Discover and read the best of Twitter Threads about #randomized
Most recents (4)
1/
Vaccine safety: We compared excess adverse events after #COVID19 vaccination (Pfizer-BioNTech) and after documented #SARSCoV2 infection.
nejm.org/doi/full/10.10…
Take-home message: Low excess risk of adverse events after vaccination, higher after infection.
Some thoughts👇
Vaccine safety: We compared excess adverse events after #COVID19 vaccination (Pfizer-BioNTech) and after documented #SARSCoV2 infection.
nejm.org/doi/full/10.10…
Take-home message: Low excess risk of adverse events after vaccination, higher after infection.
Some thoughts👇
2/
Preferring #SARSCoV2 infection over vaccination has become even harder. (Remember: infection also increases the risk of severe disease/death)
This is a good illustration of how #randomized trials and #observational studies complement each other for better #causalinference...
Preferring #SARSCoV2 infection over vaccination has become even harder. (Remember: infection also increases the risk of severe disease/death)
This is a good illustration of how #randomized trials and #observational studies complement each other for better #causalinference...
3/
The original #randomized trial estimated vaccine effectiveness to prevent symptomatic infection, but was too small to quantify vaccine safety.
That's what #observational studies do.
Now a different sort of question: Why could we do this study in the first place?
2 reasons.
The original #randomized trial estimated vaccine effectiveness to prevent symptomatic infection, but was too small to quantify vaccine safety.
That's what #observational studies do.
Now a different sort of question: Why could we do this study in the first place?
2 reasons.
1/
We've just confirmed the effectiveness of the Pfizer-BioNTech vaccine outside of randomized trials.
Details @NEJM: nejm.org/doi/full/10.10…
Yes, great news, but let's talk about methodological issues that arise when using #observational data to estimate vaccine effectiveness.
We've just confirmed the effectiveness of the Pfizer-BioNTech vaccine outside of randomized trials.
Details @NEJM: nejm.org/doi/full/10.10…
Yes, great news, but let's talk about methodological issues that arise when using #observational data to estimate vaccine effectiveness.
2/
A critical concern in observational studies of vaccine effectiveness is #confounding:
Suppose that people who get vaccinated have, on average, a lower risk of infection/disease than those who don't get vaccinated.
Then, even if the vaccine were useless, it'd look beneficial.
A critical concern in observational studies of vaccine effectiveness is #confounding:
Suppose that people who get vaccinated have, on average, a lower risk of infection/disease than those who don't get vaccinated.
Then, even if the vaccine were useless, it'd look beneficial.
3/
To adjust for confounding:
We start by identifying potential confounders.
For example: Age
(vaccination campaigns prioritize older people and older people are more likely to develop severe disease)
Then we choose a valid adjustment method. In our paper, we matched on age.
To adjust for confounding:
We start by identifying potential confounders.
For example: Age
(vaccination campaigns prioritize older people and older people are more likely to develop severe disease)
Then we choose a valid adjustment method. In our paper, we matched on age.
BREAKING: Risk of #COVID19 hospitalization in 77,590 persons with #HIV by antiretroviral type:
TDF/FTC: 10.5
TAF/FTC: 20.3
ABC/3TC: 23.4
Other: 20.0
per 10,000 (Febr-April 2020)
WANTED: Randomized trials of TDF/FTC (Tenofovir/Emtricitabine)
doi.org/10.7326/M20-36…
TDF/FTC: 10.5
TAF/FTC: 20.3
ABC/3TC: 23.4
Other: 20.0
per 10,000 (Febr-April 2020)
WANTED: Randomized trials of TDF/FTC (Tenofovir/Emtricitabine)
doi.org/10.7326/M20-36…
That is, individuals on TDF/FTC had about half the risk of #COVID19 hospitalization than those on TAF/FTC or ABC/3TC.
Rate ratio 0.53 (95% CI 0.29, 0.95)
journals.lww.com/epidem/Citatio…
Any reasonable person should be concerned about confounding, so we did the following 3 things
👇
Rate ratio 0.53 (95% CI 0.29, 0.95)
journals.lww.com/epidem/Citatio…
Any reasonable person should be concerned about confounding, so we did the following 3 things
👇
1) We restricted the analysis to individuals younger than 60 years, who have the lowest prevalence of comorbidities.
Rate ratio of #COVID19 hospitalization: 0.55 (0.29–1.04) for TDF/FTC compared with TAF/FTC.
Confounding by comorbidities appears less likely now.
Rate ratio of #COVID19 hospitalization: 0.55 (0.29–1.04) for TDF/FTC compared with TAF/FTC.
Confounding by comorbidities appears less likely now.
1/
Suppose you want to extend causal inferences from a randomized trial to a target population.
Is that #transportability or #generalizability?
Issa Dahabreh and I propose an answer in this brief commentary in the European Journal of Epidemiology:
ncbi.nlm.nih.gov/pubmed/31218483
Suppose you want to extend causal inferences from a randomized trial to a target population.
Is that #transportability or #generalizability?
Issa Dahabreh and I propose an answer in this brief commentary in the European Journal of Epidemiology:
ncbi.nlm.nih.gov/pubmed/31218483
2/
For those interested in methods for extending inferences from randomized trials to a target population:
Take a look at our tutorial
arxiv.org/pdf/1805.00550…
(soon to appear in Statistics in Medicine)
You will find identification conditions AND three estimation approaches.
For those interested in methods for extending inferences from randomized trials to a target population:
Take a look at our tutorial
arxiv.org/pdf/1805.00550…
(soon to appear in Statistics in Medicine)
You will find identification conditions AND three estimation approaches.
3/
Want more?
This article in @Biometrics_ibs considers estimators to generalize inferences from individuals in randomized trials to all trial-eligible individuals:
ncbi.nlm.nih.gov/pubmed/30488513
And this article in @EpidemiologyLWW clears some confusions:
journals.lww.com/epidem/fulltex…
Want more?
This article in @Biometrics_ibs considers estimators to generalize inferences from individuals in randomized trials to all trial-eligible individuals:
ncbi.nlm.nih.gov/pubmed/30488513
And this article in @EpidemiologyLWW clears some confusions:
journals.lww.com/epidem/fulltex…
