A population-based study on the incidence of inflammatory bowel disease in Oviedo (Northern Spain)

to assess the incidence of inflammatory bowel disease in Oviedo (Northern Spain), and to describe the clinical features of new patients. a prospective population-based study was made at the Health Area IV, Principality of Asturias (Oviedo, 312,324 inhabitants). All new diagnosed patients with inflammatory bowel disease were registered over a 2-year period. a total of 85 patients were included, 47 of these with ulcerative colitis (UC), 37 with Crohńs disease (CD), and 1 with undetermined colitis. The overall adjusted incidence rate of UC and CD per 105 inhabitants between 15-64 years was 9.1 (95% CI: 5-13.1) and 7.5 (95% CI: 3.8-11.2), respectively. The global male/female ratio was 0.9, without significant differences between both diseases. CD patients were younger than those with UC (33 +/- 15 years vs 45 +/- 20 years; p < 0.05). Mostly, CD patients were diagnosed at an age younger than 35 years (65%), while UC patients were diagnosed at an age between 25 and 64 years (81%). Disease extension in UC was proctitis in 11%, left-side colitis in 53% and extensive colitis in 36%. With respect to CD, the ileo-colonic form predominated (49%), followed by the ileal (40%) and colonic (11%) forms; an inflammatory, stenotic and fistulous pattern was seen in 54, 22 and 24% of patients, respectively. in our area, the incidence of CD is similar to that in other Northern European countries, while UC has a lower incidence. CD mainly affects young people, while UC predominates in middle-aged patients. At diagnosis, UC is predominantly localized, the ileo-colonic form and an inflammatory pattern being most frequent in CD patients.