INCIDENCE OF INFLAMMATORY BOWEL-DISEASE ACROSS EUROPE - IS THERE A DIFFERENCE BETWEEN NORTH AND SOUTH - RESULTS OF THE EUROPEAN COLLABORATIVE STUDY ON INFLAMMATORY BOWEL-DISEASE (EC-IBD)

Background-It has been suggested that the incidence of inflammatory bo wel disease (IBD), which includes ulcerative colitis (UC) and Crohn's disease (CD), is three or more times higher in northern than in southe rn Europe. The aim of this EC funded study was to investigage this app arent variation by ascertaining-the incidence of IBD across Europe. Me thods-For the period 1 October 1991 to 30 September 1993 all new patie nts diagnosed with IBD were prospectively identified in 20 European ce ntres according to a standard protocol for case ascertainment and defi nition. Findings-Altogether 2201 patients aged 15 years or more were i dentified, of whom 1379 were diagnosed as UC (including proctitis), 70 6 as CD, and 116 as indeterminate. The overall incidence per 100 000 a t ages 15-64 years (standardised for age and sex) of UC was 10 . 4 (95 % confidence interval (95% CI) 7 . 6 to 13 . 1) and that of CD was 5 . 6 (95% CI 2 . 8 to 8 . 3). Rates of UC in northern centres were 40% h igher than those in the south (rate ratio (RR) = 1 . 4 (95% CI 1 . 2 t o 1 . 5)) and for CD they were 80% higher (RR = 1 . 8 (95% CI 1 . 5 to 2 . 1)). For UC the highest reported incidence was in Iceland (24 . 5 , 95% CI 17 . 4 to 31 . 5) and for CD, Maastricht (The Netherlands; 9 . 2, 95% CI 6 . 5 to 11.8) and Amiens (north west France; 9 . 2, 95% C I 6 . 3 to 12 . 2). The lowest incidence of UC was in Almada (southern Portugal) (1 . 6, 95% CI 0 . 0 to 3 . 2) and of CD in Ioannina (north west Greece) (0 . 9, 95% CI 0 . 0 to 2 . 2). An unexpected finding wa s a difference in the age specific incidence of UC in men and women wi th the incidence in women but not men declining with age. Interpretati on-The higher overall incidence rates in northern centres did not seem to be explained by differences in tobacco consumption or education. N evertheless, the magnitude of the observed excess for both conditions is less than expected on the basis of previous studies. This may refle ct recent increases in the incidence of IBD in southern Europe whereas those in the north may have stabilised.