Comprehensive studies of sleep and medical intern performance

Brigham and Women’s Hospital (BWH), in two of the nation’s first comprehensive studies of sleep and medical intern performance, has found evidence that indicates eliminating extended work shifts of 24 hours or more, implementing shift limits of 16 hours or less and reducing work weeks to less than 80-hours, decreases the number of medical errors performed by this group of physicians.

In the two studies, senior researcher Charles A. Czeisler, PhD, MD, chief of BWH’s Sleep Medicine Division and colleagues, gathered evidence evaluating the effect of eliminating extended works shifts. BWH is unveiling its plan to enhance patient safety through regulating shifts for its post-graduate year-one (PGY-1) interns, including:

• Restricting first year intern hours to 80 hours a week or less;
• Mandating first year interns do not work more than 24 hours consecutively; and,
• Mandating by July 2005 that first year interns cannot write orders for patient care activities after 18 consecutive hours on a shift.

According to BWH’s Chief Medical Officer Andy Whittemore, MD, the hospital’s preliminary plan could serve as a model for other medical institutions around the country. “BWH began implementing these guidelines in the summer of 2004. We believe they will be helpful to similar institutions in their efforts to increase patient safety and enhance the quality of interns’ lives – goals of our nationwide medical system. While reducing first year intern work hours requires a very significant hospital-wide effort, we have had support from the entire community as everyone recognizes that this is an important step in addressing patient safety. BWH, along with the other hospitals which comprise Partners HealthCare System, is proud to lead the nation in these efforts and will continue to do so by supporting the necessary research and policies to institute change.”

According to Czeisler, “While sleep experts advocate eight hours of sleep per 24 hour period, it has historically been difficult to achieve in medicine as patient care is an around the clock effort. These are the first studies to demonstrate clinically that reducing work shifts and tackling sleep deprivation will help increase attentiveness and reduce medical errors.”

Brigham and Women’s Hospital Leads Nation in Sleep Research and Patient Safety

To better understand the impact sleep has on medical intern performance, researchers at BWH pioneered two studies both designed to underscore and support efforts hospitals can take to improve patient safety.

The impact extended work shifts – 24 hours or more – has on the alertness and performance of PGY-1 medical interns is not well understood. In the first study in the NEJM, lead researcher Steven W. Lockley, PhD, Czeisler and colleagues studied 20 interns during two three-week rotations in both a medical intensive care unit (MICU) and a coronary care unit (CCU). Each intern participated in a traditional schedule – more than 80 hours per week with some shifts of 24 hours or more – and an intervention schedule – less than 80 hours per week with shifts not exceeding 16 hours.

Through daily sleep and work logs and continuous eye movement monitoring through electrooculography (EOG), researchers found that interns on the intervention schedule worked 19.5 hours per week less, slept 5.8 hours per week more and slept more in the 24 hours preceding each working hour. In addition, these interns had less than half the rate of attentional failures – as defined by slow rolling eye movements – while working during on-call nights.

According to Lockley, “This evidence reveals that the long-standing medical tradition of scheduling physicians to work 24 or more hours in a row adversely impacts their ability to remain awake and sustain attention while caring for patients.”

In the second study, lead researcher Christopher P. Landrigan, MD, MPH of BWH and Children’s Hospital Boston, Czeisler and colleagues studied the impact extended work shifts and subsequent sleep deprivation had on medical errors. The researchers conducted a randomized study in which the rates of serious medical errors made by PGY-1’s in a MICU and CCU were observed when working a traditional shift with extended work shifts – 24 hours or more – and an interventional schedule that eliminated extended work shifts. The researchers found that during a total of 2,203 patient-days involving 634 admissions, interns made 35.9 percent more serious medical errors during the traditional schedule than during the intervention schedule. Note that these errors did not translate into increased serious complications leading to deaths or prolonged stays in the ICU. This may be due to the fact that BWH has implemented many patient safety improvements including enhanced computerized physician order entry and an electronic pharmacy.

“Our data suggest that limiting interns’ scheduled shifts in intensive care settings could substantially improve patient safety. The Accreditation Council for Graduate Medical Education’s duty hour regulations has focused on the 80-hour workweek, rather than the elimination of extended shifts. Our data and the sleep medicine literature indicate that shortening the length of shifts may have more impact on patient safety,” Landrigan said.

According to Whittemore, “The data from this research trial is helping reinforce BWH’s plan to reduce the hours residents work to less than the 80-hour a week limit currently required by Accreditation Council for Graduate Medical Education. We are also committed to future study to effect further improvements in patient care and safety and quality of our physicians’ lives.”

This research was supported by grants from the Agency for Healthcare Research and Quality and the National Institute for Occupational Safety and Health.