Landrigan 2004.

Study characteristics
Methods	RCT‐ individual. A prospective, randomised study comparing the rates of serious medical errors made by interns while they were working according to a traditional schedule with extended (24 hours or more) work shifts every other shift (an “every third night” call schedule) and while they were working according to an intervention schedule that eliminated extended work shifts and reduced the number of hours worked per week. Unit of allocation: doctors Unit of analysis: patients
Participants	Medical intensive care unit (MICU) and coronary care unit (CCU) of Brigham and Women's Hospital, a large academic hospital in Boston (N = 634). IP adults (ICU)
Interventions	Intervention: Structural changes/Organizational changes Intervention:limited work time. During the intervention schedule, interns’ work hours and overnight work schedules were changed. Interns’ traditional extended work shifts were divided in two: a “day‐call” intern worked the first half of a traditional call (from 7 a.m. to 10 p.m.); a “night‐call” intern worked the second half (from 9 p.m. to 1 p.m. the following day). To effect this schedule, four interns shared patient care responsibilities during the rotation. The maximum scheduled hours of work were 60 to 63 per week, with consecutive hours of work limited to approximately 16 hours. The intervention did not alter the schedules or staffing of second‐ or third‐year residents or other clinical personnel. Control: nomal work time.The traditional MICU house‐staff team consisted of three interns and three third‐year residents, whereas the CCU team consisted of three interns and two second‐year residents. Each intern and resident on these teams worked overnight in the hospital every third night. A resident from another hospital service assumed patient care responsibilities in the CCU on nights when neither of the daytime CCU residents was working. Under this rotation, interns’ scheduled workweeks averaged 77 to 81 hours, depending on the clinic assignment, with up to 34 continuous hours of scheduled work when clinic occurred after they were on call.
Outcomes	Medication error per 1000 patient‐days rate (number of errors/1000 patient‐days) Medical error: any error in the delivery of medical care, whether harmful or trivial
Notes	Supported by a grant (RO1 HS12032) from the Agency for Healthcare Research and Quality (AHRQ); by a grant (RO1 OH07567) from the National Institute for Occupational Safety and Health, by the Department of Medicine, Brigham and Women’s Hospital; by the Division of Sleep Medicine, Harvard Medical School; by the Brigham and Women’s Hospital; and by a General Clinical Research Center grant (M01RR02635) from the National Center for Research Resources. Dr. Landrigan is the recipient of an AHRQ career development award (K08 HS13333); Dr. Cronin is the recipient of an AHRQ National Research Service Award (F32 HS14130) and a National Heart, Lung, and Blood Institute fellowship in the program of training in Sleep, Circadian, and Respiratory Neurobiology at Brigham and Women’s Hospital (T32 HL079010) No trial number
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not described
Allocation concealment (selection bias)	Unclear risk	Not described
Blinding of participants and personnel (performance bias) All outcomes	High risk	Because of the nature of the interventions, participants may not have been blinded.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	"Each suspected error or adverse event identified was independently rated by two physician investigators who were unaware of the identity of those involved or whether the incident occurred during the traditional or intervention schedule. Blinded reviewers categorized each incident as an adverse event, nonintercepted serious error, intercepted serious error, or error with little potential for harm."
Incomplete outcome data (attrition bias) All outcomes	Low risk	No missing outcome data
Selective reporting (reporting bias)	Low risk	The study protocol is not available but it is clear that the published reports include all expected outcomes, including those that were prespecified.
Conflict of interest	Low risk	None detected
Other bias	High risk	Interns were randomised to work the traditional schedule in the CCU and the intervention schedule in the MICU, or vice versa. The outcome is error (for example, a medication error). Each opportunity for error is not independent, as they cluster within doctor (i.e. each doctor may be more or less likely to make errors). The analyses do not appear to account for this, so it seems that a unit of analysis error was made.