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.
The patients were treated with hydroxychloroquine, hydroxychloroquine and a macrolide antibioitic, chloroquine, or chloroquine and a macrolide antibiotic. Around 15,000 from them were given hydroxychloroquine - or related form chloroquine - either alone or with an antibiotic.
Therapies that relied on a version of hydroxychloroquine combined with an antibiotic were even more unsafe for COVID-19 patients, the study shows.
"If there was ever hope for this drug, this is the death of it", Eric Topol, a cardiologist and director of the Scripps Research Translational Institute, told the Washington Post.
- A 34% increase in risk of death for those given hydroxychloroquine, and a 137% increase in risk of serious heart arrhythmias. However, a recent study showed that the drug actually increases the risk of patients with the disease drying from it.
White House doctor Dr. Sean Conley published a note on Monday stating that after discussing the pros and cons of hydroxychloroquine, he and Trump came to the conclusion that the potential benefit of the drug over the relative risks of using it.
The report in the Lancet medical journal is not a rigorous test of hydroxychloroquine or chloroquine but an observational one.
A major study of the way hydroxychloroquine and its older version, chloroquine, have been used on six continents - without clinical trials - reveals a sobering picture.
In Switzerland, 17 hospitals are now participating in a World Health Organization (WHO) solidarity study to test the effectiveness of hydroxychloroquine.
The Lancet study looked at data from 671 hospitals, where 14,888 patients were given either hydroxychloroquine or chloroquine, with or without the antibiotic macrolide, and 81,144 patients were not on any of the treatment regimens.
While the study found an increased risk of in-hospital mortality, the relationship between death and ventricular tachycardia, or the lower chambers of the heart beating quickly, wasn't studied, the doctors said. The drug and its more toxic predecessor, chloroquine, are also linked to a unsafe heart condition.
In addition to malaria, the two drugs are used to treat autoimmune diseases like lupus and rheumatoid arthritis, and have been shown to have antiviral properties. "Randomised clinical trials are essential to confirm any harms or benefits associated with these agents". Both drugs have a good safety profile as treatments for those specific conditions, and the findings do not imply patients should stop taking these drugs if they are prescribed for approved conditions. The Food and Drug Administration last month issued a warning against their use.
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".