A new report says medical errors are the third-leading cause of death in the United States.

Researchers at Johns Hopkins University in Baltimore, Maryland, say medical errors cause more than 250,000 deaths every year.

If the research is correct, it means deaths caused by doctors' errors are greater in number than deaths by respiratory disease.

That number also is higher than the 150,000 deaths yearly reported by the Centers for Disease Control and Prevention.

The CDC keeps the official statistics about causes of death in the U.S. The Johns Hopkins researchers say the CDC's way of collecting data "fails to classify medical errors separately on the death certificate."

Dr. Martin Makary is a professor of surgery at the Johns Hopkins University School of Medicine. He is also an authority on health reform. He says there is no standardized method for collecting national statistics about such medical care problems.

The CDC's methods for following medical-error deaths were adopted in 1949, according to the researchers. They say the record-keeping needs to be changed to account for medical mistakes.

Dr. Makary said, "At that time, it was under-recognized that diagnostic errors, medical mistakes, and the absence of safety nets could result in someone's death."

He added, "medical errors were unintentionally excluded from national health statistics" for that reason.

The researchers studied death rate data from 2000 to 2008. They then took information about hospitalization rates from 2013. Using that data, they determined that medical errors caused 251,000 deaths each year out of more than 35 million hospitalizations.

This, researchers say, represents 9.5 percent of all deaths in the U.S. each year.

In 2013, the CDC said heart disease was the leading cause of death in the U.S., followed by cancer and respiratory disease.

"Top-ranked causes of death as reported by the CDC inform our country's research funding and public health priorities," Dr. Makary said.

"Right now, cancer and heart disease get a ton of attention, but since medical errors don't appear on the list, the problem doesn't get the funding and attention it deserves," he said.

The researchers warn that medical errors are not the same thing as the work of bad doctors. They say medical mistakes are the result of problems in medical systems and the coordination of care and insurance coverage.

The study says its findings should help raise awareness about the problem and support research to prevent medical errors.

I'm Mario Ritter.

This story appeared on VOANews. Mario Ritter adapted it for Learning English. Kathleen Struck was the editor.