Effects of Transcutaneous Auricular Vagal Nerve Stimulation on Chronic Constipation: A Multicenter, Randomized Controlled Study

ObjectiveThe objective of this study was to investigate the efficacy of transcutaneous auricular vagal nerve stimulation (taVNS) in adult patients with chronic constipation.DesignConsecutive patients who met the Rome IV criteria for chronic constipation were enrolled and randomly assigned to either the taVNS group or the sham-taVNS group. Treatment consisted of 30 min of therapy twice a day for 4 weeks. The primary outcome was the response rate at week 1-4, defined as the proportion of patients with a weekly complete spontaneous bowel movement (CSBM) of >= 3 and weekly excessive use of rescue medication <= 3 times. Secondary outcomes included spontaneous bowel movements, anxiety and depression scores, abdominal symptoms, and adverse events.ResultsThe study was terminated due to lack of efficacy revealed by the interim analysis. A total of 106 patients were randomized, with 52 participants in the taVNS group and 54 participants in the sham-taVNS group. After 4 weeks of treatment, the response rates were 17% (9/52) in the taVNS group and 19% (10/54) in the sham-taVNS group. There was no significant difference between the two groups in intention-to-treat (ITT) analysis (RR 0.92, 95% CI 0.30-2.80, p = 1) or in the per-protocol (PP) analysis. No serious adverse events were reported.ConclusionOur study did not support the effectiveness of 4-week 25 Hz taVNS for the treatment of adult chronic constipation patients.Trial Registration number: NCT05723731