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Extended Work Shifts Put Medical Interns At Risk Nationwide

September 5, 2006

Harvard Medical School Press Release. For more information, please contact: Lori Shanks, 617-534-1604 or, or Leah Gourley, 617-432-0442,

Fatigue and lapse in concentration increase risk for laceration and needle stick

Boston—Researchers from Harvard Medical School (HMS) and Brigham and Women’s Hospital (BWH) have found that extended work shifts (more than 20 consecutive work hours) are associated with an increase in the risk that interns will suffer a percutaneous injury, a laceration by a sharp instrument or a needle stick that causes exposure to potentially contaminated blood or body fluid.  These findings are published in the September 6 issue of the Journal of the American Medical Association.  
"Our data indicate that the odds of interns piercing themselves with needles or scalpels while caring for patients, and thereby exposing themselves to potentially contaminated body fluids, are 61 percent greater when they have been working more than 20 consecutive hours, as compared to when those same interns have been working less than 12 consecutive hours,” says senior researcher Charles A. Czeisler, PhD, MD, chief of the Divisions of Sleep Medicine at HMS and BWH and the Frank Baldino, Jr., PhD, professor of sleep medicine at HMS.

Researchers examined 498 percutaneous injuries over a period of 11 months as documented in a national web-based survey of 2,737 post-graduate first year interns noting the time of occurrence (both time of day and at what point during a shift), locations of exposure by type of residency, and the reported contributing factor for each injury.  

Researchers found that injuries occurred more often when the interns worked long hours, and specifically they report:

  • Percutaneous injuries occurred 61 percent more frequently during the day after working an overnight shift as compared to the same time of day that was not preceded by working an overnight shift.  
  • The rate of percutaneous injuries was twice as high during night shifts as compared to day shifts.  Nighttime injuries were preceded by an average of 17.5 hours of work while daytime injuries were preceded by an average of 10 hours of work.
  • Lapse in concentration was the reported contributing factor in 63.8 percent of reported percutaneous injuries and fatigue was the reported contributing factor in 31 percent of reported injuries.
  • Fatigue was the reported factor in 44 percent of percutaneous injuries that occurred during extended work shifts while only 19 percent of injuries were attributed to fatigue during non-extended work shifts.
  • Percutaneous injuries were significantly greater in the first five months of internship as compared to the last five months.

"Fatigue was a factor in a substantial proportion of reported incidences for which a contributing factor was noted.  Furthermore, fatigue was reported as a factor more frequently with injuries that occurred in the daytime after an overnight worked in the hospital, and with injuries that occurred during nighttime hours. This suggests that measures to reduce fatigue, such as reducing shift lengths, could prevent a substantial number of these injuries,” said lead author, Najib Ayas, assistant professor of medicine at the University of British Columbia.

This finding adds occupational injury to the list of hazards already associated with marathon shifts that doctors-in-training are scheduled to work in the U.S.  Other hazards include attentional failures, medical errors while caring for ICU patients, and motor vehicle crashes as shown previously by the Harvard Work Hours, Health and Safety Group in research dating back to 2004.  

“Academic medical centers should abandon the practice of scheduling physicians-in-training to work 24 consecutive hours, as it endangers both patients and the young doctors in training," says Czeisler who is also the Frank Baldino, Jr., PhD, professor of sleep medicine at HMS.  

Coauthors of the study include Laura. Barger, Ph.D, Brian Cade, MS, Dean Hashimoto, MD, Bernanrd Rosner, PhD, John Cronin, MD and Frank Speizer, MD.

This study was supported by the National Institute for Occupational Safety and Health within the U.S. Centers for Disease Control and Prevention, the Agency for Healthcare Research and Quality and BWH.


Related Link: Publication details

Related Press Release: Study Finds Nationwide Non-Compliance in First Year Following Implementation of Work-Hour Limits for Medical Interns

Harvard Medical School
Harvard Medical School has more than 7,000 full-time faculty working in eight academic departments based at the School's Boston quadrangle or in one of 47 academic departments at 18 Harvard teaching hospitals and research institutes. Those Harvard hospitals and research institutions include Beth Israel Deaconess Medical Center, Brigham and Women's Hospital, Cambridge Health Alliance, The CBR Institute for Biomedical Research, Children's Hospital Boston, Dana-Farber Cancer Institute, Forsyth Institute, Harvard Pilgrim Health Care, Joslin Diabetes Center, Judge Baker Children's Center, Massachusetts Eye and Ear Infirmary, Massachusetts General Hospital, Massachusetts Mental Health Center, McLean Hospital, Mount Auburn Hospital, Schepens Eye Research Institute, Spaulding Rehabilitation Hospital, and VA Boston Healthcare System.

Brigham and Women’s Hospital
Brigham and Women’s Hospital is a 747-bed nonprofit teaching affiliate of Harvard Medical School and a founding member of Partners HealthCare System, an integrated health care delivery network. BWH is committed to excellence in patient care with expertise in virtually every specialty of medicine and surgery.  The BWH medical preeminence dates back to 1832 and today that rich history in clinical care is coupled with its national leadership in quality improvement and patient safety initiatives, dedication to educating and training health care professionals, and strength in biomedical research. With $370M in funding and more than 500 research scientists, BWH is an acclaimed leader in clinical, basic and epidemiological investigation - including the landmark Nurses Health Study, Physicians Health Studies, and the Women's Health Initiative.  For more information about BWH, please visit:

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