Environmental factors and risk of developing paediatric inflammatory bowel disease — A population based study 2007–2009

BACKGROUND AND AIMS: To identify environmental risk factors for developing inflammatory bowel disease (IBD) in children <15 years of age. METHODS: IBD patients and randomly selected healthy controls from a well defined geographical area in Denmark were prospectively recruited in the period 1.1.2007-31.12.2009. Data regarding socioeconomic status, area of residence, living conditions, infections and diet were obtained by a questionnaire. RESULTS: A total of 118 IBD patients (59 Crohn's disease (CD), 56 ulcerative colitis (UC) and 3 IBD unclassified (IBDU)) and 477 healthy controls filled out the questionnaire. The response rates were 91% in patients and 45% in controls, respectively. Several risk factors for IBD were identified: IBD in first degree relatives (IBD: OR (odds ratio): 6.1 (95%CI: 2.5-15.0), CD (OR: 6.8 (2.3-20.2)) and UC (OR: 6.1 (2.3-16.0))); bedroom sharing (IBD: OR: 2.1 (1.0-4.3), CD (OR: 3.6 (1.3-9.4))); high sugar intake (IBD: OR: 2.5 (1.0-6.2), CD (OR: 2.9 (1.0-8.5))); prior admission to a hospital for gastrointestinal infections (IBD: 7.7 (3.1-19.1), CD (7.9 (2.5-24.9)) and UC (7.4 (2.5-21.6))); stressful events (IBD: 1.7 (1.0-2.9)). Protective factors were daily vs. less than daily vegetable consumption (CD: 0.3 (0.1-1.0), UC (0.3 (0.1-0.8))) and whole meal bread consumption (IBD: OR: 0.5 (0.3-0.9), CD (0.4 (0.2-0.9))). An increased risk of diagnosis of CD compared to UC was shown for patients living in more urban areas (OR: 1.3 (1.1-1.6)). CONCLUSION: We identified several risk and protective factors for developing IBD. Studies on the influence of environmental factors are important in our understanding of aetiology and phenotypes of paediatric IBD.