A recent randomized controlled trial in critical-care units revealed that the elimination of extended-duration work shifts (≥24 h) reduces the rates of significant medical errors and polysomnographically recorded attentional failures. This raised the concern that the extended-duration shifts commonly worked by interns may contribute to the risk of medical errors being made, and perhaps to the risk of adverse events more generally. Our current study assessed whether extended-duration shifts worked by interns are associated with significant medical errors, adverse events, and attentional failures in a diverse population of interns across the United States.
Methods and Findings
We conducted a Web-based survey, across the United States, in which 2,737 residents in their first postgraduate year (interns) completed 17,003 monthly reports. The association between the number of extended-duration shifts worked in the month and the reporting of significant medical errors, preventable adverse events, and attentional failures was assessed using a case-crossover analysis in which each intern acted as his/her own control. Compared to months in which no extended-duration shifts were worked, during months in which between one and four extended-duration shifts and five or more extended-duration shifts were worked, the odds ratios of reporting at least one fatigue-related significant medical error were 3.5 (95% confidence interval [CI], 3.3–3.7) and 7.5 (95% CI, 7.2–7.8), respectively. The respective odds ratios for fatigue-related preventable adverse events, 8.7 (95% CI, 3.4–22) and 7.0 (95% CI, 4.3–11), were also increased. Interns working five or more extended-duration shifts per month reported more attentional failures during lectures, rounds, and clinical activities, including surgery and reported 300% more fatigue-related preventable adverse events resulting in a fatality.
In our survey, extended-duration work shifts were associated with an increased risk of significant medical errors, adverse events, and attentional failures in interns across the United States. These results have important public policy implications for postgraduate medical education.
During months in which medical interns worked extended shifts, the chances of their reporting at least one fatigue-related significant medical error increased more than 3-fold compared to months with no extended shifts.
In the United States, medical students who are doing their internship (first year of postgraduate clinical training) regularly work in the clinic for longer than 24 h at a time. It is already known that doctors or students who work for long shifts make more medical errors and are less able to pay attention to what they are doing. Many thousands of adverse medical events per year including, in the extreme, deaths of patients, are thought to result from medical errors, but it is not clear whether doctors or students working long shifts—as opposed to, for example, an increase in total number of hours worked—are the cause of many or any of these errors.
Why Was This Study Done?
This research group wanted to find out whether long shifts worked by interns had an effect on reported medical errors, and hence patient safety, and specifically whether any harm that happened to patients might otherwise have been preventable.
What Did the Researchers Do and Find?
The researchers contacted all US medical school graduates beginning their internships from one particular year-group by email, and asked each person whether they wanted to take part in a confidential survey. Individuals who agreed to participate were directed to a secure website to enter basic information about themselves and then to complete a form each month. On that form the interns gave information about their working hours, hours of sleep, and number of extended-duration shifts worked, and completed questions about medical errors in the past month. Then, for each intern in the study, researchers compared month by month the number of medical errors and the number of extended-duration shifts that had been worked. A total of 2,737 interns took part in the survey.
Compared to months in which no extended-duration shifts were worked, in those months in which between one and four, and more than five extended-duration shifts were worked, the doctors were, respectively, three and seven times more likely to report at least one fatigue-related significant medical error. Similarly, fatigue-related adverse events increased by around seven and eight times, respectively, compared with months in which no extended-duration shifts were worked. Fatigue-related preventable adverse events associated with the death of the patient increased by ∼300% in interns working more than five extended-duration shifts per month; they were also more likely to fall asleep during lectures, rounds, and clinical activities, including surgery.
What Do These Findings Mean?
Guidelines for graduate medical education in the United States still allow up to nine marathon shifts (30 h at a stretch) per month, even though the total number of hours worked is capped. This study shows that the long shifts worked by interns are bad for patient safety, as they are more likely to cause harm that would not otherwise happen.
Please access these Web sites via the online version of this summary at http://dx.doi.org/doi:10.1371/journal.pmed.0030487.
The US Food and Drug Administration has resources on its website about medication errors
The National Sleep Foundation aims to improve public health and safety by achieving understanding of sleep and sleep disorders
Wikipedia (an internet encyclopedia anyone can edit) has a page about residency training in the United States