Epidemiological aspects of inflammatory bowel disease in a north Italian population: A 4-year prospective study

Objective: To determine the incidence and clinical characteristics at presentation of inflammatory bower disease (IBD) in a defined area of north Italy. Design: A 4-year prospective population-based epidemiological study. Setting: An area in Lombardia defined by the National Health Service scheme with about 294 000 inhabitants, two referral hospitals and 259 general practitioners (GPs). Patients: Subjects presenting to a GP with symptoms compatible with IBD underwent a diagnostic work-up at one of the referral hospitals. Those with ulcerative colitis (UC), Crohn's disease (CD) or indeterminate colitis diagnosed according to a defined protocol were included, as were residents of the area with IBD diagnosed elsewhere. Rigid case ascertainment methods were used. Patients were followed for one year; 125 patients were identified. Results: The patient ascertainment rate was constant over the 4 years; UC was diagnosed in 82 patients, CD in 40, and indeterminate colitis in three. The mean annual incidence of IBD for the whole period was 10.6/10⁵ inhabitants (95% confidence limits, 7.2-15.1), 7.0/10⁵ for UC (4.3-10.7) and 3.4/10⁵ (1.6-6.3) for CD. The mean interval between onset of symptoms and diagnosis was under 6 months. The clinical characteristics of our patients were similar to those of north European and American series. Conclusion: The incidence of IBD was higher than previously observed in Italy but was still lower than in some north European countries and in the USA. Our data could be used as a basis for future longitudinal studies and in international comparative investigations.