Is the vitamin D status of patients with COVID-19 associated with reduced mortality?
Abstract
Objective
A systematic review with meta-analysis was performed to assess a possible association between plasma vitamin D levels and mortality in patients with COVID – 19.
Methods
PubMed, EMBASE, and Cochrane Library databases were searched. Studies involving COVID-19 patients that reported an association between plasma vitamin D levels and COVID-19 mortality published until February 5, 2021, were included. The risk ratio (RR) and confidence interval (CI) were pooled using a fixed-effects or random-effects model.
Results
A total of 11 studies that measured plasma vitamin D levels at admission were included in the meta-analysis, ten cohorts and one case-controls. Low plasma vitamin D levels (25(OH)D) in patients with COVID-19 were not associated with mortality (RR=1.35, 95%CI 0.84–1.86). Subgroup analysis by vitamin D cut-off (<20 or 25 ng/ml and <10 or 12 ng/ml) showed were not associated with mortality. When the RR in mortality analysis was calculated included four studies that did not perform adjusted analysis for confounding factors, the result was 1.43 (95% CI 1.18-1.69), suggesting that confounders may have led many observational studies to incorrectly estimate the association between vitamin D status and mortality in COVID-19 patients.
Conclusion
Deficient vitamin D levels were not associated with a higher mortality rate in patients with COVID-19. Randomized clinical trials are needed to assess this association.
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