S1950 Risk Factors for 30-Day All-Cause Readmission Among Adults Hospitalized With Microscopic Colitis: Analysis of the National Readmissions Database

Introduction: There is limited data on hospital admissions and readmissions for microscopic colitis (MC), an inflammatory bowel disease (IBD) of increasing prevalence characterized by insidious watery diarrhea. We sought to describe the incidence, readmission rates, and associated risk factors of MC requiring hospitalization using a U.S. nationally representative database. Methods: This was a descriptive cohort study of adult patients discharged alive following hospitalization for MC as a principal or secondary diagnosis (International Classification of Diseases-10 code K52.83X) in the 2017-2019 Nationwide Readmission Database (NRD). The primary outcome was 30-day all-cause, unplanned readmission. Risk factors for readmission were selected a priori using the Anderson Model for Healthcare Utilization as a framework. We estimated risks of 30-day readmission using Cox proportional hazards regression, verifying proportionality assumption, and accounting for the complex sampling design to obtain nationally representative estimates. Results: 16,398 inpatients (mean age 71.5 years; 78.7% women) had a primary or secondary diagnosis of MC, with 2,496 (15.4%) having MC as the primary diagnosis. In this cohort, the overall 30-day readmission rate was 14.7%, with mean length of stay (LOS) of 5.10 days for index admissions and 6.54 days for readmissions. Risk factors significantly associated with all-cause 30-day readmission included higher comorbidity readmission index (odds ratio [OR] 1.04, 95% CI 1.03-1.05), diabetes with chronic complications (OR 1.25, 1.09-1.43), and longer LOS (OR 1.02, 1.02-1.03). When analyzing patients with MC as the primary diagnosis, the 30-day readmission rate was 14.4% with mean LOS of 5.12 days. Risk factors for readmission included diabetes with chronic complications (OR 1.48, 1.05-2.08) and longer LOS (OR 1.05, 1.02-1.05). No significant differences in 30-day readmission rates were observed between MC subtypes. Most common primary diagnoses for 30-day readmission were sepsis (7.07%), acute kidney failure (4.34%), hypertensive CVD with CKD (3.97%), collagenous colitis (2.44%), and enterocolitis due to C. diff (1.76%). Conclusion: Nearly 1 in 7 patients hospitalized with microscopic colitis experience readmission within 30 days. These findings highlight the need for targeted discharge planning and care coordination, particularly for high-risk patients with diabetes. Future research should focus on understanding the underlying reasons for readmission and developing interventions to reduce preventable readmissions.