Background/Aims 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). METHODS 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. RESULTS 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. CONCLUSION In this exploratory real-world analysis, hangeshashinto showed short-term symptom improvement comparable to ramosetron, and adding hangeshashinto to ramosetron was associated with lower follow-up symptom scores than ramosetron monotherapy. Prospective studies are warranted to confirm comparative effectiveness and identify patients most likely to benefit.
Nishida et al. (Mon,) studied this question.