4 ms·

The current discussion here seems to be about Vitamin D in general, and ignoring the study itself. In my reading, this study is weak evidence. This was not a r

The current discussion here seems to be about Vitamin D in general, and ignoring the study itself. In my reading, this study is weak evidence. This was not a randomized, controlled trial, but historical analyses of a natural experiment. In itself, that's not a problem: we can learn a lot from natural experiments. But I don't think this instance is much of an "experiment." As I understand it, all of the residents (96 in total) of a particular nursing home receive regular Vitamin D supplementation. Of the total residents, 66 got COVID-19. Among that group, they realized that 57 of them had received their Vitamin D supplementation either within a week of being diagnosed with COVID-19, or one month prior. That is the intervention group. The remaining 9 people are the "comparator" group. They found the intervention group had better survivability. The main three reasons I consider this study weak evidence is that the number of people in the "comparator" group is very small (9!), and they - as far as I can tell - do not explain why these people did not receive their normal Vitamin D supplementation. The "comparator" group is supposed to have had a similar baseline, but there's still, to me, a strong possibility of a confounding factor. Finally, there were four total interventions: corticosteroids, hydroxychloroquine, "dedicated antibiotics" and the observation about Vitamin D. The more things you try, the less surprising it should be that there is a correlation along one of them.

raverbashing 6y ago
> as far as I can tell - do not explain why these people did not receive their normal Vitamin D supplementation. My understanding: each patient receives a bolus dose every 2 to 3 months. The intervention group had that date within 1 mo before diagnosis (or 1wk after) > Here, the "Intervention group" was defined as all COVID-19 residents who received an oral bolus of 80,000 IU vitamin D3 either in the week following the suspicion or diagnosis of COVID-19, or during the previous month
- andy_ppp 6y ago
  80000 IU seems a lot, that’s about 100 times the RDA! Not saying it’s bad just interesting...
  - anamexis 6y ago
    That's what a "bolus dose" is, a single large dose to raise the levels in the blood to target levels in one go, as opposed to daily maintenance doses.
  - kingnothing 6y ago
    For what it's worth, there's been a lot of speculation in recent years that the RDA is far too low. 80,000 iu is still a huge dosage though!
  - lultimouomo 6y ago
    About 100 times the RDA makes sense if you take it once every 3 months, i.e. 90 days
rossdavidh 6y ago
Ditto all that, plus the mortality rate in the (very small) comparison group was 44%, which is very high even for the elderly. The mortality rate for the vit D group was not really all that great. On the flip side, given that they comparison group were receiving vit D3 occasionally, just not lately, it is possible that this underestimates the impact of vit D3 on a group that had long-term insufficient vit D3. Nothing here to say that vit D isn't good for you, especially if you have a deficiency (such as from insufficient time in the sun), but not a stunning piece of info either.
scythe 6y ago
>and they - as far as I can tell - do not explain why these people did not receive their normal Vitamin D supplementation Under subheading 2.2: "All residents in the nursing-home receive chronic vitamin D supplementation with regular maintenance boluses (single oral dose of 80,000 IU vitamin D3 every 2–3 months)," The comparator (not recent supplement) group was on a different schedule, and had received a supplement probably two months ago. >Finally, there were four total interventions: corticosteroids, hydroxychloroquine, "dedicated antibiotics" and the observation about Vitamin D. The more things you try, the less surprising it should be that there is a correlation along one of them. Are you referring to these lines: "use of corticosteroids and/or hydroxychloroquine and/or antibiotics (i.e., azithromycin or rovamycin), and hospitalization for COVID-19 were used as potential confounders." You only run up against ( https://xkcd.com/882/ https://xkcd.com/882/ ) when you perform multiple statistical tests, not when you merely have a heterogeneous study population. Unless they were also testing these other interventions, that critique does not apply.
- scott_s 6y ago
  > Unless they were also testing these other interventions, that critique does not apply. How do we know they weren't? Since this is not a RTC, but rather an analysis of historical data, we don't know how much they divided up this historical data looking for correlations.
  - scythe 6y ago
    The general problem with this line of argument is that it's meant to be a critique of a statistical fishing expedition (sharpshooter fallacy). This study is clearly not a fishing expedition because vitamin D has been a topic of interest in coronavirus disease for months now with multiple studies conducted.
    - scott_s 6y ago
      > This study is clearly not a fishing expedition because vitamin D has been a topic of interest in coronavirus disease for months now with multiple studies conducted. That others have studied something does not preclude these researchers from "fishing" their data looking for a correlation. Since we don't know what process they used, we can't say. When considering the other weaknesses (such as the small number of "comparators"), it furthers my consideration of this study being weak evidence.
ninja3925 6y ago
Honestly, I am not sure why this study is noteworthy. As you pointed you, the evidence is weak. Plus, we have the results of a good randomized controlled experiment. I don't think we need anything more to make up our mind (yes, vitamin D3 works very, very well): https://www.sciencedirect.com/science/article/pii/S0960076020302764 https://www.sciencedirect.com/science/article/pii/S096007602... Note: The study link is for treatment, not prevention.
- scott_s 6y ago
  I think we should be more measured in our conclusions. See https://www.devaboone.com/post/vitamin-d-and-covid https://www.devaboone.com/post/vitamin-d-and-covid
tinus_hn 6y ago
Meanwhile, https://news.ycombinator.com/item?id=25133165 https://news.ycombinator.com/item?id=25133165 Which one is it?
- scott_s 6y ago
  My point was that the submitted article was weak evidence. That is not the same from saying their conclusions are wrong. It very well may be the case that Vitamin D supplementation is effective against COIVD-19. But the submitted article is not strong evidence for that. As I pointed out elsewhere, a measured take: https://www.devaboone.com/post/vitamin-d-and-covid https://www.devaboone.com/post/vitamin-d-and-covid

raverbashing 6y ago

> as far as I can tell - do not explain why these people did not receive their normal Vitamin D supplementation. My understanding: each patient receives a bolus dose every 2 to 3 months. The intervention group had that date within 1 mo before diagnosis (or 1wk after) > Here, the "Intervention group" was defined as all COVID-19 residents who received an oral bolus of 80,000 IU vitamin D3 either in the week following the suspicion or diagnosis of COVID-19, or during the previous month

andy_ppp 6y ago
80000 IU seems a lot, that’s about 100 times the RDA! Not saying it’s bad just interesting...
- anamexis 6y ago
  That's what a "bolus dose" is, a single large dose to raise the levels in the blood to target levels in one go, as opposed to daily maintenance doses.
- kingnothing 6y ago
  For what it's worth, there's been a lot of speculation in recent years that the RDA is far too low. 80,000 iu is still a huge dosage though!
- lultimouomo 6y ago
  About 100 times the RDA makes sense if you take it once every 3 months, i.e. 90 days

rossdavidh 6y ago

Ditto all that, plus the mortality rate in the (very small) comparison group was 44%, which is very high even for the elderly. The mortality rate for the vit D group was not really all that great. On the flip side, given that they comparison group were receiving vit D3 occasionally, just not lately, it is possible that this underestimates the impact of vit D3 on a group that had long-term insufficient vit D3. Nothing here to say that vit D isn't good for you, especially if you have a deficiency (such as from insufficient time in the sun), but not a stunning piece of info either.

scythe 6y ago

>and they - as far as I can tell - do not explain why these people did not receive their normal Vitamin D supplementation Under subheading 2.2: "All residents in the nursing-home receive chronic vitamin D supplementation with regular maintenance boluses (single oral dose of 80,000 IU vitamin D3 every 2–3 months)," The comparator (not recent supplement) group was on a different schedule, and had received a supplement probably two months ago. >Finally, there were four total interventions: corticosteroids, hydroxychloroquine, "dedicated antibiotics" and the observation about Vitamin D. The more things you try, the less surprising it should be that there is a correlation along one of them. Are you referring to these lines: "use of corticosteroids and/or hydroxychloroquine and/or antibiotics (i.e., azithromycin or rovamycin), and hospitalization for COVID-19 were used as potential confounders." You only run up against ( https://xkcd.com/882/ https://xkcd.com/882/ ) when you perform multiple statistical tests, not when you merely have a heterogeneous study population. Unless they were also testing these other interventions, that critique does not apply.

scott_s 6y ago
> Unless they were also testing these other interventions, that critique does not apply. How do we know they weren't? Since this is not a RTC, but rather an analysis of historical data, we don't know how much they divided up this historical data looking for correlations.
- scythe 6y ago
  The general problem with this line of argument is that it's meant to be a critique of a statistical fishing expedition (sharpshooter fallacy). This study is clearly not a fishing expedition because vitamin D has been a topic of interest in coronavirus disease for months now with multiple studies conducted.
  - scott_s 6y ago
    > This study is clearly not a fishing expedition because vitamin D has been a topic of interest in coronavirus disease for months now with multiple studies conducted. That others have studied something does not preclude these researchers from "fishing" their data looking for a correlation. Since we don't know what process they used, we can't say. When considering the other weaknesses (such as the small number of "comparators"), it furthers my consideration of this study being weak evidence.

ninja3925 6y ago

Honestly, I am not sure why this study is noteworthy. As you pointed you, the evidence is weak. Plus, we have the results of a good randomized controlled experiment. I don't think we need anything more to make up our mind (yes, vitamin D3 works very, very well): https://www.sciencedirect.com/science/article/pii/S0960076020302764 https://www.sciencedirect.com/science/article/pii/S096007602... Note: The study link is for treatment, not prevention.

scott_s 6y ago
I think we should be more measured in our conclusions. See https://www.devaboone.com/post/vitamin-d-and-covid https://www.devaboone.com/post/vitamin-d-and-covid

tinus_hn 6y ago

Meanwhile, https://news.ycombinator.com/item?id=25133165 https://news.ycombinator.com/item?id=25133165 Which one is it?

scott_s 6y ago
My point was that the submitted article was weak evidence. That is not the same from saying their conclusions are wrong. It very well may be the case that Vitamin D supplementation is effective against COIVD-19. But the submitted article is not strong evidence for that. As I pointed out elsewhere, a measured take: https://www.devaboone.com/post/vitamin-d-and-covid https://www.devaboone.com/post/vitamin-d-and-covid