Cardiology/original research
Emergency Department Triage of Acute Myocardial Infarction Patients and the Effect on Outcomes

https://doi.org/10.1016/j.annemergmed.2008.11.011Get rights and content

Study objective

More than half of all acute myocardial infarction patients still do not meet benchmark reperfusion times, and the triage assessment that all patients receive when they arrive at an emergency department (ED) is a hospital-level process that has not been studied as a potential contributor to delays. Our objective was to examine the triage of acute myocardial infarction patients (ST-elevation and non–ST elevation myocardial infarction) and determine whether it is associated with subsequent delays in acute myocardial infarction processes of care.

Methods

We conducted a retrospective cohort analysis of a population-based cohort of acute myocardial infarction patients admitted to 102 acute care hospitals in Ontario, Canada, from July 2000 to March 2001. Main outcome measures were the rate of low-acuity triage (defined as a Canadian Triage and Acuity Scale score of III, IV, or V) among acute myocardial infarction patients and its association with delays in time from ED arrival to initial ECG (door-to-ECG time) and to administration of fibrinolysis (door-to-needle time).

Results

Among 3,088 acute myocardial infarction patients, the rate of low acuity triage was 50.3%. Median door-to-ECG and door-to-needle time was 12.0 and 40.0 minutes, respectively. In adjusted quantile regression analyses, low-acuity triage was independently associated with a 4.4-minute delay in median door-to-ECG time and a 15.1-minute delay in median door-to-needle time. The adjusted odds of achieving benchmark door-to-ECG and door-to-needle times were 0.54 (95% confidence interval 0.46 to 0.65) and 0.44 (95% confidence interval 0.30 to 0.65), respectively, for acute myocardial infarction patients assigned a low-acuity ED triage score.

Conclusion

Half of acute myocardial infarction patients were given a low acuity triage score when they presented to an ED in Ontario, which was independently associated with substantial delays in ECG acquisition and to reperfusion therapy. The quality of ED triage may be an important factor limiting performance on key measures of quality of acute myocardial infarction care.

Introduction

Acute myocardial infarction remains a leading cause of mortality in the US1 despite numerous therapies known to increase survival.2, 3, 4, 5, 6 Given that 6 million patients with chest pain are evaluated in US emergency departments (EDs) each year,7 a key challenge is ensuring that acute myocardial infarction patients are appropriately identified and that time-sensitive treatments are rapidly administered. Currently, performance on key acute myocardial infarction quality measures,8, 9 such as time to reperfusion, exceeds the recommended benchmark time in more than half of all acute myocardial infarction patients.10, 11, 12, 13, 14, 15

The influence of ED systems factors on these acute myocardial infarction quality measures is not well understood. Virtually all patients who present to an ED are initially assessed by a trained triage nurse; despite potentially determining such crucial factors as the timing and the location of subsequent ED care,16 the effect of the ED triage score on acute myocardial infarction quality of care has not been studied, to our knowledge. In Canada, virtually all EDs17 use the Canadian Triage and Acuity Scale18 to perform ED triage. This uniformity provides an opportunity to study the effect of triage across a population level. Australia uses a similar tool,19 whereas in the United States several triage tools are used.20

Triage assessments may be an important modifiable factor influencing treatment delays for acute myocardial infarction patients. We hypothesized that a relatively small proportion of acute myocardial infarction patients are assigned a low-acuity triage score and that this would be associated with subsequent diagnostic and treatment delays. Because the ED is a complex environment, however, a low triage score may not automatically result in fixed delays: a previous study on ED triage found that patients who are given a triage score of III actually wait longer to see a physician than those who receive a IV or V.21 Nor is it known to what extent triage delays acute myocardial infarction management, if it does. Our objectives in this study were to establish the frequency of low triage scores among acute myocardial infarction patients presenting to EDs in Ontario, Canada, and to determine the magnitude of the effect of a low ED triage score on time to ECG and time to reperfusion.

Section snippets

Study Design

This retrospective cohort study linked a population-based sample of acute myocardial infarction patients to an administrative database of all ED records in the province of Ontario, Canada, from July 2000 to March 2001, the period during which the 2 data sets overlapped. We obtained ethics approval from Sunnybrook Health Sciences Centre.

Setting

The Enhanced Feedback For Effective Cardiac Treatment (EFFECT) study contains a population-based sample of acute myocardial infarction patients from the province

Results

We linked inhospital records to ED visits for 3,088 (73.4%) of 4,210 acute myocardial infarction patients in EFFECT. Baseline characteristics of the entire study cohort are provided in Table 1. Of the 3,088 acute myocardial infarction patients, 1,552 (50.3%) were assigned a low acuity triage score. Almost half of the cohort had criteria for a STEMI (47.9%). The median door-to-ECG time for the cohort was 12.0 minutes (interquartile range [IQR] 5.0 to 24.0), and the median door-to-needle time for

Limitations

One limitation of this study was the use of only admitted acute myocardial infarction patients. This probably results in a conservative bias because we did not capture the patients who were discharged home from the ED (ie, their acute myocardial infarction was missed entirely), which might occur more frequently in acute myocardial infarction patients who are given a low-acuity triage score. Another limitation was retrospective data collection, with some of the inherent limitations of chart

Discussion

This population-based study of acute myocardial infarction patients in the province of Ontario found that half of all acute myocardial infarction patients, including 44% who had criteria for a STEMI, were assigned an inappropriately low triage score when they arrived in an ED. Low acuity triage score assignment was associated with substantial independent increases in median and 90th percentile door-to-ECG and door-to-needle times, including a 15-minute increase in median door-to-needle time and

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    Supervising editor: Judd E. Hollander, MD

    Author contributions: CLA had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. CLA, PCA, JVT, and MJS concieved the study and design. JVT acquired and managed the data, and CLA and PCA performed the statistical analysis. CLA, PCA, and MJS interpreted the data. CLA and MJS drafted the article, and and all authors contributed substantially to its revision. CLA, JVT, and MJS obtained funding for the project. CLA takes responsibility for the paper as a whole.

    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 that might create any potential conflict of interest. See the Manuscript Submission Agreement in this issue for examples of specific conflicts covered by this statement. This project was supported in part by a Canadian Insitutes of Health Research (CIHR) Team Grant in Cardiovascular Outcomes Research and by an operating grant from the Heart and Stroke Foundation of Ontario (NA5703). Dr. Atzema was supported by a Fellowship Award from CIHR, and Dr. Schull was supported by a New Investigator Award from CIHR. Dr. Tu was supported by a Canada Research Chair in Health Services Research and by a Career Investigator award from the Heart and Stroke Foundation of Ontario. The Canadian Insitutes of Health Research and the Heart and Stroke Foundation of Ontario had no involvement in the design or conduct of the study, data management or analysis, or article preparation, review, or authorization for submission.

    Publication date: Available online January 21, 2009.

    Reprints not available from the authors.

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