From Pages to Practice

By Angela Castellanos, MD

Published January 5, 2022


Discussions about limiting resident physician work hours typically begin with, “when I was a resident…” stories of more than 24 hours in the hospital, long nights in the ICU, and the complicated patients who were cared for throughout their course of treatment by one trainee. But when I was a resident, and began my intern year in 2015, interns were not allowed to work more than 16-hour shifts according to the Accreditation Council for Graduate Medical Education (ACGME) duty-hour requirement at the time. I remember feeling some relief at the restriction as I stepped into residency. Yet, despite the absence of 24-hour calls, that year was still the most tiring year of my professional life. By 2017, when the duty-hour restriction was lifted, I was a senior resident and was paired with a fresh, eager intern during some of my 24-hour calls. As the more-senior physician who had experienced a restricted training schedule, I wondered which one of us provided better patient care and got more sleep as interns due to these policy changes.

The questions of patient safety and trainee sleep and alertness outcomes associated with  flexible (no shift-limit restriction) versus standard (restricted) duty hour shifts for internal medical residents were examined in the Individualized Comparative Effectiveness of Models Optimizing Patient Safety and Resident Education (iCOMPARE) trial and published in NEJM in March. Despite the common presumption that 24-hour shifts are dangerous and must be banned, the new iCOMPARE results suggest that flexible hours are not as bad as they seem: 30-day mortality and resident restfulness were similar for flexible and restricted shift lengths, indicating that flexible (or extended) shift lengths were noninferior to restricted duty-hour shifts.

The following NEJM Journal Watch summary further explains the studies and results.


Flexible vs. Standard Duty-Hours Restrictions for Residents

In a randomized trial, flexible or standard hours resulted in similar patient-safety and trainee-restfulness outcomes.

In a randomized trial among surgical residents, flexible duty hours (i.e., allowing shifts longer than 16 hours, but maintaining an 80-hour weekly maximum and 1 day off per week) led to equivalent patient outcomes and resident satisfaction compared with restricted duty hours (i.e., prohibiting shifts longer than 16 hours; NEJM JW Gen Med Mar 1 2016 and N Engl J Med 2016; 374:713). In a subsequent study among internal medicine residents (iCOMPARE), researchers randomized 63 U.S. internal medicine residency training programs either to a flexible duty-hours schedule or to a standard restricted-hours schedule. Resident satisfaction outcomes from iCOMPARE have been reported previously (NEJM JW Gen Med May 1 2018 and N Engl J Med 2018; 378:1494).

Among >250,000 Medicare patients cared for by residents during 2 years, change in 30-day mortality from the pretrial year to the trial year was similar (<1% change in each program group). Readmissions, patient-safety indicators, and Medicare payments also were similar in the two groups. Interns in both groups averaged ≈7 hours of sleep nightly and scored similarly on a subjective sleepiness scale and an objective measure of alertness.

Comment: Patient safety and trainee restfulness are not compromised by permitting flexible duty-hours shifts, compared with more-strict duty-hours shifts, assuming an 80-hour maximum and 1 day off per week are maintained. Working more-flexible (extended-hours) shifts — even if during only part of training — might help prepare trainees to handle challenges of post-training clinical practice where hour-limit protections do not exist.

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Angela Castellanos is a general pediatrician and editorial fellow at the NEJM.