Six RCTs (3,529 patients) were included in the review.
Alosetron was more effective than placebo for adequate relief of pain or global symptoms. The pooled OR for a positive outcome for all studies was 1.81 (95% CI: 1.57, 2.10, P<0.0001).
Alosetron remained more effective than placebo following the sensitivity analysis. The pooled OR for a positive outcome after excluding one study that compared alosetron with mebeverine was 1.85 (95% CI: 1.57, 2.18, P<0.0001).
The pooled OR for a positive outcome after excluding the largest study with the largest effect size was 1.49 (95% CI: 1.25, 1.73, P<0.0001).
The pooled OR for a positive outcome after including only those patients who received 2 mg alosetron daily was 1.96 (95% CI: 1.69, 2.28, P<0.0001).
Participants in the alosetron group were more likely to report constipation than the control group (OR 5.64, 95% CI: 4.40, 7.33, P<0.0001) and were generally more likely to report any adverse event (OR 1.70, 95% CI: 1.42, 2.04, P<0.0001).