Although CSA can exert high initial efficacy for severe attacks of UC, >50% of patients who relapse require a colectomy. Specifically, mucosal healing evaluated by endoscopy was associated with the 1-year colectomy rate. In contrast, a history of adverse drug reactions was correlated with the long-term colectomy rate. Therefore, we propose that treatment of severe UC with CSA requires consideration of both initial remission and long-term maintenance as management goals.