The changing pattern of Crohn's disease incidence in northern France: a continuing increase in the 10- to 19-year-old age bracket (1988-2007)

Background: Crohn's disease incidence rates have stabilised in industrialised countries since the 1980s. Conversely, a continuing increase in childhood-onset Crohn's disease incidence has been reported.

Aim: To confirm trends in inflammatory bowel disease (IBD) incidence in northern France over an extended time period (1988-2007) with a focus on childhood-onset Crohn's disease.

Methods: The IBD patients recorded in the EPIMAD registry between 1988 and 2007 were included. Standardised incidence rates were calculated for Crohn's disease and ulcerative colitis in the entire population, and separately according to age. Evolution of phenotypes at diagnosis was also studied.

Results: A total of 12 084 incident IBD cases (7428 Crohn's disease and 4656 ulcerative colitis) were recorded. Crohn's disease incidence rates increased from 5.2 cases/100 000 persons in 1988-1990 to 6.7 in 2006-2007 (+29%), stabilising after a peak at 7.1 in 1997-1999. Crohn's disease incidence rates in the 10-19-year age category increased by 71%, from 6.5 (1988-1990) to 11.1 (2006-2007). The frequency of initial ileo-colonic localisation increased from 52.9% in 1988-1990 to 68.6% in 2006-2007 (P<0.0001). Ulcerative colitis incidence rates decreased during the same period.

Conclusions: From 1988 to 2007, Crohn's disease incidence increased by 29% in northern France and by 71% in the 10-19-year-old age group. Consequently, studies on Crohn's disease risk factors should focus on the population under 20 years of age.