[Ulcerative colitis in Iceland 1980-1989. A retrospective epidemiological study.]

To find the incidence of ulcerative colitis in Iceland during the past decade for comparison with previous study and incidence figures from neighbouring countries.

This was a nationwide retrospective study of the period 1980-1989. Cases were retrieved by reviewing all reports on tissue specimens from the large and small intestine with any type of inflammation referred to the two departments of pathology in Iceland. All possible cases of ulcerative colitis were then followed by a review of the clinical information. Only those cases fulfilling accepted diagnostic criteria were included in the study.

Thus 282 cases of ulcerative colitis were found, 166 men and 116 women, M/F ratio 1.43. The mean annual incidence for the 10 year period was 11.7/100,000. The highest age specific incidence was found in the group 30-39 years, 21/100,000/year. Most frequently the inflammation was limited to the rectum (proctitis), found in 53.9% of the patients. Proctosigmoiditis was seen in 29.8%, left-sided col notitis in 5.3% and extensive colitis in 11%. Approximately 63% of the patients had been symptomatic for less than six months before diagnosis. Information on familial cases of inflammatory bowel disease was obtained from 8.9% of the patients.

There has been a steady and significant increase in the incidence of ulcerative colitis in Iceland in the past four decades and the mean annual incidence has almost doubled from the last decade 1970-1979. This increase in incidence is considered real, i.e. not due to better methods of detection or a change in diagnostic criteria.