BACKGROUND/AIMS: The course and prognosis of ulcerative colitis (UC) are often reported in terms of mortality and cancer risk. This study examined the clinical course in terms of morbidity.

METHODS: A total of 1161 patients with UC were followed up from diagnosis up to 25 years. Actuarial analysis and Markov chain analysis were used to estimate the probabilities of remission and relapses during the disease course.

RESULTS: The distribution of disease activity was remarkably constant each year, with about 50% of patients in clinical remission. After 10 years, the colectomy rate was 24%. The cumulative probability of a relapsing course is 90% after 25 years of follow-up. The course of disease changed between remission and relapse without significant predictors, except for disease activity in foregoing years. In years 3-7 after diagnosis, 25% of patients were in remission; 18% had activity every year; and 57% had intermittent relapses. Activity in the first 2 years after diagnosis significantly correlated with having an increased probability of 5 consecutive years of disease activity (P = 0.00001). The probability of maintaining working capacity after 10 years was 92.8% (range, 90.8%-94.8%).

CONCLUSIONS: About half of patients with UC will be in remission at any time, although 90% have an intermittent course. Relapses are unpredictable except that disease activity in foregoing years indicates with 70%-80% probability that the disease will continue the following year. Although UC is troublesome, most patients' lives are relatively little influenced by it.