Placebo response to sham electroacupuncture in patients with chronic functional constipation: A secondary analysis

Abstract Background Chronic severe functional constipation is a common disease that requires novel and effective treatment strategies. Acupuncture might constitute a promising therapeutic approach for chronic constipation, but it reportedly engenders an enhanced placebo response. Herein, we aimed to determine the magnitude of the placebo responses to electroacupuncture for constipation and identify its influencing factors. Methods In this secondary analysis of a multicenter randomized trial, patients were randomized to a sham electroacupuncture group, which was administered for 8 weeks in 24 sessions of superficial needling at nonacupoints. The placebo response rates were assessed using three responder criteria: ≥3 complete spontaneous bowel movements per week (CSBMs/week), overall CSBM, and sustained CSBM. Logistic regression with backward selection method was employed to identify the potential factors that affected the placebo response. Key Results Overall, 539 patients were included in the study. The placebo response rate was 10.58%, 9.46%, and 9.09% according to the three aforementioned criteria, respectively. Those who exhibited more CSBMs/week at baseline were more likely to respond to sham electroacupuncture. Among patients with more than one CSBM per week at baseline, the response rates for achieving the criteria of ≥3 CSBMs per week, overall CSBM, and sustained CSBM were 25.40%, 30.16%, and 22.22%. Conclusions and Inference Electroacupuncture did not demonstrate a large placebo response in functional constipation treatment. The number of CSBMs at baseline may be a moderator of the placebo response to sham electroacupuncture. Thus, superficial needling sham acupuncture may be considered an ideal sham control for clinical trials of chronic constipation.