INCIDENCE OF CROHNS-DISEASE IN STOCKHOLM COUNTY 1955-1989

Aim-To evaluate the incidence of Crohn's disease in Stockholm County b etween 1955 and 1989. Methods-A cohort of 1936 patients with Crohn's d isease was retrospectively assembled. Incidence rates and changes in d isease distribution were assessed. Results-The mean increase in incide nce was 15% (95% confidence intervals 12% to 18%) per five year period with a mean annual incidence rate at 4.6/10(5) during the last two de cades. The mean incidence for the entire study period was similar for men and women. The mean age at diagnosis increased from 25 years in 19 60-64 to 32 years in 1985-89, partly because of an increasing proporti on of patients aged at least 60 years at diagnosis. The proportion of patients with colonic Crohn's disease at the time of diagnosis increas ed from 15% to 32% (17% difference; 95% confidence intervals 12% to 23 %) whereas the proportion of patients with ileocaecal disease decrease d from 58% to 41% (17% difference; 95% confidence intervals 10% to 24% ) during the study period. Elderly patients had a higher proportion of small. bowel disease and a lower proportion of ileocolonic disease co mpared with the younger patients. Conclusion-The incidence rate of Cro hn's disease in Stockholm has stabilised at 4.6/10(5) and the proporti on of elderly patients has increased during a 35 year period. Colonic Crohn's disease has increased in frequency with a reciprocal decrease in ileocaecal disease.