Randomised clinical trial: Tong‐Xie‐Yao‐Fang granules versus placebo for patients with diarrhoea‐predominant irritable bowel syndrome

BACKGROUND: Tong-Xie-Yao-Fang (TXYF) is a Chinese herbal formula for treating chronic diarrhoea accompanied by abdominal pain. The results were inconsistent in previous trials examining its effect. AIM: To study the efficacy of TXYF granules for treating diarrhoea-predominant irritable bowel syndrome (IBS-D). METHODS: We performed a double-blind, placebo-controlled randomised trial and enrolled 160 participants with IBS-D. The participants had VAS scores ≥3 cm in IBS-D global symptoms and ≥2 days in a week with abdominal pain and loose stools (Bristol score 5, 6 or 7). They were randomly assigned to received TXYF or placebo during a treatment period of 4 weeks, and they were followed up for 8 weeks after treatment. The primary outcome was adequate relief of IBS-D global symptoms for at least 2 of 4 weeks during weeks 1-4. Secondary outcomes included mean weekly VAS scores of IBS-D major symptoms, mean weekly stool frequency, mean weekly Bristol score, and adverse events. RESULTS: 155 of 160 patients completed the trial. We found a significantly higher rate of adequate relief of global symptoms in TXFY group during weeks 1 to 4 (57.5% vs 37.5%, χ2 = 5.6391, P = 0.017); logistic regression analysis showed a similar result (OR 2.2, 95% CI 1.2-4.4, P = 0.016). Most of the secondary outcomes showed superiority of TXYF over placebo in weekly assessment from week 3 to week 7. The adverse event rate was low in both groups (3.8% vs 3.8%, P = 1.000). CONCLUSION: During a 4 week trial, TXFY granules were superior to placebo in controlling symptoms of IBS-D.