Brehm JM, Celedón JC, Soto-Quiros ME, et al. Am J Respir Crit Care Med. 2009;179(9):765–771
PURPOSE OF THE STUDY. To determine whether vitamin D levels are associated with asthma severity and allergy during childhood.
STUDY POPULATION. Six hundred sixteen Costa Rican children with asthma, 6 to 14 years of age, were included. Asthma was defined as physician-diagnosed asthma and ≥2 respiratory symptoms or asthma attacks in the past year.
METHODS. Study participants were identified on the basis of questionnaires sent to 113 Costa Rican schools. Participants answered additional questions and underwent pulmonary function testing, methacholine challenge testing, allergy skin-prick testing, serum total immunoglobulin E (IgE) and allergen-specific IgE measurements, peripheral blood eosinophil counts, and serum 25- hydroxyvitamin D3 measurements. Linear and logistic regression models were created to assess associations between factors.
RESULTS. Twenty-eight percent of participants had vitamin D levels of <30 ng/mL, which is the lower limit of the normal range. Each 1-log unit increase in vitamin D level was associated with decreased odds of any hospitalization in the past year (odds ratio [OR]: 0.05 [95% confidence interval [CI]: 0.004–0.71]), use of inhaled corticosteroids and/or leukotriene inhibitors in the past year (OR: 0.18 [95% CI: 0.05–0.67]), and increased airway hyperresponsiveness (OR: 0.15 [95% CI: 0.024–0.097]). In multivariate analysis, increasing serum levels of vitamin D were associated with lower total serum IgE levels, peripheral eosinophil counts, and dust mite–specific IgE levels.
CONCLUSIONS. Vitamin D deficiency is relatively frequent in Costa Rican children, and lower levels are associated with increased markers of allergy and asthma severity.
REVIEWER COMMENTS. 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. This study found an association between reduced vitamin D levels and increased markers of allergy and asthma severity in a population of Costa Rican children with asthma. Additional study of this topic using an unselected birth cohort, a case-control approach, or a clinical trial of vitamin D supplementation would be a preferable next step. Also of note, although the authors used the current standard “normal” lower threshold to define vitamin D deficiency, there is substantial debate about what the appropriate lower limit should be.
- Copyright © 2009 by the American Academy of Pediatrics