The large observational analysis looked at nearly 100,000 COVID-19 patients in 671 hospitals between December 20, 2019 and April 14, 2020 but it was not a clinical trial.
Published in The Lancet, the study included 14,888 people who were treated with hydroxychloroquine or chloroquine.
Hydroxychloroquine has been much hyped as a COVID-19 treatment since French doctor Didier Raoult said he was treating patients in Marseille with the drug and an antibiotic. He published a small study without a control group in March.
The drug is being studied in several clinical trials globally including the World Health Organization’s Solidarity trial.
The new global analysis found no benefit in COVID-19 patients but instead a greater risk of heart problems and death.
Around 9% of patients died in the control group compared with roughly 16% of those taking chloroquine, the study said.
The study also showed a greater risk in patients treated with chloroquine or hydroxychloroquine and an antibiotic.
Around 22% of patients treated with chloroquine and an antibiotic died and 23% of those taking hydroxychloroquine and an antibiotic died, according to the study.
Chloroquine is a drug that has been around since the 1940s to treat malaria and hydroxychloroquine is a less toxic derivative of it but it has some serious side effects including headache, dizziness, nausea, and in some cases heart problems.
Read more: What do we know about Hydroxychloroquine?
US President Donald Trump had touted the drug’s use against COVID-19 in mid-March, stating that it showed “very very encouraging early results”. He said this month controversially that he had been taking it as a precaution against coronavirus and said he felt fine.
France’s health minister Olivier Véran tweeted that an advisory counsel would look into the use of the drug following the release of The Lancet study in order to review government guidance around its use.
Hype over the drug’s use spurred global supply shortages that put patients with autoimmune disorders who rely on the drug for treatment at risk.
Read more: Coronavirus: Lifesaving lupus drug ‘in short supply’ amid hype as a COVID-19 antidote
“Our study has several limitations. The association of decreased survival with hydroxychloroquine or chloroquine treatment regimens should be interpreted cautiously,” due to the observational nature of the study, researchers said of the new global study published Friday.
But Dr David Aronoff, an infectious diseases chief at Vanderbilt University Medical Centre, told AP that the scope of the study gives it impact.
“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,” Aronoff, who was not involved in the study, told the AP.