Extracolonic diagnoses in ulcerative colitis: an epidemiological study.

In a population-based study of 1274 patients with ulcerative colitis (UC), the overall prevalence of extracolonic diagnoses was 21%. Seventy percent of patients with extracolonic diagnoses had extensive colitis. Patients without extracolonic diagnoses had only 28% extensive colitis (p less than 0.001), compared with 37% in the entire test population. The prevalence was higher in familial UC (p less than 0.05). The extracolonic diagnoses could be classified into two major groups, activity related and autoimmune, with regard to the extent and activity of UC and to the effects of medical and surgical treatment. Three hundred sixty-four diagnoses were distributed in 271 UC patients. It is concluded that extracolonic diagnoses are less frequent in an unselected patient group. However, extracolonic diagnoses are associated with the extent of UC at the time of diagnosis and with familial UC, and they can be classified as either activity related or autoimmune, with characteristic combinations of several extracolonic diagnoses occurring in 25% of the 271 patients.