Sir,
It was with great interest that I read the paper by Seal et al.,1 which dealt with the possible association between vitamin D status and the resulting COVID-19-associated hospitalisation and mortality risk. The article gives much needed insight on possible vitamin deficiencies and their direct and indirect associations with severity of disease manifestation. Though the insights procured from the study are greatly contributing towards disease treatment, yet, one needs to question the large-scale validity of the findings.
The main reason for the question of validity is concern regarding the study population. As the study involves only Veterans, one needs to be concerned with factors including age and gender. Firstly, the participants had a mean age of 62.6 years and, also, were predominantly male at 87.2% with very few female participants (only 12.8%). A large-scale systematic review and meta-analysis indicates that the male gender shows a higher risk of mortality due to COVID-19 and that patients of ≥50 years of age show a 15.4-fold significantly higher risk for death due to Covid than patients with an age <50 years.2 Due to these observations, the deaths and hospitalisation may have possible associations with blood 25(OH)D levels but one needs to keep in mind that both age and gender also play an important role in the outcome of this study.
Second, studies have also indicated that vitamin D deficiency (25(OH)D < 20 ng/mL) affects approximately 40% of Veterans.3 Considering this, one questions the study validity in a generalised population. Acknowledging the fact that the study is named “Association of Vitamin D Status and COVID-19-Related Hospitalization and Mortality”, one needs to realise that the title may be ever so slightly misleading. The study has minimal validity in a generalised population of different ages. But, the study provides a reliable result analysis about the risks associated in an at-risk population for vitamin D deficiency.
Declarations
Conflict of interest
The author declares that he does not have a conflict of interest.
Footnotes
It is imperative that the authors consider that the selected study population may have a considerable effect on research findings. Furthermore, the authors could correspondingly provide a more generalised study finding by having participants of different age groups, occupations, and an equitable gender spread. This could potentially allow these findings to be used with a large-scale premise so that a definitive risk analysis on the corresponding association between vitamin D deficiency and COVID-19-related hospitalisation and mortality can be understood and delineated.
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References
- 1.Seal KH, Bertenthal D, Carey E, Grunfeld C, Bikle DD, Lu CM. Association of vitamin D status and COVID-19-related hospitalization and mortality. J Gen Intern Med [Internet]. 2022;37(4):853–61. Available from: 10.1007/s11606-021-07170-0 [DOI] [PMC free article] [PubMed]
- 2.Biswas M, Rahaman S, Biswas TK, Haque Z, Ibrahim B. Association of sex, age, and comorbidities with mortality in COVID-19 patients: A systematic review and meta-analysis. Intervirology [Internet]. 2020;64(1):1–12. Available from: 10.1159/000512592 [DOI] [PMC free article] [PubMed]
- 3.Islam T, Peiris P, Copeland RJ, El Zoghby M, Peiris AN. Vitamin D: Lessons from the veterans population. J Am Med Dir Assoc [Internet]. 2011;12(4):257–62. Available from: 10.1016/j.jamda.2010.08.004 [DOI] [PubMed]