title: Serum vitamin D levels and markers of severity of childhood asthma in Costa Rica.
abstract: BACKGROUND
  Maternal vitamin D intake during pregnancy has been inversely associated with asthma symptoms in early childhood. However, no study has examined the relationship between measured vitamin D levels and markers of asthma severity in childhood.
  
  
  OBJECTIVE
  To determine the relationship between measured vitamin D levels and both markers of asthma severity and allergy in childhood.
  
  
  METHODS
  We examined the relation between 25-hydroxyvitamin D levels (the major circulating form of vitamin D) and markers of allergy and asthma severity in a cross-sectional study of 616 Costa Rican children between the ages of 6 and 14 years. Linear, logistic, and negative binomial regressions were used for the univariate and multivariate analyses.
  
  
  RESULTS
  Of the 616 children with asthma, 175 (28%) had insufficient levels of vitamin D (<30 ng/ml). In multivariate linear regression models, vitamin D levels were significantly and inversely associated with total IgE and eosinophil count. In multivariate logistic regression models, a log(10) unit increase in vitamin D levels was associated with reduced odds of any hospitalization in the previous year (odds ratio [OR], 0.05; 95% confidence interval [CI], 0.004-0.71; P = 0.03), any use of antiinflammatory medications in the previous year (OR, 0.18; 95% CI, 0.05-0.67; P = 0.01), and increased airway responsiveness (a < or =8.58-mumol provocative dose of methacholine producing a 20% fall in baseline FEV(1) [OR, 0.15; 95% CI, 0.024-0.97; P = 0.05]).
  
  
  CONCLUSIONS
  Our results suggest that vitamin D insufficiency is relatively frequent in an equatorial population of children with asthma. In these children, lower vitamin D levels are associated with increased markers of allergy and asthma severity.
authors.affiliation: Channing Laboratory, 181 Longwood Avenue, Boston, MA 02115, USA.
authors.forename: John M
authors.initials: JM
authors.lastname: Brehm
authors.forename: Juan C
authors.initials: JC
authors.lastname: Celedón
authors.forename: Manuel E
authors.initials: ME
authors.lastname: Soto-Quiros
authors.forename: Lydiana
authors.initials: L
authors.lastname: Avila
authors.forename: Gary M
authors.initials: GM
authors.lastname: Hunninghake
authors.forename: Erick
authors.initials: E
authors.lastname: Forno
authors.forename: Daniel
authors.initials: D
authors.lastname: Laskey
authors.forename: Jody S
authors.initials: JS
authors.lastname: Sylvia
authors.forename: Bruce W
authors.initials: BW
authors.lastname: Hollis
authors.forename: Scott T
authors.initials: ST
authors.lastname: Weiss
authors.forename: Augusto A
authors.initials: AA
authors.lastname: Litonjua
mesh_terms: D000293:Adolescent; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use; D001249:Asthma / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D001985:Bronchial Provocation Tests; D016085:Bronchoconstrictor Agents; D002648:Child; D003364:Costa Rica; D004804:Eosinophils / Q000378:metabolism; D005260:Female; D005541:Forced Expiratory Volume; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D006967:Hypersensitivity / Q000097:blood; D007073:Immunoglobulin E / Q000097:blood; D007958:Leukocyte Count; D008297:Male; D016210:Methacholine Chloride; D015999:Multivariate Analysis; D012720:Severity of Illness Index; D013147:Spirometry; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D000893:Anti-Inflammatory Agents; D015415:Biomarkers; D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride; D014807:Vitamin D; D007073:Immunoglobulin E; C104450:25-hydroxyvitamin D