BACKGROUND: Hospitalization costs for ulcerative colitis (UC) following the introduction of infliximab have not been evaluated.OBJECTIVE: To study predictors of costs for UC patients who were hospitalized for a flare or colectomy.METHODS: Population-based surveillance identified adults (≥18 years of age) admitted to hospital for UC flare or colectomy between 2001 and 2009 in the Calgary Health Zone (Alberta). Medical charts were reviewed and patients stratified into three admission types: responsive to inpatient medical therapy (n=307); emergent colectomy (n=227); and elective colectomy (n=208). The annual median cost with interquartile range (IQR) was calculated. Linear regression determined the effect of admission type on hospital charges after adjusting for age, sex, smoking, comorbidities, disease extent, medication use (eg, infliximab) and year. The adjusted cost increase was presented as the percent increase with 95% CIs. Joinpoint analysis assessed for an inflection point in hospital cost after the introduction of infliximab.RESULTS: Median hospitalization cost for UC flare, emergent colectomy and elective colectomy, respectively, were: $5,499 (IQR $3,374 to $8,904), $23,698 (IQR $17,981 to $32,385) and $14,316 (IQR $11,932 to $18,331). Adjusted hospitalization costs increased approximately 6.0% annually (95% CI 4.5% to 7.5%). Adjusted costs were higher for patients who underwent an elective colectomy (percent increase cost 179.8% [95% CI 151.6% to 211.1%]) or an emergent colectomy (percent increase cost 211.1% [95% CI 183.2% to 241.6%]) than medically responsive patients. Infliximab in hospital was an independent predictor of increased costs (percent increase cost 69.5% [95% CI 49.2% to 92.5%]). No inflection points were identified.CONCLUSION: Hospitalization costs for UC increased due to colectomy and infliximab.