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Analysis of vitamin D level among asymptomatic and critically ill COVID‐19 patients and its correlation with inflammatory markers

Our take —

In this study of 154 patients with asymptomatic or severe COVID-19 in India, individuals with severe COVID-19 (defined as ICU admission) had lower vitamin D levels and were more likely to have vitamin D deficiency. Those with vitamin D deficiency were more likely to die than those without deficiency. However, caution is warranted as these findings do not provide evidence that vitamin D supplementation can prevent severe COVID-19, results were not adjusted for any potential confounders (including age), and vitamin D levels were measured after illness onset. Further research regarding this relationship is warranted.

Study design

Case-Control, Prospective Cohort

Study population and setting

This observational study at the M.L.B. Medical College in Jhansi, India was designed to evaluate the association between vitamin D and COVID-19 disease severity. Individuals aged 30-60 years with PCR-confirmed COVID-19 starting were consecutively enrolled for 6 weeks starting on June 5, 2020. Patients were included if they were asymptomatic at admission and remained so until their discharge (Day 12) or if they required ICU admission due to severe COVID-19 disease, defined as clinical pneumonia with respiratory rate >30 or oxygen levels <90%, signs of multi-organ impairment, or laboratory evidence of coagulation abnormalities. Vitamin D levels were estimated from Serum 25 (OH)D, and levels <20 ng/mL were considered as vitamin D deficiency. Participants were followed until death or discharge alive from the hospital.

Summary of Main Findings

In total, 154 patients were included: 91 were asymptomatic (53% male; mean age: 42 years) and 63 had severe COVID-19 (67% male, mean age: 51 years). The mean concentration of 25 (OH)D was higher among asymptomatic cases (mean: 27.9 ng/mL, 32% with vitamin D deficiency), compared to those with severe disease (mean: 14.4 ng/mL, 97% with vitamin D deficiency). Serum inflammatory markers, such as IL-6, ferritin, and TNF-alpha, were also associated with vitamin D deficiency. Regardless of symptom severity at enrollment, those with vitamin D deficiency were more likely to die (19/90 [21%] vs. 2/64 [3%]).

Study Strengths

This was a prospective cohort study with completed follow-up of included participants.

Limitations

No adjusted analyses were presented, and confounding is likely due to differences in age and comorbidities between asymptomatic and severely ill COVID-19 patients (older age is a known risk factor for vitamin D deficiency). The timing of vitamin D measurement relative to SARS-CoV-2 infection is not reported. Temporality between vitamin D levels and COVID-19 severity cannot be established; it is unknown whether vitamin D deficiency is a cause or consequence of severe disease. The sample size was relatively small and did not include patients with moderate disease (symptoms but not requiring ICU admission), which limits generalizability and inhibits inferences about any potential dose-response relationship between vitamin D levels and COVID-19 severity.

Value added

This is one of the first studies examining the relationship between Vitamin D and COVID-19 disease severity.

This review was posted on: 11 December 2020