Serum vitamin D level as a predictor of bronchial asthma in Egyptian children

الملخص EN

This study was designed to assess the relationship between the serum level of 25-hydroxyvitamin D and the clinical, functional severity and the level of asthma control among Egyptian asthmatic children. Patients and methods : This case–control cross-sectional study was conducted on 50 asthmatic patients from those regularly attending the Pediatric Chest Clinic, Children’s Hospital, Ain Shams University.

Twenty healthy children of matched age and sex were recruited as the control group. Results : Pulmonary function tests were significantly decreased in the asthmatic cases compared with the control (P < 0.01).

The serum vitamin D level was found to be significantly decreased in asthmatic children compared with the control group (P < 0.001).

Out of the 50 asthmatic children, 20 had a serum vitamin D level of less than 25 ng / ml, and were considered to be ‘vitamin D deficient’, whereas the remaining 30 children had a level ranging between >25 ng / ml and ≤30 ng / ml and were considered to be ‘vitamin D insufficient’.

The asthmatic children had a highly significant increase in the total leukocytic count, the eosinophilic count, serum immunoglobulin E, and serum alkaline phosphatase (P < 0.001 in all).

There was also a significant increase in the serum phosphorus level in the asthmatic children group compared with the control group (P < 0.01).

The serum vitamin D level was 24.1 ng / ml ± 2.9 in the asthmatic patients on inhaled corticosteroid therapy and 28 ng / ml ± 1.4 in those not on inhaled corticosteroid therapy.

Significant positive correlations were found between the serum vitamin D level and the predicted percentage of forced expiratory volume in 1 s (r = 0.871, P < 0.001).

A highly significant negative correlation was found between the serum vitamin D level and serum immunoglobulin E (marker of allergy ; r = −0.589, P < 0.001).

Moreover, serum vitamin D showed an inverse correlation with the clinical severity of bronchial asthma (r = 0.903, P < 0.001) and the level of control of asthma (r = 0.923, P < 0.001), classified according to the Global Initiative for Asthma (GINA) classification.

The accuracy of vitamin D as a predictor of asthma was found to be 88 % by automatic linear modeling. Conclusion : Our results revealed an important support for the association between bronchial asthma in children and vitamin D deficiency, with a direct relationship between its serum level and pulmonary function test measures and the increased asthma severity.

Vitamin D deficiency can be considered as a strong predictor of asthma.

Improving the vitamin D status can help in the primary prevention of asthma and in decreasing exacerbations of attacks.

Clinical trials of vitamin D supplementation to prevent asthma exacerbation are recommended.