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Environmental Risk Factors of Pediatric-Onset Primary Sclerosing Cholangitis and Autoimmune Hepatitis

Objectives: The aim of this population-based observational case-control questionnaire study was to investigate the possible role of environmental risk factors associated with pediatric-onset autoimmune liver diseases. Methods: Seventy-one patients with autoimmune liver diseases (<16 years) received a questionnaire with 22 items, evaluating contact with environmental factors (eg, family manners, type of housing, pets) before the diagnosis. Two age- and sex-matched control groups were used: inflammatory bowel disease (IBD; n = 91) and healthy subjects (n = 716; matched also for place of residence at birth). Univariate analysis (odds ratio [OR] and 95% confidence interval) for all variables was calculated. Fisher exact test was performed to depict associations between variables and the multivariate logistic regression to test their interactions. Results: In the final analyses, the responses of 51 autoimmune liver diseases cases (n = 51/71, 72%), 59 IBD controls (n = 59/91, 65%), and 292 healthy controls (n = 292/716, 41%) were investigated. In univariate analysis only having a cat, a dog, and a cat or a dog were risk factors of autoimmune liver diseases (OR varying between 2.6–3.4); no other significant associations (eg, place of residence, number of siblings, family manners) were found. Multivariate logistic regression analyses showed that especially living with a cat in block of flats was a risk factor (OR 3.6, 1.2–10.8). Conclusions: Living in a close contact with a pet (especially a cat) was a risk factor of autoimmune liver diseases. This finding may suggest an involvement of an unidentified agent (ie, toxin/microbe) among the triggers of these diseases.