In this study we found that hospital emergency departments perform fairly poorly in seeing acutely ill patients within the time recommended by the triage nurse, and in keeping ED visits for admitted patients within 4 or 6 hours. Less than one fifth of EDs were able to see at least 90% of their emergent or urgent patients (those triaged to be seen in an hour or less) within an hour; only half kept the ED visit under 6 hours for at least 90% of their admitted patients.
Performance was not only deficient at the median, it was highly variable across EDs. The median wait time at the slowest 25% of EDs was at least twice as long as the median wait time of the fastest quartile of EDs, and patients admitted from the slowest quartile of EDs spent a median of at least 2.3 more hours in the ED than patients admitted from the quartile with shortest visit length. EDs were most variable in their care of their most acutely ill patients. There was a three-fold difference between the bottom and top quartiles of EDs in median wait times of patients triaged to be seen within 15 minutes.
The reasons for the wide disparity in these outcomes among EDs are likely several, including factors both within and outside a hospital's control. First, hospitals differ in patient, visit and hospital characteristics. However, together these factors explained only a portion of the variability in wait time and length of visit, leaving most of the variability unexplained. Second, higher-volume EDs may be more crowded, increasing wait times and visit lengths.33
These are factors that not often under the control of the ED and reflect the larger social and economic features of the hospital's environment.
It has recently been suggested, however, that the largest contributors to ED crowding and delays in care are not these immutable “input” factors, but rather “throughput” and “output” factors that are at least partially modifiable.4, 34
Numerous studies have shown improved wait time or length of visit after improvements in ED throughput, including changes in triage,35–37
or combinations thereof.12, 18, 37, 45–48
Perhaps most important is “output”: the availability of inpatient beds into which to move patients.4
For example, ED length of visit increases as hospital occupancy rates rise.49–53
Our study provides new evidence for the importance of these hospital-level effects, particularly for patients with more severe illness.4
For admitted patients, we found that 33.2% of the variability in length of visit was attributable to the hospital level (between-hospital effect), suggesting that hospital-level factors may be an important driver of visit length for admitted patients. Furthermore, our multivariate models for admitted patients explained only 6.9% of the total variation. This finding implies that the hospital-level data available to us (e.g., region, urban status, ownership, proportion of uninsured patients) are not the major determinants of hospital variability for admitted patients' length of visit. Rather, output factors at each hospital, such as inpatient occupancy, transport availability, housekeeping practices, admitting procedures and prioritization of non-ED admissions, are likely also important determinants of hospital-level variability in ED length of stay.4
Performance measures for ED patient flow have not yet been widely adopted in the United States.17, 25
In this study we report several measures, including median performance and percent performance within goals. Medians are useful to describe the range of performance across EDs, identify benchmark values, and define outliers,25
and have been endorsed by the NQF.17
For wait time, however, reporting an overall median is imperfect since the clinically acceptable wait time varies markedly by patient acuity. Instead, the GAO has reported the proportion of patients overall in the U.S. who are seen within the time recommended by triage assessment.4
Therefore, we also measured the proportion of patients at each ED seen within the time recommended by the triage assessment. For length of visit, we reported both ED median, and the proportion of patients exceeding a predetermined “excess” length of visit. Excess length of visit has variously been defined as 4 hours in the United Kingdom,54
4–6 hours in Canada,23
and 8 hours in Australia.55
The NQF has not defined a target length of visit in the U.S. In this study, we examined performance relative to both 4- and 6-hour visit length targets.
Should ED wait time and visit length be national quality measures, as the NQF proposes? Our findings of marked variability in wait time and visit length across EDs highlight the potential of these quality measures to prompt fundamental changes in ED processes. To achieve improvements in their performance, hospitals would have to focus attention on a wide range of institutional practices involving triage, registration, patient flow, physical environment, laboratory testing, admission processes and policies, workload assignment, staffing and others. Because these measures are correlated with patient outcomes such as leaving before being seen,13, 14
receipt of recommended care,6, 8
and in-hospital length of stay,5
improving performance in wait time and visit length could have a large impact on quality of care for all patients seen in the ED. An example of the implementation of these measures is the United Kingdom, where public reporting of ED visit length has been linked to substantial reduction in ED visit lengths, reduced variability and improved patient outcomes without evidence of “gaming” the measure.56
In 2008, 98% of ED visit lengths in the U.K. were 4 hours or less.57
However, some have complained that the focus on the four hour target has come at the expense of professionalism, collegiality and morale.58, 59
Although apparently successful in the UK, there are several reasons these performance measures should be piloted before widespread adoption in this country. A focus on short wait times might have the unintended consequence of distracting attention from patients already in the ED unless visit length was also simultaneously tracked. Furthermore, a focus on time might prompt EM physicians to prioritize efficiency over accuracy, thoroughness and perhaps safety. Time-based measures are quite susceptible to “gaming” by altering practice and documentation patterns, and have been observed to some degree in the UK.60
Finally, the “optimal” length of visit for an admitted ED patient is unclear. Excessive length of visit is detrimental, but premature discharge or transfer to an inpatient unit may also have adverse consequences.
In summary, we found that United States hospital emergency departments have relatively poor performance in wait time and length of ED visit for their most acutely ill patients, and furthermore, that hospitals themselves vary widely in performance. Attention to these outcomes on a hospital level may provide insight into hospital practices that could improve the quality and efficiency of emergency department care.