Mo1268 Characterization of Stool Microbiota in Subjects With IBS-D Receiving Repeat Treatments With Rifaximin in the TARGET 3 Study

the primary endpoint significantly favored RFX (33%) vs. PBO (25%, p=0.02). Regarding demographic characteristics, the RFX repeat treatment effect was evident in subjects 30 kg/m2 (Δ=5%, p=0.3035) (Figure). By race, the magnitude of the treatment effect was pronounced in white subjects (Δ=12%), but similar in non-white subjects (Δ=0.1%). A treatment by race interaction analysis yielded a p-value of 0.2440, an indication that race was not an effect modifier. Regarding baseline disease characteristics, the treatment effect was apparent in subjects with severe (Δ=10%, p=0.1564) and non-severe IBS (Δ= 10%, p=0.0185), and consistent across IBS symptom duration. Similar subpopulation results were observed for AP and SC when examined separately. Conclusions: Rifaximin response in subjects with IBS-D was significantly greater than placebo for the primary endpoint for all subgroups except non-white subjects where the sample size was quite small. These findings support the generalizability of the primary endpoint results.