Studies evaluating the association between vitamin D level and COVID-19 disease severity
| Author, year, and location | Controls: number (N) and mean or median age (yrs) | Subjects: number (N) and mean or median age (yrs) | Serum 25(OH)D concentration in controls vs. subjects, p-value | Outcome based on comorbidities and vitamin D levels, p-value |
|---|---|---|---|---|
| Radujkovic, 2020, Germany | Controls: COVID-19 outpatients, N=92, Median age=56 | Subjects: COVID-19 inpatients, N=93, Median age=63 | Median: 18.6 vs. 14.6 ng/mL, p=0.001 | Adjusted by age, gender, and comorbidities, VDD (<12 ng/mL) was associated with invasive mechanical ventilation and death (HR 6.12 and 14.73, respectively. p<0.001 for both). |
| Luo, 2020, China | Controls: Non-severe COVID-19, N=261, Median age=54.0 | Subjects: Severe COVID-19, N=74, Median age=62.5 | Median: 11.0 vs. 9.24 ng/mL, p<0.0001 | Adjusted by sex, age, comorbidities, BMI, smoking status, and vitamin D status, VDD (<12 mg/L) was associated with COVID-19 severity (OR 2.72, 95% CI 1.23–6.01, p=0.014), but VDD was not associated with mortality (p=1.0). |
| Karahan, 2021, Turkey | Controls: Moderate COVID-19, N=47, Mean age=56.1 | Subjects: Severe-critical COVID-19, N=102, Mean age=67.0 | Median: 26.3 vs. 10.1 ng/mL, p<0.001 | 25(OH)D levels significantly predictive of in-hospital mortality (multivariate analysis: OR 0.927, 95%CI 0.875–0.982, p=0.01). |
| Jain, 2020, India | Controls: Asymptomatic COVID-19, N=91, Mean age=42.34 | Subjects: Severely ill COVID-19, N=63, Mean age=51.41 | Mean: 27.89 vs. 14.35 ng/mL, p=0.0001 | Fatality rate for VDD (<20 ng/mL) higher than that for normal 25(OH)D (21.1% vs. 31.1%, p-value NR). |
| Macaya, 2020, Spain | Controls: Non-severe COVID-19, N=49, Median age=63 | Subjects: Severe COVID-19, N=31, Median age=75 | Median: 19 vs. 13 ng/mL, p=0.145 | Adjusted by age, gender, obesity, cardiac disease, and CKD, VDD (<20 ng/mL) did not significantly predict higher risk of developing severe COVID-19 (OR 3.2, 95% CI 0.9–11.4, p=0.07). |
| Ye, 2020, China | Controls: Mild/moderate COVID-19, N=50, Median age=39 | Subjects: Severe/critical COVID-19, N=10, Median age=65 | Median: 22.64 vs. 15.28 ng/mL, p<0.05 | Multivariate analysis including VDD, age, sex, renal failure, diabetes, and HTN: Statistically significant association between VDD (<20 ng/mL) and severe/critical COVID-19 disease (OR 15.18, 95% CI 1.23–187.45). |
| Kerget, 2020, Turkey | Controls: COVID-19 without ARDS, N=53, Mean age=38.3 | Subjects: COVID-19 with ARDS, N=35, Mean age=67.9 | Mean: 21.8 vs. 16.8 ng/mL, p=0.102 | NR |
| Campi, 2021, Italy | Controls: Severely symptomatic COVID-19 hospital ward admits, N=49, Mean age=68.82 | Subjects: Severely symptomatic COVID-19 ICU admits, N=54, Mean age=63.67 | Mean: 22.4 vs. 14.4 ng/mL, p=0.0003 | 25(OH)D levels inversely correlated with subsequent need for ICU admission in severely symptomatic patients (RR 0.989, 95%CI 0.981–0.997, p=0.011), and also inversely correlated with in-hospital mortality (p=0.002). |
Units for vitamin D levels in two studies (Luo et al. and Ye et al.), originally reported in nmol/L, were converted to ng/mL in order to achieve consistency in the units across all studies. 25(OH)D=25-hydroxyvitamin D, VDD=Vitamin D Deficiency, HR=Hazard Ratio, OR=Odds Ratio, RR=Relative Risk, NR=Not Reported