The Incidence of Crohn's Disease in Northern Norway from 1983 to 1986

In a prospective epidemiologic multicentre study in Northern Norway, the incidence of Crohn's disease was 5.8 per 100,000 per year. The highest incidence was found in the county of Nordland, located in the south, and the lowest in Finnmark, located in the north of the region (6.7 and 3.9 per 100,000 per year, respectively). Similarly, there was a lower incidence in rural than in urban areas. Crohn's disease was found as frequently in the large as in the small bowel. The location in the large bowel seemed more often to be associated with extraintestinal manifestations. The male to female ratio was almost 1:1. In males a peak incidence was seen in the age group 20–29 years old, whereas no similar peak was seen in the females. Twenty-two per cent of the cases were diagnosed before the age of 20. In 13.4% of the cases a family history of inflammatory bowel disease was found.