First-year doctors-in-training reported that working five extra-long shifts of 24 hours or more at a time without rest per month led to a 300 percent increase in their chances of making a fatigue-related preventable adverse event that contributed to the death of a patient, according to a new study. Preventable adverse events are defined as medical errors that cause harm to a patient.

The study, which was funded by HHS’ Agency for Healthcare Research and Quality and the Centers for Disease Control and Prevention’s National Institute for Occupational Safety and Health, is published on December 12 in the online journal PLoS Medicine.

The study carries significant implications for the way first-year residents, or interns, are trained in the United States. Unlike previous studies on interns and fatigue that have suggested a link between resident work hours and medical errors that harmed patients, this study has a sample size large enough to demonstrate that the rate of preventable adverse events grows when interns work shifts of 24 hours or more.

According to the study, interns were three times more likely to report at least one fatigue-related preventable adverse event during months in which they worked between one and four extended-duration shifts. In months in which they worked more than five extended-duration shifts, the doctors were seven times more likely to report at least one fatigue-related preventable adverse event and were also more likely to fall asleep during lectures, rounds, and clinical activities, including surgery.

"Given the number of extended-duration work shifts that interns routinely put in, these findings are very troubling," said AHRQ Director Carolyn M. Clancy, M.D. "These findings underscore the urgency of focusing on both high-quality learning and high-quality patient care."

Laura K. Barger, Ph.D., a research associate in medicine at Brigham and Women’s Hospital and Harvard Medical School in Boston, and her colleagues analyzed the results of a national, Web-based survey in which 2,737 interns completed 17,003 monthly reports. Researchers assessed the association between the number of extended-duration shifts worked in the month and the reporting of significant medical errors, preventable adverse events, and attentional failures.

The findings are significant because interns routinely work extended shifts in teaching hospitals. Guidelines for graduate medical education in the United States still allow up to nine “marathon” shifts (30 hours at a stretch) per month, even though the total number of hours worked is capped. This study shows that the long shifts worked by interns are bad for patient safety, as they are more likely to cause harm that would not otherwise happen.

"It is clear that sleep deprivation takes its toll over time on physicians," Dr. Barger said. "While tradition holds that forcing young doctors to work extended-duration shifts teaches them to become better doctors, the evidence shows that this method of education is dangerous to patients."

The study builds on previous research and the growing awareness that sleep-deprived interns working 24-hour shifts make many more serious medical errors while working in intensive care units and crash their cars more often than those whose work is limited to 16 consecutive hours; that most interns are working hours that exceeded the limits of a 2003 national standard implemented by Accreditation Council for Graduate Medical Education; and that interns are more likely to injure themselves mistakenly with a needle or another sharp instrument when working in a hospital more than 20 consecutive hours, or at night.

"Considered as a whole, the evidence demonstrates that academic medicine is failing both doctors and patients by routinely requiring exhausted doctors to work marathon 30-hour shifts. The human brain simply does not perform reliably for 30 consecutive hours without sleep." said Charles A. Czeisler, M.D., Ph.D, Chief, Division of Sleep Medicine at Brigham and Women’s Hospital and Baldino Professor of Sleep Medicine at Harvard Medical School.

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