An investigation into the correlation of vitamin D status and management outcomes in patients with severe COVID-19 at a South African tertiary hospital

Background: Severe coronavirus disease 2019 (COVID-19) has a poor prognosis, and biomarkers may predict disease severity. The aim of this study was to assess the effect of baseline vitamin D (VitD) inadequacy on the outcomes of patients with severe COVID-19 admitted to the intensive care unit (ICU) of a tertiary hospital in South Africa. Methods: Patients with confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) were recruited during wave II of the pandemic in Cape Town. Eighty-six patients were included in the study. They were categorized into three groups: VitD deficient, VitD insufficient, and VitD sufficient. The VitD deficient and VitD insufficient groups were combined to form a ‘VitD inadequate’ group. Cox regression analysis was done to assess the association between VitD status and mortality. Factors with P < 0.05 in the adjusted multivariable Cox regression analysis were considered statistically significant. Results: The proportion of VitD inadequacy was 64% (55/86); this group had a significantly higher proportion with hypertension (66%; P = 0.012). The Kaplan–Meier curve showed no significant difference in the probability of survival among the COVID-19 patients admitted to the ICU with or without VitD inadequacy. However, patients with elevated serum creatinine were significantly more at risk of dying (adjusted hazard ratio 1.008, 95% confidence interval 1.002–1.030; P = 0.017). Conclusions: This study found a high prevalence of VitD inadequacy (combined deficiency and insufficiency) in COVID-19 patients admitted to the ICU. This may indicate a possible risk of severe disease. Whilst there was no statistically significant relationship between VitD status and mortality in this cohort, baseline VitD may be an important prognostic biomarker in COVID-19 patients admitted to the ICU, particularly in those with comorbidities that predispose to VitD deficiency.