title: A population-based study of childhood respiratory morbidity after severe lower respiratory tract infections in early childhood.
abstract: OBJECTIVE
  To estimate the risk of childhood chronic respiratory morbidity among those hospitalized for severe lower respiratory tract infection (LRTI) in early childhood, and to determine whether severe LRTI is an independent predictor.
  
  
  METHODS
  The population-based Régie de l'Assurance Maladie du Québec datasets were used to identify LRTI hospitalizations before age 2 years in a birth cohort from 1996-1997 and a comparison cohort of children without an LRTI hospitalization. The incidence rate and incidence rate ratio of chronic respiratory morbidity before age 10 years were calculated, and multivariable logistic regression was performed to estimate the impact of LRTI hospitalization on chronic respiratory morbidity. Population-attributable risks of chronic respiratory morbidity due to severe LRTI were estimated, and similar analyses were performed for respiratory syncytial virus LRTI.
  
  
  RESULTS
  Among the birth cohort, 7104 patients (4.9%) were hospitalized for LRTI before age 2 years. By age 10 years, 52.5% of the LRTI cohort and 27.9% of the nonhospitalized cohort had developed chronic respiratory morbidity; the incidence rate ratio was 1.81 (95% CI, 1.76-1.86) for males and 1.91 (95% CI, 1.84-1.99) for females. The OR for chronic respiratory morbidity based on LRTI hospitalization before age 2 years was 2.79 (95% CI, 2.66-2.93). The population-attributable risk of chronic respiratory morbidity due to any LRTI was approximately 25%, and that for respiratory syncytial virus LRTI was similar.
  
  
  CONCLUSIONS
  Hospitalization of young children for LRTIs is associated with two-fold increased risk of childhood chronic respiratory morbidity, demonstrating the ongoing impact of LRTI in infancy.
authors.affiliation: ICON Epidemiology, Vancouver, British Columbia, Canada.
authors.forename: Shelagh M
authors.initials: SM
authors.lastname: Szabo
authors.affiliation: AbbVie, Abbott Park, IL.
authors.forename: Katherine L
authors.initials: KL
authors.lastname: Gooch
authors.affiliation: ICON Epidemiology, Vancouver, British Columbia, Canada.
authors.forename: Ellen E
authors.initials: EE
authors.lastname: Korol
authors.affiliation: Azdoe Inc, Libertyville, IL.
authors.forename: Pamela
authors.initials: P
authors.lastname: Bradt
authors.affiliation: Department of Pediatrics, Alberta Children's Hospital, Calgary, Alberta, Canada.
authors.forename: Ian
authors.initials: I
authors.lastname: Mitchell
authors.affiliation: AbbVie, Abbott Park, IL.
authors.forename: Pamela
authors.initials: P
authors.lastname: Vo
authors.affiliation: ICON Epidemiology, Vancouver, British Columbia, Canada; Department of Community Health and Epidemiology, Dalhousie University, Halifax, Nova Scotia, Canada. Electronic address: adrian.levy@dal.ca.
authors.forename: Adrian R
authors.initials: AR
authors.lastname: Levy
mesh_terms: D002675:Child, Preschool; D002908:Chronic Disease; D015331:Cohort Studies; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D015994:Incidence; D007223:Infant; D016015:Logistic Models; D008297:Male; D009017:Morbidity; D011792:Quebec; D018357:Respiratory Syncytial Virus Infections / Q000401:mortality* / Q000821:virology; D012136:Respiratory Syncytial Viruses / Q000472:pathogenicity*; D012141:Respiratory Tract Infections / Q000401:mortality* / Q000821:virology; D012189:Retrospective Studies; D012307:Risk Factors