Objective: To clarify the relationship between childhood environment and the risk of subsequent development of Crohn's disease or ulcerative colitis.
Design and outcome measures: A case-control study, assessing the risk of inflammatory bowel disease in relation to a series of historical and serological markers of childhood circumstance, analysed using the maximum likelihood form of conditional logistic regression.
Setting: District general hospital (secondary care institution).
Participants: Subjects with Crohn's disease (n = 139) or ulcerative colitis (n = 137) aged between 16 and 45 years, each matched for sex and age with an outpatient control.
Results: Helicobacter seroprevalence was substantially reduced in Crohn's disease (OR 0.18; 95% CI, 0.06-0.52) but not in ulcerative colitis (OR 0.91; 95% CI, 0.38-2.16). In ulcerative colitis, a strong negative association with childhood appendectomy was confirmed (OR 0.05; 95% CI, 0.01-0.51). Crohn's disease was associated with childhood eczema (OR 2.81; 95% CI, 1.23-6.42) and the frequent use of a swimming pool (OR 2.90; 95% CI 1.21-6.91). There was no association between hepatitis A seroprevalence and either disease.
Conclusion: The findings are consistent with the hypothesis that improved childhood living conditions are associated with increased risk of Crohn's disease. The study confirms that the negative association between appendectomy and ulcerative colitis relates primarily to events in childhood. Overall, the findings strongly support the assertion that childhood environment is an important determinant of the risk of inflammatory bowel disease in later life, with quite distinct risk factors for ulcerative colitis and Crohn's disease.