Initial Effects of Electroacupuncture for Chronic Severe Functional Constipation and the Potential Underlying Factors: Secondary Analysis of a Randomized Controlled Trial

BACKGROUND: Electroacupuncture (EA) has been found to be effective for treating chronic severe functional constipation (CSFC). However, the initial effects of treatment usually affect the acceptability and compliance of patients with chronic disease in particular. Which class of CSFC patients will have a better initial response to EA remains uncertain and requires investigation. METHODS: This was a secondary analysis of an original multicenter randomized controlled trial in which patients with CSFC were randomly assigned to receive 28 sessions of EA or sham electroacupuncture (SA) over 8 weeks with 12 weeks of follow-up. The primary outcome, namely, response with complete spontaneous bowel movements (CSBMs), required participants to have ≥ 3 CSBMs and an increase of ≥ 1 CSBM from the baseline over the first week of treatment. Logistic regression analysis with bootstrapping techniques was performed to determine independent factors related to the response. RESULTS: A total of 1051 eligible patients were included in this study of whom 161 patients were classified as responders at week 1. The CSBM response rate was higher in the EA group (17.5%) than in the SA group (13.2%). And the proportion of these 1-week early responders remained to have higher clinical response at the end of 8-week treatment and 12 weeks after treatment. Age and higher baseline CSBMs were related to CSBM response within the first week: with every 1-year increase in age, the likelihood of clinical response was reduced by 1.7% (odds ratio [OR] 0.983, 95% confidence interval [CI] 0.972 to 0.993; P=0.001). The odds of a CSBM response in patients with 1< CSBMs ≤ 2 at baseline were 4.64 times higher than that in patients with CSBMs ≤ 1 (OR 4.64, 95%CI 4.01 to 5.27). CONCLUSIONS: EA produced its initial effects within the first week of treatment. And the effects could last until week 8 and week 20. A younger age and higher number of CSBMs at baseline may increase likelihood of a response.