Vitamin D deficiency and level of asthma control in women from North of Jordan: a case-control study.

INTRODUCTION

Reduced vitamin-D levels in patients with asthma have been associated with impaired lung function, increased airway hyper-responsiveness, and reduced glucocorticoid responsiveness. Nationwide studies revealed a considerable prevalence of vitamin-D deficiency (VDD) in Jordanian women.

OBJECTIVE

A case-control study was conducted to determine the relationship between serum vitamin A and D levels and asthma among women in North of Jordan.

METHODS

Sixty-eight asthmatics, age range between 14 and 65 years and 77 healthy women, age range between 19 and 51 years, were enrolled. Asthma severity was classified using Global Initiative for Asthma (GINA) guidelines and Asthma Control Test (ACT) questionnaire. Serum vitamin-A and 25-hydroxyvitamin-D (25(OH)D3) levels were measured using high-performance liquid chromatography (HPLC) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods, respectively.

RESULTS

The prevalence of VDD (<15 ng/ml) was higher but not statistically significant for women with asthma compared with controls (95.6% vs. 87.0%; p = 0.070). The severity of VDD correlated with the number of asthma medications (p = 0.020). 25(OH)-D3 serum levels directly correlated with asthma control level using ACT score (p = 0.012) and GINA classification (p = 0.046). After adjusting for age, the odds of having VDD for asthmatic women were 35.9 times higher than that for women with no asthma. There was no difference in serum vitamin-A level between healthy and asthmatic women (p = 0.214) and none had vitamin-A deficiency (<200 µg/dl).

CONCLUSIONS

VDD is prevalent in women with asthma in northern Jordan. The severity of VDD correlated with poor asthma control and a need for more medications to control asthma. There was no association between vitamin-A and asthma.