Performance and potential impact of a chest pain prediction rule in a large public hospital

Emergency physicians’ attitudes toward a clinical prediction rule for the identification and early discharge of low risk patients with chest discomfort

Objectives:

To determine Canadian emergency physicians’ estimates regarding the safety and efficiency of chest discomfort management in their emergency department (ED), and their attitudes toward and perception of the need for a chest discomfort clinical prediction rule that identifies very low risk patients who are safe to discharge after a brief ED assessment.

Methods:

300 members of the Canadian Association of Emergency Physicians (CAEP) were randomly selected to receive a confidential mail survey, which invited them to provide information on current disposition of patients with chest discomfort and their opinions regarding the value of a clinical prediction rule to identify patients with chest discomfort who are safe to discharge after a brief (~2 hour) assessment.

Results:

Of the 300 physicians selected, 288 were eligible for the survey and 235 (82%) responded. Only 5% follow discharged patients to measure safe practice. Overall, 165 (70%) felt the proposed prediction rule would be very useful and 43 (18%) felt it would be useful. Almost all (94%) believed a prediction rule would be useful if it identified patients safe for discharge without increasing the current rate of missed acute myocardial infarction (estimated at 2%). Most respondents (59%) believed that a clinical prediction rule should suggest a course of action, while 30% felt it should convey a probability of disease.

Conclusions:

Canadian emergency physicians support the concept of a clinical prediction rule for the early discharge of patients with chest discomfort. Most believe that such a rule would be useful if it identified patients who are safe for discharge after a brief assessment, while maintaining current levels of safety. Future research should be aimed at deriving a clinical prediction rule to identify low risk patients who can be safely discharged after a limited emergency department evaluation.

A study to derive a clinical decision rule for triage of emergency department patients with chest pain: design and methodology

BACKGROUND

Chest pain is the second most common chief complaint in North American emergency departments. Data from the U.S. suggest that 2.1% of patients with acute myocardial infarction and 2.3% of patients with unstable angina are misdiagnosed, with slightly higher rates reported in a recent Canadian study (4.6% and 6.4%, respectively). Information obtained from the history, 12-lead ECG, and a single set of cardiac enzymes is unable to identify patients who are safe for early discharge with sufficient sensitivity. The 2007 ACC/AHA guidelines for UA/NSTEMI do not identify patients at low risk for adverse cardiac events who can be safely discharged without provocative testing. As a result large numbers of low risk patients are triaged to chest pain observation units and undergo provocative testing, at significant cost to the healthcare system. Clinical decision rules use clinical findings (history, physical exam, test results) to suggest a diagnostic or therapeutic course of action. Currently no methodologically robust clinical decision rule identifies patients safe for early discharge.

METHODS/DESIGN

The goal of this study is to derive a clinical decision rule which will allow emergency physicians to accurately identify patients with chest pain who are safe for early discharge. The study will utilize a prospective cohort design. Standardized clinical variables will be collected on all patients at least 25 years of age complaining of chest pain prior to provocative testing. Variables strongly associated with the composite outcome acute myocardial infarction, revascularization, or death will be further analyzed with multivariable analysis to derive the clinical rule. Specific aims are to: i) apply standardized clinical assessments to patients with chest pain, incorporating results of early cardiac testing; ii) determine the inter-observer reliability of the clinical information; iii) determine the statistical association between the clinical findings and the composite outcome; and iv) use multivariable analysis to derive a highly sensitive clinical decision rule to guide triage decisions.

DISCUSSION

The study will derive a highly sensitive clinical decision rule to identify low risk patients safe for early discharge. This will improve patient care, lower healthcare costs, and enhance flow in our busy and overcrowded emergency departments.

A clinical prediction rule for early discharge of patients with chest pain

STUDY OBJECTIVE

Current risk stratification tools do not identify very-low-risk patients who can be safely discharged without prolonged emergency department (ED) observation, expensive rule-out protocols, or provocative testing. We seek to develop a clinical prediction rule applicable within 2 hours of ED arrival that would miss fewer than 2% of acute coronary syndrome patients and allow discharge within 2 to 3 hours for at least 30% of patients without acute coronary syndrome.

METHODS

This prospective, cohort study enrolled consenting eligible subjects at least 25 years old at a single site. At 30 days, investigators assigned a diagnosis of acute coronary syndrome or no acute coronary syndrome according to predefined explicit definitions. A recursive partitioning model included risk factors, pain characteristics, physical and ECG findings, and cardiac marker results.

RESULTS

Of 769 patients studied, 77 (10.0%) had acute myocardial infarction and 88 (11.4%) definite unstable angina. We derived a clinical prediction rule that was 98.8% sensitive and 32.5% specific. Patients have very low risk of acute coronary syndrome if they have a normal initial ECG, no previous ischemic chest pain, and age younger than 40 years. In addition, patients at least 40 years old and with a normal ECG result, no previous ischemic chest pain, and low-risk pain characteristics have very low risk if they have an initial creatine kinase-MB (CK-MB) less than 3.0 microg/L or an initial CK-MB greater than or equal to 3.0 microg/L but no ECG or serum-marker increase at 2 hours.

CONCLUSION

The Vancouver Chest Pain Rule for early discharge defines a group of patients who can be safely discharged after a brief evaluation in the ED. Prospective validation is needed.

Are we appropriately triaging patients with unstable angina?

BACKGROUND

It is uncertain how aggressively patients should be monitored and admitted to the hospital for chest pain syndromes and if the monitoring itself affects patient care, process, or outcomes. We assessed the appropriateness of care based on retrospective analysis of admission bed assignment (nonmonitored vs monitored) and Thrombolysis in Myocardial Infarction (TIMI) risk score in patients from the Global Unstable Angina Registry and Treatment Evaluation (GUARANTEE) Registry.

METHODS

Baseline characteristics, process of care, and outcomes were compared among 2939 patients admitted to 1 of 35 hospitals in the United States. Patients were stratified into low (0-2), intermediate (3 or 4), and high (5-7) risk based on TIMI risk score.

RESULTS

Among the patients, 92 (3%) were admitted to the cardiac care unit (CCU), 1602 (56%) were admitted to the telemetry unit, and 1163 (41%) were admitted to an unmonitored bed. Paradoxically, high-risk patients comprised only 1% of those in the CCU, 5% of those in telemetry, and 10% of those in nonmonitored units. Conversely, low-risk patients were 64% of those in the CCU, 53% of those in telemetry, and 42% of those in unmonitored beds. Procedures were done more often on patients admitted to nonmonitored units than those on telemetry or in the CCU irrespective of TIMI risk score.

CONCLUSIONS

This registry suggests that triage of patients does not routinely follow the risk-based approach suggested in the American College of Cardiology and American Heart Association guidelines and could therefore potentially lead to inefficiencies in care. Better implementation of risk stratification for acute coronary syndrome evaluation and management is necessary.

Clinical features in the emergency department can identify patients with suspected acute coronary syndromes who are safe for care in unmonitored hospital beds

BACKGROUND

Standard practice for patients requiring hospital admission with suspected acute coronary syndromes (ACS) is admission to a monitored cardiology bed. The Western Hospital Chest Pain Protocol was developed to identify a subset of these patients who could be safely managed in an unmonitored bed.

AIM

The objective of this prospective study of chest pain patients classified as 'high' or 'intermediate' risk by the Agency for Health Care Policy and Research/National Health and Medical Research Council guidelines was to further evaluate the safety of this protocol.

METHODS

This study was a prospective, observational, cohort study investigating the outcomes of patients admitted to hospital with suspected ACS. The primary outcome of interest was death or life-threatening arrhythmia within 24 h of hospital admission.

RESULTS

If the Western Hospital Chest Pain Protocol had been strictly applied, there would have been one death in the group assigned to unmonitored beds (1/750; 0.13%, 95% confidence interval 0.01-0.85%) and no other life-threatening arrhythmias.

CONCLUSION

There is a subgroup of patients with suspected ACS who require hospital admission who can, based on clinical and biochemical features in the emergency department, be safely assigned to unmonitored beds.

Bedside diagnosis of coronary artery disease: a systematic review

PURPOSE

To assess the accuracy of bedside findings for diagnosing coronary artery disease and acute myocardial infarction.

METHODS

A MEDLINE search was performed to retrieve articles published from January 1966 to January 2003 that were relevant to the bedside diagnosis of coronary disease in adults.

RESULTS

In patients with stable, intermittent chest pain, the most useful bedside predictors for a diagnosis of coronary disease were found to be the presence of typical angina (likelihood ratio [LR]=5.8; 95% confidence interval [CI]: 4.2 to 7.8), serum cholesterol level >300 mg/dL (LR=4.0; 95% CI: 2.5 to 6.3), history of prior myocardial infarction (LR=3.8; 95% CI: 2.1 to 6.8), and age >70 years (LR=2.6; 95% CI: 1.8 to 4.0). Nonanginal chest pain (LR=0.1; 95% CI: 0.1 to 0.2), pain duration >30 minutes (LR=0.1; 95% CI: 0.0 to 0.9), and intermittent dysphagia (LR=0.2; 95% CI: 0.1 to 0.8) argued against a diagnosis of coronary disease. In patients with acute chest pain, the most important bedside predictors for a diagnosis of myocardial infarction were new ST elevation (LR=22; 95% CI: 16 to 30), new Q waves (LR=22; 95% CI: 7.6 to 62), and new ST depression (LR=4.5; 95% CI: 3.6 to 5.6). A normal electrocardiogram (LR=0.2; 95% CI: 0.1 to 0.3), chest wall tenderness (LR=0.3; 95% CI: 0.2 to 0.4), and pain that was pleuritic (LR=0.2; 95% CI: 0.2 to 0.3), sharp (LR=0.3; 95% CI: 0.2 to 0.5), or positional (LR=0.3; 95% CI: 0.2 to 0.5) argued against the diagnosis of myocardial infarction.

CONCLUSION

The accuracy of bedside predictors depends on the clinical setting. In the evaluation of stable, intermittent chest pain, a patient's description of pain was found to be the most important predictor of underlying coronary disease. In the evaluation of acute chest pain, the electrocardiogram was the most useful bedside predictor for a diagnosis of myocardial infarction. Aside from the extremes in cholesterol values, the analysis of traditional risk factors changed the probability of coronary disease or myocardial infarction very little or not at all.

Triage of patients with chest pain in the emergency department: a comparative study of physicians' decisions

PURPOSE

Little is known about physicians' triage decisions for patients with chest pain in the emergency department. We sought to understand better the variability and accuracy of physicians' triage decisions.

SUBJECTS AND METHODS

We used 20 simulated cases to compare triage decisions by 147 physicians (46 emergency medicine, 87 internal medicine, and 14 cardiology physicians) with triage decisions recommended by a previously validated prediction rule. We calculated triage sensitivity and specificity using the prediction rule to estimate the likelihood that each of the simulated patients would suffer a major complication. Triage sensitivity was defined as the proportion of all patients expected to have major complications who were triaged to the coronary care or inpatient telemetry unit.

RESULTS

Triage specificity was defined as the proportion of all patients without complications who were triaged to sites other than the coronary care or inpatient telemetry unit.Physicians' triage decisions were less sensitive (85% vs. 96%, P <0.001) and less specific (38% vs. 41%, P = 0.02) than decisions recommended by the prediction rule. Physicians overestimated patients' risk of complications and triaged more patients to inpatient monitored beds. Despite their preference for inpatient monitored beds, physicians' decisions would have resulted in four times as many major complications in patients who were not triaged to inpatient monitored beds, compared with decisions recommended by the prediction rule (2.4% vs. 0.6%, P <0.001). Although physicians' decisions were best explained by their provisional diagnoses, interphysician agreement about triage decisions (kappa = 0.34) and diagnosis (kappa = 0.31) was only fair.

CONCLUSIONS

In simulated cases, physicians' triage decisions varied widely and their predictions of patient outcomes differed markedly from that of the validated prediction rule, suggesting that use of the prediction rule in the emergency department could improve physicians' decisions and patients' outcomes.

It is safe to manage selected patients with acute coronary syndromes in unmonitored beds

This prospective, observational study evaluated the safety of the Western Hospital admission protocol for patients with suspected acute coronary syndromes. The study included all patients admitted from the Emergency Department with an admission diagnosis of unstable angina, post infarct angina, atypical chest pain, or chest pain for evaluation. Data collected included demographic data, admission diagnosis, location of admission (bed with or without cardiac monitoring), past medical history and presenting chest pain history to determine Agency for Health Care Policy (AHCPR) and Western Hospital (WH) protocol classifications, cardiac enzyme assays, electrocardiogram analysis, adverse outcomes [death, myocardial infarction (MI), dysrhythmia, acute pulmonary edema, recurrent pain], diagnosis at hospital discharge, and length of stay-(LOS). There were 508 patients with a mean age of 63.7 years enrolled in the study. Three hundred nineteen (62.8%) were admitted to beds without any cardiac monitoring. There was one unexpected death in the unmonitored group, an 85 year-old patient who suffered a presumed dysrhythmia and whom the treating physician had decided was not for resuscitation. Twelve patients suffered nonfatal MI, and none suffered pulmonary edema. All MI patients made an uneventful recovery, and none required thrombolysis. If all patients had been admitted to an area of care based on AHCPR guidelines, an additional 310 admissions to monitored beds would have been required. The results of this study suggest that selected patients with suspected acute coronary syndromes can be safely managed in beds without continuous cardiac monitoring.

Emergency department admissions to inpatient cardiac telemetry beds: a prospective cohort study of risk stratification and outcomes

PURPOSE

Little is known about physicians' use of inpatient cardiac telemetry units among emergency department patients at risk for cardiac complications. We therefore studied the outcomes of patients admitted to inpatient telemetry beds to identify a subset of patients from whom cardiac monitoring could be withheld safely.

SUBJECTS AND METHODS

We conducted a prospective cohort study of 1, 033 consecutive adult patients admitted to an inpatient telemetry unit from the emergency department of a 700-bed urban public teaching hospital. Subjects with or without chest pain were risk-stratified using a prediction rule and observed for in-hospital cardiac complications, acute myocardial infarction, and transfer to an intensive care unit (ICU).

RESULTS

There were no significant differences between patients with (n = 677) or patients without chest pain (n = 356) in the rates of major cardiac complications, myocardial infarctions, or transfers to an ICU. Among 318 patients with chest pain who were classified as being very low risk, none suffered major complications (negative predictive value 100%; 95% confidence interval [CI]: 98.8% to 100%). Among 214 very low risk patients without chest pain, 1 (0.5%) had a major complication (negative predictive value 99.5%; 95% CI: 97.4% to 99.9%).

CONCLUSIONS

The prediction rule accurately identified patients with or without chest pain who were at very low risk of major complications, identifying a subset from whom cardiac monitoring could be withheld safely.