Vitamin D deficiency and SARS‑CoV‑2 infection: A retrospective case-Control study with big-data analysis covering March 2020 to March 2021.

Background: Vitamin D may have immunomodulatory functions, and might therefore play a role in the pathogenesis of acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. However, no conclusive evidence exists regarding its impact on the prevalence of this infection, the associated course of disease, or prognosis.
Objective: To study the association between SARS-CoV-2 infection and vitamin D deficiency in patients attending a tertiary university hospital, and to examine the clinical course of infection and prognosis for these patients.
Methods: This non-interventional, retrospective study, which involved big-data analysis and employed artificial intelligence to capture data from free text in the electronic health records of patients diagnosed with SARS-CoV-2, was undertaken at a tertiary university hospital in Madrid, Spain, between March 2020 and March 2021. The variables recorded were vitamin D deficiency, sociodemographic and clinical characteristics, course of disease, and prognosis.
Results: Of the 143,157 patients analysed, 36,261 had SARS-CoV-2 infection (25.33%) during the study period, among whom 2,588 (7.14%) had a vitamin D deficiency. Among these latter patients, women (OR 1.45 [95%CI 1.33-1.57]), adults over 80 years of age (OR 2.63 [95%CI 2.38-2.91]), people living in nursing homes (OR 2.88 [95%CI 2.95-3.45]), and patients with walking dependence (OR 3.45 [95%CI 2.85-4.26]) appeared in higher proportion. After adjusting for confounding factors, a higher proportion of subjects with SARS-CoV-2 plus vitamin D deficiency required hospitalisation (OR 1.38 [95%CI 1.26-1.51]), and had a longer mean hospital stay (3.94 compared to 2.19 days in those with normal levels; P = 0.02).
Conclusion: A low serum 25(OH) vitamin D concentration in patients with SARS-CoV-2 infection is significantly associated with a greater risk of hospitalisation and a longer hospital stay. Among such patients, higher proportions of institutionalised and dependent people over 80 years of age were detected.
Competing Interests: The authors have declared that no competing interests exist.
(Copyright: © 2023 Neira Álvarez et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)