The role of vitamin D in outcomes of critical care in COVID-19 patients: Evidence from an umbrella meta-analysis of interventional and observational studies.

OBJECTIVES:Several meta-analyses have suggested the beneficial effect of vitamin D on patients infected with SARS-CoV-2. This umbrella meta-analysis aims to evaluate influence of vitamin D supplementation on clinical outcomes and the mortality rate of COVID-19 patients. DESIGN:Present study was designed as an umbrella meta-analysis. The following international databases were systematically searched till March 2023: Web of Science, PubMed, Scopus, and Embase. SETTINGS:Random-effects model was employed to perform meta-analysis. Using AMSTAR critical evaluation tools, the methodological quality of the included meta-analyses was evaluated. PARTICIPANTS:Adult patients suffering from COVID-19 were studied. RESULTS:Overall, 13 meta-analyses summarizing data from 4 RCTs and 9 observational studies were identified in this umbrella review. Our findings revealed that vitamin D supplementation and status significantly reduced mortality of COVID-19 [Interventional studies: (ES= 0.42; 95% CI: 0.10, 0.75, p <0.001; I2 = 20.4%, p=0.285) and observational studies (ES= 1.99; 95% CI: 1.37, 2.62, p <0.001; I2 = 00.0%, p=0.944). Also, vitamin D deficiency increased risk of infection and disease severity among patients. CONCLUSION:Overall, vitamin D status is a critical factor influencing the mortality rate, disease severity, admission to ICU and being detached from mechanical ventilation. It is vital to monitor the vitamin D status in all patients with critical conditions including COVID patients.