Inflammatory bowel disease in Iceland, 1980-89 -: A retrospective nationwide epidemiologic study

Background: A previous nationwide epidemiologic study of inflammatory bowel disease (IBD) in Iceland in 1950-79 showed a low but steadily rising incidence. The incidence of IBD in Iceland in 1980-89 was investigated and compared with reports from neighboring countries. Methods: Cases were retrieved by a review of all small-and large-intestinal tissue specimens with any type of inflammation submitted to the only two departments of pathology in Iceland. All small-intestinal X-ray records suggestive of Crohn's disease (CD) in the three major hospitals were also screened. All hospital and outpatient records of cases suggestive of IBD were then reviewed using accepted criteria for confirmation or exclusion. Results: The mean annual incidence of ulcerative colitis (UC) was 11.7/100,000, and that of CD 3.1/100,000. The highest age-specific incidence of UC was in the group 30-39 years old and for CD in the group 60-69 years old. The most frequent involvement at diagnosis of UC was proctitis only, in 54%, and in CD colon only, in 54.7% of the patients. Conclusions: This study shows a continuing increase in the incidence of both diseases. Compared with the period 1970-79, there has been an almost twofold increase in the mean annual incidence of UC and more than a threefold increase of CD, a statistically significant increase in both instances.