Background: Limiting resident work hours may improve patient safety, but unintended adverse effects are also possible. We sought to assess the impact of Accreditation Council for Graduate Medical Education resident work hour limits implemented on July 1, 2003, on resident experiences and perceptions regarding patient safety.
Methods: All trainees in 76 accredited programs at 2 teaching hospitals were surveyed in 2003 (preimplementation) and 2004 (postimplementation) regarding their work hours and patient load; perceived relation of work hours, patient load, and fatigue to patient safety; and experiences with adverse events and medical errors. Based on reported weekly duty hours, 13 programs experiencing substantial hours reductions were classified into a "reduced-hours" group. Change scores in outcome measures before and after policy implementation in the reduced-hours programs were compared with those in "other programs" to control for temporal trends, using 2-way analysis of variance with interaction.
Results: A total of 1770 responses were obtained (response rate, 60.0%). Analysis was restricted to 1498 responses from respondents in clinical years of training. Residents in the reduced-hours group reported significant reductions in mean weekly duty hours (from 76.6 to 68.0 hours, P < .001), and the percentage working more than 80 hours per week decreased from 44.0% to 16.6% (P < .001). No significant increases in patient load while on call (patients admitted, covered, or cross covered) were observed. Between 2003 and 2004, there was a decrease in the proportion of residents in the reduced-hours programs indicating that working too many hours (63.2% vs 44.0%; P < .001) or cross covering too many patients (65.9% vs 46.9%; P = .001) contributed to mistakes in patient care. There were no significant reductions in these 2 measures in the other group, and the differences in differences were significant (P = .03 and P = .02, respectively). The number of residents in reduced-hours programs who reported committing at least 1 medical error within the past week remained high in both study years (32.9% in 2003 and 26.3% in 2004, P = .27).
Conclusions: It is possible to reduce residents' hours without increasing patient load. Doing so may reduce the extent to which fatigue affects patient safety as perceived by these frontline providers.