Objective Evidence-based treatment guidelines have been unable to provide evidence-based guidance on the effects of acupuncture for irritable bowel syndrome (IBS) because the only previous systematic review included only small, heterogeneous and methodologically unsound trials. We conducted a new systematic review and meta-analysis of randomized controlled trials (RCTs) to estimate the effects of acupuncture for treating IBS. Methods MEDLINE, the Cochrane Central Register of Controlled Trials, EMBASE, Cumulative Index to Nursing and Allied Health, and the Chinese databases Sino-Med, CNKI, and VIP were searched through November 2011. Eligible RCTs compared acupuncture with sham acupuncture, other active treatments, or no (specific) treatment, and evaluated acupuncture as an adjuvant to another treatment. Our outcomes were overall IBS symptom severity and health-related quality of life. Dichotomous data were pooled to provide a relative risk (RR) of substantial improvement after treatment, and continuous data were pooled to provide a standardized mean difference (SMD) in post-treatment scores between groups. Results Seventeen RCTs (N=1806) were included. We found no evidence of an improvement with acupuncture relative to sham acupuncture on symptom severity (SMD = −0.11, 95% confidence interval: −0.35 to 0.13; 4 RCTs) or quality of life (SMD = −0.03, −0.27 to 0.22; 3 RCTs). Because of the homogeneity of the results of the sham-controlled trials, results were unaffected by restriction to the 4 sham-controlled RCTs that used adequate randomization, blinding, and had few withdrawals/drop-outs. Among RCTs that did not use a placebo control, acupuncture was more effective than pharmacological therapy (RR of symptom improvement=1.28, 1.12 to 1.45; 5 RCTs) and no (specific) treatment (RR = 2.11, 1.18 to 3.79; 2 RCTs). There was no difference between acupuncture and Bifidobacterium (RR = 1.07, 0.90 to 1.27; 2 RCTs) or between acupuncture and psychotherapy (RR=1.05, 0.87 to 1.26; 1 RCT). Acupuncture as an adjuvant to another Chinese medicine treatment was statistically significantly better than the other treatment alone, in trials with a high risk of bias (RR = 1.17, 1.02 to 1.33; 4 RCTs). Conclusions Sham-controlled RCTs have found no benefits of acupuncture relative to a credible sham acupuncture control on IBS symptom severity or IBS-related quality of life. In comparative effectiveness Chinese trials, patients reported greater benefits from acupuncture than from pharmacological therapies. Future trials may help clarify whether or not these reportedly greater benefits of acupuncture relative to pharmacological therapies are due entirely to patients’ preferences for acupuncture or patients’ greater expectations of improvement on acupuncture relative to drugs.

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