Vitamin d deficiency is mainly associated with severe lung involvement, longer disease duration and risk of death in elderly COVID-19 patients

Sulli, A.; Gotelli, E.; Casabella, A.; Grosso, M.; Schenone, C.; Pizzorni, C.; Paolino, S.; Alessandri, E.; Smith, V.; Cutolo, M.

Background: Vitamin D regulates the innate and adaptive immune system responses and low vitamin D levels have been associated with the increased risk of respiratory tract infections (1). Vitamin D deficiency has been recently reported to interfere with the prognosis of COVID-19 (2,3). Objectives: The aim of this study was to correlate the 25OH-vitamin D serum levels with lung involvement and disease severity, in a cohort of elderly patients hospitalized for SARS-CoV-2 infection. Methods: Sixty-five COVID-19 patients (mean age 76±13 years) and sixty-five sex-and age-matched control subjects (CNT) were included in the study. Respiratory parameters (PaO2, SO2, PaCO2, PaO2/FiO2), clinical and laboratory parameters (including 25OH-vitamin D, D-dimer, C-reactive protein) and type of radiological pulmonary involvement were collected at hospital admission. Statistical analysis was performed by non-parametric tests. Results: Vitamin D sufficiency (≥30 ng/ml), insufficiency (between 20 and 30 ng/ ml), deficiency (between 10 and 20 ng/ml) and severe deficiency (<10 ng/ml) were observed respectively in 11, 11, 21 and 57 % of COVID-19 patients. Vitamin D serum levels were found significantly lower in COVID-19 patients than in CNT (median 8 vs 16 ng/ml, p=0.001). A statistically significant positive correlation was observed between vitamin D serum levels and SO2 (p=0.05), PaO2 (p=0.03), PaO2/FiO2 (p=0.02). A statistically significant negative correlation was found between vitamin D serum levels and severity of radiologic pulmonary involvement: vitamin D was significantly lower in COVID-19 patients with either diffuse/ severe interstitial lung involvement (p=0.05) or multiple lung consolidations (p=0.0001) than in those with mild radiological lung involvement. Significantly lower vitamin D serum levels were found in COVID-19 patients who died during hospitalization, compared to those who survived (median 3 vs 8 ng/ml, p=0.05). Finally, a statistically significant negative correlation was found between vitamin D serum levels and D-dimer (p=0.04), C-reactive protein (p=0.04) and disease duration (p=0.05). Conclusion: This study confirms that severe vitamin D deficiency is associated with more severe lung involvement, longer disease duration and risk of death in elderly COVID-19 patients.