Familial aggregation of inflammatory bowel disease: A population-based study in South Limburg, the Netherlands

Background: The aim of our study was to investigate the prevalence of Crohn's disease (CD) and ulcerative colitis (UC) in first-degree relatives of IBD patients living in a well-defined area. Methods: IBD patients known at the IBD Registration South Limburg as well as population controls were asked about the occurrence of IBD in their first-degree relatives. Results: IBD was reported and confirmed in 16 (out of 1554) relatives by 11 (out of 245) patients. Prevalence of IBD was highest for siblings (1.5%) and children (1.3%), while only 0.2% of the parents were affected with IBD. among relatives of the control subjects, IBD was observed in 0.8% (versus 4.5% in IBD patients), resulting in an odds ratio of 5.7 (95% CI: 2.0-16.7). Conclusions: The observed risk of IBD for first-degree relatives of IBD patients was higher than in controls. However, the risk in our population is lower than has been reported by other centres, possibly because of the population-based character of our study.