Last week, Tyler Cowen published a link to a recent study of the use of ivermectin in patients who had had Covid-19 for a median of 6 days. As is his wont, he doesn’t say much about the study (other than a quizzical comment about Scott Alexander) but simply links to it. Many of the commenters on that site, though, seem very sure that ivermectin is not beneficial for those in the early stages of Covid-19. Of course, as with most comments, it’s difficult to tell what bases they have for their views.
Charley Hooper and I have written extensively about ivermectin (for example, here, here, here, and here) and have pointed out how poor some of the main studies and, in particular, the TOGETHER study, are.
This latest study appears to be no exception. Here’s an extensive critique.
The thing Charley and I noticed right way in that critique is what the evaluators label as Critical problem #13: Very late treatment.
If you go to this page and scroll down a little to the graph of efficacy versus treatment delay in days, you see that most of the treatments studied need to be administered in the first 2 to 4 days. When was the treatment in this latest study administered? The median time was 6 days.
Also, note the Critical problem #33: Extreme conflict of interest. “The ACTIV executive committee was chaired by employees of J&J and NIH, and is now chaired by employees of Pfizer and NIH. Other members of the committee are from NIAID (Dr. Fauci), FDA, and Pfizer.”
If you want to find that ivermectin is ineffective, you can surely do so.
READER COMMENTS
Anonymous
Mar 1 2023 at 12:14pm
All studies are flawed. If your game is to pick studies having the outcome you don’t like and identify flaws in each, you will succeed.
Charley Hooper
Mar 1 2023 at 6:11pm
Of course, all studies have some flaws. That’s a fact of life.
However, some studies have such serious flaws that one must wonder what was going on behind the scenes. Was it bad luck? Incompetence? Too many cooks in the kitchen? A desire to conduct a study that was so poorly designed that it would inevitably produce the favored result?
Those who know a lot about clinical trials also know ways to game them.
Mark Brophy
Mar 3 2023 at 2:33pm
This is the same flaw repeated many times. Loads of studies of ivermectin administer it when it is too late to be effective. You ought to k yourself why ivermectin is so effective in Africa and so ineffective in studies in rich countries.
Roger McKinney
Mar 1 2023 at 2:26pm
Pneumonia and cancer treatments are similar. The earlier you catch them, the better the treatment works. That was true of hydroxychloroquine
TGGP
Mar 2 2023 at 9:33am
I think that you’ve gone beyond your domain of competence. You noted that a number of libertarians supported the freedom to use ivermectin as a treatment for COVID, so now arguing in favor of the effectiveness of ivermectin feels like supporting that group of libertarians even though you had no expertise in evaluating antiviral therapy prior to COVID-19. The GMU betting norm or futarchy should be used on such a controversy rather than incessant arguing and cherry-picking of studies.
David Henderson
Mar 2 2023 at 9:57am
You write:
I think you’re wrong. You would have a stronger case if I had written these things without a co-author who, as part of his day job, delves into such studies. Even then, though, there’s nothing magic about working one’s way through various studies and evaluating them.
You write:
I’m not sure that I did note that. Can you give me a cite?
You don’t even know me, so how would you know that that’s why I’m arguing in favor of the effectiveness of ivermectin? In fact, that’s not my motive at all. I see libertarians arguing for a number of things that I don’t support.
It’s true that that I had no expertise in evaluating antiviral therapy prior to COVID-19. It’s also true that I had no expertise in evaluating lockdowns prior to COVID-19. But when important issues present themselves, I develop expertise or work with someone who has such expertise.
What I noticed early on is that many people rejected ivermectin even though dozens and dozens of studies showed its effectiveness when taken early. Charley and I didn’t cherry pick. We considered the whole array of studies.
I’m curious about something. I think you would agree with me that Tyler Cowen rejects ivermectin as an effective way to deal with COVID-19. Are you willing to go on his blog and tell him that he has no expertise in evaluating such therapy?
TGGP
Mar 3 2023 at 12:11am
Here is my cite:
https://www.econlib.org/bryan-caplans-defective-demarcation-of-libertarians-on-covid/
I can’t remember the last time Cowen blogged about ivermectin. But he also blogs more frequently than just about anybody. If you want me to ding him for a lack of expertise, I’ll say this: while he reads a lot over a wide variety of subject matter, I’ve never been impressed with the depth of his knowledge relative to other GMU economists. His co-blogger Alex has been acknowledged as being the better “truth tracker”, and since Cowen has belittled Robin Hanson’s goal of overcoming bias as not being obviously more important than overcoming an insufficient appreciation of some regional cuisine, I don’t think Alex needs to be worried about Tyler overtaking him.
Both of you & Charlie say you’re not cherry-picking, the anti-ivermectin people are cherry-picking. This is just the sort of thing I’m complaining about as inferior to things like prediction markets. The pro & anti sides can spout a never ending stream of words words words at each other without ever resolving anything.
David Henderson
Mar 3 2023 at 12:34pm
That cite doesn’t back up your statement. What I said in that post is:
I didn’t say that other libertarians supported this, although I suspect they did. The only person I referred to as supporting this freedom was I.
Charley Hooper
Mar 2 2023 at 8:56pm
We aren’t the ones cherry picking.
Based on 95 studies covering almost 135,000 patients, ivermectin has shown impressive safety and efficacy. That’s not cherry picking.
Then, when studies like this one come along, we ask ourselves whether this study is solid enough to suggest that ivermectin really doesn’t work. But, alas, the studies that get the most press and “prove” that ivermectin doesn’t work have universally been so awful as to leave us scratching our heads.
The people cherry picking are generally the ones who are trying to show that ivermectin doesn’t work. (And the cherries they pick have worms.)
I can imagine the outcry if the situation were reversed and most of the studies suggested that ivermectin doesn’t work and then a few flawed studies showed that it did.
steve
Mar 2 2023 at 12:04pm
Your expert has never prescribed or treated pts with the drug. Those of us who did use it did not see the positive effects. What you are promoting are claims with such high success rates that it would be a miracle drug. Not what we saw, or much of anyone else in the US or other first world facilities.
Steve
David Henderson
Mar 2 2023 at 12:49pm
How many times did you use it? Also, how many days after the patient had COVID-19 did you use it?
Charley Hooper
Mar 2 2023 at 8:58pm
I understand the point you are trying to make. However, we can only analyze the data we have and we don’t have any of your data.
Jim Glass
Mar 2 2023 at 1:00pm
Much more relevant to actual future health care: Masking. The ‘gold standard’ data on the effectiveness of masking is coming in — e.g., Cochrane January 2023 review of randomized controlled studies — and the verdict is…
https://www.youtube.com/watch?v=XZ1n_woWVkQ
Compelled masking is an offense against “liberty” too, isn’t it? And this really matters going forward, for all the next times.
Ivermectin, OTOH, face it, is moot. Reasonable people can believe that if it provided significant benefits they would have shown up somewhere in the scores of studies that have concluded otherwise — but even granting all your arguments (Merck would disapprove its own drug, etc.), it doesn’t matter. There are better treatments for Covid now than it. Ivermectin is never coming back as a treatment for Covid. It’s history.
Let’s move our finite efforts into areas that matter for the future.
Charley Hooper
Mar 2 2023 at 9:01pm
What treatments work better than ivermectin? I’m not aware of any.
steve
Mar 2 2023 at 4:42pm
My direct team used it only in the ICU so it was generally 3-8 days after onset though if the pt started out on the floor and was not a direct admission to ICU they would most of the time have received some before coming to ICU. (I think this onset thing is actually kind of hard to define especially since most of the early signs are so vague.) Our PCPs would order it on the day they first saw a pt. For our inpatients IIRC we stopped using it after about 600 pts, about the same number when we decided to stop HCQ. For our PCPs I would have to ask them for numbers. We let them decide what they wanted to order and by the middle of last year ID told them they should stop ordering it but they had stopped anyway unless they had a request as the PCPs didnt think they were seeing any effect.
You do realize that you cannot start a drug until the pt shows up I hope. When a pt decides to show up after showing symptoms is highly variable (which is true for almost everything). Enough so that I suspect there is likely some heterogeneity in the group that shows up extra early. We have also had a number of pts show up in the ICU who were on Ivermectin at home. Anecdotal but then some advocates are claiming 100% prevention (Kory?).
What does Merck say about it?
“Even then, though, there’s nothing magic about working one’s way through various studies and evaluating them.”
I will largely agree with you here with the caveat that you wont know which people or groups are more likely to do credible or poor research and it wont stand out to you like it did most physicians that we weren’t seeing the claimed results in places that practice first world medicine while seeing very strong assertions in areas that do not.
Steve
Steve
David Henderson
Mar 2 2023 at 5:50pm
Thanks, steve.
Charley Hooper
Mar 2 2023 at 9:04pm
We’re not saying it’s easy and we’re not saying it’s 100% accurate, but every trial of a product like this includes the question: “When did your symptoms begin?”
Michael Sandifer
Mar 4 2023 at 8:08am
I think that patients should be allowed to take Ivermectin for any reason they like, unless any increased demand justifies government rationing, with provision to those who need it most for the most proven benefit. We shouldn’t forget that this is an extremely important drug with proven benefits for those with non-viral parasites, for example, so speculative use of the drug should always occur within that context.
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