title: Environmental Risk Factors of Pediatric-Onset Primary Sclerosing Cholangitis and Autoimmune Hepatitis.
abstract: OBJECTIVE
  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.
authors.affiliation: *Clinic of Gastroenterology †Department of Pediatric Nephrology and Transplantation, University of Helsinki and Helsinki University Hospital ‡University of Helsinki §Department of Pathology, University of Helsinki and Helsinki University Hospital ||Department of Pediatric Gastroenterology, University of Helsinki and Children's Hospital, Helsinki, Finland ¶Gastroenterology and Endoscopy Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Milan, Italy #Department of Virology and Immunology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
authors.forename: Andrea
authors.initials: A
authors.lastname: Tenca
authors.forename: Martti
authors.initials: M
authors.lastname: Färkkilä
authors.forename: Hannu
authors.initials: H
authors.lastname: Jalanko
authors.forename: Katariina
authors.initials: K
authors.lastname: Vapalahti
authors.forename: Johanna
authors.initials: J
authors.lastname: Arola
authors.forename: Tytti
authors.initials: T
authors.lastname: Jaakkola
authors.forename: Roberto
authors.initials: R
authors.lastname: Penagini
authors.forename: Olli
authors.initials: O
authors.lastname: Vapalahti
authors.forename: Kaija-Leena
authors.initials: KL
authors.lastname: Kolho
mesh_terms: D000293:Adolescent; D000818:Animals; D016022:Case-Control Studies; D002415:Cats; D002648:Child; D002675:Child, Preschool; D015209:Cholangitis, Sclerosing / Q000209:etiology*; D004285:Dogs; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D019693:Hepatitis, Autoimmune / Q000209:etiology*; D006801:Humans; D007223:Infant; D016015:Logistic Models; D008297:Male; D010372:Pediatrics; D012307:Risk Factors; D011795:Surveys and Questionnaires