The study of adverse events by Petersen and colleagues [1] raises some important issues. The authors conclude that the care of patients by cross-covering housestaff increases the likelihood of preventable adverse events. Few adverse events occurred, however, when patients were covered by an experienced night float resident. Thus, factors other than discontinuity of care were clearly responsible for negative events. Intern mistakes during cross-coverage may have been related to fatigue, excessive patient load, inexperience, or a lack of adequate "sign out" by coresidents. Fatigued residents make an excessive number of errors [2, 3]. Thirty percent of interns meet the criteria for major depression while on a service with a high number of working hours [4]. The number and quality of sign-out rounds could have played an important role but was not mentioned. Other potential causes of adverse outcomes may be related to the adequacy of support during periods of cross-coverage (that is, limited attending availability, access to ancillary support, nursing quality and ratios, and so forth).

At our hospital, the housestaff have participated in the development of a coverage system whose primary objective is continuity of care. The system also incorporates housestaff "quality-of-life issues." We have both an intern and a resident "night float" system. Interns work a 12-hour evening shift. They are responsible for cross-coverage on medical patients whose intern has gone home. They do not admit new patients. They receive an extensive computerized sign-out including problem list and full medication summary. The "night float" resident begins work at 8:00 p.m. He or she is available to assist the night float interns with cross-coverage issues. In addition, the night float resident and the two interns who have remained on call admit new patients from 8:00 p.m. to 8:00 a.m.

Housestaff must manage increasingly complex cases. Petersen and colleagues show that discontinuity of care can lead to adverse outcomes. However, a system must exist to maximize the quality of patient care and to provide humane working conditions for residents. Better cross-coverage systems can be developed that enable well-rested residents to both learn and manage their patients more effectively.