'Serious' questions raised about hydroxychloroquine study, medical journal says

The Lancet medical journal said on Tuesday "serious scientific questions" had been brought to its attention about the validity of the data behind a widely cited and already corrected study on the dangers of the use of the anti-malarial drug hydroxychloroquine in hospitalized patients with COVID-19.

The Lancet's "expression of concern" follows theMay 22 publication of a studythat found hydroxychloroquine, which U.S. President Donald Trump took and has urged others to use, was tied to an increased risk of death in hospitalized COVID-19 patients.

Several clinical trials, including in Canada, were put on hold after the study was published.

The article, called "Hydroxychloroquine or chloroquine with or without a macrolide for treatment of COVID-19: a multinational registry analysis," was an observational study meaning it compiled real-world data, rather than conducting a traditional clinical trial and used data provided by health-care data analytics firm Surgisphere.

The Lancet last week issued a correction to the study regarding the location of some patients following criticism of its methodology, but said the conclusions were not changed.

Also last week, nearly 150 doctors signed an open letter to the journal calling the article's conclusions into question and asking to make public the peer review comments that led to it being published.

Although it wasn't a rigorousexperiment that could give definitive answers, the Lancet study had wide influence because of its size.

The World Health Organization said it would temporarily stop a study of hydroxychloroquine and France stopped allowing its use in hospitals.

Health Canada has not paused trials it has authorized on hydroxychloroquine in COVID-19 patients. Instead, the regulator is asking for new safety assessments from the independent committee of experts who regularly reviewsafety data collected during clinical trials.

"Based on this information, Health Canada will determine whether additional measures should be taken with respect to these clinical trials," a spokesperson said in an email last week. "While this review is still ongoing, Health Canada is not aware of any reports of cardiac arrhythmias in the clinical trials that have been authorized in Canada."

TheNew England Journal of Medicine also issued an "expression of concern" Tuesday on a study it published May 1 that suggestedwidely used blood pressure medicines were not raising the risk of death for people with COVID-19.

Dr. Mandeep Mehra of Brigham and Women's Hospital in Boston ledboth studies, whichrelied on Surgisphere'sdatabase of health records from hundreds of hospitals around the world. Editors at the New England Journal of Medicine wrote that they've asked the authors to provide evidence the information is reliable.

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