Risk Factors For 90-Day Readmission Among Hospitalized Patients With Ulcerative Colitis

INTRODUCTION: The hospitalization of a patient with an ulcerative colitis (UC) flare reflects a severe disease state and is a significant contributor to the overall costs of care. Thus, understanding which factors influence the likelihood of readmission among patients hospitalized for UC is critical to providing high quality, low cost care. This study aims to evaluate which factors for patients admitted with UC are associated with an increased risk for 90-day readmission. METHODS: We designed a retrospective study including all patients 18 years or older with an admission for ulcerative colitis at the University of Chicago Medical Center between 1/1/2013 and 4/1/2018. Cases of ulcerative colitis were identified using the ICD-9 code 556.X and ICD-10 code K51.X and separately reviewed based on clinical, radiographic, histologic and endoscopic information. Data was analyzed using a Wilcoxon rank-sum test for continuous variables and Fischer’s exact test for categorical variables. Multivariate logistic regression was performed to identify independent risk factors for 90-day readmission. RESULTS: 1,455 admissions were reviewed. 1,046 were excluded for age < 18 (n = 102), diagnosis of Crohn’s disease (n = 42), colitis other than UC (n = 13), history of colectomy (n = 245), admissions unrelated to a UC flare (n = 430), planned surgical procedures (n = 199) and other (i.e. duplicate records, leaving against medical advice; n = 19). An additional 149 were removed for being rehospitalizations (n = 103), absence of 90 day follow up (n = 42). Of the 260 patients remaining, 48 patients (18%) were re-admitted to the hospital within 90 days. Factors associated with re-admission on univariate analysis included: history of parenteral nutrition use prior to colectomy (17.1% vs 6.2%, P = 0.036), use of steroids as an outpatient prior to admission (77.1% vs 57.1%, P = 0.013), and mean units of blood transfused during hospitalization (0.46 vs 0.25, P = 0.006). After controlling for factors in univariate analysis, only outpatient steroid use prior to admission was associated with increased risk of 90-day readmission (OR 3.52; 95% CI 1.32-9.33) (Table 1). CONCLUSION: Of the factors studied, only steroid use prior to admission was an independent risk factor for readmission. Additional factors related to readmission risk throughout the hospitalization to include laboratory and vital sign trends may offer additional insights into the risk of readmission.