Objective: Vitamin D deficiency was previously correlated with incidence and severity of COVID-19. We investigated the correlation between serum 25(OH)D level on admission and radiological stage and outcome of COVID-19 pneumonia. 

Methods: Retrospective observational trial on 186 SARS-CoV-2-infected individuals hospitalized from March 1, 2020 to April 7, 2020 with combined chest CT and 25(OH)D measurement on admission. Multivariate analysis was performed to study if vitamin D deficiency (25(OH)D < 20 ng/mL) predicts survival independently of confounding comorbidities. 

Results: 59% of COVID-19 patients were vitamin D deficient on admission: 47% of females and 67% of males. Particularly male COVID-19 patients showed progressively lower 25(OH)D with advancing radiological stage, with deficiency rates increasing from 55% in stage 1 to 74% in stage 3. Vitamin D deficiency on admission was not confounded by age, chronic lung disease, coronary artery disease/hypertension or diabetes and was correlated with mortality (OR=3.87, 95%CI 1.30-11.55), independently of other predictors including age (OR=1.09, 95%CI 1.03-1.14), chronic lung disease (OR=3.61, 95% CI 1.18-11.09) and extent of lung damage expressed by chest CT severity score (1.12, 95% CI 1.01-1.25). 

Conclusions: low 25(OH)D levels on admission are associated with COVID-19 disease mortality

Statistical analysis Data (not normally distributed) are expressed as medians (IQR) and Mann-Whitney test was used to test statistical differences between groups. Proportions for categorical variables were compared using chi-squared test. Multivariate analysis was done by logistic regression or multiple regression as indicated. Odds ratios and 95% CIs were calculated with bivariable logistic regression for assessment of demographic characteristics and comorbidities associated with 25-OH vitamin deficiency, and for assessment of demographic characteristics, comorbidities, vitamin D status and CT findings on admission associated with survival outcome. The authors did not correct for multiple comparisons. Statistical analyses were performed using MedCalc (version 12.2.1, Mariakerke, Belgium) and considered significant if P value was less than .05.  

Supplementary methods: detailed scanning and image analysis protocol chest CT

This file contains descriptive information on statistical analysis (including multivariate analysis to predict COVID-19 outcome) and chest CT.

Source data (25(OH)D and structured chest CT data) are available upon email request to geert.martens@azdelta.be