but little is known about long term outcomes. To address this question we followed up participants of a past randomised controlled trial of acupuncture to assess outcomes after 5.5 to 7 years.Methods A postal questionnaire assessing pain, quality of life, disability, experience with back pain and healthcare resource use was sent to all 239 participants of the York Acupuncture for Back Pain trial.Results Response to the survey was low at 43.9%. Pain measured by the SF-36 Bodily Pain dimension was maintained in the acupuncture group since the last follow up 3.5 to 5 years previously. The usual care group had improved over the intervening years and there was now no evidence of a difference between the groups (difference -0.4 points, 95% confidence interval -10.1 to 9.7). The results were unchanged on sensitivity analysis using multiple imputation. In both groups back pain had not completely resolved and worry about back health was moderate. Physiotherapy and acupuncture were used at similar rates for continuing treatment.Discussion We theorise that exposure to a short course of acupuncture speeds natural recovery from a back pain episode, but improvements plateau after two years. Acupuncture is often accessed privately for long term management of back pain but is rarely available within the health service. While our study methods were robust, the low response rate means that our findings should be interpreted with caution.