title: Sudden infant death syndrome and residential altitude.
abstract: BACKGROUND
  Theories of sudden infant death syndrome (SIDS) suggest hypoxia is a common pathway. Infants living at altitude have evidence of hypoxia; however, the association between SIDS incidence and infant residential altitude has not been well studied.
  
  
  METHODS
  We performed a retrospective cohort study by using data from the Colorado birth and death registries from 2007 to 2012. Infant residential altitude was determined by geocoding maternal residential address. Logistic regression was used to determine adjusted association between residential altitude and SIDS. We evaluated the impact of the Back to Sleep campaign across various altitudes in an extended cohort from 1990 to 2012 to assess for interaction between sleep position and altitude.
  
  
  RESULTS
  A total of 393 216 infants born between 2007 and 2012 were included in the primary cohort (51.4% boys; mean birth weight 3194 ± 558 g). Overall, 79.6% infants resided at altitude <6000 feet, 18.5% at 6000 to 8000 feet, and 1.9% at >8000 feet. There were no meaningful differences in maternal characteristics across altitude groups. Compared with residence <6000 feet, residence at high altitude (>8000 feet), was associated with an adjusted increased risk of SIDS (odds ratio 2.30; 95% confidence interval 1.01-5.24). Before the Back to Sleep campaign, the incidence of SIDS in Colorado was 1.99/1000 live births and dropped to 0.57/1000 live births after its implementation. The Back to Sleep campaign had similar effect across different altitudes (P = .45).
  
  
  CONCLUSIONS
  Residence at high altitude was significantly associated with an increased adjusted risk for SIDS. Impact of the Back to Sleep campaign was similar across various altitudes.
authors.affiliation: Divisions of Cardiology, and david.katz@ucdenver.edu.
authors.forename: David
authors.initials: D
authors.lastname: Katz
authors.affiliation: Division of Cardiology, Emory University School of Medicine, Atlanta, Georgia; and.
authors.forename: Supriya
authors.initials: S
authors.lastname: Shore
authors.affiliation: University of Colorado School of Medicine, Aurora, Colorado;
authors.forename: Brian
authors.initials: B
authors.lastname: Bandle
authors.affiliation: Neonatology.
authors.forename: Susan
authors.initials: S
authors.lastname: Niermeyer
authors.affiliation: Vital Statistics Unit, Colorado Department of Public Health and Environment.
authors.forename: Kirk A
authors.initials: KA
authors.lastname: Bol
authors.affiliation: Divisions of Cardiology, and.
authors.forename: Amber
authors.initials: A
authors.lastname: Khanna
mesh_terms: D000531:Altitude; D015331:Cohort Studies; D003120:Colorado; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D008297:Male; D012111:Residence Characteristics; D012189:Retrospective Studies; D013398:Sudden Infant Death / Q000453:epidemiology*