Association Between Severe Vitamin D Deficiency, Lung Function and Asthma Control.

INTRODUCTION: To examine the relationship between severe vitamin D deficiency, asthma control, and pulmonary function in Turkish adults with asthma.

METHODS: One hundred six asthmatic patients underwent pulmonary function tests skin prick test, peripheral blood eosinophil counts, IgE, body mass index and vitamin D levels were determined. Patients were divided into 2 subgroups according to vitamin D levels (vitamin D level<10ng/ml and vitamin D level≥10 ng/ml). Asthma control tests were performed.

RESULTS: The mean age of subgroup i (vitamin D level<10) was 37±10 and the mean age of subgroup ii (vitamin D level≥10ng/ml) was 34±8. Sixty-six percent of patients had severe vitamin D deficiency (vitamin D level<10 ng/ml). There was a significant trend towards lower absolute FEV1 (L) values in patients with lower vitamin D levels (P=.001). Asthma control test scores were significantly low in the severe deficiency group than the other group (P=.02). There were a greater number of patients with uncontrolled asthma (asthma control test scores<20) in the severe vitamin D deficiency group (P=.040). Patients with severe vitamin D deficiency had a higher usage of inhaled corticosteroids than the group without severe vitamin D deficiency (P=.015). There was a significant trend towards lower absolute FEV1 (L) (P=.005, r=.272) values in patients with lower vitamin D levels. Vitamin D levels were inversely related with body mass index (P=.046).

CONCLUSION: The incidence of severe vitamin D deficiency was high in adult Turkish asthmatics. In addition, lower vitamin D levels were associated with poor asthma control and decreased pulmonary function.