Given Donald Trump’s enthusiastic participation, the debate on hydroxychloroquine and Covid 19 has become very heated. As I wrote
here I agree with Trump. This is unusual (not unique he and I both advocating cutting interests rates long ago before the Fed Open Market Committee cut them to 0-0.25 again). My view (and as far as I can make sense of anything he says his) is that it is wise to prescribe hydroxychloroquine for patients with Covid 19 even though there is not decisive evidence that it helps.
I think this because it inhibits coronovirus reproduction in vitro, and sometimes in vitro results lead to clinically useful therapies (I tend to guess more often they don’t not that I really know (I think it is known but I don’t know)). Currently it is being used in many hospitals. I also don’t know what fraction of Covid 19 patients are taking 400 mg of hydroxychloroquine a day, but it is clearly large. It is officially recommended in China.
What if it turns out in the end that it just doesn’t work ? I will not consider myself to have been wrong. My view is that the weight of, currently very limited, evidence makes it reasonable to infer that the expected benefit (taking expected values over a reasonable posterior probability distribution) is greater than the expected cost. The costs are real and important — hydroxychloroquine slows the heart beat and can be dangerous especially for people who already have irregular heart beats (remaining a non physician, I would recommend an EKG before prescribing). Prolonged use can also damage the retina, so people who take it regularly have to have their eyesight checked.
The debate should be resolved soon as there are ongoing large scale (phase III) clinical trials.
This update really has three parts (after the jump)
1) what about that study in Marseilles (TL DR it’s crap)
2) what about other studies ? (TL DR mixed evidence including proof that it is not a miracle drug)
3) what about the debate (TL DR even if Trump says something, that isn’t proof it is false — no one is perfect not even Trump)
4) Name 2 non physicians who are pontificating about this in spite of having (identical) irrelevant formal qualifations (TL DR Peter Navarro and Robert Waldmann (who is about to scream after typing that)).
1) The study is ruthlessly and convincingly critiqued here. The key issue is that 4 patients who were treated with hydroxychloroquine were not discussed in the paper. One died and 3 were transfered to an intensive care unit. This is not OK. I have read this claim on the web, but now it’s published in The Guardian and no one contests the claim of fact. It is also true that the study was not randomized and has a small sample even including the 4 who must be included).
2) One other study is an actual (tiny) controlled trial in Shanghai. They found no benefit from hydroxychloroquine but the control group did so well that it is impossible for a test based on their principal outcome measure to reject the null that there was no benefit. The test has no power (not low power exactly zero power).
There is another uncontrolloed study of 11 patients in Paris. One died. Two were free from Sars Cov2 at the end of the study. This is close to (or worse than) baseline. This study provides weak evidence against hydroxychloroquine
The Guardian article mentions an unpublished controlled trial in Wuhan with rumoured positive results.
The experience of clinicians (many of whom are using hydroxychloroquine) does not include any enthusiastic reports of dramatic benefits.
3) On Twitter, the issue is clearly viewed as something Donald Trump said. Hydroxychloroquine is just a molecule. It didn’t vote for Trump. leave hydroxychloroquine alooooone
4) My horror at Navarro is not just that he has the same degree which I have, but also that he makes exactly the argument which I often make. We argue that one doesn’t need an MD to be able to understand statistics and to interpret data.
On the other hand, I can tell that the Marseilles study is crap, and he can’t, so there is that.