An influential medical journal article that found hydroxychloroquine increased the risk of death in Covid-19 patients was retracted on Thursday, adding to the controversy around a drug championed by U.S. President Donald Trump.

A pharmacy worker shows pills of hydroxychloroquine used to treat the coronavirus disease (COVID-19) in Belgium.courtesy: Reuters

Hydroxychloroquine- a risk factor?

Three of the authors of the article retracted it, citing concerns about the quality and veracity of data in the study.

The anti-malarial drug has been controversial in part due to support from Trump, as well as implications of the study published in British medical journal the Lancet last month, which led several Covid-19 studies to be halted.

The three authors said Surgisphere, the company that provided the data, would not transfer the dataset for an independent review and that they "can no longer vouch for the veracity of the primary data sources."

The fourth author of the study, Dr. Sapan Desai, the chief executive of Surgisphere, declined to comment on the retraction.

What New England Journal says

"When you have reputable journals that put this kind of work out and are retracted 10 days later, it just increases mistrust," said Dr. Walid Gellad, a professor at University of Pittsburgh's medical school.

"It just adds fuel to the fire of this controversy around hydroxychloroquine. It's the last thing we needed with this particular drug."

Another study published in the New England Journal of Medicine that relied on Surgisphere data and shared the same lead author, Harvard Medical School Professor Mandeep Mehra, was also retracted for the same reason.

The observational study published in The Lancet on May 22 said it looked at 96,000 hospitalized Covid-19 patients, some treated with the decades-old malaria drug. It claimed that those treated with hydroxychloroquine or the related chloroquine had a higher risk of death and heart rhythm problems than patients who were not given the medicines.