4 ms·

"However, vaccination was associated with a reduced risk of stroke overall across all ages and risk profiles with the exception of individuals without hypertens

by petodo 4y ago

"However, vaccination was associated with a reduced risk of stroke overall across all ages and risk profiles with the exception of individuals without hypertension." https://www.thelancet.com/journals/lanpub/article/PIIS2468-2667(22)00222-5/fulltext https://www.thelancet.com/journals/lanpub/article/PIIS2468-2... ROFL So, if you are normal (un)healthy person and you DON'T HAVE HYPERTENSION then this amazing flu vaccine won't lower your risk of stroke at all, this study applies only to people with hypertension.

icegreentea2 4y ago
Yeah, it's actually kind of nuts how much higher your baseline risk of stroke is with hypertension that even though only ~10% of their study population has hypertension that the effect (vaccination correlated with reduced risk of stroke) just shows up on a the global analysis.
tptacek 4y ago
This would be a better dunk if hypertension wasn't the dominant risk factor in all strokes, but it is, so you haven't actually made a point here.
- petodo 4y ago
  I've made point, the headline reads "Flu vaccine lowers risk of stroke", which is very different from "Flu vaccine lowers risk of stroke for people with hypertensia". The linked article does not mention this hypertensia fact at all, there is not a single mention of hypertensia in it and it is not clearly communicated anywhere in study besides one small fine print, that their findings actually affect only very narow group of people.
  - tptacek 4y ago
    You've managed to add "in the cohort of pts likely to have strokes" to the headline, which is not an interesting wrinkle. That's the population you'd most hope to see the effect in.
- throwaway5752 4y ago
  And if 47% of adults in the US didn't have hypertension.
  - petodo 4y ago
    Only 20% of adult Canadians. "Seven and a half million people in Canada, about 1 in 5 adults, live with hypertension." https://hypertension.ca/about-us/ https://hypertension.ca/about-us/
FiloSottile 4y ago
“Without adjustment for other covariates, influenza vaccination was not protective in patients either with or without hypertension. After adjusting for comorbidities, vaccination was strongly associated with a reduced risk of stroke in patients with hypertension; however, there was a non-intuitive interaction, contrasting with previous studies, such that vaccination in patients without hypertension was associated with a marginally higher risk of stroke compared with no vaccination. We observed that the non-hypertensive vaccinated population was much more likely to be female, and that the young average age of the non-hypertensive never-vaccinated stratum was associated with a small number of outcomes. A possible explanation for this finding is that the increase in stroke risk in vaccinated non-hypertensive individuals might represent vaccine-seeking behaviour due to other non-vascular risk factors for poor health outcomes, such as a history of cancer or autoimmune disease, conditions for which we could not adjust. In this situation, vaccination is acting as a latent variable, identifying these individuals at risk of stroke rather than being causative in increasing the risk of stroke. Another possibility is the misclassification of hypertension status by way of undiagnosed hypertension. We also do not have blood pressure measurement or medication data and therefore cannot classify the severity of hypertension or compliance with hypertension treatment, which might influence our findings. Alternatively, this finding might simply be due to chance.” Note that if you separate a population by enough factors, at least one will show an effect different from the aggregate, by pure probability.

by petodo 4y ago

icegreentea2 4y ago

Yeah, it's actually kind of nuts how much higher your baseline risk of stroke is with hypertension that even though only ~10% of their study population has hypertension that the effect (vaccination correlated with reduced risk of stroke) just shows up on a the global analysis.

tptacek 4y ago

This would be a better dunk if hypertension wasn't the dominant risk factor in all strokes, but it is, so you haven't actually made a point here.

petodo 4y ago
I've made point, the headline reads "Flu vaccine lowers risk of stroke", which is very different from "Flu vaccine lowers risk of stroke for people with hypertensia". The linked article does not mention this hypertensia fact at all, there is not a single mention of hypertensia in it and it is not clearly communicated anywhere in study besides one small fine print, that their findings actually affect only very narow group of people.
- tptacek 4y ago
  You've managed to add "in the cohort of pts likely to have strokes" to the headline, which is not an interesting wrinkle. That's the population you'd most hope to see the effect in.
throwaway5752 4y ago
And if 47% of adults in the US didn't have hypertension.
- petodo 4y ago
  Only 20% of adult Canadians. "Seven and a half million people in Canada, about 1 in 5 adults, live with hypertension." https://hypertension.ca/about-us/ https://hypertension.ca/about-us/

FiloSottile 4y ago

“Without adjustment for other covariates, influenza vaccination was not protective in patients either with or without hypertension. After adjusting for comorbidities, vaccination was strongly associated with a reduced risk of stroke in patients with hypertension; however, there was a non-intuitive interaction, contrasting with previous studies, such that vaccination in patients without hypertension was associated with a marginally higher risk of stroke compared with no vaccination. We observed that the non-hypertensive vaccinated population was much more likely to be female, and that the young average age of the non-hypertensive never-vaccinated stratum was associated with a small number of outcomes. A possible explanation for this finding is that the increase in stroke risk in vaccinated non-hypertensive individuals might represent vaccine-seeking behaviour due to other non-vascular risk factors for poor health outcomes, such as a history of cancer or autoimmune disease, conditions for which we could not adjust. In this situation, vaccination is acting as a latent variable, identifying these individuals at risk of stroke rather than being causative in increasing the risk of stroke. Another possibility is the misclassification of hypertension status by way of undiagnosed hypertension. We also do not have blood pressure measurement or medication data and therefore cannot classify the severity of hypertension or compliance with hypertension treatment, which might influence our findings. Alternatively, this finding might simply be due to chance.” Note that if you separate a population by enough factors, at least one will show an effect different from the aggregate, by pure probability.