Antimalarial drugs promoted by President Donald Trump as a treatment for coronavirus did not work and were linked to an increased risk of death and arrhythmias in a new study published on Friday that covered almost 100,000 patients in various parts of the world.

The document published in the Lancet journal is not a rigorous study on hydroxychloroquine or chloroquine, but it is the most comprehensive look to date for its use in real settings: 671 hospitals around the world.

“Not only is there no benefit, but we saw a constant indication of harm,” said one of the study’s leaders, Dr. Mandeep Mehra, a heart specialist at Brigham and Women’s Hospital in Boston.

The researchers estimate that the death rate attributable to the use of these drugs, whether or not accompanied by an antibiotic such as azithromycin, is approximately 13%, for 9% of patients who do not take them. The risk of developing a serious arrhythmia problem is more than five times higher.

Even though it is only observational, the study has great repercussions for its magnitude and scope, said Dr. David Aronoff, director of infectious diseases at Vanderbilt University Medical Center.

The study “really gives us some degree of confidence that we are unlikely to see great benefits from these drugs in the treatment of COVID-19 and indeed possibly harm,” said Aronoff, who was not involved in the research.

Trump has promoted both antimalarial drugs and claims he takes hydroxychloroquine to prevent infection or minimize COVID-19 symptoms.

The drugs are approved to treat lupus and rheumatoid arthritis as well as to prevent and treat malaria, but no large and rigorous study has been found to be safe or effective in preventing or treating COVID-19.

The use by people with coronaviruses that warrant hospitalization is not the same because they are sick enough than healthy people in other situations, therefore, it cannot be assumed that they are safe for their previous use, Mehra said.

These drugs also have possible serious side effects. The United States Food and Drug Administration has warned against taking hydroxychloroquine with antibiotics and has said that the antimalarial should only be used in formal studies on coronavirus.

In the absence of stricter study results, “one needs to examine the available evidence in the real world” to measure safety or efficacy, Mehra said. The results on these patients, obtained from a global research database created a long time ago, correspond “to the reality of a database,” he added.

Their study covered almost 15,000 people with COVID-19 who were given one of the antimalarials with or without one of the suggested antibiotics, and more than 81,000 patients who were not given any of these drugs.

In total, 1,868 took chloroquine alone; 3,873 chloroquine and an antibiotic; 3,016 hydroxychloroquine only, and 6,221 hydroxychloroquine and an antibiotic.

Approximately 9% of patients who did not take any of the medications died in hospital compared to 16% who were given chloroquine, 18% hydroxychloroquine, 22% chloroquine and an antibiotic, and 24% hydroxychloroquine and an antibiotic.

After considering age, smoking, various health conditions, and other factors that affect survival, the researchers say the use of medications could have contributed between 34% and 45% of the excess risk of death they observed.

Approximately 8% of those who took hydroxychloroquine and an antibiotic developed arrhythmia, compared to 0.3% of patients who took none in the study. More of these problems were also seen with the other medications.

The results hint that these drugs “are not helpful and can be harmful” for people hospitalized with COVID-19, said Professor Christian Funck-Brentano of the Sorbonne University in Paris, in a comment presented in the publication. He did not participate in the study.

The experiments now underway to test these drugs more strictly “need to be completed and should not be stopped prematurely,” said Aronoff.

Although the study published in Lancet was extensive, as it was observational, “you cannot control every possible factor that may have contributed to the observed results,” he said.

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Marilynn Marchione is on Twitter at http://twitter.com/MMarchioneAP

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