Association between vitamin D status and risk of covid-19 in-hospital mortality: A systematic review and meta-analysis of observational studies.
Level 3 - non-randomized controlled study
Systematic review and meta-analysis of observational studies
PubMed 34882024 · doi:10.1080/10408398.2021.2012419
What was done
Authors conducted a systematic review and meta-analysis following PRISMA guidelines to assess the relationship between vitamin D status and in-hospital COVID-19 mortality. They searched PubMed, Scopus, and Web of Science up to July 27, 2021. Two independent reviewers screened studies and extracted data from observational studies. Odds ratios were pooled using a random-effects model.
What was found
A total of 13 observational studies were included: - Pooling 9 studies that categorized vitamin D status showed a significant association between vitamin D deficiency and COVID-19 in-hospital mortality (OR: 2.11; 95% CI: 1.03 to 4.32). - Pooling 5 studies evaluating continuous vitamin D showed each unit increment in serum vitamin D concentration was associated with lower mortality risk (OR: 0.94; 95% CI: 0.89 to 0.99).
Why it matters
This review aggregates early pandemic observational data indicating that lower serum vitamin D concentrations correlate with increased risk of death in hospitalized COVID-19 patients.
Limits
The analysis relies entirely on observational studies, precluding causal inference due to potential confounding factors such as age, adiposity, chronic comorbidities, and reverse causation (e.g., vitamin D dropping as an acute phase reactant). The abstract does not report total participant counts, between-study heterogeneity statistics, or specific cutoffs used to define deficiency across included studies.
Cited by
- supports Research during the COVID-19 pandemic demonstrated that people who were vitamin D deficient had higher mortality from COVID-19.