The news from the Institute of Medicine last fall was shocking - as many as 98,000 hospital deaths each year were blamed on mistakes.
But scientists at the Indiana University School of Medicine, writing in the Journal of the American Medical Association, say the research does not directly link mistakes with death -- and other patient risks may have been under-estimated. CBS News Correspondent Steve Kathan reports.
The Indiana scientists said they suspect the death toll from errors is in fact very small and called the parts of the November report from the Institute of Medicine "hot and shrill."
The report, the researchers said, never established that medical errors caused the deaths and failed to eliminate other risks for sick patients before drawing conclusions.
"The available data do not support IOM's claim of large numbers of deaths caused by adverse events, (preventable or otherwise)," wrote Clement J. McDonald and two Indiana colleagues in JAMA.
The chief author of the original study fired back in a rebuttal article, saying the problem may actually be worse because many errors never make it into hospital reports.
Dr. Lucian L. Leape, of the Harvard School of Public Health, co-authored the IOM report and conducted some of the research upon which it is based.
The groundbreaking report said medical errors kill anywhere from 44,000 to 98,000 hospitalized Americans each year and called for major changes in the nation's health care system to protect patients.
The report said the problem isn't recklessness by doctors or nurses as much as it is the result of flaws in the way hospitals, clinics and pharmacies operate. After the report, President Clinton said hospitals should agree to routine reporting of serious and deadly mistakes.
In Wednesday's rebuttal, Leape said the report did not examine injuries outside the hospital. More than half of surgical procedures take place outside of a hospital setting, Leape wrote.
Leape defended the report's research methodology, saying screening criteria eliminated patients who were extremely ill or had complicated conditions. He said the patients were not as ill as the Indiana researchers implied and likely would have lived if not for the mistakes.
"The IOM report has galvanized a national movement to improve patient safety," Leape writes. "It is about time."
Despite their differences, the Indiana researchers said they agreed with the report's call to understand the cause of medical errors and for the development of mechanisms to reduce error rates.