THE CASUAL ROLE OF VITAMIN D SUPPLEMENTATION IN THE COVID-RELATED HEALTH OUTCOMES (RETROSPECTIVE CROSS-SECTION STUDY)

The aim of our study was to investigate the causal role of vitamin D supplementation in the COVID-related health outcomes (hospitalization, transfer to ICU unit, requirement of oxygen therapy, the treatment by glucocorticoids) of the patients with SARS infection. Methods. Presented retrospective cross-section study was performed based on the data of National Center of Disease control and Public Health (NCDC) of Georgia. 475 records of the patients with determined serum 25-hydroxivitamin D [25(OH)D] were randomly selected for the study. Researchers provided the visits of these patients and after obtaining the written informed consent 384 persons from the NCDC database have been included in the study group. Study subjects were divided by the presence of vitamin D supplementation before SARS-virus was confirmed: the group 1 – patients with vitamin D supplementation – n=224; the group 2 – patients without vitamin D supplementation – n=160. The patients were surveyed by the special structured questionnaires to provide the information about the presence of vitamin D supplementation before the SARS-virus confirmation. Results. Mean level of serum 25-hydroxivitamin D [25(OH)D] in the study group 1 was 22.5±9.9 ng/ml, and in the study group 2 was 16.9±8.2 ng/ml; The difference of these values between the groups was significant - t=5.861, p<0.001. The odds of hospitalization in the group 2 were 3.6 times higher compared to group 1 (OR = 3.60, 95%CI 1.85 – 7.03, F-test = 3.76, p<0.001). The odds of the requirement of transfer to ICU unit (OR = 0.93, 95%CI 0.15 – 5.65, F-test = 0.08, p=0.939), the requirement of oxygen therapy (OR = 1.66, 95%CI 0.86 – 6.65, F-test = 1.66, p=0.097), and the treatment by glucocorticoids (OR = 1.41, 95%CI 0.49 – 4.13, F-test = 0.64, p=0.521) between the groups were not significant. Conclusion. Vitamin D supplementation was associated with 3.6-fold lower risk of hospitalization due to SARS-CoV-2 infection. Therefore, COVID-19-related morbidity was associated with the decreased serum 25(OH)D levels. Future studies should also investigate any potential role of vitamin D sufficiency in the prevention of SARS-CoV-2 infection and mortality. Notably, the relation between vitamin D sufficiency and infection with various strains of SARS-CoV-2 requires paying the special attention.