Health policy and clinical practice/original research
The Effect of Low-Complexity Patients on Emergency Department Waiting Times

https://doi.org/10.1016/j.annemergmed.2006.06.027Get rights and content

Study objective

The extent to which patients presenting to emergency departments (EDs) with minor conditions contribute to delays and crowding is controversial. To test this question, we study the effect of low-complexity ED patients on the waiting times of other patients.

Methods

We obtained administrative records on all ED visits to Ontario hospitals from April 2002 to March 2003. For each ED, we determined the association between the number of new low-complexity patients (defined as ambulatory arrival, low-acuity triage level, and discharged) presenting in each 8-hour interval and the mean ED length of stay and time to first physician contact for medium- and high-complexity patients. Covariates were the number of new high- and medium-complexity patients, mean patient age, sex distribution, hospital teaching status, work shift, weekday/weekend, and total patient-hours. Autoregression modeling was used given correlation in the data.

Results

One thousand ninety-five consecutive 8-hour intervals at 110 EDs were analyzed; 4.1 million patient visits occurred, 50.8% of patients were women, and mean age was 38.4 years. Low-, medium-, and high-complexity patients represented 50.9%, 37.1%, and 12% of all patients, respectively. Mean (median) ED length of stay was 6.3 (4.7), 3.9 (2.8), and 2.2 (1.6) hours for high-, medium-, and low-complexity patients, respectively, and mean (median) time to first physician contact was 1.1 (0.7), 1.3 (0.9), and 1.1 (0.8) hours. In adjusted analyses, every 10 low-complexity patients arriving per 8 hours was associated with a 5.4-minute (95% confidence interval [CI] 4.2 to 6.0 minutes) increase in mean length of stay and a 2.1-minute (95% CI 1.8 to 2.4 minutes) increase in mean time to first physician contact for medium- and high-complexity patients. Results were similar regardless of ED volume and teaching status.

Conclusion

Low-complexity ED patients are associated with a negligible increase in ED length of stay and time to first physician contact for other ED patients. Reducing the number of low-complexity ED patients is unlikely to reduce waiting times for other patients or lessen crowding.

Introduction

In 2002, more than 110 million emergency department (ED) visits occurred in the United States, a 23% increase since 1992.1 This increase in utilization has coincided with a period of worsened ED crowding, with surveys reporting the problem in almost every state2, 3, 4, 5 on almost every day.3, 5 Several studies have documented substantial utilization of EDs by low-acuity patients,6, 7, 8 but no study has found a convincing association between low-acuity utilization and ED crowding. Nonetheless, some observers have concluded that crowding might be alleviated by diverting low-acuity patients away from EDs.9, 10, 11, 12, 13, 14

Studies of the causes of crowding have found the problem to be associated primarily with higher-acuity patients, especially those who require hospital admission,15, 16 and we are unaware of published evidence suggesting that low-acuity patients directly contribute to crowding. However, treating any ED patient, even ones with minor complaints and injuries, requires a treatment space and staff time, both of which could otherwise be devoted to the treatment of other patients. Thus, it has been theorized that treating low-acuity patients distracts ED personnel from the treatment of more acutely ill patients, leading to longer delays for those patients and hence to worsened crowding.10, 11, 17

The goal of this study is to test whether low-acuity ED patients delay the treatment of the higher-acuity patients. Our objectives were to determine whether the volume of ED patients with minor conditions is associated with, first, the length of stay of other ED patients and, second, the timeliness of treatment of other ED patients defined as the time to first physician assessment. Our hypothesis was that the volume of patients with minor conditions is not associated with delays for other patients. These results have policy relevance because measures designed to divert minor patients away from EDs are unlikely to reduce crowding unless they affect the treatment given to other patients.

Section snippets

Study Design and Setting

Previous studies on ED crowding suggested that causes could be divided into input, throughput, and output domains.18 Input factors include patient volume and case mix (reflected by age and sex, acuity of illness, mode of arrival in the ED), throughput factors include those influencing efficiency of assessment and treatment, and output factors include admission rates and the efficiency of disposition. Both throughput and output factors are reflected in total ED length of stay. Other factors that

Results

There were a total 4,771,092 visits to 173 EDs in the province, 86.1% of them to nonteaching hospitals. Sixty-three low-volume or specialized pediatric EDs were excluded, leaving 110 EDs (94 community and 16 teaching hospitals). Table 1 provides the demographic and presenting clinical data for the patients. A total of 760 records were excluded because of missing or invalid sex, age, length of stay, or triage data. Other records with missing or invalid health care numbers (n=165,310) or postal

Limitations

Our study is limited by several factors. There is no standard definition of a low-complexity patient28, 29; hence, we chose a definition based on features at presentation and disposition, which was intended to result in a more specific definition, not one that could be used prospectively to identify such patients. By design, our analysis considered only the effect of changes to the number of low-complexity patients presenting to EDs, given current ED staffing and resource configurations.

Discussion

Our results suggest that the number of patients presenting to EDs with minor illnesses and injuries has a negligible effect on the overall waiting times of other ED patients. In a typical 8-hour interval, a median of 16 new low-complexity ED patients presented for treatment, which is associated with an increase in mean ED length of stay of 8.6 minutes for non–low-complexity patients (representing a 4.2% increase) and a 3.4-minute increase in mean time to first physician contact (representing a

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    • Cited by (0)

    Supervising editor: David J. Magid, MD, MPH

    Author contributions: MJS originated the hypothesis, designed the study, and had main responsibility for interpreting the results and writing the manuscript. AK and J-PS helped design the study, conducted data analyses, and helped interpret the results and write the manuscript. AK organized a database and conducted data analyses. MJS takes responsibility for the paper as a whole.

    Funding and support: This study was funded by the Canadian Institutes for Health Research and the Social Sciences and Humanities Research Council of Canada.

    Reprints not available from the authors.

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    Copyright © 2007 American College of Emergency Physicians. Published by Mosby, Inc. All rights reserved.