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

OBJECTIVE: to assess the incidence of inflammatory bowel disease in Oviedo (Northern Spain), and to describe the clinical features of new patients. PATIENTS AND METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.