title: Serious early childhood wheezing after respiratory syncytial virus lower respiratory tract illness in preterm infants.
abstract: BACKGROUND
  Respiratory syncytial virus (RSV) lower respiratory tract infection (LRI) in early life has been associated with sustained airway hyperreactivity during childhood; however, corresponding data in premature infants are sparse.
  
  
  OBJECTIVE
  The objective of this study was to determine whether RSV-LRI during early infancy of preterm infants was associated with an increased risk for serious early childhood wheezing (SECW) by age 3 years.
  
  
  METHODS
  A retrospective cohort study was conducted using data from a large (∼14 million members) US health plan database. The study population included infants ≤ 6 months of age born at ≤ 36 weeks' gestational age or weighing <2500 g, or both. Preterm infants with any medically attended RSV-LRI from May 2001 through April 2004 with 3 years of continuous eligibility were selected and propensity matched with ≤ 3 control infants. SECW was defined as >3 office, outpatient, or emergency department (ED) visits with asthma or wheezing; ≥ 1 office, outpatient, or ED visit with asthma or wheezing plus treatment with systemic corticosteroids within 7 days; ≥ 1 inpatient stay with asthma or wheezing; or ≥ 150 days' supply of asthma-control medications. The presence of SECW between ages 2 and 3 years was compared between infants with and without RSV-LRI using univariate and multivariate methods. Health care costs for patients with SECW were explored.
  
  
  RESULTS
  A total of 378 infants with RSV were matched to 606 controls. The prevalence of SECW between ages 2 and 3 years was 16.7% in the RSV-LRI group versus 8.6% in the control group (P < 0.001). Logistic regression showed that preterm infants with RSV in early life were 2.52-fold (95% CI,1.65-3.85) more likely to present with SECW between ages 2 and 3 years (P < 0.001). Patients with SECW had a mean SECW-related cost of US $1378 (95% CI, $939-$1816) and total health care cost of $7138 (95% CI, $5087-$9189) compared with $37 (95% CI, $24-$51) and $2521 (95% CI, $1789-$3253), respectively, for patients without SECW. After adjusting for possible confounders, patients with SECW had a significantly higher total health care cost than did patients without evidence of SECW (P < 0.001).
  
  
  CONCLUSIONS
  The development of RSV-LRI in infancy in preterm infants was associated with an increased prevalence of SECW between ages 2 and 3 years. Patients with SECW had higher total health care costs than those who did not have SECW.
authors.affiliation: Department of Pediatrics, Arkansas Children's Hospital and University of Arkansas for Medical Sciences, Little Rock, Arkansas 72202-3591, USA. RomeroJose@uams.edu
authors.forename: José R
authors.initials: JR
authors.lastname: Romero
authors.forename: Dan L
authors.initials: DL
authors.lastname: Stewart
authors.forename: Erin K
authors.initials: EK
authors.lastname: Buysman
authors.forename: Ancilla W
authors.initials: AW
authors.lastname: Fernandes
authors.forename: Hasan S
authors.initials: HS
authors.lastname: Jafri
authors.forename: Parthiv J
authors.initials: PJ
authors.lastname: Mahadevia
mesh_terms: D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature; D007235:Infant, Premature, Diseases / Q000503:physiopathology; D008297:Male; D012135:Respiratory Sounds / Q000175:diagnosis; D018357:Respiratory Syncytial Virus Infections / Q000150:complications* / Q000503:physiopathology; D012141:Respiratory Tract Infections / Q000503:physiopathology / Q000821:virology*; D012189:Retrospective Studies; D012720:Severity of Illness Index