Vitamin D deficiency on admission to hospital was associated with a 3.7-fold increase in the odds of dying from COVID-19, according to an observational study looking back at data from the first wave of the pandemic.
Nearly 60% of patients with COVID-19 were vitamin D deficient upon hospitalization, with men in the advanced stages of COVID-19 pneumonia showing the greatest deficit.
Importantly, the results were independent of comorbidities known to be affected by vitamin D deficiency, say the authors, led by Dieter De Smet, MD, from AZ Delta General Hospital, Roeselare, Belgium.
"[The findings] highlight the need for randomized controlled trials specifically targeting vitamin D–deficient patients at intake, and make a call for a general avoidance of vitamin D deficiency as a safe and inexpensive possible mitigation of the SARS-CoV-2 pandemic," said De Smet and colleagues in their article, published online November 25 in the American Journal of Clinical Pathology.
A search of ClinicalTrials.gov reveals there are currently close to 40 ongoing intervention trials with vitamin D in COVID-19 around the world for varying purposes, including prevention, and varying forms of treatment.
Consider Vitamin D to Prevent COVID-19 Infection
With regard to the potential role in prevention, "Numerous observational studies have shown that low vitamin D levels are a major predictor for poor COVID outcomes," notes Jacob Teitelbaum, MD, an internist who specializes in treating chronic fatigue syndrome and fibromyalgia who also has an interest in COVID-19.
"This study shows how severe a problem this is," Teitelbaum told Medscape Medical News. "A 3.7-fold increase in death rate if someone's vitamin D level was below 20 [ng/mL] is staggering. It is arguably one of the most important risk factors to consider."
"What is not clear is whether vitamin D levels are acting as an acute-phase reactant, dropping because of the infection, with larger drops indicating more severe disease, or whether vitamin D deficiency is causing worse outcomes," added Teitelbaum, who is director of the Center for Effective CFIDS/Fibromyalgia Therapies, Kailua-Kona, Hawaii.
Also asked to comment, Andrea Giustina, MD, president of the European Society of Endocrinology, said: "The paper by De Smet et al confirms what we already hypothesized in BMJ last March: that patients with low vitamin D levels are at high risk of hospitalization for COVID-19 and developing severe and lethal disease."
"This is likely due to the loss in the protective action of vitamin D on the immune system and against the SARS-CoV-2-induced cytokine storm."
He said it is particularly interesting that the authors of the new study had reported more prevalent vitamin D deficiency among men than women, most likely because women are more often treated with vitamin D for osteoporosis.
The new study should prompt all clinicians and health authorities to seriously consider vitamin D supplementation as an additional tool in the fight against COVID-19, particularly for the prevention of infection in those at high risk of both COVID-19 and hypovitaminosis D, such as the elderly, urged Giustina, of San Raffaele Vita-Salute University, Milan, Italy.
Results Adjusted for Multiple Confounders
De Smet and colleagues looked at serum 25-hydroxyvitamin D (25(OH)D) levels in 186 patients hospitalized for severe COVID-19 infection as a function of radiologic stage of COVID-19 pneumonia as well as the association between vitamin D status on admission and COVID-19 mortality.
Cognizant of the potential for confounding by multiple factors, they adjusted for age, sex, and known vitamin D–affected comorbidities such as diabetes, chronic lung disease, and coronary artery disease.
Patients were hospitalized from March 1 to April 7, 2020 (the peak of the first wave of the pandemic) at their institution, AZ Delta General Hospital, a tertiary network hospital.
The mean age of patients was 69 years, 41% were women, and 59% had coronary artery disease. Upon admission to hospital, median vitamin D level was 18 ng/mL (women, 20.7 ng/mL; men, 17.6 ng/mL).
A remarkably high percentage (59%, 109/186) of patients with COVID-19 were vitamin D deficient (25(OH)D < 20 ng/mL) when admitted (47% of women and 67% of men), write the authors.
"What surprises me," said Teitelbaum, is that almost 60% "of these patients had 25(OH)D under 20 ng/mL but most clinicians consider under 50 to below."
All patients had a chest CT scan to determine the radiologic stage of COVID-19 pneumonia and serum vitamin D measurement on admission. The radiologic stage of pneumonia was used as a proxy for the immunologic phase of COVID-19.
Vitamin D Deficiency Correlated With Worsening Pneumonia
Among men, rates of vitamin D deficiency increased with advancing disease, with rates of 55% in stage 1, 67% in stage 2, and up to 74% in stage 3 pneumonia.
There is therefore "a clear correlation between 25(OH)D level and temporal stages of viral pneumonia, particularly in male patients," write the authors.
"Vitamin D dampens excessive inflammation," said Teitelbaum. "In these patients with acute respiratory distress syndrome, the immune system has gone wild."
"The study was carried out in Belgium, so there's less sunlight there than some other places, but even here in Hawaii, with plenty of sunshine, we have vitamin D deficiency," he added.
"More studies are needed, but I think there are enough data to suggest a multivitamin should be used to aid prophylaxis, and this is reflected in [some] infectious disease recommendations," he noted.
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