title: Tobacco smoke exposure and allergic sensitization in children: a propensity score analysis.
abstract: OBJECTIVE
  There is conflicting evidence of the effect of environmental tobacco smoke (ETS) on the development of allergic diseases in children. Studies have shown that this relationship differs depending on maternal history of the disease. We employed the rigour of propensity score methods to assess this relationship using data from a birth cohort.
  
  
  METHODS
  Using n = 662 children from the Wayne County Health, Environment, Allergy and Asthma Longitudinal Study, we assessed the relationship between early-life ETS and subsequent allergic sensitization via a positive skin prick test (SPT+) or at least one specific immunoglobulin E (IgE) ≥ 0.35 (sIgE+) in children aged 2-3 years. Propensity score estimation followed by full and nearest neighbour matching was compared with standard multivariable regression models.
  
  
  RESULTS
  Among children without a maternal history of allergic disease, ETS was positively associated with allergic sensitization in children with an adjusted odds ratio (aOR) for SPT+ of 2.32 (95% confidence interval (CI): 1.28-4.22) and the aOR for sIgE+ was 2.53 (95% CI: 1.43-4.48). Contrarily, for children with a positive maternal history, the aOR for SPT+ and sIgE+ was 0.56 (95% CI: 0.24-1.32) and 0.43 (95% CI: 0.20-0.91), respectively.
  
  
  CONCLUSIONS
  Using propensity score methods to rigorously control for confounding factors, ETS exposure was found to reduce the risk of allergic sensitization in children with a positive maternal history. There is a strong association between early-life ETS and the development of allergic sensitization for children aged 2-3 years without maternal history.
authors.affiliation: Department of Public Health Sciences, Henry Ford Hospital, Detroit, Michigan, USA. shavsta1@hfhs.org
authors.forename: Suzanne L
authors.initials: SL
authors.lastname: Havstad
authors.forename: Christine Cole
authors.initials: CC
authors.lastname: Johnson
authors.forename: Edward M
authors.initials: EM
authors.lastname: Zoratti
authors.forename: Jerel M
authors.initials: JM
authors.lastname: Ezell
authors.forename: Kimberly
authors.initials: K
authors.lastname: Woodcroft
authors.forename: Dennis R
authors.initials: DR
authors.lastname: Ownby
authors.forename: Ganesa
authors.initials: G
authors.lastname: Wegienka
mesh_terms: D002648:Child; D002675:Child, Preschool; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D006801:Humans; D006967:Hypersensitivity / Q000453:epidemiology / Q000209:etiology*; D007114:Immunization; D007073:Immunoglobulin E; D008297:Male; D011247:Pregnancy; D057216:Propensity Score; D012307:Risk Factors; D012882:Skin Tests; D012907:Smoking / Q000009:adverse effects*; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*
chemical_list: D014028:Tobacco Smoke Pollution; D007073:Immunoglobulin E