S135 Bile Acid Sequestrants in Microscopic Colitis: Clinical Outcomes and Utility of Bile Acid Testing

Abstract

Introduction: Bile acid sequestrants (BAS) may be an effective non-corticosteroid treatment in patients with microscopic colitis (MC), but data are lacking. We evaluated the effectiveness of BAS therapy in MC and assessed the utility of bile acid testing to predict response. Methods: Adults diagnosed with MC and treated with BAS at Mayo Clinic Rochester (1/1/2010 - 12/31/2020) were identified. Response was assessed at 12 +/- 4 weeks after initiation of BAS therapy and defined as: complete (resolution of diarrhea), partial (≥50% improvement in number of bowel movements), nonresponse (< 50% improvement), and intolerance (discontinuation due to side-effects). Bile acid malabsorption was defined by elevated serum 7⍺-hydroxy-4-cholesten-3-one or by fecal testing using previously validated cutoffs (total bile acids (BA) >2,337 μmol/48 hours, primary BA >10%, or primary BA >4% with total BA >1,000 μmol/48 hours). Univariate and multivariable logistic regression was used to identify predictors of response to BAS. Results: A total of 282 patients were identified [median age 59 (20-87) years; 88.3% women] with a median duration of follow-up of 4.5 (0.4-9.1) years (Table). Prior to BAS therapy, 278 (98.6%) were treated with another medication (loperamide, budesonide, bismuth subsalicylate, or mesalamine) for MC. Patients were treated with the following BAS: 183 (64.9%) cholestyramine, 61 (21.6%) colesevelam, and 38 (13.5%) colestipol. Clinical outcomes with BAS were: 139 (49.3%) complete response, 46 (16.3%) partial response, 70 (24.8%) no response, and 27 (9.6%) intolerance. In patients with complete or partial response to BAS, 65/185 (35.1%) were on a concomitant medication for MC. The dose of BAS did not vary between response and non-response groups (p=0.51). A total of 90/282 (31.9%) had bile acid testing and 51/90 (56.7%) had a positive test. Age at MC diagnosis, smoking history, baseline diarrhea severity, history of cholecystectomy, use of prior MC medications, and abnormalities on bile acid testing did not predict response to BAS. After BAS discontinuation, 77/185 (41.6%) responders had recurrence at a median of 21 (1-172) weeks. Conclusion: In one of the largest cohorts evaluating BAS treatment in MC, we demonstrate that nearly two-thirds had a partial or complete response to these agents. Additional research is needed to determine the role of bile acid malabsoprtion in MC, as well as the subset of patients that are most likely to benefit from BAS therapy. Table 1. - Baseline Characteristics in Microscopic Colitis Patients With and Without Bile Acid Testing Median (range) or n (%) Characteristics All Patients(n = 282) Bile Acid Testing Performed(n = 90) No Bile Acid Testing Performed(n = 192) p-value Age 59 (20-87) 57 (23-87) 60 (20-87) 0.35 Sex, female 249 (88.3%) 82 (91.1%) 167 (87.0%) 0.31 Race, white 276 (97.9%) 89 (98.9%) 187 (97.4%) 0.53 Subtype, lymphocytic colitis 139 (49.3%) 52 (57.8%) 87 (45.3%) 0.06 Bowel movements, number 6 (3-20) 6 (3-20) 5 (3-15) 0.45 Body mass index (kg/m2) 25.4 (16.2-47.0) 24.5 (16.2-47.0) 25.7 (16.7-46.4) 0.21 Smoking history 95 (33.7%) 37 (41.1%) 58 (30.2%) 0.17 Cholecystectomy 69 (24.5%) 28 (31.1%) 41 (21.4%) 0.08 Celiac disease 20 (7.1 %) 5 (5.6%) 15 (7.8%) 0.39 Previous medications* 278 (98.6%) 88 (97.8%) 190 (98.9%) 0.44 *Medications for microscopic colitis prior to bile acid sequestrant treatment.