shift duration (in hours) were estimated using regression models. The p-values for the adjusted incidence rate ratios were constructed based on robust variance estimates, with α = 0.05. Near-errors were examined using the same procedures.

For all study nurses, the overall error rate was 0.00336 errors per hour worked. Working overtime—working longer than scheduled on a given day or working extra shifts (“scheduled overtime”)—had no effect on error rates unless shift durations exceeded 12 consecutive hours. Once shift durations exceed 12 consecutive hours, both voluntary and mandated overtime significantly increased error rates (0.00375/hour and 0.00490/hour, respectively) (p = 0.02 for voluntary overtime and 0.03 for mandated overtime). Results remained consistent when outliers (i.e., 54 extremely long shifts of more than 23 hours, nurses with more than 7 errors each) were removed from the analyses. Results were somewhat different for near-errors. Being mandated to work overtime was associated with significant increases in the rate of near-errors for shifts scheduled for 12 hours or more; however, the rate of near-errors associated with working voluntary overtime for periods exceeding 12 consecutive hours was not increased.4

Data on Nurse Work Hours

Nursing staff working in in-patient facilities have traditionally worked in 8-hour shifts, but increasingly work longer hours. Reasons for these increases include the desire for increased compensation (elective overtime), requirements by health care organizations to work overtime (mandatory overtime) to compensate for insufficient staffing, and the desire for more flexible work hours (e.g., 10- or 12-hour shifts) to accommodate either facility or individual nurse needs or both. Scheduled shifts may be 8, 10, or 12 hours and may not follow the traditional pattern of day, evening, or night shifts. Nurses working on specialized units, such as the operating room, dialysis units, and some intensive care units, may be required to be on call in addition to their regularly scheduled shifts (Rogers, 2002).

Representative, quantitative data describing the work hours of nurses are scarce. Evidence of the long hours worked by direct-care nurses working in hospitals and nursing homes was obtained from a random sample survey of nurses licensed to work in either Illinois or North Carolina5 as part of a longitudinal study of nurses’ worklife and health funded by the


Unpublished study data from Ann Rogers, Ph.D., University of Pennsylvania (personal communications on January 25, 2003, June 29, 2003 and July 18, 2003).


These states were selected because they have large ethnic diversity in their registered nurse (RN) populations and because they renew RN licenses annually, providing up-to-date mailing lists.

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