Abstract
BackgroundIn a recent individual patient data meta-analysis, acupuncture was found to be superior to both sham and non-sham controls in patients with chronic pain. In this paper we identify variations in types of sham and non-sham controls used and analyze their impact on the effect size of acupuncture.MethodsBased on literature searches of acupuncture trials involving patients with headache and migraine, osteoarthritis, and back, neck and shoulder pain, 29 trials met inclusion criteria, 20 involving sham controls (n = 5,230) and 18 non-sham controls (n = 14,597). For sham controls, we analysed non-needle sham, penetrating sham needles and non-penetrating sham needles. For non-sham controls, we analysed non-specified routine care and protocol-guided care. Using meta-regression we explored impact of choice of control on effect of acupuncture.FindingsAcupuncture was significantly superior to all categories of control group. For trials that used penetrating needles for sham control, acupuncture had smaller effect sizes than for trials with non-penetrating sham or sham control without needles. The difference in effect size was −0.45 (95% C.I. −0.78, −0.12; p = 0.007), or −0.19 (95% C.I. −0.39, 0.01; p = 0.058) after exclusion of outlying studies showing very large effects of acupuncture. In trials with non-sham controls, larger effect sizes associated with acupuncture vs. non-specified routine care than vs. protocol-guided care. Although the difference in effect size was large (0.26), it was not significant with a wide confidence interval (95% C.I. −0.05, 0.57, p = 0.1).ConclusionAcupuncture is significantly superior to control irrespective of the subtype of control. While the choice of control should be driven by the study question, our findings can help inform study design in acupuncture, particularly with respect to sample size. Penetrating needles appear to have important physiologic activity. We recommend that this type of sham be avoided.
Highlights
One of the challenges of conducting a non-pharmacological clinical trial is choosing an appropriate control intervention
Types of Sham Acupuncture Controls The characteristics we aimed to study in those trials with a sham acupuncture control group included whether or not a needle was used, whether a needle that penetrated the skin was used, whether sham was performed on true acupuncture points or nonacupuncture points, and whether needle insertion was deep or superficial
Using the same rationale for exclusions, overall we found larger effect sizes were associated with acupuncture vs. non-penetrating sham needles (0.43; 95%CI: 0.01, 0.85) than vs. penetrating sham needles (0.17; 95%CI: 0.11, 0.23) the difference between groups did not reach conventional levels of statistical significance
Summary
One of the challenges of conducting a non-pharmacological clinical trial is choosing an appropriate control intervention. The simplest control arm is to offer patients routine clinical care without the experimental treatment. This controls for the expected course of the disease. The control arm can be designed to control for other factors, for example, the non-specific effects associated with the time and attention that a patient receives from a clinician. In an individual patient data meta-analysis of high quality trials conducted by the Acupuncture Trialists’ Collaboration [2], acupuncture reduced pain scores by 0.15 to 0.23 standard deviations in comparison to sham (placebo) acupuncture. In a recent individual patient data meta-analysis, acupuncture was found to be superior to both sham and non-sham controls in patients with chronic pain. In this paper we identify variations in types of sham and non-sham controls used and analyze their impact on the effect size of acupuncture
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