Incidence of Inflammatory Bowel Disease in Italy: A Nationwide Population-Based Study

Background. The epidemiology of inflammatory bowel disease (IBD) in Southern Europe is still unclear. Sporadic reports suggest a lower incidence of IBD in Italy than in other Western Countries and the USA. Methods. A nationwide population-based study was carried out to estimate IBD incidence rates in eight Italian cities. All new cases of IBD diagnosed over 4 years in the target populations were collected from multiple information sources. Results. From 1989 to 1992, 509 ulcerative colitis (UC), 222 Crohn's disease (CD) and 10 undefined IBD cases were collected, giving age-adjusted incidence rates (per 100 000 per year) of 5.2 for UC and 2.3 for CD. Using the capture-recapture method, an estimated completeness of 0.81 was obtained for case archives, without appreciable and significant differences between areas. The rates computed after correcting underestimation were 6.8 for UC and 2.8 for CD. The sex ratio M/F was 1.7 for UC and 1.0 for CD. The highest age-specific incidence rates were between 30 and 39 years for UC and between 20 and 29 years for CD. Conclusions. The incidence rate of CD in Italy is homogeneous between the cities investigated and lower than those reported for other Mediterranean countries. In contrast, the UC incidence rate is within the range of those reported in European studies. A wide variability in the UC rates between the cities was also observed. These results could be related to different environmental factors or the genetic background of the populations, or both.