"What we have here is the smoking gun," said Lucian L. Leape, a health care quality expert at the Harvard School of Public Health. Leape was a co-author of an influential 1999 Institute of Medicine report that estimated between 44,000 and 98,000 hospitalized Americans die each year from medical errors. "People have said over and over that a lack of sleep does not inhibit doctor performance. This is the first rigorous study that shows that it does. This is a landmark study."
The Accreditation Council for Graduate Medical Education, which oversees 7,300 medical residency programs nationwide, will examine the new data to see if the current guidelines should be adjusted, said David C. Leach, the group's executive director.
"This may call for a further refinement of our standards," Leach said. He noted that the group last year limited hours to no more than 80 per week, with no more than 24 hours in a row, though another six hours can be added for paperwork and classes. Many factors need to be taken into consideration before further changes are mandated, he said.
"I cannot emphasize enough that this situation is more complicated than just one variable. I don't know if it's as simple as reducing hours," Leach said. "We could end up doing more harm than good."
The issue of excessively long hours for young doctors came into the spotlight in 1984, when the death of Libby Zion, 18, was blamed on overworked, unsupervised medical residents in a New York hospital. It has continued to be the subject of intense debate, with some arguing that long hours enable doctors to bond with their patients and provide a crucial continuity of care.
"The tradition has been for doctors to work these extended shifts because it was felt that it was beneficial for their education and for patient care," said Christopher P. Landrigan of Brigham and Women's Hospital, who led the second study. "The presumption has been a doctor who knows the patient better will provide better care. What our study found is that once a certain biological threshold has been crossed, that is no longer true."
The findings indicate that in addition to limiting the total number of hours interns should work, more attention needs to be paid to the length of shifts, the researchers said.
"Prior to this, there was never been a study demonstrating there's any risk to the patient," Czeisler said. "Now the burden of proof has been shifted to those defending the tradition of working these long hours."