NEW YORK - Three authors of a study that found hydroxychloroquine could be harmful to COVID-19 patients retracted the report Thursday after doubts were raised about the patient data it was based on.

The headline-grabbing study, published last month in the medical journal The Lancet, found that both hydroxychloroquine and chloroquine were associated with a higher risk of death and heart abnormalities than other COVID-19 treatments, and suggested the drugs not be used outside of clinical trials.

It was based on records of about 96,000 COVID-19 patients from around the world. But doctors, researchers and academics almost immediately questioned the origins of the data.

Thursday, three of the report’s authors said independent reviewers were denied access to the raw data, which is controlled by a company called Surgisphere. The fourth author of the study, Dr. Sapan Desai, is the founder of Surgisphere.

"Based on this development, we can no longer vouch for the veracity of the primary data sources. Due to this unfortunate development, the authors request that the paper be retracted,” they wrote. "We deeply apologise to you, the editors, and the journal readership for any embarrassment or inconvenience that this may have caused."

The study had significant impact. Following its publication, the World Health Organization said it was suspending testing of the drug. 

Hydroxychloroquine became the center of controversy after President Trump publicly promoted the drug before it had been proven effective or safe. Last month he said he took hydroxychloroquine as part of a two-week drug regimen.