Outcomes of Bismuth Subsalicylate Treatment in Patients With Microscopic Colitis

Abstract

Introduction: Bismuth subsalicylate (BSS) is commonly used to treat microscopic colitis (MC) with limited data on response and recurrence rates from small clinical trials. We aimed to evaluate clinical response and recurrence to BSS for MC. Methods: Patients with collagenous colitis (CC) or lymphocytic colitis (LC) treated with BSS at a single tertiary care institution from 12/31/2001 to 12/31/2016 were included. MC was defined by presence of diarrhea with normal endoscopy and compatible histopathology. Complete response to BSS was defined as normalization of stool frequency and partial response was defined as at least 50% reduction in stool frequency from baseline at 8±2 weeks. Recurrence was defined by return of increased stool frequency with no alternative etiology after complete resolution. Results: Overall, 94 patients (91.4% female, median age 69.4 years; 49 (52%) had LC and 45 (48%) had CC) were treated with BSS with a median duration of follow-up of 2 years (range, 0.1-11 years). Fifty four (57.4%) had complete response, 20 (21.2%) had partial response, and 20 (21.2%) had no response. Of the 54 patients with complete response, 28 (51.8 %) had recurrence. The median time to recurrence was 12.5 weeks after stopping BSS. Of the patients with recurrence, 23 (82.1%) were retreated successfully with BSS, 3 (10.7%) with loperamide and 2 (7.1%) were treated with budesonide. There were no serious adverse events reported with BSS.On univariate analysis, there was evidence for a dose response, with a higher dose being associated with a higher rate of complete response (P=0.0025, Table 1). Moreover, response rates varied by MC subtype (with LC more likely to have a complete response than CC (67.3% vs 48.8%, P=0.003)), but not by age or diarrhea severity.On multivariate analysis after adjusting for age and gender, both a higher dose (P=0.0044) and presence of LC (P=0.03) were associated with a higher response to BSS. Recurrence rates were not dependent on dose (Table 1), number of baseline bowel movements per day or type of MC.Table: Table. Dose response and recurrence for BSS for MCConclusion: Patients with microscopic colitis treated with BSS have a high clinical response rate but also have a high risk of recurrence. A higher dose is associated with a higher response rate and patients with LC are more likely to respond compared to CC. A large prospective clinical trial is needed to evaluate the efficacy of BSS for MC patients.