title: Persistent recurring wheezing in the fifth year of life after laboratory-confirmed, medically attended respiratory syncytial virus infection in infancy.
abstract: BACKGROUND
  Respiratory syncytial virus (RSV) infection in infancy is associated with subsequent recurrent wheezing.
  
  
  METHODS
  A retrospective cohort study examined children born at ≥32 weeks gestation between 1996-2004. All children were enrolled in an integrated health care delivery system in Northern California and were followed through the fifth year of life. The primary endpoint was recurrent wheezing in the fifth year of life and its association with laboratory-confirmed, medically-attended RSV infection during the first year, prematurity, and supplemental oxygen during birth hospitalization. Other outcomes measured were recurrent wheezing quantified through outpatient visits, inpatient hospital stays, and asthma prescriptions.
  
  
  RESULTS
  The study sample included 72,602 children. The rate of recurrent wheezing in the second year was 5.6% and fell to 4.7% by the fifth year. Recurrent wheezing rates varied by risk status: the rate was 12.5% among infants with RSV hospitalization, 8% among infants 32-33 weeks gestation, and 18% in infants with bronchopulmonary dysplasia. In multivariate analyses, increasing severity of respiratory syncytial virus infection was significantly associated with recurrent wheezing in year 5; compared with children without RSV infection in infancy, children who only had an outpatient RSV encounter had an adjusted odds ratio of 1.38 (95% CI,1.03-1.85), while children with a prolonged RSV hospitalization had an adjusted odds ratio of 2.59 (95% CI, 1.49-4.50).
  
  
  CONCLUSIONS
  Laboratory-confirmed, medically attended RSV infection, prematurity, and neonatal exposure to supplemental oxygen have independent associations with development of recurrent wheezing in the fifth year of life.
authors.affiliation: Division of Research, Perinatal Research Unit, Kaiser Permanente Medical Care Program, Oakland, CA, USA. gabriel.escobar@kp.org
authors.forename: Gabriel J
authors.initials: GJ
authors.lastname: Escobar
authors.forename: Anthony S
authors.initials: AS
authors.lastname: Masaquel
authors.forename: Sherian X
authors.initials: SX
authors.lastname: Li
authors.forename: Eileen M
authors.initials: EM
authors.lastname: Walsh
authors.forename: Patricia
authors.initials: P
authors.lastname: Kipnis
mesh_terms: D001249:Asthma / Q000209:etiology; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D007234:Infant, Premature; D007235:Infant, Premature, Diseases / Q000209:etiology; D016015:Logistic Models; D008297:Male; D015999:Multivariate Analysis; D016017:Odds Ratio; D016016:Proportional Hazards Models; D012008:Recurrence; D012135:Respiratory Sounds / Q000209:etiology*; D018357:Respiratory Syncytial Virus Infections / Q000150:complications*; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index