[Incidence of inflammatory bowel disease in Aragon: outcome of a prospective population-based study]

To identify every new case of ulcerative colitis (UC) (including ulcerative proctitis), Crohn's disease (CD) and indeterminate colitis (IC) in Aragon, in Spain (population: 1,189,000, area: 47,719 km2) and to compare the incidence in this region with that in the rest of Spain and Europe.

We designed a prospective, population-based study based on inception cohorts. During a 3-year predetermined period (1st February 1992-31st January 1995) we identified every new case of inflammatory bowel disease in Aragon by checking the records in all the hospitals, outpatient clinics and private practices in this region.

The overall adjusted incidence rate per 100,000 inhabitants/year was 7.2 for UC (a figure lower than the average for Europe) and 3.9 for Crohn's disease (a rate similar to that of Southern Europe). These rates are much higher than those previously described in Spanish studies, probably due to the design and methods used as well as to a real increase in the incidence of CD in Spain. The age and sex pattern was similar to those other studies.

The incidence rates for inflammatory bowel disease in Aragon are higher than those previously described, the incidence of UC being inferior to that of Europe. Nevertheless, the incidence of CD is similar the average for southern Europe, which suggests that there has been a recent increase in the incidence of this disease in Aragon.