title: Environmental factors in infancy and ulcerative colitis in the Central South of Chile: a case-control study.
abstract: OBJECTIVE
  Evidence for the role of the hygiene hypothesis and the development of Ulcerative Colitis (UC) is unclear. We aimed to explore the association between environmental factors in infancy and UC.
  
  
  METHODS
  A hospital-based case-control study (52 UC cases, response: 77%, 174 age- , sex and place of living matched controls, response: 62%) was carried out in the Central South of Chile in 2009/2010. Patients or parents underwent a personal interview about early life experiences.
  
  
  RESULTS
  High paternal education (adjusted Odds Ratio (aOR): 2.1; 95% CI: 1.0-4.5) as proxy for socioeconomic status was positively associated with case status in the final multivariate logistic regression model. Likewise, having older siblings was a risk factor for UC (aOR: 2.2; 95%CI: 1.1.-4.4).
  
  
  CONCLUSIONS
  The importance for some early life environmental factors in the development of UC was established. However, the role of the hygiene hypothesis could not be confirmed for all environmental factors.
authors.affiliation: Unit for Occupational and Environmental Epidemiology & Net Teaching, Institute and Outpatient Clinic for Occupational-, Social- and Environmental Medicine, University Hospital of Munich (LMU), Munich, Germany. Anja.Boneberger@med.uni-muenchen.de
authors.forename: Anja
authors.initials: A
authors.lastname: Boneberger
authors.forename: Eduardo Hebel
authors.initials: EH
authors.lastname: Weiss
authors.forename: Mario
authors.initials: M
authors.lastname: Calvo
authors.forename: Lilibeth
authors.initials: L
authors.lastname: Torres
authors.forename: Johanna
authors.initials: J
authors.lastname: Wagner
authors.forename: Michael
authors.initials: M
authors.lastname: Kabesch
authors.forename: Katja
authors.initials: K
authors.lastname: Radon
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D002648:Child; D002677:Chile; D003093:Colitis, Ulcerative / Q000208:ethnology / Q000209:etiology*; D004522:Educational Status; D004777:Environment; D005260:Female; D006801:Humans; D061148:Hygiene Hypothesis; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D012307:Risk Factors; D035781:Siblings; D011795:Surveys and Questionnaires; D055815:Young Adult