Association of 25-Hydroxyvitamin D Level with COVID-19-Related in-Hospital Mortality: A Retrospective Cohort Study.

BACKGROUND

The primary aim of this study was to compare the 25(OH)D level between patients with COVID-19 and the reference population. The secondary aim was to determine the association of 25(OH)D level with COVID-19-related in-hospital mortality.

METHODS

The COVID-19-positive group comprised 520 hospitalized patients and the reference population comprised 15,789 COVID-19-negative patients. The 25(OH)D level was categorized as vitamin D deficiency (25[OH]D < 20 ng/mL) and severe vitamin D deficiency (25[OH]D < 12 ng/mL).

RESULTS

While the incidence of vitamin D deficiency was similar in both groups, the incidence of severe vitamin D deficiency was higher in patients with COVID-19 than in the reference population (68.3% [ = 355] vs. 55.1% [ = 8,692],  < 0.001). Severe vitamin D deficiency in patients with COVID-19 was higher in the intensive care unit (ICU) group than in the non-ICU group (75.3% [ = 183] vs. 62% [ = 172],  = 0.001). The incidence of severe vitamin D deficiency was 65.4% ( = 280) in survivors and 81.5% ( = 75) in nonsurvivors ( = 0.003). However, multivariable Cox proportional hazard regression analysis showed no relationship between 25(OH)D level and in-hospital mortality. The median survival times of patients with and without severe vitamin D deficiency were not different, as shown by Kaplan-Meier survival analysis.

CONCLUSION

Severe vitamin D deficiency is more common in patients with COVID-19 and may play a significant role in worsening the prognosis of these patients. However, the 25(OH)D level was not observed to effect COVID-19-related in-hospital mortality.