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

Respir Med. 2019 Apr;150:85-94. doi: 10.1016/j.rmed.2019.02.016. Epub 2019 Feb 21.

Abstract

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 randomized 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 randomized 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.

Keywords: Asthma; Meta-analysis; RCTs; Treatment; Vitamin D.

Publication types

  • Comparative Study
  • Meta-Analysis
  • Review

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Asthma / drug therapy*
  • Asthma / metabolism
  • Asthma / physiopathology
  • Child
  • Child, Preschool
  • Disease Progression
  • Exhalation
  • Female
  • Forced Expiratory Volume / drug effects
  • Humans
  • Infant
  • Interleukin-10 / analysis
  • Male
  • Middle Aged
  • Nitric Oxide / analysis
  • Randomized Controlled Trials as Topic
  • Respiratory Function Tests / methods
  • Symptom Assessment / methods*
  • Symptom Assessment / statistics & numerical data
  • Treatment Outcome
  • Vitamin D / adverse effects
  • Vitamin D / therapeutic use*
  • Vitamin D Deficiency / complications
  • Vitamin D Deficiency / drug therapy
  • Vitamin D Deficiency / epidemiology
  • Vitamins / adverse effects
  • Vitamins / therapeutic use*

Substances

  • Vitamins
  • Interleukin-10
  • Vitamin D
  • Nitric Oxide