Severe vitamin D deficiency is not related to SARS-CoV-2 infection but may increase mortality risk in hospitalized adults: a retrospective case-control study in an Arab Gulf country

Purpose: As the world continues to cautiously navigate its way through the coronavirus disease 2019 (COVID-19) pandemic, several breakthroughs in therapies and vaccines are currently being developed and scrutinized. Consequently, alternative therapies for severe acute respiratory coronavirus 2 (SARS-CoV-2) prevention, such as vitamin D supplementation, while hypothetically promising, require substantial evidence from countries affected by COVID-19. The present retrospective case-control study aims to identify differences in vitamin D status and clinical characteristics of hospitalized patients screened for SARS-CoV-2, and determine associations of vitamin D levels with increased COVID-19 risk and mortality.

Methods: A total of 222 [SARS-CoV-2 (+) N = 150 (97 males; 53 females); SARS-CoV-2 (-) N = 72 (38 males, 34 females)] out of 550 hospitalized adult patients screened for SARS-CoV-2 and admitted at King Saud University Medical City-King Khalid University Hospital (KSUMC-KKUH) in Riyadh, Saudi Arabia from May-July 2020 were included. Clinical, radiologic and serologic data, including 25(OH)D levels were analyzed.

Results: Vitamin D deficiency (25(OH)D < 50 nmol/l) was present in 75% of all patients. Serum 25(OH)D levels were significantly lower among SARS-CoV-2 (+) than SARS-CoV-2 (-) patients after adjusting for age, sex and body mass index (BMI) (35.8 ± 1.5 nmol/l vs. 42.5 ± 3.0 nmol/l; p = 0.037). Multivariate regression analysis revealed that significant predictors for SARS-CoV-2 include age > 60 years and pre-existing conditions (p < 0.05). Statistically significant predictors for mortality adjusted for covariates include male sex [Odds ratio, OR 3.3 (95% confidence interval, CI 1.2-9.2); p = 0.02], chronic kidney disease [OR 3.5 (95% CI 1.4-8.7); p = 0.008] and severe 25(OH)D deficiency (< 12.5 nmol/l), but at borderline significance [OR 4.9 (95% CI (0.9-25.8); p = 0.06].

Conclusion: In hospital settings, 25(OH)D deficiency is not associated with SARS-CoV-2 infection, but may increase risk for mortality in severely deficient cases. Clinical trials are warranted to determine whether vitamin D status correction provides protective effects against worse COVID-19 outcomes.