The practice of emergency medicine/systematic review/meta-analysis
Triage Performance in Emergency Medicine: A Systematic Review

https://doi.org/10.1016/j.annemergmed.2018.09.022Get rights and content

Study objective

Rapid growth in emergency department (ED) triage literature has been accompanied by diversity in study design, methodology, and outcome assessment. We aim to synthesize existing ED triage literature by using a framework that enables performance comparisons and benchmarking across triage systems, with respect to clinical outcomes and reliability.

Methods

PubMed, EMBASE, Scopus, and Web of Science were systematically searched for studies of adult ED triage systems through 2016. Studies evaluating triage systems with evidence of widespread adoption (Australian Triage Scale, Canadian Triage and Acuity Scale, Emergency Severity Index, Manchester Triage Scale, and South African Triage Scale) were cataloged and compared for performance in identifying patients at risk for mortality, critical illness and hospitalization, and interrater reliability. This study was performed and reported in adherence to Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines.

Results

A total of 6,160 publications were identified, with 182 meeting eligibility criteria and 50 with sufficient data for inclusion in comparative analysis. The Canadian Triage and Acuity Scale (32 studies), Emergency Severity Index (43), and Manchester Triage Scale (38) were the most frequently studied triage scales, and all demonstrated similar performance. Most studies (6 of 8) reported high sensitivity (>90%) of triage scales for identifying patients with ED mortality as high acuity at triage. However, sensitivity was low (<80%) for identification of patients who had critical illness outcomes and those who died within days of the ED visit or during the index hospitalization. Sensitivity varied by critical illness and was lower for severe sepsis (36% to 74%), pulmonary embolism (54%), and non–ST-segment elevation myocardial infarction (44% to 85%) compared with ST-segment elevation myocardial infarction (56% to 92%) and general outcomes of ICU admission (58% to 100%) and lifesaving intervention (77% to 98%). Some proportion of hospitalized patients (3% to 45%) were triaged to low acuity (level 4 to 5) in all studies. Reliability measures (κ) were variable across evaluations, with only a minority (11 of 42) reporting κ above 0.8.

Conclusion

We found that a substantial proportion of ED patients who die postencounter or are critically ill are not designated as high acuity at triage. Opportunity to improve interrater reliability and triage performance in identifying patients at risk of adverse outcome exists.

Introduction

Triage, a concept developed and refined on the battlefield, has been central to the practice of emergency medicine for more than half a century.1 As emergency departments (EDs) face escalating patient volumes,2 persistent crowding,3 and patient populations with more complex disease,4 the need for accurate and reliable triage has intensified. This has spurred the development and rapid adoption of a set of standardized triage systems designed to structure the triage decisionmaking process. Triage systems with published evidence of widespread adoption include the Australasian Triage Scale (ATS),5 Canadian Triage and Acuity Scale (CTAS),6 Emergency Severity Index (ESI),7 Manchester Triage Scale (MTS),8 and South African Triage Scale (SATS).9

Editor’s Capsule Summary

What is already known on this topic

Numerous emergency department (ED) triage scales exist to prioritize the immediacy with which patients should be treated.

What question this study addressed

This study examined the reliability, as well as the sensitivity and specificity of predicting mortality (ED, inhospital, 1 day, and 7 days after the ED visit), critical illness, and hospitalization for 5 ED triage scales.

What this study adds to our knowledge

Not enough studies with similar methodology exist to compare the scales' validity for the outcomes identified. None of the scales demonstrated consistently high reliability.

How this is relevant to clinical practice

More studies are needed to compare the performance of ED triage scales for clinically important outcomes and within different ED patient populations.

These standardized triage systems share core elements (Table 1): their objective is to identify and prioritize patients with critical time-sensitive care needs; all deploy a 5-level classification scheme, a general practice endorsed by the American College of Emergency Physicians (ACEP) and Emergency Nursing Association10; all set targets for timeliness to physician contact per triage level; all were developed through provider group consensus; and they universally rely on some level of subjective judgment by trained triage providers to execute.

Despite their shared characteristics, there is substantial divergence in approach. The degree of reliance on provider judgment varies considerably by triage system. For example, the CTAS and MTS are on the prescriptive end of the spectrum, translating detailed clinical discriminators and vital sign combinations to specific triage levels. In comparison, the user-friendly ESI provides higher-level guidance with some vital sign–based recommendations, lending itself to heavier dependence on triage provider intuition. The ESI is also the only major triage system to incorporate projected resource use into triage decisionmaking with patient flow in mind. Furthermore, the ATS (Australia), CTAS (Canada), ESI (United States), and MTS (United Kingdom) were developed for use in high-resource settings, whereas only the SATS (South Africa) considers resource-limited environments.9 These triage system differences and variability in published evaluations (evaluation design, outcomes, and analytic methods) significantly limit the collective value of a large and rapidly increasing body of emergency medicine triage literature. Although several reviews on the topic have been performed, to our knowledge none have explored this variability or proposed a framework to facilitate standardization of study design and reporting.

The primary objective of this systematic review was to characterize the most commonly studied ED triage systems across the globe and to evaluate their performance with respect to identifying clinical outcomes and reliability. The goal was to develop and apply a framework to compare scientific evaluations of ED triage to establish a foundation to benchmark assessments of triage for both research and quality improvement across triage systems, and to illuminate evidence and gaps in performance of specific triage systems generally, and among particular demographic and clinical subpopulations treated in the ED.

Section snippets

Selection of Participants

Published articles were identified by a systematic search of PubMed, EMBASE, Scopus, and Web of Science, including all articles through December 31, 2016, using the search terms detailed in Appendix E1 (available online at http://www.annemergmed.com). Abstracts for original research were screened for study inclusion with the following eligibility criteria: the triage system studied was designed for use in an ED, and the triage system assessed was intended for application in a clinically

Results

The database search strategy yielded 6,160 unique publications for screening, with 182 (3%) meeting overarching eligibility criteria (Figure 1). Interrater agreement between the 3 screening authors was good (κ=0.77; 95% confidence interval 0.74 to 0.80). Of the 182 eligible studies, a major 5-level triage system was evaluated in 73% of them: ATS (14 studies), CTAS (32), ESI (43), MTS (38), and SATS (12). The countries where triage evaluation was most frequently performed included the United

Limitations

There were several limitations to our systematic review. First, only studies available through our search engines and criteria were available to review. This excluded any data, write-ups, or presentations not reported in a scientific journal article and introduced potential for publication bias. This also excluded all non-English literature, biasing the geography of study sites to English-speaking countries. However, all 5 of the widely adopted triage systems were developed in English, and the

Discussion

Triage remains a central process for safe management of patients under circumstances of excess demand common in many EDs. Increases in patient volume in developed countries and new evolving emergency care systems in developing countries, particularly in population epicenters, stress the need for more accurate and reliable triage. As a result, the body of scientific literature evaluating ED triage has increased (Figure 2).

The purpose of this systematic review was to introduce a framework for

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    Please see page 141 for the Editor’s Capsule Summary of this article.

    Supervising editor: Melissa L. McCarthy, ScD, MS

    Author contributions: SL conceived and designed the study. JSH, SC, KG, and SL performed literature review and data extraction. MW and BH provided content expertise and advice on the study design. DAM performed data analysis and data visualization. JSH and SL drafted the article, and all authors contributed to its revision. JSH takes responsibility for the paper as a whole.

    All authors attest to meeting the four ICMJE.org authorship criteria: (1) Substantial contributions to the conception or design of the work; or the acquisition, analysis, or interpretation of data for the work; AND (2) Drafting the work or revising it critically for important intellectual content; AND (3) Final approval of the version to be published; AND (4) Agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

    Funding and support: By Annals policy, all authors are required to disclose any and all commercial, financial, and other relationships in any way related to the subject of this article as per ICMJE conflict of interest guidelines (see www.icmje.org). This work was funded by grant R21HS023641 from the Agency for Healthcare Research and Quality. Dr. Levin is an engineer and the owner of a start-up company, StoCastic, LLC, that has developed several machine-learning and electronic health record-based tools to improve patient safety and throughput throughout the hospital, including a tool that aims to improve reliability of ED triage. Dr. Hinson serves as a consultant for StoCastic, LLC.

    The content is solely the responsibility of the authors and does not necessarily represent the official views of Johns Hopkins or the Agency for Healthcare Research and Quality.

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