Effect of vitamin D and inhaled corticosteroid treatment on lung function in children.
BACKGROUND
Low vitamin D levels are associated with asthma and decreased airway responsiveness. Treatment with inhaled corticosteroids improves airway responsiveness and asthma control.


OBJECTIVE
To assess the effect of vitamin D levels on prebronchodilator FEV(1), bronchodilator response, and responsiveness to methacholine (PC(20), provocative concentration of methacholine producing a 20% decline in FEV(1)) in patients with asthma treated with inhaled corticosteroids.


METHODS
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, sex, body mass index, race, history of emergency department visits, hospitalizations, and season that vitamin D specimen was drawn. Our main outcome measures were change in prebronchodilator FEV(1), bronchodilator response, and PC(20) from enrollment to 8-12 months.


RESULTS
Of the 1,024 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, African American, and have a higher body mass index compared with the vitamin D-sufficient and insufficient subjects. In the inhaled corticosteroid treatment group, prebronchodilator FEV(1) increased from randomization to 12 months by 140 ml in the vitamin D-deficient group and prebronchodilator FEV(1) increased by 330 ml in the vitamin D insufficiency group and by 290 ml in the vitamin D sufficiency group (P = 0.0072), in adjusted models.


CONCLUSIONS
In children with asthma treated with inhaled corticosteroids, vitamin D deficiency is associated with poorer lung function than in children with vitamin D insufficiency or sufficiency.
Center for Child Health Care Studies, Department of Population Medicine, Harvard Pilgrim Health Care Institute and Harvard Medical School, Boston, MA 02215-5301, USA. ann.wu@childrens.harvard.edu
Ann Chen
AC
Wu
Kelan
K
Tantisira
Lingling
L
Li
Anne L
AL
Fuhlbrigge
Scott T
ST
Weiss
Augusto
A
Litonjua
D000280:Administration, Inhalation; D001249:Asthma / Q000097:blood / Q000188:drug therapy* / Q000503:physiopathology; D019819:Budesonide / Q000008:administration & dosage*; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008991:Monitoring, Physiologic / Q000379:methods; D017835:Nedocromil / Q000008:administration & dosage*; D011446:Prospective Studies; D012016:Reference Values; D012129:Respiratory Function Tests; D018570:Risk Assessment; D012720:Severity of Illness Index; D013147:Spirometry / Q000379:methods; D016896:Treatment Outcome; D014807:Vitamin D / Q000097:blood* / Q000378:metabolism; D014808:Vitamin D Deficiency / Q000097:blood* / Q000188:drug therapy
D017835:Nedocromil; D014807:Vitamin D; D019819:Budesonide