The epidemiology of inflammatory bowel diseases in Finland

There is evidence that the incidence of inflammatory bowel diseases is increasing, but the data are inconsistent. For appropriate allocation of health care resources, knowledge of the actual occurrence of diseases is important. We here conducted an epidemiological survey using a population-based register in a well-defined area representative of the whole Finnish population.

The collection of cases took place in 1986-1999 in the Tampere region, which comprised 363,000 adults in 1999. All municipal centers detecting and managing inflammatory bowel diseases participated in the study. Particular effort was made to register all cases.

The total number of patients was 1691. The prevalence per 100,000 inhabitants in 1986 was 119 for ulcerative colitis (UC), 40 for Crohn's disease (CD) and 9 for inflammatory bowel disease unclassified (IBDU); in 1999 the respective figures were 291, 124 and 27. During the study period, the annual incidence of UC increased from 13.3 to 19.6 per 100,000, and that of CD from 5.0 to 9.4, whereas the incidence of IBDU decreased from 1.2 to 0.3. The extent of the diseases remained by and large unaltered over the time of survey.

An increasing trend was observed in the number of patients with inflammatory bowel disease, and the frequency was higher than that reported in most surveys. This increase constitutes a challenge for the health care system.