Association between vitamin D status and risk of covid-19 in-hospital mortality: A systematic review and meta-analysis of observational studies

Abstract

Some earlier studies reported higher risk of COVID-19 mortality in patients with vitamin D deficiency, while some others failed to find such as association. Due to inconsistences between earlier meta-analyses and needs for an updated study, we conducted current systematic review and meta-analysis on the association between vitamin D status and risk of COVID-19 in-hospital mortality among observational studies. We searched PubMed, Scopus and Web of Science up to 27 July 2021. We conduct our systematic review and meta-analysis in according to PRISM statement. Two authors independently screened studies and extracted data from the relevant ones. All types of observational studies about the association between vitamin D status and in hospital COVID-19 mortality were included. Data was pooled using a random-effect model. P-values ˂ 0.05 was assumed as statistically significant. We identified 13 observational studies. Pooling 9 studies which categorized vitamin D level, a significant positive relationship was found between vitamin D deficiency and risk of COVID-19 in-hospital mortality (Odds Ratio (OR): 2.11; 95% Confidence Interval (CI): 1.03, 4.32). All subgroup analyses also showed significant relationship between vitamin D deficiency and risk of COVID-19 in-hospital mortality. In the other analysis, pooling data from 5 studies in which vitamin D level was entered as a continues variable, we found an inverse significant association between each unit increment in serum vitamin D concentrations and risk of COVID-19 in-hospital mortality (OR: 0.94; 95% CI: 0.89, 0.99). We found a significant direct association between vitamin D deficiency and elevated risk of COVID-19 in-hospital mortality. Moreover, each unit increment in serum vitamin D levels was associated to significant reduction in risk of COVID-19 mortality. Further prospective studies are needed to confirm our findings.

Keywords:

• COVID-19
• meta-analysis
• mortality
• vitamin D

Authors’ contributions

AE and AM planned and conceived the experiments. AE and SM performed the literature search in databases. AM, AE, BN and SK contributed to quality assessment and statistical analysis. AE and AM contributed to the interpretation of the results. AM took the lead in writing the manuscript. All authors provided critical feedback and helped shape the research, analysis and manuscript. All authors read and approved the final manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Funding

The author(s) reported there is no funding associated with the work featured in this article.