They then played a clip of the president's "reckless" promotion of the drug, during which he calls hydroxychloroquine "a gift from heaven" but admits he is not a doctor.
Treatment with the medications among patients with Covid-19, either alone or in combination with antibiotics, was linked to an increased risk of serious heart rhythm complications and death.
Arrhythmia's greatest risk was in the group who received hydroxychloroquine and a macrolide antibiotic such as azithromycin (8% versus 0.3% of controls), and this regimen was associated with a more than five-fold risk of developing an arrhythmia while hospitalized, though cause and effect can not be inferred, the group noted. It is known that the drug can cause heart irregularities, but many have claimed it is safe because of its long use treating malaria.
The drug "can be harmful and nobody should take it outside of a clinical trial", said Cleveland Clinic cardiologist Steven Nissen. The study involved more than 96 thousand patients from 671 hospitals on six continents.
Further, the researchers concluded that they were unable to "confirm a benefit of hydroxychloroquine or chloroquine when used alone or with a macrolide, on in-hospital outcomes for COVID-19".
The drug hydroxychloroquine offers no benefit to patients hospitalised with Covid-19, according to a new study in The Lancet.
But the problem is that, while researchers can control for risk factors that they know about, they can't rule out that patients getting chloroquine and hydroxychloroquine are dying for reasons they don't understand that have nothing to do with the drugs.
"Randomized clinical trials will be required before any conclusion can be reached regarding benefit or harm of these agents in COVID-19 patients", the paper said.
Those who were treated with hydroxychloroquine with a macrolide had a mortality rate of 23.8 percent.
"Several countries have advocated use of chloroquine and hydroxychloroquine, either alone or in combination, as potential treatments for Covid-19", said Frank Ruschitzka, director of the Heart Centre at University Hospital Zurich and co-author of the study.
About 9% of patients taking none of the drugs died in the hospital, versus 16% on chloroquine, 18% on hydroxychloroquine, 22% on chloroquine plus an antibiotic, and 24% on hydroxychloroquine plus an antibiotic.
- A 45% increase in risk of death for those given hydroxychloroquine and an antibiotic, and a 411% increase in risk of serious heart arrhythmias.
"I started taking it, because I think it's good", Trump said.
A trial is under way to see whether the anti-malarial drug could prevent Covid-19.
Experts who spoke to The Washington Post agree that hydroxychloroquine is a bad idea for COVID-19 patients in light of the study.
Another study involving the use of hydroxychloroquine at veterans hospitals found no benefit among COVID-19 patients.
He offered similar pushback Thursday to a new study from Columbia University's Mailman School of Public Health.
Hydroxychloroquine is approved to treat malaria - replacing chloroquine in many parts of the world after the malaria parasite became resistant to chloroquine - as well as some autoimmune disorders like rheumatoid arthritis and lupus, because of its ability to tamp down inflammation.