Comparative Effectiveness of Hangeshashinto and Ramosetron for the Treatment of Irritable Bowel Syndrome with...

Evidence-based pharmacological options for irritable bowel syndrome with diarrhea (IBS-D) remain limited, and complementary approaches are of interest. We evaluated the real-world effectiveness of hangeshashinto (TJ-14), ramosetron, and their combination in patients with IBS-D or mixed-type IBS (IBS-M).

This retrospective observational pilot study included 56 patients with IBS-D/IBS-M treated for 4 weeks with ramosetron (n = 12), hangeshashinto (n = 31), or combination therapy (n = 13). Symptoms were assessed at baseline and week 4 using the Izumo scale. Within-group changes were examined using nonparametric tests. To address baseline imbalances, pairwise propensity score analyses were performed using Average Treatment effect on the Treated (ATT) weighting with weighted outcome regression adjusting for pretreatment Izumo scores and prespecified covariates.

All groups showed improvement in Izumo symptom scores over 4 weeks. In ATT-weighted analyses, follow-up Izumo scores were comparable between hangeshashinto and ramosetron (adjusted mean difference [Hangeshashinto - Ramosetron] -0.269, 95% CI: -1.402 to 0.863). Combination therapy was associated with lower follow-up scores than ramosetron alone (adjusted mean difference [Combination - Ramosetron] -1.849, 95% CI: -3.571 to -0.127), while the comparison with hangeshashinto alone did not reach statistical significance (adjusted mean difference [Combination - Hangeshashinto] -0.845, 95% CI: -1.763 to 0.074). Higher pretreatment Izumo scores were independently associated with greater improvement.

In this exploratory real-world analysis, hangeshashinto showed short-term symptom improvement similar to ramosetron, and combination therapy was associated with lower follow-up symptom scores than ramosetron monotherapy in propensity score-adjusted analyses. However, given the retrospective design, small sample size, and inconsistent findings across analytical approaches, these results should be interpreted cautiously and warrant confirmation in larger prospective studies.