The relationship between 25(OH) vitamin D levels and COVID-19 onset and disease course in Spanish patients.

OBJECTIVE

Currently, there are no definitive data on the relationship between low levels of vitamin D in the blood and a more severe disease course, in terms of the need for hospital admission, intensive care unit (ICU) stay, and mortality, in patients with coronavirus disease 2019 (COVID-19), the disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We aimed to study the association between levels of circulating 25-hydroxyvitamin D (25(OH)D) and adverse clinical outcomes linked to SARS-CoV-2 infection. We further aimed to observe the incidence of low, below-average, and normal levels of 25(OH)D in patients hospitalized for COVID-19 between March 12, 2020, and May 20, 2020, and assess whether these values differed between these patients and a normal population. Finally, we determined whether the need for transfer to the intensive care unit (ICU) and the mortality rate were related to low levels of 25(OH)D.

STUDY DESIGN

Retrospective observational study.

SETTING

Quironsalud Hospitals in Madrid, Spain.

PARTICIPANTS

We analyzed 1549 patients (mean age, 70 years; range, 21-104 years); 835 were male (53.9 %; mean age, 73.02 years), and 714 were female (46.1 %; mean age, 68.05 years). Subsequently, infected patients admitted to the ICU (n = 112) and those with a fatal outcome (n = 324) were analyzed.

PROCEDURES

Serum concentrations of 25(OH)D were measured by electrochemiluminescence.

RESULTS

More hospitalized patients (66 %, n = 1017) had low baseline levels of 25(OH)D (<20 ng/mL) than normal individuals (45 %) (p < 0.001). An analysis by age group revealed that COVID-19 patients between the ages of 20 and 80 years old had significantly lower vitamin D levels than those of the normal population (p < 0.001). Patients admitted to the ICU tended to have lower levels of 25(OH)D than other inpatients (p < 0.001); if we stratified patients by 25(OH)D levels, we observed that the rate of ICU admission was higher among patients with vitamin D deficiency (p < 0.001), indicating that higher vitamin D levels are associated with a lower risk of ICU admission due to COVID-19. ICU admission was related to sex (higher rates in men, p < 0.001) and age (p < 0.001). When using a logistic regression model, we found that vitamin D levels continued to show a statistically significant relationship with ICU admission rates, even when adjusting for sex and age. Therefore, the relationship found between vitamin D levels and the risk of ICU admission was independent of patient age and sex in both groups. Deceased patients (n = 324 tended to have lower levels of 25 (OH)D that normal population of the same age (p < 0.001).

CONCLUSION

Vitamin D deficiency in patients with COVID-19 is correlated with an increased risk of hospital admission and the need for critical care. We found no clear relationship between vitamin D levels and mortality.