Vitamin D, vitamin D-binding protein, free vitamin D and COVID-19 mortality in hospitalized patients



Subramanian, Sreedhar, Rhodes, Jonathan M ORCID: 0000-0002-1302-260X, Taylor, Joseph M, Milan, Anna M, Lane, Steven, Hewison, Martin, Chun, Rene F, Jorgensen, Andrea ORCID: 0000-0002-6977-9337, Richardson, Paul, Nitchingham, Darshan
et al (show 6 more authors) (2022) Vitamin D, vitamin D-binding protein, free vitamin D and COVID-19 mortality in hospitalized patients. AMERICAN JOURNAL OF CLINICAL NUTRITION, 115 (5). pp. 1367-1377.

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Abstract

<h4>Background</h4>Vitamin D deficiency has been associated with worse coronavirus disease 2019 (COVID-19) outcomes, but circulating 25-hydroxyvitamin D [25(OH)D] is largely bound to vitamin D-binding protein (DBP) or albumin, both of which tend to fall in illness, making the 25(OH)D status hard to interpret. Because of this, measurements of unbound ("free") and albumin-bound ("bioavailable") 25(OH)D have been proposed.<h4>Objectives</h4>We aimed to examine the relationship between vitamin D status and mortality from COVID-19.<h4>Methods</h4>In this observational study conducted in Liverpool, UK, hospitalized COVID-19 patients with surplus sera available for 25(OH)D analysis were studied. Clinical data, including age, ethnicity, and comorbidities, were extracted from case notes. Serum 25(OH)D, DBP, and albumin concentrations were measured. Free and bioavailable 25(OH)D were calculated. Relationships between total, free, and bioavailable 25(OH)D and 28-day mortality were analyzed by logistic regression.<h4>Results</h4>There were 472 patients with COVID-19 included, of whom 112 (23.7%) died within 28 days. Nonsurvivors were older (mean age, 73 years; range, 34-98 years) than survivors (mean age, 65 years; range, 19-95 years; P = 0.003) and were more likely to be male (67%; P = 0.02). The frequency of vitamin D deficiency [25(OH)D < 50 nmol/L] was similar between nonsurvivors (71/112; 63.4%) and survivors (204/360; 56.7%; P = 0.15) but, after adjustments for age, sex, and comorbidities, increased odds for mortality were present in those with severe deficiency [25(OH)D < 25 nmol/L: OR, 2.37; 95% CI, 1.17-4.78] or a high 25(OH)D (≥100 nmol/L; OR, 4.65; 95% CI, 1.51-14.34) compared with a 25(OH)D value of 50-74 nmol/L (reference). Serum DBP levels were not associated with mortality after adjustments for 25(OH)D, age, sex, and comorbidities. Neither free nor bioavailable 25(OH)D values were associated with mortality.<h4>Conclusions</h4>Vitamin D deficiency, as commonly defined by serum 25(OH)D levels (<50 nmol/L), is not associated with increased mortality from COVID-19, but extremely low (<25 nmol/L) and high (>100 nmol/L) levels may be associated with mortality risks. Neither free nor bioavailable 25(OH)D values are associated with mortality risk. The study protocol was approved by the London-Surrey Research Ethics Committee (20/HRA/2282).

Item Type: Article
Uncontrolled Keywords: bioavailable vitamin D, COVID-19 mortality, free vitamin D, vitamin D, vitamin D-binding protein
Divisions: Faculty of Health and Life Sciences
Faculty of Health and Life Sciences > Institute of Life Courses and Medical Sciences
Faculty of Health and Life Sciences > Institute of Population Health
Faculty of Health and Life Sciences > Institute of Systems, Molecular and Integrative Biology
Depositing User: Symplectic Admin
Date Deposited: 18 May 2022 11:16
Last Modified: 14 Mar 2024 18:41
DOI: 10.1093/ajcn/nqac027
Related URLs:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3155035