The effect of vitamin D supplementation on mortality and intensive care unit admission of COVID-19 patients. A systematic review, meta-analysis and meta-regression.

ABSTRACT

AIMS: The aim of this systematic review and meta-analysis was to investigate the effect of vitamin D supplementation on mortality and admission to intensive care unit (ICU) of COVID-19 patients. METHODS: A systematic search of PubMed, Google Scholar, Embase, Web of Science and medRxiv with terms relative to vitamin D supplementation and COVID-19 was conducted on 26 March 2021. Comprehensive Meta-Analysis software was used for the quantitative assessment of data and random-effects model was applied. To investigate the association between the dose of vitamin D and the outcomes of interest, meta-regression analysis was performed. RESULTS: Two thousand and seventy-eight patients from nine studies with data on mortality were included (583 received vitamin D supplementation, while 1495 did not). Sixty-one (10.46%) individuals in the treated group died, compared to 386 (25.81%) in the non-treated group (odds ratio [OR] 0.597; 95% CI 0.318-1.121; p = 0.109). Eight hundred and sixty patients from six studies with data on ICU admission were included (369 received vitamin D supplementation, while 491 did not). Forty-five (12.19%) individuals in the treated group were admitted to ICU, compared to 129 (26.27%) in the non-treated group (OR 0.326; 95% CI 0.149-0.712; p = 0.005). No significant linear relationship between vitamin D dose and log OR of mortality or log OR of ICU admission was observed. CONCLUSION: This meta-analysis indicates a beneficial role of vitamin D supplementation on ICU admission, but not on mortality, of COVID-19 patients. Further research is urgently needed to understand the benefit of vitamin D in COVID-19.