title: 25-hydroxy vitamin D levels are associated with childhood asthma in a population-based study in Peru.
abstract: BACKGROUND
  Vitamin D deficiency may be associated with an increased risk of asthma.
  
  
  OBJECTIVE
  We studied the association between 25-hydroxy (25-OH) vitamin D deficiency and asthma prevalence in two Peruvian populations close to the equator but with disparate degrees of urbanization.
  
  
  METHODS
  We conducted a population-based study in 1441 children in two communities in Peru, of which 1134 (79%) provided a blood sample for 25-OH vitamin D analysis.
  
  
  RESULTS
  In these 1134 children, mean age was 14.8 years; 52% were boys; asthma and atopy prevalence was 12% in Lima vs. 3% in Tumbes (P < 0.001) and 59% in Lima vs. 41% in Tumbes (P < 0.001), respectively; and, mean 25-OH vitamin D level was 20.8 ng/mL in Lima vs. 30.1 ng/mL in Tumbes (P < 0.001). Prevalence of 25-OH vitamin D deficiency (< 20 ng/mL) was 47% in Lima vs. 7% in Tumbes (P < 0.001). In multi-variable logistic regression, we found that lower 25-OH vitamin D levels were associated with an increased odds of asthma (OR = 1.7 per each 10 ng/mL decrease in 25-OH vitamin D levels, 95% CI 1.2-2.6; P < 0.01). In stratified analyses, the association between lower 25-OH vitamin D levels and asthma was limited to children with atopy (OR = 2.2, 95% CI 1.3-3.6) and not in those without atopy (OR = 0.9, 95% CI 0.5-2.0). We did not find associations between 25-OH vitamin D levels and other clinical biomarkers for asthma, including exhaled nitric oxide, total serum IgE and pulmonary function.
  
  
  CONCLUSIONS
  Both asthma and 25-OH vitamin D deficiency were common among children living in Lima (latitude = 12.0 °S) but not among those in Tumbes (3.6 °S). The relationship between 25-OH vitamin D deficiency and asthma was similar in both sites and was limited among children with atopy. Future supplementation trials may need to consider stratification by atopy at the time of design.
authors.affiliation: Division of Pulmonary and Critical Care, School of Medicine, Johns Hopkins University, Baltimore, MD, USA; Program in Global Disease Epidemiology and Control, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.
authors.forename: W
authors.initials: W
authors.lastname: Checkley
authors.forename: C L
authors.initials: CL
authors.lastname: Robinson
authors.forename: L M
authors.initials: LM
authors.lastname: Baumann
authors.forename: N N
authors.initials: NN
authors.lastname: Hansel
authors.forename: K M
authors.initials: KM
authors.lastname: Romero
authors.forename: S L
authors.initials: SL
authors.lastname: Pollard
authors.forename: R A
authors.initials: RA
authors.lastname: Wise
authors.forename: R H
authors.initials: RH
authors.lastname: Gilman
authors.forename: E
authors.initials: E
authors.lastname: Mougey
authors.forename: J J
authors.initials: JJ
authors.lastname: Lima
mesh_terms: D000293:Adolescent; D001249:Asthma / Q000097:blood* / Q000150:complications / Q000453:epidemiology*; D002112:Calcifediol / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D010568:Peru / Q000453:epidemiology; D014808:Vitamin D Deficiency / Q000097:blood* / Q000150:complications / Q000453:epidemiology*
chemical_list: D002112:Calcifediol
keywords: Peru; asthma; childhood; vitamin D