Observational studyThe American journal of clinical nutrition2022
Vitamin D, vitamin D-binding protein, free vitamin D and COVID-19 mortality in hospitalized patients.
Observational study in The American journal of clinical nutrition, 2022. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 10 papers, 2 of them syntheses that pooled it.
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
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Who cites it
10 citing papers in PubMed, 2 syntheses or guidelines pooled it, 18 citations in OpenAlex.
- Micronutrients, Vitamin D, and Inflammatory Biomarkers in COVID-19: A Systematic Review and Meta-analysis of Causal Inference Studies.Nutrition reviews · 2025Pooled it
- Vitamin D-Binding Protein, Bioavailable, and Free 25(OH)D, and Mortality: A Systematic Review and Meta-Analysis.Nutrients · 2022Pooled it
- Group-specific component and 25-hydroxylase gene polymorphisms in nasopharyngeal carcinoma: Associations with susceptibility and radiotherapy response.World journal of clinical oncology · 2025Article
- Vitamin D Binding Protein: A Potential Factor in Geriatric COVID-19 Acute Lung Injury.Journal of inflammation research · 2024Article
- Correlation of Plasma 25(OH)DNutrients · 2023Article
- Vitamin D and COVID-19-Revisited.Journal of internal medicine · 2022Review
- Impaired Vitamin D Metabolism in Hospitalized COVID-19 Patients.Pharmaceuticals (Basel, Switzerland) · 2022Article
- The Role of Vitamin D in Supporting Health in the COVID-19 Era.International journal of molecular sciences · 2022Review
- Commentary: Vitamin D Status in Relation to the Clinical Outcome of Hospitalized COVID-19 Patients.Frontiers in medicine · 2022Article
- Could vitamin D supplementation play a role against COVID-19?Frontiers in immunology · 2022Article
Corrections and comments
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Authors and funding
16 authors at 3 institutions in 2 countries.
Funding
No grant is acknowledged in the PubMed record.
Abstract
backgroundVitamin 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.
objectivesWe aimed to examine the relationship between vitamin D status and mortality from COVID-19.
methodsIn 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.
resultsThere 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.
conclusionsVitamin 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).
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