Abstract
OBJECTIVE: The objective of this study was to investigate the efficacy of transcutaneous auricular vagal nerve stimulation (taVNS) in adult patients with chronic constipation. DESIGN: Consecutive 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. RESULTS: The 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. CONCLUSION: Our study did not support the effectiveness of 4-week 25 Hz taVNS for the treatment of adult chronic constipation patients. TRIAL REGISTRATION: clinicaltrials.gov number: NCT05723731.