Low Vitamin D Status at Admission as a Risk Factor for Poor Survival in Hospitalized Patients With COVID-19: An Italian Retrospective Study

Abstract

Objective

Preliminary findings suggest a relationship between lower serum 25-hydroxyvitamin D [25(OH)D] levels and incidence and severity of COVID-19. The aim of this study was to evaluate the relationship between vitamin D status at admission and different markers of inflammation, coagulation, and sepsis in hospitalized patients with COVID-19.

Method

We conducted a retrospective study on 137 consecutive patients with SARS-CoV-2 infection and available data on serum 25(OH)D levels, who were admitted to our Institution between March 1 and April 30, 2020. Patients were divided into two groups: survivors (n = 78; 57%) and non-survivors (n = 59; 43%).

Results

At admission, all patients showed hypovitaminosis D. Median total serum 25(OH)D levels at admission were significantly higher in survivors than non-survivors (12 ng/mL vs 8 ng/mL; p < 0.01). Non-survivors exhibited significantly higher median levels of white blood cell (WBC) count, neutrophil-to-lymphocyte count ratio (NLR), high-sensitivity C-reactive protein (hsCRP), ferritin, interleukin 6 (IL-6), D-dimer, fibrinogen, and procalcitonin (PCT) compared to survivors at three different time points during hospitalization. In a multivariate analysis performed by a logistic regression model, serum 25(OH)D levels were significantly inversely associated with risk of COVID-19-related in-hospital mortality (odds ratio, 0.91; 95% confidence interval, 0.85–0.98; p = 0.01). According to receiver operating characteristic curve analysis, hsCRP, NLR, ferritin, and D-dimer were the best predictive biomarkers for poor prognosis of COVID-19, whereas IL-6, PCT, fibrinogen, 25(OH)D, WBC count, and tumor necrosis factor alpha (TNF-α) may serve as supportive biomarkers for worse clinical course of the disease.

Conclusions

We found a markedly high prevalence (100%) of hypovitaminosis D in patients admitted to hospital with COVID-19, suggesting a possible role of low vitamin D status in increasing the risk of SARS-CoV-2 infection and subsequent hospitalization. The inverse association between serum 25(OH)D levels and risk of in-hospital mortality observed in our cohort suggests that a lower vitamin D status upon admission may represent a modifiable and independent risk factor for poor prognosis in COVID-19.

Keywords:

• Vitamin D status
• inflammatory markers
• mortality
• SARS-CoV-2
• cytokine storm
• COVID-19

Acknowledgments

We acknowledge all medical staff involved in the diagnosis and treatment of patients with COVID-19 at Tor Vergata University Hospital-PTV.

Authors’ contributions

MI and MM designed the research project, wrote the paper, supervised the project, and equally contributed to the manuscript. AB collected and retrieved clinical data, analyzed results, and contributed to the research project. MP performed statistical analysis. SL and MN performed, collected, and retrieved biochemical data. SB, AF, MIa, MA, and VC supervised the research project and reviewed the manuscript. All authors edited the manuscript. No honorarium, grant, or other forms of payment were received by authors to write this manuscript.

Disclosure statement

No author has potential conflicts of interest to disclose.

Funding

This study did not receive any funding for the conduct of the research and/or preparation of the article.