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