Association between low serum vitamin D and increased mortality and severity due to COVID-19: reverse causality?

Abstract

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Frequency of COVID-19 Infection as a Function of Vitamin D Levels

“…For instance, standard total hip replacement, even without any concomitant infection, is associated with around a 21–34% decrease in 25OHD levels [ 23 ]. Hence, some authors, e.g., Oscanoa et al [ 24 ], warn about a possibility of “reverse causality” or ”backward causation”, which might have caused a significant bias in several studies on vitamin D and COVID-19 severity. In other words, “reverse causality” applies to a situation where an outcome seemingly determines the cause, thus leading to an erroneous conclusion where in fact an opposite relationship might exist.…”

Platelet-to-lymphocyte ratio as a prognostic biomarker for COVID-19 severity: a single center retrospective data analysis and systematic review with meta-analysis of 187 studies

“…The clinical presentation varies from no symptoms to acute respiratory failure, shock, and multi-organ system dysfunction [4]. Pandemics provide a significant challenge to healthcare systems and the rapid identification of severe cases is of the utmost significance because of the requirement of appropriate medical workforce allocation, symptomatic treatment, timely access to the intensive care unit, and patient isolation in an attempt to prevent the illness from spreading [5][6][7]. According to the findings of immunological research, severe cases of COVID-19 are distinguished by very significant amounts of cytokines that promote inflammation.…”

Vitamin E supplementation's role in COVID-19

“…To the Editor, we read with great interest the article by Oscanoa et al on the effect of 25(OH)D3 levels on the incidence and severity of COVID-19 [1]. Other authors [2] have confirmed the existence of a link between low levels of 25(OH)D3 [2].…”