A few highly publicized instances of errors made by overworked resident physicians have helped change regulations about how long they may work. Nurses' work hours, however, are not widely regulated, nor has the effect of their work schedules on patient safety been extensively studied. Researchers at the University of Pennsylvania and colleagues at other institutions tracked the hours worked by nurses and also recorded the errors and near errors made during the shift.

What the researchers wanted to know: Do nurses make more medical errors when they work more than 12 hours straight, work overtime, or work more than 40 hours per week?

What they did: Almost 400 full-time registered nurses recorded hours worked (scheduled and actual), time of day worked, overtime, days off, and sleep patterns in logbooks provided by the researchers. They also recorded the type and number of errors and near errors, if any, they made during the shift.

What they found: Nurses worked longer than scheduled, usually more than 40 hours per week. Work duration, overtime, and number of hours worked per week all affected errors. The likelihood of making an error increased with longer work hours and was three times higher when nurses worked shifts lasting 12.5 hours or more, the authors said.

What it means to you: The widespread nursing shortage makes it difficult to avoid hospitals with overworked nursing staffs. And it isn't too reassuring that more than half the errors involved medication administration. However, there is growing awareness of the problem. The Institute of Medicine recently recommended that voluntary overtime be limited.

Caveats: The data are self-reported, though anonymity removes much of the incentive to underreport errors. The 393 respondents also represent just a tiny percentage of the more than 2 million nurses in the United States, and those who responded may not reflect the larger population in their degree of conscientiousness.

Find out more: You can read the Institute of Medicine's report at http://www.iom.edu/report.asp?id=16173.

Read the article: Rogers, AE et al. The Working Hours of Hospital Staff Nurses and Patient Safety. Health Affairs. July/August, Vol. 23, No. 4, pp. 202–211.