Am J Respir Crit Care Med. 2012 Jul 12.
Wu AC, Tantisira K, Li L, Fuhlbrigge AL, Weiss ST, Litonjua A; for the Childhood Asthma Management Program Research Group.
Harvard Medical School and Harvard Pilgrim Health Care, Department of Population Medicine, Boston, Massachusetts, United States.
Low vitamin D levels are associated with asthma and decreased airway responsiveness. Treatment with inhaled corticosteroids improves airway responsiveness and asthma control.
To assess the effect of vitamin D levels on pre-bronchodilator forced expiratory volume in 1 second (FEV1), bronchodilator response (BDR), and responsiveness to methacholine (PC20) in asthmatics treated with inhaled corticosteroids.
We measured 25-hydroxyvitamin D levels in the serum of children with persistent asthma at the time of enrollment in the Childhood Asthma Management Program. We divided subjects into the vitamin D sufficiency (>30 ng/ml), insufficiency (20-30 ng/ml), and deficiency (<20 ng/ml) groups. Covariates included age, treatment, gender, BMI, race, history of emergency department visits, hospitalizations, and season that vitamin D specimen was drawn. Our main outcome measures were change in pre-bronchodilator FEV1, BDR, and PC20 from enrollment to 8-12 months.
Of the 1024 subjects, 663 (65%) were vitamin D sufficient, 260 (25%) were insufficient, and 101 (10%) were deficient. Vitamin D deficient subjects were more likely to be older, be African American and have higher BMI compared to the vitamin D sufficient and insufficient subjects. In the inhaled corticosteroid treatment group, pre-bronchodilator FEV1 increased from randomization to 12 months by 140 ml in the vitamin D deficient group while prebronchodilator FEV1 increased by 330 ml in the vitamin D insufficiency group and 290 ml in the vitamin D sufficiency group (p=0.0072), in adjusted models.
In asthmatic children treated with inhaled corticosteroids, vitamin D deficiency is associated with poorer lung function than children with vitamin D insufficiency or sufficiency.
– – – – – – – – – – –
Iimprovement in breathing vs vitamin D levels