Asthma: vitamin D levels correlate with lung function in meta-analysis

  • Liu J & al.
  • Respir Res
  • 8 Oct 2019

  • International Clinical Digest
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Takeaway

  • A meta-analysis finds that vitamin D levels are positively correlated with lung function, meaning that lower levels are indicative of poorer function.

Why this matters

  • Vitamin D supplements should be considered if levels are low.

Study design

  • Meta-analysis of 27 studies (n>2200) after a search of OVID, MEDLINE, Web of Science, and PubMed.
  • 19 studies were cross-sectional, 6 were case-control, 2 were cohorts.
  • Funding: Zhejiang Province Public Welfare, China.

Key results

  • Low vitamin D levels (vs sufficient levels) had lower:
    • Forced expiratory volume in 1 second (FEV1; mean difference [MD], −0.1; P<.01>
    • FEV1% (FEV1 expressed as a percentage of forced vital capacity [FVC]; MD, −10.02; P<.01>
    • FEV1/FVC (MD, −1.52; P=.07).
  • Vitamin D levels were positively correlated (pooled r) with lung function:
    • FEV1 (r, 0.12; P=.003).
    • FEV1% (r, 0.19; P<.001>
    • FVC (r, 0.17; P=.05).
    • FEV1/FVC (r, 0.4; P<.001>
    • Asthma control test (ACT; r, 0.33; P<.001>
  • Subgroup analysis found similarly positive correlation in children and adults.

Limitations

  • Observational design.
  • High heterogeneity across studies.
  • Many studies had small numbers of subjects.