title: Influence of host and environmental factors on wheezing severity in infants: findings from the PARIS birth cohort.
abstract: BACKGROUND
  Determinants of wheezing severity are poorly documented in infants.
  
  
  OBJECTIVE
  To study the determinants of wheezing severity in infants aged 18 months followed-up in the PARIS (« Pollution and Asthma Risk : an Infant Study ») birth cohort.
  
  
  METHODS
  Data on wheezing disorders, medical visits and medications, as well as biological markers of atopy, were collected during a medical examination at age 18 months. Severe wheeze was defined as wheeze that required inhaled corticosteroid and/or hospital-based care. Environmental exposures were assessed prospectively with regular questionnaires. Risk factors for wheeze in the first 18 months of life were assessed by multivariate regression models.
  
  
  RESULTS
  Participation in the medical examination concerned 48.2% of the original cohort. Prevalence of wheeze was 560/1879 (35.7%) and was influenced by male gender, parental history of asthma, siblings, daycare attendance, heavy parental smoking at home, and carpet covered floor in the child's bedroom. Being overweight increased the risk of wheeze by 62% (OR = 1.62, 95%CI 1.13-2.32). In addition, trends towards an increased risk of wheeze were found in infants exposed to daily use of cleaning sprays and to renovation activities. Conversely, the presence of a cat reduced the risk of wheeze (OR = 0.65, 95%CI 0.47-0.89), without any evidence of healthy-pet keeping effect. Severe wheeze concerned 286 of the wheezers (42.7%). The prevalence of severe wheeze was related to atopy, and risk of severe wheeze was in particular increased in infants having eosinophilia (OR = 1.76, 95%CI 1.21-2.55) or being sensitized to ≥ 2 allergens (OR = 1.88, 95%CI 1.13-3.14).
  
  
  CONCLUSIONS
  Whilst risk factors for wheeze before 18 months of age are factors related to infections, indoor air pollution, and being overweight, the severity of wheeze is mainly due to the atopic status of the child. We suggest that atopy should be further considered in the assessment of wheezing severity in infants.
authors.affiliation: Univ Paris Descartes, Sorbonne Paris Cité, Laboratoire Santé Publique et Environnement, Paris, France.
authors.forename: M
authors.initials: M
authors.lastname: Herr
authors.forename: J
authors.initials: J
authors.lastname: Just
authors.forename: L
authors.initials: L
authors.lastname: Nikasinovic
authors.forename: C
authors.initials: C
authors.lastname: Foucault
authors.forename: A-M
authors.initials: AM
authors.lastname: Le Marec
authors.forename: J-P
authors.initials: JP
authors.lastname: Giordanella
authors.forename: J I
authors.initials: JI
authors.lastname: Momas
mesh_terms: D016902:Air Pollution, Indoor / Q000009:adverse effects*; D000818:Animals; D001249:Asthma / Q000453:epidemiology / Q000209:etiology; D002415:Cats; D015331:Cohort Studies; D004781:Environmental Exposure / Q000009:adverse effects*; D004802:Eosinophilia / Q000453:epidemiology / Q000209:etiology; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007239:Infections / Q000150:complications / Q000453:epidemiology; D008297:Male; D050177:Overweight / Q000150:complications / Q000453:epidemiology; D015995:Prevalence; D012135:Respiratory Sounds; D012307:Risk Factors; D012720:Severity of Illness Index; D012737:Sex Factors