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Duty Hours and Patient Safety

September 7, 2019


Long and unpredictable work hours have been a staple of medical training for centuries. In fact, the term "resident" is a relic of times when physicians in postgraduate training literally lived at the hospital. Though this system faded away several decades ago, as recently as 15 years ago, resident physicians routinely worked 90–100 hours per week, for up to 36 consecutive hours without rest, for the entire duration of residency training. These grueling hours were viewed by many as a necessary "rite of passage" and were considered essential to ensure that physicians developed their clinical acumen and would be capable of independent practice once training was completed.

Little attention was paid to the potential patient safety effects of fatigue among residents until March 1984, when 18-year-old Libby Zion died at New York Hospital due to a medication-prescribing error while under the care of residents in the midst of a 36-hour shift. The subsequent investigation into her death led to the formation of the Bell Commission, which passed regulations in 1987 mandating that residents at New York hospitals should work no more than 80 hours per week and no more than 24 consecutive hours.

Though work hours and shift duration decreased somewhat for residents over the next decade, it was not until the goals of the patient safety movement aligned with research documenting a connection between fatigue and clinical performance that stronger regulations came into place. In 2003, the Accreditation Council for Graduate Medical Education (ACGME) implemented rules limiting work hours for all residents, with the key components being that residents should work no more than 80 hours per week or 24 consecutive hours on duty, should not be "on-call" more than every third night, and should have 1 day off per week. (Some fields, principally surgical specialties, received partial exemption from the regulations.) The ACGME's current duty hour regulations went into effect in July 2011. These regulations maintained a maximum limit of 80 work hours per week, but eliminated extended duration shifts (which have been linked to errors in prior studies) for first-year residents, and strengthened oversight by senior physicians. (By comparison, residents in many other countries work significantly fewer hours; the European Working Time Directive currently limits residents in Europe to no more than 48 hours per week on duty.)

Effect of Resident Duty Hour Regulations

Duty hour regulations have engendered significant controversy since their implementation, and thus far, their overall effect appears to be mixed. A systematic review found that while resident well-being improved after implementation of the 2003 work hour regulations, there was no clear effect on patient safety or clinical outcomes. Reviews including data since the 2011 regulations were implemented have reached similar conclusions. The reasons for the regulation's lack of effect on safety outcomes are unclear and may be due to several factors. Residents are more closely supervised than in the past, which may mitigate the effect of trainee discontinuity. Any potential benefit of duty hour reductions may be attenuated because of the increased number of patient handoffs, which may result in more safety hazards. Finally, burnout and fatigue—known risk factors for poor job performance—remain common among residents despite reduced duty hours.

The impact of the duty hour regulations on educational variables has also been surprisingly mixed. Residents' educational experience appears to have been adversely affected by the regulations. Surveys of key clinical faculty and residents themselves have found that, although residents' quality of life has improved since 2004, their overall educational experience may have worsened, because they have less time available for teaching and to attend educational activities. A 2014 systematic review found that surgical residents had lower case volumes and scored more poorly on certification exams after implementation of duty hour restrictions.


Key clinical faculty feel that duty hour regulations have worsened resident patient care (Continuity of care 87%, Communication with patients 66%, Overall quality of patient care 60%)

Source: Reed DA, Levine RB, Miller RG, et al. Effect of Residency Duty-Hour Limits. Arch Intern Med. 2007;167:1487-1492. [go to PubMed]

Despite concerns about duty hour regulation's effect on education, a 2014 study found that patient outcomes for doctors who trained under reduced duty hours were similar to those who trained prior to implementation of the regulations.

Practicing Clinicians

Duty hour regulations for residents have also spurred interest in the issue of fatigue among practicing clinicians. One study found that many attending physicians, particularly surgeons, routinely work hours that would be prohibited in residency programs. Despite this fact, available data seems to indicate that physician sleep deficits do not affect the safety of surgical care. One case-control study found no increase in complications in elective procedures performed by surgeons who had operated the night before (compared to those with no overnight responsibilities), and another population-based study found no differences in mortality, complications, or readmissions between procedures performed by surgeons with sleep loss compared to those without sleep loss.

Current Context

Two randomized trials of different duty hour structures, conducted in general surgery and internal medicine residency programs, have been conducted in recent years. The Flexibility in Duty Hour Requirements for Surgical Trainees (FIRST) trial, published in 2015, randomized 118 general surgery residency programs to adhere to the 2011 ACGME regulations or to abide by more flexible rules that essentially followed the prior standard of a maximum 80-hour workweek. The study found no significant differences in patient outcomes, including death and serious complications. The iCompare trial, a similar study involving internal medicine residency programs, published its initial results in 2018; the study found that examination scores and time spent in direct patient care did not differ between groups, although educational satisfaction was lower among residents in programs assigned to flexible duty hour rules. On the basis of these results, the ACGME eliminated the 16-hour shift limit for first-year residents, but kept the remainder of the 2011 regulations: an overall 80-hour per weekwork limit, maximum shift duration of 24 hours (plus 4 hours for transitioning care), one day off per week (averaged over a 4-week period), and on-call no more than once every 3 nights. These new regulations went into effect in July 2017.

This project was funded under contract number 75Q80119C00004 from the Agency for Healthcare Research and Quality (AHRQ), U.S. Department of Health and Human Services. The authors are solely responsible for this report’s contents, findings, and conclusions, which do not necessarily represent the views of AHRQ. Readers should not interpret any statement in this report as an official position of AHRQ or of the U.S. Department of Health and Human Services. None of the authors has any affiliation or financial involvement that conflicts with the material presented in this report. View AHRQ Disclaimers
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