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P358. Environmental factors in infancy and ulcerative colitis in Chile: A case–control study

A. Boneberger1, E. Hebel Weiss2, M. Calvo3, L. Torres1, J. Wagner1, M. Kabesch4, K. Radon1

1Hospital of the Ludwig-Maximilians-University Munich, Munich, Germany; 2Universidad de la Frontera, Facultad de Medicina, Temuco, Chile; 3Universidad Austral, Valdivia, Chile; 4Hannover Medical School, Hannover, Germany

Aim: Inflammatory Bowel Disease (IBD) with its two major forms Crohn's Disease and Ulcerative Colitis (UC) is largely seen as a disease of Western, industrialized nations. Rising incidences have been reported for other regions, such as Asia and Latin America. Genetic predisposition is unquestionable, but environmental factors play a crucial role as well in these countries currently facing profound social, demographic and epidemiological transitions. We conducted a case–control study to investigate the potential role of early life environmental factors for the development of UC in Chile.

Material and Methods: A hospital-based case–control study including 52 cases with Ulcerative Colitis, and 174 age- and sex frequency (1:3) matched controls (Response: 77% among cases, 62% among controls) aged 9–44 years was carried out in two cities in the Central South of Chile (Temuco, Valdivia). Agriculture and wood production are the major economies in these cities representing about 4% of the Chilean population. It is the region with the highest number of Mapuche, the largest group of “indígenas” in Chile (around 1.4 million). Patients or parents underwent a personal interview about early life experiences. Unadjusted and adjusted odds ratios (aOR) with 95% confidence intervals (CI) are presented.

Results: Both high paternal education (aOR: 2.3; 95%CI: 1.1–5.0) and having at least one older sibling (aOR: 2.0; 1.0–4.1) were positively associated with case status in multivariate logistic regression model. Having Mapuche descent (OR: 0.7; 95%CI: 0.3–1.7) or a cat in the home during the 1st year of life (OR: 0.7; 95%CI: 0.3–1.4) were both inversely related to case status.

Conclusions: The importance of early life environmental factors was confirmed for the development of UC in Chile. Our study results reinforce the potential role of the hygiene hypothesis for disease aetiology in this South American IBD population.