Study designs of evaluations included in the review
No criteria for study design were specified.
Specific interventions included in the review
The studies needed to assess a system change designed to counteract the effects of work hours, fatigue or sleep deprivation. The interventions used were float systems, other cross-coverage systems, or unspecified schedule changes.
Participants included in the review
Inclusion criteria for the participants were not stated. The participants included were interns and residents. 'Interns' were defined as physicians in their first year of postgraduate training, while 'residents' were defined as those in at least their second year of training.
Outcomes assessed in the review
The studies needed to include an outcome directly related to patient safety (e.g. death, morbidity and patient care errors).
How were decisions on the relevance of primary studies made?
Two authors independently reviewed the articles from the first search (1966 to 2002), while one author reviewed the articles from the second search (2002 to 2004) using the same criteria.