How many myocardial infarctions should we rule out?

Systematic Review of Economic Evaluations of Units Dedicated to Acute Coronary Syndromes

BACKGROUND

Dedicated units for the care of acute coronary syndrome (ACS) have been submitted to economic evaluations; however, the results have not been systematically presented.

OBJECTIVE

To identify and summarize economic outcomes of studies on hospital units dedicated to the initial care of patients with suspected or confirmed ACS.

METHODS

A systematic review of literature to identify economic evaluations of chest pain unit (CPU), coronary care unit (CCU), or equivalent units was done. Two search strategies were used: the first one to identify economic evaluations irrespective of study design, and the second one to identify randomized clinical trials that reported economic outcomes. The following databases were searched: MEDLINE, EMBASE, CENTRAL, and National Health Service (NHS)Economic Evaluation Database. Data extraction was performed by two independent reviewers. Costs were inflated to 2012 values.

RESULTS

Search strategies retrieved five partial economic evaluations based on observational studies, six randomized clinical trials that reported economic outcomes, and five model-based economic evaluations. Overall, cost estimates based on observational studies and randomized clinical trials reported statistically significant cost savings of more than 50% with the adoption of CPU care instead of routine hospitalization or CCU care for suspected low-to-intermediate risk patients with ACS (median per-patient cost US $1,969.89; range US $1,002.12-13,799.15). Model-based economic evaluations reported incremental cost-effectiveness ratios below US $ 50,000/quality-adjusted life-year for all comparisons between intermediate care unit, CPU, or CCU with routine hospital admissions. This finding was sensible to myocardial infarction probability.

CONCLUSIONS

Published economic evaluations indicate that more intensive care is likely to be cost-effective in comparison to routine hospital admission for patients with suspected ACS.

Costs and outcomes of patients admitted with chest pain and essentially normal electrocardiograms

BACKGROUND

Although inroads have been made in the outpatient evaluation of chest pain, the majority of hospitals in the United States do not have chest pain centers and the direct costs associated with hospital admissions in low-risk patients is unknown.

HYPOTHESIS

The study was undertaken to evaluate the cost and outcomes of admission to the hospital for patients with acute chest pain and essentially normal electrocardiograms (ECGs).

METHODS

For that purpose, we reviewed 1,670 patients presenting to our emergency department with chest pain over a 5-month period in 1994. Of these, 567 [34.0%, confidence interval (CI) 95%, 31.7-36.3%] patients were considered to be low risk by ECG criteria alone.

RESULTS

Complete clinical and financial data were available in 445 cases of which 152 had a previous history of coronary artery disease (CAD) and 31 (7.0%, CI 95%, 4.9-9.6%) were ultimately proven to have acute myocardial infarction (AMI). There were no deaths. All patients initially underwent noninvasive evaluation, and an additional 177 (39.8%) underwent subsequent cardiac catheterization. Of those, 107 (60.5%) had significant CAD (at least one vessel > 70% stenosis). We assumed an expected mortality rate of 1% in the AMI group based on previously reported series with all the mortalities preventable by hospitalization. This yielded a valuation of $1.7 million dollars per life saved. Sensitivity analysis revealed the practice of admission and in-patient evaluation for this group of patients was cost ineffective at all assumption levels.

CONCLUSION

The practice of hospital admission for patients with chest pain and essentially normal ECGs is not cost favorable, and all hospital facilities should consider outpatient chest pain evaluation strategies.

Direct hospital costs of chest pain patients attending the emergency department: a retrospective study

Background

Chest pain is one of the most common complaints in the Emergency Department (ED), but the cost of ED chest pain patients is unclear. The aim of this study was to describe the direct hospital costs for unselected chest pain patients attending the emergency department (ED).

Methods

1,000 consecutive ED visits of patients with chest pain were retrospectively included. Costs directly following the ED visit were retrieved from the hospital economy system.

Results

The mean cost per patient visit was 26.8 thousand Swedish kronar (kSEK) (median 7.2 kSEK), with admission time accounting for 73% of all costs. Mean cost for patients discharged from the ED was 1.4 kSEK (median 1.3 kSEK), and for patients without ACS admitted 1 day or less 7.6 kSEK (median 6.9 kSEK). The practice in the present study to admit 67% of the patients, of whom only 31% proved to have ACS, was estimated to give a cost per additional life-year saved by hospital admission, compared to theoretical strategy of discharging all patients home, of about 350 kSEK (39 kEUR or 42 kUSD).

Conclusion

Costs for chest pain patients are large and primarily due to admission time. The present admission practice seems to be cost-effective, but the substantial overadmission indicates that better ED diagnostics and triage could decrease costs considerably.

How to find evidence when you need it, part 4: Matching clinical questions to appropriate databases

Practitioners seeking enhancement of clinical care through consideration of research require rapid and efficient point-of-care access to current studies and summaries pertaining to specific clinical queries. MEDLINE and other large databases usually contain the citations relevant to such questions but frequently fall short of the practical requirements of busy clinicians. We present a summary of the knowledge and skills required for physicians to select and use smaller databases appropriate to particular types of questions arising from emergency care. We outline a step-by-step approach that begins at the bedside with the sorting of questions into appropriate categories of knowledge and research design. We identify commonly encountered pitfalls in the process of connecting a particular question to an appropriate database. We illustrate the approach through a set of demonstration questions pertaining to patients presenting to emergency departments with chest pain consistent with acute coronary ischemia. We describe a selection of resources and databases and summarize their performance in locating articles relevant to the demonstration questions.

Principles of observation medicine

The defining characteristic of emergency medicine is "time," or the acuity of disease presentation. Observation, like resuscitation, involves the management of time-sensitive conditions. In the ED there is a continuum of time-sensitive conditions. This continuum extends from resuscitation on one end to observation on the other. When performed well, observation services have been shown to improve diagnostic accuracy, improve treatment outcomes, decrease costs, and improve patient satisfaction. For the subset of ED patients who would have been inappropriately discharged or unnecessarily admitted, the OU has become a safety net of the ED itself. Like EDs, OUs have progressed from being poorly managed areas of the hospital to the cutting edge of acute health care. The principles developed through past experience and research provide a framework for future developments in emergency medicine.

Implementing emergency department observation units within a multihospital network

BACKGROUND

The proportion of emergency department (ED) chest pain patients who undergo an extended "rule out MI (myocardial infarction)" evaluation beyond the ED determines both the quality and cost of patient care. The higher an organization's rate of such evaluations, the lower the average miss rate for MI. Five of the 13 hospitals in the Voluntary Hospital Association Northeast multihospital network implemented ED observation units by June 1997 for outpatient rule out MI evaluations.

RESULTS

Compared with historical and case controls, the five hospitals with ED observation units had a higher observation rate (16% versus 0% [p < .001] and 2% [p < .001]) and a higher rule out MI evaluation rate (61% versus 46% [p < .01] and 45% [p < .01]), without a significantly higher admission rate (47% versus 46% and 45%). For the three hospitals with observation units that collected charge data during 1997 on a consecutive series of chest pain patients who had negative rule out MI evaluations, charges for patient services were lower for patients evaluated in the ED observation unit ($2,214.80 +/- $80.40) than in the hospital ($5,464.30 +/- $393.60).

CONCLUSIONS

ED observation units represent a cost-effective restructuring of the diagnostic approach to patients with acute chest pain. In an improvement of quality of patient care, a larger proportion of ED chest pain patients receive an extended evaluation than is possible with hospital admission as the only ED disposition option.

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

PURPOSE

To evaluate the performance of a previously validated prediction rule for patients presenting to the emergency department with chest pain and the potential impact of the rule on triage decisions.

SUBJECTS AND METHODS

In a prospective cohort study, physician investigators interviewed consecutive patients admitted for suspected acute ischemic heart disease (n = 207) by emergency department attending physicians who had not used the prediction rule. We measured the accuracy of the rule in predicting cardiac complications in these patients, and compared actual triage decisions with those that might have been recommended by use of the prediction rule. We also measured comorbid illnesses among patients stratified as very low risk by the prediction rule, as well as the effect of standardizing the definition of unstable angina and interpretation of electrocardiograms (ECG) on the rule's sensitivity and specificity.

RESULTS

Overall, the rate of major cardiac complications (4.3%) was similar to that reported in the original study (3.6%). The prediction rule performed well in predicting these complications in our patients (area under receiver operating characteristic curve 0.84 versus 0.80 in the original study; difference 0.04, 95% confidence interval [CI] -0.07, 0.14). Standardized definitions of unstable angina and interpretation of ECGs improved the specificity of the prediction rule in predicting complications (55% versus 47%; difference 8%, 95% CI 1.5%, 13.7%). The prediction rule recommended admission to telemetry units in 65 fewer patients than actually occurred (31% of the entire cohort). None of these patients had major complications. A substantial minority of "very low risk" patients (27%) had comorbid illnesses requiring inpatient treatment.

CONCLUSIONS

This independent validation of the prediction rule suggests that it can improve triage decisions for patients admitted with suspected acute ischemic heart disease. Additional studies are needed to test prospectively the performance of the prediction rule in actual decision making, its acceptance by clinicians, and its cost effectiveness.

Use of electron-beam computed tomography in the evaluation of chest pain patients in the emergency department

STUDY OBJECTIVE

We sought to determine whether electron-beam computed tomography (EBCT) could be used as a triage tool in the emergency department for patients with angina-like chest pain, no known history of coronary disease, normal or indeterminate ECG findings, and normal initial cardiac enzyme concentrations.

METHODS

We conducted a prospective observational study of 105 patients admitted between December 1995 and October 1997 to the ED of a large tertiary care hospital with 70,000 annual ED visits. The study group was comprised of women aged 40 to 65 years and men aged 30 to 55 years who presented with angina-like chest pain requiring admission to the hospital or chest pain observation unit. All patients underwent EBCT of the coronary arteries, along with other cardiac testing as deemed necessary by staff physicians.

RESULTS

Of the 105 patients, 100 underwent other cardiac testing during hospitalization. Evaluation included treadmill exercise testing in 58, coronary angiography in 25, radionuclide stress testing in 19, and echocardiography in 11. Results of EBCT and cardiac testing were negative for both in 53 patients (53%), positive for both in 14 (14%), positive for tomography and negative for cardiac testing in 32 (32%), and negative for tomography and positive for cardiac testing in only 1 patient. This positive test result, on a treadmill exercise test, was ruled a false positive by an independent staff cardiologist. Two other female patients with normal exercise sestamibi or coronary angiography and EBCT findings also had false-positive treadmill exercise results. The sensitivity of EBCT was 100% (95% confidence interval, 77% to 100%), with a negative predictive value of 100% (95% confidence interval, 94% to 100%). Specificity was 63% (95% confidence interval, 54% to 75%).

CONCLUSION

EBCT is a rapid and efficient screening tool for patients admitted to the ED with angina-like chest pain, normal cardiac enzyme concentrations, indeterminate ECG findings, and no history of coronary artery disease. Our study suggests that patients with normal initial cardiac enzyme concentrations, normal or indeterminate ECG findings, and negative results on EBCT may be safely discharged from the ED without further testing or observation. Larger studies are required to confirm this conclusion.

Development of new methods to assess the outcomes of emergency care

This article provides information supporting the need for new outcome measures in emergency care. It also addresses the use of outcome measures in emergency care, the impact of emergency care, identification of at-risk groups, new approaches to measuring patient satisfaction, quality of life and cost-effectiveness, and the unique related implications for emergency medicine.

Development of new methods to assess the outcomes of emergency care

This article provides information supporting the need for new outcome measures in emergency care. It also addresses the use of these measures in emergency care, the impact of emergency care, identification of at-risk groups, new approaches to measuring patient satisfaction, quality of life, and cost-effectiveness, and the related unique implications for emergency medicine.

Evaluation of chest pain in the emergency department

The evaluation of chest pain in the emergency setting should be systematic, risk based, and goal driven. An effective program must be able to evaluate all patients with equal thoroughness under the assumption that any patient with chest pain could potentially be having an MI. The initial evaluation is based on the history, a focused physical examination, and the ECG. This information is sufficient to categorize patients into groups at high, moderate, and low risk. Table 14 is a template for a comprehensive chest-pain evaluation program. Patients at high risk need rapid initiation of appropriate therapy: thrombolytics or primary angioplasty for the patients with MIs or aspirin/heparin for the patients with unstable angina. Patients at moderate risk need to have an acute coronary syndrome ruled in or out expediently and additional comorbidities addressed before discharge. Patients at low risk also need to be evaluated, and once the likelihood of an unstable acute coronary syndrome is eliminated, they can be discharged with further evaluation performed as outpatients. Subsequent evaluation should attempt to assign a definitive diagnosis while also addressing issues specific to risk reduction, such as cholesterol lowering and smoking cessation. It is well documented that 4% to 5% of patients with MIs are inadvertently missed during the initial evaluation. This number is surprisingly consistent among many studies using various protocols and suggests that an initial evaluation limited to the history, physical examination, and ECG will fail to identify the small number of these patients who otherwise appear at low risk. The solution is to improve the sensitivity of the evaluation process to identify these patients. It appears that more than simple observation is required, and at the present time, no simple laboratory test can meet this need. However, success has been reported with a number of strategies including emergency imaging with either radionuclides such as sestamibi or echocardiography. Early provocative testing, either stress or pharmaceutic, may also be effective. The added value of these tests is only in their use as part of a systematic protocol for the evaluation of all patients with acute chest pain. The initial evaluation of the patient with chest pain should always consider cardiac ischemia as the cause, even in those with more atypical symptoms in whom a cardiac origin is considered less likely. The explicit goals for the evaluation of acute chest pain should be to reduce the time to treat MIs and to reduce the inadvertent discharge of patients with occult acute coronary syndromes. All physicians should become familiar with appropriate risk stratification of patients with acute chest pain. Systematic strategies must be in place to assure rapid and consistent identification of all patients and the expedient initiation of treatment for those patients with acute coronary syndromes. These strategies should include additional methods of identifying acute coronary syndromes in patients initially appearing as at moderate or low risk to assure that no unstable patients are discharged. All patients should be followed up closely until the cardiovascular evaluation is completed and, when possible, a definitive diagnosis is determined. Finally, this must be done efficiently, cost-effectively, and in a manner that will result in an overall improvement in patient care.

Early CK-MB elevations predict ischemic events in stable chest pain patients

OBJECTIVE

To demonstrate that creatine kinase-MB fraction (CK-MB) elevations within three hours of presentation in the emergency department (ED) are associated with subsequent ischemic events in clinically stable chest pain patients.

METHODS

Prospective cohort study at two university- affiliated teaching hospitals. Participants were consenting ED chest pain patients 25 years old or older without evidence of rhythm or hemodynamic instability (n = 449). Exclusions included ST-segment elevation > or = 0.1 mV in > or = 2 electrocardiogram leads, chest wall trauma, abnormal x-ray studies, and incomplete data collection. Measurements included presenting and three-hour CK-MB levels, presenting ECG, initial clinical impression of coronary care unit need, and clinical follow up. Monitored adverse events included myocardial ischemia necessitating coronary angioplasty or cardiac bypass surgery, recurrent in-hospital myocardial infarction, bradycardia requiring pacing, emergent cardioversion, cardiogenic shock, ventricular fibrillation, and death.

RESULTS

Overall, nine (2%) of 449 patients experienced an ischemic event within the first 48 hours. All nine patients required either coronary angioplasty or bypass surgery. Four (44%) of the nine patients with 48-hour ischemic events had elevated CK-MB levels. Of 23 patients who had complications within one week of ED presentation, seven (30%) had elevated ED CK-MB levels. An elevated CK-MB level was associated with an ischemic event both within 48 hours (risk ratio 9.5; 95% CI 2.7-33.7) and within one week (risk ration 5.2; 95% CI 2.3-11.7).

CONCLUSIONS

An elevated CK-MB level within three hours of ED presentation is associated with a subsequent ischemic event in the clinically stable chest pain patient without ST-segment elevation. However, the ED CK-MB identifies only a minority or otherwise low-risk patients who develop ischemic events; other markers for diagnosing myocardial ischemia in the ED are needed.

The diagnosis of acute myocardial infarction in the emergency department; Part 1

Despite major advances in treatment, the accurate diagnosis of acute myocardial infarction (AMI) in the emergency department (ED) remains a difficult clinical problem and is still mainly based on the history and interpretation of the electrocardiogram. Although the physician's clinical impression is a highly sensitive indicator for AMI, at least 4% of patients presenting to the ED with AMI may be mistakenly sent home. Although chest pain is the most common chief complaint, the clinical presentation can be extremely variable, particularly in the elderly. Complaints of sharp chest pain or chest wall tenderness should not be relied upon to exclude AMI. Radiation of chest pain is an important symptom. With careful analysis, the electrocardiogram may yield a higher diagnostic sensitivity than is commonly accepted.