New Paper - Vit D use and Covid Risk

Medical Q&A [Moderated]
1

I saw this new paper in Nature Scientific Reports and thought I’d share it to get your perspective given your skepticism on the general value of Vit D supplementation

https://www.nature.com/articles/s41598-022-24053-4#Sec19

In short it’s a retrospective cohort study of people in the VA system comparing risk of covid infection and mortality between those who were Rxed Vit D vs those who were not. In their analysis, supplementation was associated with reduced risk of all outcomes, with the association being greater the higher the Vit D levels measured

Reasons for skepticism

  • Rx does not actually mean supplementation
  • They used a propensity matching approach to control for confounders that eliminated 340,000 controls from their analysis population (approx 80%). The more statistical fuckery employed, especially when not well described, the more dubious I am.
  • One of the characteristics controlled for was Vit D deficiency. This means the supplementation (assuming Rx does equal supplementation) wasnt even addressing Vit D deficiency. In that context, I am not sure what supplementation is supposed to represent, but presumably could represent some sort of cohrt bias (are the people, regardless of Vit D status) who obtain Vit D from their VA doctor in some way different regarding health consciousness?
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2

Yeah, these sorts of retrospective correlational studies can be hypothesis-generating for prospective randomized trials, but otherwise don’t really add anything to the conversation beyond what we’ve already discussed on our Vit D podcast.

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