The study was published Friday in the medical journal The Lancet and detailed in a report by The Washington Post. Almost 15,000 patients were treated with one of the following: chloroquine (which is an older version of hydroxychloroquine), hydroxychloroquine, or either of those drugs in combination with an antibiotic.
Patients from these four groups were compared with the remaining control group of 81,144 patients, the researchers said.
People treated with hydroxychloroquine, or the closely related drug chloroquine, were also more likely to develop a type of irregular heart rhythm, or arrhythmia, that can lead to sudden cardiac death, it concluded.
Authors adjusted for demographic factors, as well as cardiovascular disease, diabetes, lung disease, smoking, immunosuppressed conditions and baseline disease severity.More news: Khashoggi sons' pardon is step towards killers' release, says United Nations investigator
Frontline health workers in the United Kingdom will be given hydroxychloroquine, the malaria drug touted by Donald Trump, in a clinical trial to test if the malaria drug prevents coronavirus, the study's organisers said. "There was no evidence of benefit, and a consistent signal of harm - and in particular, harm linked to heart rhythm disturbances".
Again, that can only come from randomized controlled studies.Hydroxychloroquine use spiked dramatically after the drug was embraced by President Trump, who on Monday said that he himself was taking the drug, and commentators on Fox News.
Dr Stephen Griffin, associate professor in the school of medicine, University of Leeds, said the paper was "potentially a landmark study for Covid-19 therapy". Hydroxychloroquine has been widely used in America for the treatment of malaria, lupus and some other diseases upon prescription for more than six decades, however its utility for the treatment of coronavirus is at best unproven.
But there is growing evidence that the medication may not be as helpful as doctors had hoped. It is based on a retrospective analysis of medical records, not a controlled study in which patients are divided randomly into treatment groups - a method considered the gold standard of medicine.More news: Palestinians Stop Sharing Intelligence With CIA Over West Bank Land Grab Plans
Despite Trump's enthusiasm for using hydroxychloroquine for COVID-19 treatment, his own government's Food and Drug Administration warns against it.
Professor Mandeep Mehra, lead author of the study and executive director of the Brigham and Women's Hospital Centre for Advanced Heart Disease in Boston in the United States, said: "This is the first large scale study to find statistically robust evidence that treatment with chloroquine or hydroxychloroquine does not benefit patients with Covid-19".
The difficulty with observational (sometimes called "real-world") studies is that, often, the patients whom doctors choose to treat with a drug are different - in this case, probably sicker - than those who go untreated.
Those given chloroquine had a 37 percent increased risk of death and a 256 percent increased risk of serious heart arrhythmias.More news: Tributes for White House veteran who served 11 presidents
The researchers said that after considering multiple confounding factors when compared with mortality in the control group, hydroxychloroquine, hydroxychloroquine with macrolide, chloroquine, and chloroquine with a macrolide were "independently associated with an increased risk of de-novo ventricular arrhythmia during hospitalization". For your security, we've sent a confirmation email to the address you entered. Click the link to confirm your subscription and begin receiving our newsletters.