Incidence and prevalence of ulcerative colitis and Crohn's disease in urban and rural areas of Spain from 1981 to 1988.

We retrospectively investigated the annual incidence and prevalence of inflammatory bowel disease (IBD) from 1981 to 1988 in an urban and a rural area of central Spain. Two hundred and eighty-one patients presented with IBD; 193 ulcerative colitis (UC) and 88 Crohn's disease (CD) (prevalence 43.4/100,000 and 19.8/100,000, respectively). Of these patients, 168 were diagnosed for the first time during the study period. One hundred and eleven UC and 57 CD (incidence 3.16/100,000 and 1.61/100,000 respectively). Within the urban area, the UC incidence was 3.15/100,000 and the CD 1.87/100,000. In the rural area, the incidence for the UC was 3.25/100,000 and 0.86/100,000 for the CD. No sex differences were found. The incidence rates have increased significantly (p < 0.05) for CD in the study period. However, for UC rates did not change. During 1986-1988, the patient's age at the time of diagnosis was significantly lower than that of 1981-1983 (p < 0.05).