They're in training to save lives, but medical interns sometimes threaten them: Lack of sleep from very long hospital shifts can make young doctors behind the wheel as dangerous as drunks, researchers found.
Doctors in training were more than twice as likely to get in a car crash while driving home after working 24 hours or longer, compared with when they worked shorter shifts, according to a study by Harvard Medical School researchers.
The study also found that after extended shifts young doctors were about six times more likely to report a near-miss accident and that they sometimes fell asleep driving.
"A lot of the lay public doesn't realize that twice a week most young doctors in this country are forced by hospitals to work these marathon shifts of 30 hours in a row," said senior researcher Dr. Charles A. Czeisler, professor of sleep medicine at Harvard Medical School and head of sleep medicine at Brigham and Women's Hospital in Boston.
"If they're going to require these trainees to work such long hours, they should at least provide them with transportation home."
The study, reported in today's New England Journal of Medicine, was done by some of the same Harvard Medical School researchers who just last fall reported that sleep-deprived doctors made one-third more medical errors during their many long shifts, compared with shorter ones.
The new study found that more than two-thirds of the drowsy doctors drove home from work.
The data, including police accident reports, showed that each extended work shift per month increased chances of a car crash by 16 percent while commuting home and raised the risk of any crash by 9 percent.
The researchers found the doctors worked on-call shifts averaging 32 hours in which they were lucky to grab a few hours' sleep, and about half worked from 81 to 140 hours per week.
An accompanying editorial by traffic safety consultant C. Dennis Wylie of Santa Barbara, Calif., noted the increased accident risk for interns after an extended work shift roughly corresponds to the impairment of a driver with a blood alcohol level of 0.06 to 0.09 percent. The legal limit is 0.08 for drivers in most states.
In July 2003, just after this study concluded, the Accreditation Council for Graduate Medical Education set standards limiting interns' duty hours.
They now are limited to 80 hours per week and no more than three on-call shifts a week, both averaged over four weeks. Interns can work up to 24 straight hours, plus up to six additional hours for educational activities, and must get one day off per week on average.
"Residents are doing more work in less time with less help," said Dr. David Leach, the council's executive director. "We are absolutely convinced we moved in the right direction, and the study validates that, but we still don't think we've got it absolutely right."
Leach said hospitals have been shifting more patient care to newly hired physician assistants and nurse practitioners.
Czeisler said there's been some improvement, but the biggest danger — marathon shifts — hasn't been addressed.
"This is a group of individuals that are dedicating their lives to public health, and unfortunately, as a result of the schedules they're forced to keep, they become a public health threat when they hit the road," said Darrel Drobnich, spokesman for the National Sleep Foundation. "The policy of long schedules needs to be reconsidered."
He said the dangers of drowsy driving led New Jersey — the first state to introduce roadside bumpy strips to jar dozing drivers — to make driving while fatigued a crime in fatal crashes. New York, Massachusetts, Maryland and Michigan have similar laws pending.
Drobnich said federal data indicate fatigue-related crashes cause 71,000 injuries and 1,550 deaths each year. Surveys by his group consistently find half of Americans have driven drowsy and one in five have fallen asleep at the wheel at least once in the prior year.