Effect of intern's consecutive work hours on safety, medical education and professionalism

We would like to thank Dr Sarani and Dr Alarcon for their critique of our work, published online in Critical Care on 12 January 2005 [1]. We have reviewed the critique, and in general we think that it appropriately describes both the strengths and limitations of our studies. We would like to make a few minor factual clarifications. First, although the study by Lockley and colleagues used a within-subjects analytical design [2], the study by Landrigan and colleagues did not [3]. A systemic-level approach rather than a within-subjects analysis was used in comparing interns' serious medical error rates, making these analyses comparable with analyses of errors system wide (i.e. those that involved both interns and other personnel), where a within-subjects design was not appropriate. Data from 20 interns were analyzed in Lockley and colleagues' study, as the authors note; however, data from an additional four interns contributed to the analysis in the study by Landrigan and colleagues. Our power to detect a 16% difference in serious medical errors was calculated to be 80%, not 90%. In addition, there is one error in the description of the limitations that we would like to point out. Dr Sarani and Dr Alarcon note: " There were more patients admitted to the ICU and more ICU patient-days in the traditional arm than in the intervention arm. Although these differences were not statistically significant, it does raise the possibility that interns in the traditional arm had more opportunities to make serious errors. " Differences in the incidence of serious errors were analyzed using rates (per patient-day), and therefore the fact that there were more patient-days in the traditional schedule cannot explain the results. On a per patient-day basis, there were no more opportunities to err in the traditional schedule. This is further confirmed by the fact that there were no more medications ordered or diagnostic tests interpreted in the traditional schedule per patient-day, and there were in fact fewer procedures performed in the traditional schedule per patient-day. With respect to the recommendations following from our findings, we strongly disagree with Dr Sarani and Dr Alarcon's statement that our study supports the Accreditation Council for Graduate Medical Education (ACGME) duty-hour standards: " Based on the results of these studies, it seems that the ACGME resident work hour restrictions are warranted, at least for interns, and that efforts to reduce the number of hours worked by interns …