Open Label Experience With Bismuth Subsalicylate in Patients With Microscopic Colitis

Introduction: Microscopic colitis (MC) is a common cause of chronic watery diarrhea. Several treatment options exist, including anti-diarrheal agents and corticosteroids. Bismuth subsalicylate (BSS) is used but the evidence for this treatment is limited. We sought to evaluate symptom response and subsequent recurrence in patients (pts) with MC treated with BSS at our institution. Methods: For this retrospective chart review, pts with biopsy-proven MC treated with at least 3 weeks of BSS were identified electronically. Cases were confirmed and data abstracted by chart review. The primary objectives were to determine symptom response (complete = resolution of diarrhea, partial = at least 50% improvement, nonresponse = < 50% improvement) and the rate of subsequent symptomatic recurrence. Results: A total of 128 pts were included (median age 50.5 years, 88% women; median #BM/d = 6 (range, 3-20); 44% lymphocytic colitis, 56% collagenous colitis) with median follow-up of induction therapy of 7.2 weeks (range, 3-23). Total follow-up was 163 weeks (range, 3-951). Eighty pts (63%) had received other treatments before BSS, and 48 (37%) used BSS as first-line treatment. Full-dose BSS (9 pills per day) was used in 80 pts (63%), and 48 (37%) used lower doses. Of the 128 pts, 72 had complete response (56%), 33 had partial response (26%), and 23 were nonresponsive (18%). There was evidence of a dose response, with full-dose BSS having a higher rate of complete response (68%) than lower doses (34%), P=0.01. Response was not associated with MC subtype (lymphocytic vs collagenous colitis, P=0.53), whether BSS was used first-line or after failure of other drugs (P=0.19), or if loperamide was used concomitantly (in 44% of subjects, P=0.47). Of the 72 pts with complete response, 30 had symptomatic recurrence (42%) at a median of 59.9 weeks (range, 1-343) after discontinuation of BSS. Recurrences were treated with BSS (43%) +/- other drugs such as loperamide or budesonide (57%). Adverse events were recorded for 6 pts (headache, nausea, inner ear pain, tinnitus, hypercalcemia, and mouth pain associated with the chewable tablets). In only 1 pt was the AE (headache) treatment-limiting. Conclusion: In this uncontrolled experience, BSS was an effective treatment for MC with low risk of mostly mild adverse events. The rate of recurrence was lower than has been reported for budesonide. Further research is necessary to determine predictors of response to BSS.