Epidemiology of ulcerative colitis in western Norway.

The incidence of ulcerative colitis (UC) in the three counties that compose Western Norway was registered in a prospective study during the years 1984 and 1985. Both inpatients and outpatients were included. Five hundred and fifty general practitioners and 12 hospitals participated in the study. A total of 239 patients were diagnosed in this area with 807,000 inhabitants, giving a mean annual incidence of 14.8 per 100,000. For patients between 30 and 35 years of age the age-specific incidence rate was 31.2. The M/F sex ratio was 1.10. Familial occurrence of inflammatory bowel disease was found in 11% of the patients. Patients with rectal involvement only constituted 35% of the patients.