A large-scale study has shown that chloroquine and hydroxychloroquine do not help in the treatment of COVID-19 and may even cause harm. In a paper published Friday in The Lancet, researchers analyzed data from tens of thousands of patients taking the drugs. Their results were no better than those of people who did not take the drug — in fact, they were more likely to die or develop arrhythmia.
The analysis covered a registry of about 15,000 patients, spanning multiple continents, all of whom were given oxychloroquine, chloroquine, or one of the drugs paired with a class of antibiotics called large cyclosteric esters. These patients were compared with groups of about 81,000 patients who were not given the drug. The results are not encouraging. People who were treated with both drugs had a higher mortality rate and an increased risk of developing ventricular arrhythmia.
Chloroquine and hydroxychloroquine are linked to worse outcomes, even after controlling for other risk factors such as age, existing health status and other risk factors such as current smokers. The researchers completely excluded patients who received treatment within 48 hours of diagnosis, as well as anyone who took ridsieve, a different experimental treatment.
This is not conclusive evidence that these drugs are dangerous. Researchers, including Harvard Medical School, University Hospital Zurich, the University of Utah and Surgisphere, warn that there may be other variables that are not taken into account. But there is “no evidence” that these drugs are helpful. The researchers stressed the urgent need to control clinical trials, rather than passively observing patients like this to provide more information to the study.
Chlorquin and hydroxychloroquine initially looked like promising treatments for COVID-19. The evidence included preliminary studies involving dozens of patients, but one study was later withdrawn because of modifications. Subsequent studies cast doubt on its results. A paper in the New England Journal of Medicine earlier this month compared about 800 patients who were given hydroxychloroquine with about 560 who did not give the drug and found “no significant association” between the drug’s use and survival.
Nevertheless, chloroquine and hydroxychloroquine have become touchstones in the cultural war. Tesla CEO Elon Musk, Fox News and U.S. President Donald Trump defended them with minimal evidence, announcing earlier this week that he had been taking hydroxychloroquine to prevent COVID-19. (Instead, Trump refuses to wear masks in public, despite preliminary evidence that masks slow the spread of COVID-19.) Some doctors complain that the politicization of these drugs makes research more difficult, and speculation has left people taking these drugs to treat other diseases such as lupus and rheumatoid arthritis.
The Lancet study did not examine whether these drugs were likely to prevent COVID-19, and it specifically examined the health risks of people who are already sick. These drugs are currently approved for the treatment of autoimmune diseases and the prevention of malaria, although they have known side effects, including arrhythmia. Clinical trials are still ongoing to see if they can prevent COVID-19.
Media say the study may not quell the political debate over hydroxychloroquine and chloroquine. News of Mr. Trump’s announcement that he was taking one of the drugs has reignited interest from supporters, including a defensive tweet by Trump’s campaign manager, touting a misleading statistical analysis.