Date Published: October 11, 2013
Publisher: Public Library of Science
Author(s): Hugh MacPherson, Alexandra C. Maschino, George Lewith, Nadine E. Foster, Claudia Witt, Andrew J. Vickers, Sam Eldabe.
Recent evidence shows that acupuncture is effective for chronic pain. However we do not know whether there are characteristics of acupuncture or acupuncturists that are associated with better or worse outcomes.
An existing dataset, developed by the Acupuncture Trialists’ Collaboration, included 29 trials of acupuncture for chronic pain with individual data involving 17,922 patients. The available data on characteristics of acupuncture included style of acupuncture, point prescription, location of needles, use of electrical stimulation and moxibustion, number, frequency and duration of sessions, number of needles used and acupuncturist experience. We used random-effects meta-regression to test the effect of each characteristic on the main effect estimate of pain. Where sufficient patient-level data were available, we conducted patient-level analyses.
When comparing acupuncture to sham controls, there was little evidence that the effects of acupuncture on pain were modified by any of the acupuncture characteristics evaluated, including style of acupuncture, the number or placement of needles, the number, frequency or duration of sessions, patient-practitioner interactions and the experience of the acupuncturist. When comparing acupuncture to non-acupuncture controls, there was little evidence that these characteristics modified the effect of acupuncture, except better pain outcomes were observed when more needles were used (p=0.010) and, from patient level analysis involving a sub-set of five trials, when a higher number of acupuncture treatment sessions were provided (p<0.001). There was little evidence that different characteristics of acupuncture or acupuncturists modified the effect of treatment on pain outcomes. Increased number of needles and more sessions appear to be associated with better outcomes when comparing acupuncture to non-acupuncture controls, suggesting that dose is important. Potential confounders include differences in control group and sample size between trials. Trials to evaluate potentially small differences in outcome associated with different acupuncture characteristics are likely to require large sample sizes.
A recent individual patient data meta-analysis conducted by the Acupuncture Trialists’ Collaboration provided clear evidence that acupuncture is of benefit for chronic pain. The study included close to 18,000 patients with one of four chronic pain conditions: osteoarthritis, headache, back and neck pain, shoulder pain. Comparisons were made between acupuncture and sham acupuncture, as well as between acupuncture and a range of non-acupuncture controls, such as wait list and usual care. Benefits in terms of effect sizes (standardised mean differences) were in the order of 0.15 to 0.23 for the comparison between acupuncture and sham and 0.5 for the comparison with non-acupuncture controls.
Characteristics of each individual trial are presented in Appendix S1. Table 1 provides a summary of the trial-level characteristics, while Table 2 provides a summary of patient-level characteristics. In a majority of trials the acupuncture was based on traditional Chinese acupuncture (59%) and had a flexible point prescription (55%). In all 29 trials manual needle stimulation was used in the acupuncture group, while only about quarter of trials allowed the addition of electrical stimulation (n=7) and 14% allowed moxibustion (n=4). Attempts to elicit de qi in the acupuncture group were made in all 25 trials that provided this information. The maximum number of sessions varied widely, from 3 to 30, as did the mean number of needles used (range 1-18) and the mean session duration (range 15 to 32 minutes). The mean session frequency ranged from one session every eight days to two sessions a week.
We found little evidence of important effects on pain outcomes associated with different characteristics of acupuncture or acupuncturists, including style of acupuncture, the frequency or duration of sessions, patient-practitioner interactions or the years of experience of the acupuncturists. Increased number of needles and more sessions appear to be associated with better outcomes when comparing acupuncture to non-acupuncture controls. This suggests that the dose of acupuncture is important. Trials designed to evaluate the potentially small differences in outcome associated with different acupuncture or acupuncturist characteristics are likely to require large sample sizes. There is room for a diversity of practice in acupuncture, and no strong evidence that such diversity leads to some patients receiving sub-optimal outcomes.