title: Prematurity and prescription asthma medication from childhood to young adulthood: a Danish national cohort study.
abstract: BACKGROUND
  Preterm birth is associated with increased risk of asthma-like symptoms and purchase of prescription asthma medication in childhood. We investigated whether this association persists into adulthood and whether it is affected by accounting for neonatal respiratory morbidity (acute respiratory disease and bronchopulmonary dysplasia).
  
  
  METHODS
  A national cohort of all infants born in Denmark in the period 1980-2009 was included in this register study. Data on purchase of asthma medication (combination of inhaled β-2 agonists and other drugs for obstructive airway disease) in 2010-2011 were obtained from the Danish National Prescription Registry. Associations between gestational age (GA), neonatal respiratory morbidity and a cross-sectional evaluation of asthma medication purchase were explored by multivariate logistic regressions.
  
  
  RESULTS
  A full dataset was obtained on 1,790,241 individuals, 84.6% of all infants born in the period. Odds-ratios (95% CI) for the association between GA and purchase of asthma medication during infancy were: 3.86 (2.46-6.04) in GA 23-27 weeks, 2.37 (1.84-3.04) in GA 28-31 weeks and 1.59 (1.43-1.77) in GA 32-36 weeks compared to term infants with GA 37-42 weeks. Associations weakened in older age groups and became insignificant in young adults born extremely and very preterm with odds-ratios: 1.41 (0.63-3.19) and 1.15 (0.83-1.60) in GA 23-27 and 28-31 respectively. When adjusting for neonatal respiratory morbidity, the associations weakened but persisted both in childhood and adolescence.
  
  
  CONCLUSIONS
  There was a strong dose-response association between gestational age and the purchase of prescription asthma medication in infancy and childhood. This association weakened during adolescence and was mostly non-significant in young adulthood. The increased risk of prescription asthma medication purchase in ex-preterm children could only partly be explained by neonatal respiratory morbidity.
authors: Department of Neonatology, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark.
authors: Anne Louise
authors: AL
authors: Damgaard
authors: Department of Neonatology, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark.
authors: Bo Mølholm
authors: BM
authors: Hansen
authors: Department of Pediatric and Adolescent Medicine, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark.
authors: René
authors: R
authors: Mathiasen
authors: Dept. of Pediatric and Adolescent Medicine, Pulmonary Service, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark.
authors: Frederik
authors: F
authors: Buchvald
authors: Dept. of Biostatistics, University of Copenhagen, Copenhagen, Denmark.
authors: Theis
authors: T
authors: Lange
authors: Department of Neonatology, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark.
authors: Gorm
authors: G
authors: Greisen
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D018927:Anti-Asthmatic Agents / Q000627:therapeutic use*; D001249:Asthma / Q000188:drug therapy / Q000209:etiology*; D001997:Bronchopulmonary Dysplasia / Q000150:complications*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D003718:Denmark; D005260:Female; D005865:Gestational Age; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D016017:Odds Ratio; D011247:Pregnancy; D047928:Premature Birth; D055553:Prescription Drugs / Q000627:therapeutic use*; D012127:Respiratory Distress Syndrome, Newborn / Q000150:complications*; D055815:Young Adult
chemical_list: D018927:Anti-Asthmatic Agents; D055553:Prescription Drugs
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