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Exploring the link between Vitamin D and clinical outcomes in COVID-19

Take Home Message

This retrospective cohort study evaluated the role of serum vitamin D levels in severe disease outcomes among COVID-19 patients in Detroit, MI and found no association of vitamin D levels with mortality, the need for mechanical ventilation, ICU admission and thromboembolism in COVID-19.


Two-thousand one patients who received a positive COVID-19 PCR diagnosis at Detroit Medical Center (Michigan, USA) between March 10, 2020 and June 30, 2020.

Length of Study

Between March 10, 2020 and June 30, 2020


  • Of the 270 patients included in the study, 117 were male (43.3%) and 153 female (56.7%) with a mean age of 63.81 ± 14.69 years. More than half (n = 139, 51.5%) were age 65 and older and Black was the predominant race (n = 216, 80%).  
  • More than one-third of the patients had serum 25(OH)D levels < 20 ng/mL (n = 95, 35.2%). About 70% of patients had three or more comorbid diseases (n = 187, 69.3%). The mean BMI of patients was 32.0 ± 9.12, and more than 50% of patients (n = 139) were in the obese category as per the World Health Organization criteria. 
  • The total mortality was 26.7% (n = 72). Approximately one in every three patients in this study (n = 87, 32.2%) required ICU care. Close to 81% (n = 219) of patients required supplemental oxygen during hospitalization and 21.9% (n = 59) required mechanical ventilation. About 2.2% of the patients (n = 6) developed new DVT or PE during their hospitalization.  
  • In the cohort analysis, vitamin D levels showed no significant association with mortality, need for mechanical ventilation , new DVT or PE or ICU admission. 
  • No correlation between vitamin D and mortality was noted in the total cohort when adjustment was made for age, sex, BM, and presence of comorbidities.

Things to Keep in Mind

  • Although a large database of over 2000 patients was used, numerous patients did not have recorded vitamin D levels within the last year. This significantly reduced the number of patients who could be included in this study.  
  • Electronic medical records and clinical notes were relied upon to gather data including the presence of comorbidities and documentation of vitamin D levels. Hence, there is a possibility of both selection and information bias.  
  • The data for this study were collected from 4 hospitals in southeast Michigan, predominantly serving an underserved population having multiple comorbidities. 
  • The sample size consisted of very few patients with other races besides Black and White, thereby limiting analysis in these population groups
  • Using vitamin D levels measured in the year before the patients contracted COVID-19 helped avoid the negative acute phase impact of the illness on vitamin D levels. However, it would have been better if  the measurements were taken immediately preceding COVID-19 infection.  

Author’s Conclusions

This study did not find any significant association of vitamin D levels with mortality, the need for mechanical ventilation, ICU admission and the development of thromboembolism in patients with COVID-19. Further studies are warranted before any conclusive association can be made between vitamin D levels and the clinical course of COVID 19 patients. 

Study Design

  • This study is a retrospective cohort study. 
  • Two-hundred seventy patients received a positive COVID-19 PCR diagnosis and had a documented serum 25(OH)D level measured within the past 12 months at Detroit Medical Center. 
  • These patients were classified into two groups based on their serum 25(OH)D levels: ³50 nmol/L (patients with normal vitamin D levels) and < 50 nmol/L (patients with low vitamin D levels). 
  • For stratification of vitamin D levels, patients with normal 25(OH)D levels were further divided into two subgroups: patients with vitamin D level 5075 nmol/L and patients with vitamin D level >75 nmol/L.  
  • The main outcomes were mortality, the need for mechanical ventilation, new deep vein thrombosis (DVT) or pulmonary embolism (PE) during hospitalization, and ICU admission. 
  • All of the patients included in the study had a documented outcome (mortality or discharge).  
  • The number of prior comorbidities, BMI, disposition upon emergency department (ED) visit (discharge home, inpatient admission and direct ICU admission) and maximum oxygen requirement during admission were collected.  
  • Demographic data collected included age, sex and race. 


Lohia P, Nguyen P, Patel N, Kapur S. Exploring the link between vitamin D and clinical outcomes in COVID-19. Am J Physiol Endocrinol Metab. 2021 Mar 1;320(3):E520-E526. doi: 10.1152/ajpendo.00517.2020. Epub 2021 Jan 6. PMID: 33404354.

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