In COVID-19 patients, low 25-hydroxyvitamin D level in serum is associated with longer viral clearance time and higher risk of intensive care unit admission

Purpose This study aims to investigate the association between vitamin D measured in serum 25 hydroxyvitamin D [25(OH)D] and outcomes of COVID-19 patients in Bahrain. This paper hypothesized that lower serum 25(OH)D concentration in COVID 19 patients is associated with longer viral clearance time (VCT) and higher risk of admission to the intensive care unit (ICU). Design/methodology/approach This study used a retrospective cohort design of patients admitted to Salmaniya Medical Complex, Manama, Kingdom of Bahrain, from February to June 2020. This study included patients with positive, confirmed COVID-19 diagnosis made using reverse transcription-polymerase chain reaction (RT-PCR), World Health Organization diagnosis manual and local diagnostic guidelines. Primary outcome measures were: VCT measured as the time in days between the first positive RT-PCR test result and the first of two consecutive negative RT-PCR results on recovery and admission need to ICU. Findings A total of 450 patients were analyzed; mean age was 46.4 ± 12.4 years and 349 (78%) were men. Mean 25(OH)D concentration was 41.7 ± 23.7 nmol/L for the entire sample. Severe vitamin D deficiency (<25 nmol/L) was present in 20%, mild-to-moderate deficiency (25–50 nmol/L) in 55%, insufficiency (50 to <75 nmol/L) in 18% and sufficiency (=75 nmol/L) in 7%. The mean VCT was 12.9 ± 8.2 days. Multivariate linear regression analysis showed that severe vitamin D deficiency was associated with longer VCT, with an average of three extra days after correction for age and sex ( β = 3.1; p = 0.001). Multinomial regression analysis showed that vitamin D deficiency was associated with an 83% increased risk of admission to ICU after correction for age and sex (odds ratio = 1.8; p = 0.03). Originality/value The results showed that severe vitamin D deficiency was associated with longer recovery time from COVID-19. Low serum 25(OH)D is associated with increased need for critical care in an ICU. Large-scale randomized controlled trials are necessary to further investigate the complex association between vitamin D and COVID-19 infection.