3 ms·

I beg to differ. I think you and the paper are committing another falacy: getting hung up on relative instead of absolute hazards. Myocarditis and pericarditis

by amluto 4y ago

I beg to differ. I think you and the paper are committing another falacy: getting hung up on relative instead of absolute hazards. Myocarditis and pericarditis (at least the reportable kind studied in the paper) are rare — all groups had incidence well under 0.01%. That’s 10 per 100k for those who prefer those units. The study enrolled almost 200k COVID patients and over 500k controls. This is a lot of power to bound the absolute risk, but it is indeed underpowered to get good bounds on the hazard ratio. The paper would be substantially improved if it said “the absolute risk of myo/pericarditis in COVID patients is <10 per 100k with confidence 99.9%” or “the increased risk is <9 per 100k with confidence such-and-such” (I made up the numbers, but the analysis is easy.) So yes, a 2x increased risk would be consistent with the data, but an actual substantial risk would not be consistent with the data.

capnrefsmmat 4y ago
Yes, I agree that it's important to put the absolute risk in context. The NEJM paper that started the concern about myocarditis put it this way: > Vaccination was most strongly associated with an elevated risk of myocarditis (risk ratio, 3.24; 95% confidence interval [CI], 1.55 to 12.44; risk difference, 2.7 events per 100,000 persons; 95% CI, 1.0 to 4.6) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9025013/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9025013/ Giving the risk difference in terms of events per 100,000 people is useful. It's also trickier to interpret because the length of the follow-up period is important: if the vaccine changes the rate of events, then a study that observes patients for two years after vaccination will have (roughly) double the number of events of a study that follows patients for one year after vaccination. That's why people like relative risks in this setting.

by amluto 4y ago

capnrefsmmat 4y ago

Yes, I agree that it's important to put the absolute risk in context. The NEJM paper that started the concern about myocarditis put it this way: > Vaccination was most strongly associated with an elevated risk of myocarditis (risk ratio, 3.24; 95% confidence interval [CI], 1.55 to 12.44; risk difference, 2.7 events per 100,000 persons; 95% CI, 1.0 to 4.6) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9025013/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9025013/ Giving the risk difference in terms of events per 100,000 people is useful. It's also trickier to interpret because the length of the follow-up period is important: if the vaccine changes the rate of events, then a study that observes patients for two years after vaccination will have (roughly) double the number of events of a study that follows patients for one year after vaccination. That's why people like relative risks in this setting.