The News What's true of doctors is true of registered nurses: Those who routinely work long, often unpredictable hours, such as shifts that exceed 12 hours, make more mistakes than those who work fewer hours.

That's the conclusion of a federally funded study in the July/August issue of the journal Health Affairs. The study is one of the first to examine the relationship between medical errors and fatigue among registered nurses, who provide most of the direct care to hospital patients.

The Study Ann Rogers, an associate professor at the University of Pennsylvania School of Nursing, and her colleagues studied 393 nurses who worked full time in hospitals around the country. Nearly all were female and most were white, middle-aged, employed by large urban hospitals and had more than a decade of experience.

For two weeks each nurse kept a detailed log of her hours, breaks and mistakes. Overall 199 errors and 213 near-errors were detected, usually by the nurses themselves. Most errors or near-errors involved medication, including the wrong drug, wrong dose, wrong patient, wrong method of administration, wrong time or failure to give it altogether.

Errors and near-errors increased when nurses' shifts exceeded 12 hours per day, when their work weeks exceeded 40 hours or when they worked unplanned overtime at the end of a regular shift. "Nurses are no different than other occupational groups," Rogers said. "When they work longer hours, the risk of errors goes up."

The Impact on Patients Like previous studies of medical residents, this one did not attempt to link errors directly to patient harm. An earlier study conducted in Pennsylvania found that adding an extra surgical patient to a nurse's workload increased her patients' chances of dying or suffering a serious complication.

And More Broadly Concern about the prevalence of medical errors and the effects of fatigue on doctors-in-training have led to new rules in some specialties that limit their work weeks to 80 hours and shifts to a maximum of 24 hours. Some states are considering imposing limits on nurses' shifts, which have lengthened in the past decade because of staff cutbacks by hospitals as well as a nationwide nursing shortage.

-- Sandra G. Boodman