Research Paper Title

Association between vitamin D status and asthma control: A meta-analysis of randomized trials.

Background

There is a controversy in terms of the efficacy of vitamin D supplementation in improving asthma symptom control.

Moreover, whether there is a difference in the treatment effect with respect to baseline vitamin D status remains unknown.

This meta-analysis was to assess the correlations of vitamin D status with asthma-related respiratory outcomes.

Methods

PubMed, EMBASE, and Cochrane Library were searched for randomised controlled trials of vitamin D supplementation in patients with asthma.

Primary outcomes were the rate of asthma exacerbation and predicted percentage of forced expiratory volume in first second (FEV1%).

Secondary outcomes were asthma control test (ACT) scores, fractional exhaled nitric oxide (FeNO), interleukin-10 (IL-10) and adverse events.

Results

A total of 14 randomised controlled trials (1421 participants) fulfilled the inclusion.

Vitamin D supplementation was associated with a significant reduction in the rate of asthma exacerbation by 27% (RR: 0.73 95%Cl (0.58-0.92)).

In subgroup analysis, the protective effect of exacerbation was restricted in patients with vitamin D insufficiency (vitamin D < 30 ng/ml) (RR: 0.76 95%Cl (0.61-0.95)).

An improvement of FEV1% was demonstrated in patients with vitamin D insufficiency and air limitation (FEV1% < 80%) (MD: 8.3 95%Cl (5.95-10.64).

No significant difference was observed in ACT scores, FeNO, IL-10 and adverse events.

Conclusions

Vitamin D supplementation reduced the rate of asthma exacerbation, especially in patients with vitamin D insufficiency.

Additionally, the benefit of vitamin D had a positive effect on pulmonary function in patients with air limitation and vitamin D insufficiency.

Reference

Wang, M., Liu, M., Wang, C., Xiao, Y., An, T., Zou, M. & Cheng, G. (2019) Association between vitamin D status and asthma control: A meta-analysis of randomized trials. Respiratory Medicine. 85-94. doi: 10.1016/j.rmed.2019.02.016. Epub 2019 Feb 21.