Patient Safety Outcomes under Flexible and Standard Resident Duty-Hour Rules

Abstract

Background: Concern persists that extended shifts in medical residency programs may adversely affect patient safety.

Methods: We conducted a cluster-randomized noninferiority trial in 63 internal-medicine residency programs during the 2015-2016 academic year. Programs underwent randomization to a group with standard duty hours, as adopted by the Accreditation Council for Graduate Medical Education (ACGME) in July 2011, or to a group with more flexible duty-hour rules that did not specify limits on shift length or mandatory time off between shifts. The primary outcome for each program was the change in unadjusted 30-day mortality from the pretrial year to the trial year, as ascertained from Medicare claims. We hypothesized that the change in 30-day mortality in the flexible programs would not be worse than the change in the standard programs (difference-in-difference analysis) by more than 1 percentage point (noninferiority margin). Secondary outcomes were changes in five other patient safety measures and risk-adjusted outcomes for all measures.

Results: The change in 30-day mortality (primary outcome) among the patients in the flexible programs (12.5% in the trial year vs. 12.6% in the pretrial year) was noninferior to that in the standard programs (12.2% in the trial year vs. 12.7% in the pretrial year). The test for noninferiority was significant (P = 0.03), with an estimate of the upper limit of the one-sided 95% confidence interval (0.93%) for a between-group difference in the change in mortality that was less than the prespecified noninferiority margin of 1 percentage point. Differences in changes between the flexible programs and the standard programs in the unadjusted rate of readmission at 7 days, patient safety indicators, and Medicare payments were also below 1 percentage point; the noninferiority criterion was not met for 30-day readmissions or prolonged length of hospital stay. Risk-adjusted measures generally showed similar findings.

Conclusions: Allowing program directors flexibility in adjusting duty-hour schedules for trainees did not adversely affect 30-day mortality or several other measured outcomes of patient safety. (Funded by the National Heart, Lung, and Blood Institute and Accreditation Council for Graduate Medical Education; iCOMPARE ClinicalTrials.gov number, NCT02274818.).

Figure 1.. Patient Safety Outcomes.

Shown are one-sided 95% confidence intervals for the difference between flexible programs and standard programs in the primary and secondary outcomes for patient safety. An outcome in the flexible programs was deemed to be noninferior to that in the standard programs if the upper limit of the confidence interval for the difference (the value in the flexible programs minus the value in the standard programs) was less than the noninferiority margin of 1 percentage point. Confidence intervals for binary outcomes represent the absolute difference in the outcome between the trial year minus the pretrial year in the flexible programs minus the corresponding absolute difference in the standard programs. Confidence intervals for payments represent the percent change (trial year vs. pretrial year) in the flexible programs minus the percent change in the standard programs with the use of log transformation. Patient safety indicators were determined according to the criteria of the Agency for Healthcare Research and Quality. Details regarding the cutoff points for determining whether a hospital stay has a prolonged length for various medical conditions are provided in Table S5 in the Supplementary Appendix.

Figure 2.. Subgroup Analysis of Flexible-Shift Implementation.

Shown are the results of a subgroup analysis of data from the patients in Figure 1 who were treated on services that were specifically designated for flexible-shift implementation by the program director during the trial year; all the pretrial-year patients in this subgroup had been treated by the same attending physicians who worked on the flexible services during the trial year. In the standard programs, all the patients of attending physicians who were working during both years were included. To maximize the stability of the estimates, only programs with a minimum of 100 eligible patients in each year (20 flexible programs and 30 standard programs) were included in the analysis. All analyses are risk-adjusted for coexisting medical conditions, as described in Table S6 in the Supplementary Appendix. An outcome in the flexible programs was deemed to be noninferior to that in the standard programs if the upper limit of the confidence interval for the difference (the value in the flexible programs minus the value in the standard programs) was less than the noninferiority margin of 1 percentage point.