title: Higher altitude and risk of bronchopulmonary dysplasia among preterm infants.
abstract: OBJECTIVE
  To assess the association between altitudes of neonatal intensive care units (NICU) and the rate of bronchopulmonary dysplasia (BPD) and BPD/death in very preterm infants.
  
  
  METHODS
  Data from infants born at <33 weeks' gestation admitted to Canadian Neonatal Network during 2008 and 2009 were analyzed. The associations between the altitude of NICU and the BPD and altitude and BPD/death were determined using logistic regression models.
  
  
  RESULTS
  Of 7551 eligible infants, 1540 (20%) were admitted to NICUs at an altitude > 400 m, 3661 (48%) between 86 and 400 m, 2350 (31%) at ≤85 m. The incidences of BPD (21.7% versus 17.2%) and BPD/death (26.2% versus 23.0%) were significantly higher in the infants admitted to NICUs at >400 m altitude versus those ≤400 m altitude (p < 0.01). In multivariable analyses, the adjusted odds ratio was 1.81 (95% confidence interval [CI] 1.05 to 3.12) for BPD and 1.79 (95% CI 1.12 to 2.85) for BPD/death among infants admitted to NICUs at altitude > 400 m compared with NICUs at altitude ≤ 400 m. For each 100-m increase in altitude, the odds increased by 8% for BPD (95% CI 4 to 13%) and 9% for BPD/death (95% CI 5 to 13%); however, the increase was mainly due to increase in BPD.
  
  
  CONCLUSIONS
  For very preterm infants, higher altitude of NICUs increased the risk of BPD.
authors.affiliation: Department of Pediatrics, University of Toronto, Maternal-Infant Care Research Center, Mount Sinai Hospital, Toronto, Ontario, Canada.
authors.forename: Shoo K
authors.initials: SK
authors.lastname: Lee
authors.forename: Xiang Y
authors.initials: XY
authors.lastname: Ye
authors.forename: Nalini
authors.initials: N
authors.lastname: Singhal
authors.forename: Sarah
authors.initials: S
authors.lastname: De La Rue
authors.forename: Abhay
authors.initials: A
authors.lastname: Lodha
authors.forename: Prakesh S
authors.initials: PS
authors.lastname: Shah
mesh_terms: D000531:Altitude; D001997:Bronchopulmonary Dysplasia / Q000453:epidemiology* / Q000401:mortality; D002170:Canada / Q000453:epidemiology; D016001:Confidence Intervals; D005260:Female; D005865:Gestational Age; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D007234:Infant, Premature; D007363:Intensive Care Units, Neonatal; D016015:Logistic Models; D008297:Male; D015999:Multivariate Analysis; D016017:Odds Ratio; D012307:Risk Factors