The anti-malarial drug promoted by President Donald Trump as a COVID-19 treatment has been linked to higher death rates and heart rhythm problems among coronavirus patients, a global study suggests.
The report in the Lancet medical journal is not a rigorous test of hydroxychloroquine or chloroquine but an observational one.
However, it is by far the largest look at their use in real-world settings, studying 96,000 patients at 671 hospitals on six continents.
One leader of the study, Dr Mandeep Mehra, a heart specialist at Brigham and Women’s Hospital in Boston, Massachusetts, said: “Not only is there no benefit, but we saw a very consistent signal of harm.”
Researchers estimate that the death rate attributable to use of the drugs, with or without an antibiotic such as azithromycin, is roughly 13% versus 9% for patients not taking them.
The risk of developing a serious heart rhythm problem is more than five times greater.
Even though it is only observational, the size and scope of the study gives it a lot of impact, said Dr David Aronoff, infectious diseases chief at Vanderbilt University Medical Centre.
“It really does give us some degree of confidence that we are unlikely to see major benefits from these drugs in the treatment of COVID-19 and possibly harm,” said Dr Aronoff, who was not involved in the research.
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President Trump has repeatedly pushed the malaria drugs and has said he is taking hydroxychloroquine to try to prevent infection or minimise symptoms from the coronavirus.
The president – who has previously suggested potential coronavirus cures such as injecting disinfectant – cited “calls” and “good stories” as his evidence of hydroxychloroquine’s success.
The drugs are approved for treating lupus and rheumatoid arthritis and for preventing and treating malaria, but no large rigorous tests have found them safe or effective for preventing or treating COVID-19.
The Food and Drug Administration has warned hydroxychloroquine can cause heart rhythm problems and Anthony Fauci, director of the US National Institute of Allergy and Infectious Diseases, said there was no evidence the drug could prevent coronavirus.
The New York Times has reported there may be more to Mr Trump’s determined promotion of the drug as certain pharmaceutical companies will profit if it is accepted as a COVID-19 treatment.