Medical Interns Work Too Long, Study Says

Two studies released yesterday by Harvard Medical School (HMS) researchers found that medical school interns work too many hours, and suggested that their shifts be reduced by half.

The year-long studies, both carried out at Brigham and Women’s Hospital (BWH), measured how sleep—or the lack thereof—affects intern performance. The results were published in the New England Journal of Medicine yesterday.

According to educational guidelines for accredited residency programs, medical residents may not work more than 80 hours a week or longer than 30 hours per shift.

These regulations were put into effect last year in July, and set by the Accreditation Council for Graduate Medical Education (ACGME), the umbrella organization that holds authority over all 8,000 residency programs in the United States, said Julie A. Jacob, manager of communications for the council.

Despite these rules, interns usually work longer than the 30-hour limit, said HMS instructor Steven W. Lockley, lead researcher of one of the studies. He said that the average work shift is around 32 hours.

Charles A. Czeisler ’74, chief of the Division of Sleep Medicine at HMS, said that these long hours are dangerous for both patients and interns.

“The data indicate that the tradition of working 30-hour shifts may be the Achilles heel of the medical education system,” said Czeisler, who is also the senior author of both studies, a title given to the head of the laboratory in which the work is conducted. “We are subjecting patients to increased hazards, impairing the ability of the interns to learn and potentially subjecting the intern to health and safety risks.”

BWH Director of the Sleep and Patient Safety Program Christopher P. Landrigan, the lead researcher for the second study, recommended that interns work no more than 16-hour shifts.

“For truck driving, federal laws limit consecutive driving time to 10 hours,” he said. “Risks fatal to drivers increase exponentially until at the 24th hour the risk for a crash is 56-fold the baseline.”

While the ACGME requires all residency programs to limit shifts to 30 hours, there are currently no criminal laws that limit work hours for physicians.

David C. Leach, executive director of ACGME, said in a press release yesterday that these studies “help validate that the ACGME is moving in the right direction in its regulation of duty hour standards.” He added that “continuing efforts to further refine the standards are needed.”

Landrigan found that compared to an alternate working schedule where interns worked a maximum of 16 hours per shift, current interns make 36 percent more serious medical errors and five times more serious diagnostic errors.

This data closely corroborated Lockley’s findings that interns working 30-hour shifts had twice the rates of attention failures and fell asleep more frequently on their shifts.

Leach, however, pointed out that the study may not have taken all factors into consideration.

“The number of hours worked is an important variable, but not the only one in the learning environment,” he said. “Working fewer hours may reduce fatigue, but the numbers of patients seen and their acuity also contribute to medical errors.”

According to Landrigan, the long hours of an intern are due in large part to how residences are historically based on an apprenticeship model. This model, which encouraged doctors to stay with patients every step of the way, is now outdated, he said.

“We have a residual system...whose most critical element has been continuity of care—single physicians follow through with each patient,” said Landrigan. “The reality of modern medicine is that you’re being taken care of by multiple teams of doctors.”

In 1999, the Institute of Medicine reported that 44,000 to 98,000 patients die each year due to medical errors, making this the eighth leading cause of death in the United States.

—Staff writer Risheng Xu may be reached at xu4@fas.harvard.edu.