RT @EricTopol@twitter.com

Just published @TheLancet@twitter.com
The largest study of hydroxychloroquine shows a significant increase in death (~35%) and >2-fold increase of serious heart arrhythmias. ~96,000 patients, ~15,000 on HCQ or CQ from 671 hospitals, 6 continents.

🐦🔗: twitter.com/EricTopol/status/1

This is a retrospective study, and the big question is: why were those people prescribed those drugs in the first place, and people of control group weren’t? This wasn’t a randomized study where you’d take people and randomly put one third of them on a drug, and the other two thirds on another one. No, in this study they took people that were prescribed the drugs and people that weren’t, and compared, without first investigating how different those two groups of people were.

My first guess would be that people who did get those drugs were much more severely ill, and doctors took chances with these drugs to save their lives. And there’s more mortality in that group not because of the drugs, but because those patients were more severe in the first place.

This is exactly why they teach basic statistics in medical schools, and yet you people fall for such papers.

@evgenykuznetsov.org They go into why some people were prescribed those drugs and others weren't. Basically hospitals in the US are allowed to experiment in these cases and some did, as far as I understand it. From their data they seemed to have controlled both groups quite well for a number of factors both known to affect COVID-19 and arrhythmias -- which, surprise, are often the same factors.


@evgenykuznetsov.org As for your guess that the people on the drugs were more severely ill, I doubt that. First off, that's not how antiviral treatment works. You have to start with the drugs as soon as possible (goes for antivirals like remdesivir too) so you have no time to see how someone develops. They excluded all patients who were put on chloroquine more than 48 hrs after diagnosis.

@evgenykuznetsov.org Also: It would be extremely unethical to "take more chances" just because someone looks sicker to you. That's generally something most doctors I know would be very cautious of. If only from the experience that these kind of judgements are often wrong. It's very hard to judge how sick someone really is, especially with a systemic illness like this.

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