Doi:10.1016/j.annemergmed.2005.08.007

A Clinical Prediction Rule for Early Discharge From the University of British Columbia (Christenson, Innes, McKnight, Thompson, Wong, Yu, Boychuk, Grafstein, Rosenberg, Gin, Anis, Singer); St. Paul’s Hospital (Christenson,Innes, Thompson, Boychuk, Grafstein, Rosenberg); Vancouver Hospital (McKnight, Gin); and the Center for Health Evaluation and Outcome Sciences (Christenson, Innes, Grafstein, Wong, Yu, Anis, Singer) Vancouver, British Columbia, Canada.
Study objective: Current risk stratification tools do not identify very-low-risk patients who can be safelydischarged without prolonged emergency department (ED) observation, expensive rule-out protocols, orprovocative testing. We seek to develop a clinical prediction rule applicable within 2 hours of ED arrivalthat would miss fewer than 2% of acute coronary syndrome patients and allow discharge within 2 to3 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 asingle site. At 30 days, investigators assigned a diagnosis of acute coronary syndrome or no acutecoronary syndrome according to predefined explicit definitions. A recursive partitioning model includedrisk 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%) definiteunstable 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 previousischemic chest pain, and age younger than 40 years. In addition, patients at least 40 years old andwith a normal ECG result, no previous ischemic chest pain, and low-risk pain characteristics have verylow risk if they have an initial creatine kinase-MB (CK-MB) less than 3.0 mg/L or an initial CK-MB greaterthan or equal to 3.0 mg/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 besafely discharged after a brief evaluation in the ED. Prospective validation is needed. [Ann Emerg Med.
2006;47:1-10.] 0196-0644/$-see front matterCopyright ª 2006 by the American College of Emergency Physicians.
doi:10.1016/j.annemergmed.2005.08.007 of 241 (4.6%) missed cases of acute myocardial infarction and 10 of 157 (6.4%) cases of missed unstable angin Approximately 15% to 25% of patients who present to Chest pain units reduce the rate of missed myocardial infarction emergency departments (EDs) with undifferentiated chest pain but do so in part by including very-low-risk patients in prove to have acute coronary syndrome within 30 days. US data extensive rule-out myocardial infarction proto suggest that 2.1% of patients with acute myocardial infarction Many investigators have developed chest pain risk and 2.3% of patients with unstable angina are initially stratification tools. Goldman et aldeveloped a clinical/ECG misdiagnosed,whereas a recent Canadian study identified 11 algorithm that identified patients with less than 7% risk of acute Clinical Prediction Rule for Early Discharge of Chest Pain Patients without acute coronary syndrome were discharged less than What is already known on this topicAlthough several algorithms and computer programs have been developed for emergency department (ED) Clinical prediction rules are decisionmaking tools for patients with potential acute coronary syndrome, none clinicians that contain elements of the medical history, physical has achieved sufficient accuracy to allow safe and rapid examination, and simple diagnostic tests.An objective clinical discharge of ED chest pain patients.
prediction rule to identify very-low-risk patients with chestpain who can be safely discharged without prolonged ED observation, expensive rule-out protocols, or provocative This study developed a clinical decision rule to identify testing is needed. Such a rule would help reduce emergency low-risk ED chest pain patients who can be safely crowding, minimize patient inconvenience, and improve discharged within 2 hours of presentation. This study did cost-effectiveness of acute coronary syndrome diagnostic testing.
not prospectively evaluate this rule.
Our specific objective was to develop a clinical prediction Not surprisingly, this study found that patients younger rule that would improve on current practice by identifying than 40 years and with normal initial ECG results and no patients with chest pain who are safe for discharge after 2 hours previous ischemic chest pain were at very low risk of acute of ED evaluation. The rule will miss fewer than 2% of acute coronary syndrome. Additionally, patients older than coronary syndrome patients and allow discharge within 2 to 40 years had low-risk if they had a normal ECG result, no 3 hours of at least 30% of patients without acute coronary previous ischemic chest pain, low risk chest pain characteristics, and an initial creatine kinase-MB(CK-MB) less than 3.0 ug/L or an initial CK-MB greater than 3.0 ug/L but without an increase or ECG changes Using established methodology for clinical prediction rules,this prospective cohort study was conducted in 2 This derivation study should not change clinical practice separate periods between June 29, 2000, and January 24, 2003, because it has not yet been validated. It does, however, when research assistants were funded.
provide support for the general belief that young patientswith a normal ECG result and no cardiac risk factors are at very low risk of an adverse cardiovascular event.
Patients presenting to St. Paul’s Hospital, an urban tertiary care ED, with a primary complaint of anterior or lateral chestpain were eligible for the study. Research assistants obtained myocardial infarction. Limkakeng et subsequently found informed consent and enrolled eligible patients between 7 AM that 4.9% of patients who had low-risk Goldman criteria and 10 PM 7 days per week. Patients were excluded if they were and a negative initial troponin I assay result experienced death, younger than 25 years, had a clear traumatic or radiologically acute myocardial infarction, or revascularization within 30 days.
evident cause, were enrolled in the study in the previous 30 Pozen et aldeveloped a 7-item predictive equation that days, had a terminal noncardiac illness, had severe reduced coronary care unit admissions but not inappropriate communication problems, were without a fixed address in the discharges. Selker et modified this to create the acute province of British Columbia, or were without available cardiac ischemia time-insensitive predictive instrument telephone contact. The Providence Health Care Research Ethics (ACI-TIPI), which defined low risk as less than 10% chance of acute coronary syndrome. The Erlanger protocis anintense 2-hour assessment that includes serial ECGs and creatine kinase-MB (CK-MB) and troponin measurements, This report conforms to the published standard reporting but it does not define a subset of patients who can forgo guidelines for studies evaluating risk stratification of ED nuclear stress testing. The American Heart Association/Agency patients with potential acute coronary syndalthough for Health Care Policy and Research guidelines suggest early they were developed before this publication. A total of 123 discharge only for patients with ‘‘evidence’’ of an alternate potential predictor variables were screened (). During diagnosis.Unfortunately, few patients clearly fall into this the first 2 hours of the index visit, research assistants category. Our own study of patients with chest pain at 2 documented vital signs every 30 minutes, initiated ST-segment Vancouver hospitals identified that 5.4% of patients with monitoring, and ensured that serial ECGs (0, 1, and 2 hours) acute coronary syndrome were discharged from the ED without were performed. Cardiac markers at 0 and 2 hours were a diagnosis or planned investigations and only 30% of those evaluated on several platforms: creatine phosphokinase (Access, Clinical Prediction Rule for Early Discharge of Chest Pain Patients Pain and Associated Symptom Characteristics Parent or sibling with heart attack \65 years 2-h ST segment monitoring (any ST elevation or ST depression)* Difference in CPK (2 h–0 h) (Standard)* Difference in Tn I or T (2 h–0 h) (Standard)* Difference in CK-MB (2 h–0 hour) (Biosite)* Difference in myoglobin (2 h–0 h) (Biosite)* Pain diagnosed in past as either AMI or angina Previous angiogram yes and previous lesion O50%* Did pain improve within 5 minutes of nitroglycerin?* Did pain improve within 5 minutes of oxygen? Did pain improve within 5 minutes of liquid antacid? During 2 hours, did pain relieve and not return?* Right arm systolic pressure, left arm systolic pressure Systolic pressure \90 mm Hg in 2 hoursBradycardia \50 beats/min in 2 hours* Figure 1. List of all predictors collected for possible inclusion in the prediction rule. Those meeting criteria for inclusion in the model are identified with an asterisk.
AMI, Acute myocardial infarction; Hx, history; MI, myocardial infarction; PCI, percutaneous coronary intervention; CABG, coronary artery bypass graft; CVA, cerebrovascular accident; TIA, transientischemic attack; ASA, acetyl salicylic acid; ACE, angiotensin-converting enzyme.
Clinical Prediction Rule for Early Discharge of Chest Pain Patients Table 1. Baseline characteristics and outcomes of patient Table 2. Univariate predictive statistics for predictors used in Mean pulse rate on arrival (beats/minGSD) Mean respiratory rate on arrival (breaths/minGSD) % With pain radiating to left arm, jaw, or neck % With pain increasing with a deep breath % With any increase in CK-MB during 2 hours No acute coronary syndrome or adverse event Mortality with definite unstable angina (%) Mortality with possible unstable angina (%) Mortality with no acute coronary syndrome Mortality with no acute coronary syndrome Beckman Coulter, Mississauga, Ontario, Canada), troponin I (Access and Biosite Triage, San Diego, CA), troponin T (Roche Elecsys, Hoffman LaRoche, LaValle, Quebec, Canada), *Predictors with an odds ratio O1 indicate that the predictor is associated with an myoglobin (Biosite Triage), and CK-MB (Biosite Triage).
increased risk of acute coronary syndrome.
y‘‘ECG normal’’ is defined as no ST-segment deviation and no T-wave inversion Serum markers ordered by research protocol but not for regardless of conditions such as left ventricular hypertrophy or left bundle-branch clinical purposes were unavailable to clinicians. They acquired block. T-wave flattening was not defined as abnormal.
chest pain characteristics, patient risk factors, and medicalhistory independently of clinicians and recorded physicalfindings determined by emergency physicians, provisional intervention, chest compressions, percutaneous intervention, emergency diagnosis, admission and discharge times, and coronary artery bypass grafting.
consultations, cardiac medications administered, other cardiac Interobserver reliability was estimated by having a second investigations, hospital discharge diagnoses, and predefined emergency physician blindly evaluate 95 patients.
At 30 days, research staff telephoned patients to review Adverse events included death, tachycardia requiring current medications, physician visits, and hospital visits. Reports intervention, bradycardia requiring intervention, assisted of all diagnostic tests performed during the 30 days in any ventilations, proven pulmonary thromboembolism, proven setting were obtained, and relevant physicians were contacted aortic aneurysm or dissection, new congestive heart failure for confirmation of any new diagnoses. In cases in which patient requiring intravenous therapy, hypotension requiring contact was lost, other city hospital records were reviewed to Clinical Prediction Rule for Early Discharge of Chest Pain Patients identify hospital visits, procedures, and new diagnoses, and the pre- or postmorbid investigation. The diagnosis of definite study list was cross-referenced against the British Columbia unstable angina required rest pain greater than or equal to 20 minutes and at least 1 of the following related to the presentingsymptoms: (1) troponin increase 0.1 to 0.99 mg/L but no other acute myocardial infarction criteria, (2) dynamic ECG changes Investigators used predefined explicit criteria to assign a consistent with ischemia in 2 contiguous leads (dynamic ST 30-day outcome diagnosis of acute myocardial infarction, definite depression O0.5 mm or dynamic deep T-wave inversion) but no unstable angina, possible unstable angina, or no acute coronary persistent ST elevation, (3) a coronary angiogram with greater syndrome. The primary outcome was definite acute coronary than 70% lesion plus hospital admission for acute coronary syndrome (acute myocardial infarction or definite unstable syndrome, or (4) a positive stress test result (radionuclide scan, angina). The diagnosis of acute myocardial infarction required echo, or ECG stress test) plus admission for acute coronary any one of the following: (1) a CK-MB increase definite for acute myocardial infarction based on the specific hospital If a diagnosis could not be assigned or if an investigator criteria or troponin I level greater than or equal to1.0 mg/L; assigned a diagnosis of ‘‘no acute coronary syndrome’’ despite (2) a troponin I increase (O0.1 mg/L but \1.0 mg/L) with objective criteria (eg, positive troponin assay result), or if an dynamic ECG changes consistent with ischemia, a coronary investigator assigned a diagnosis of ‘‘definite unstable angina’’ angiogram with greater than 70% lesion, a positive stress test based only on a positive troponin assay result, 2 cardiologist result (radionuclide scan, echocardiogram, or ECG), or urgent coinvestigators independently reviewed all clinical data and revascularization; (3) ECG evolution consistent with acute assigned an adjudicated outcome diagnosis. If necessary, final myocardial infarction; (4) fibrinolytic therapy or primary diagnosis was based on agreement of any 2 adjudicators and the angioplasty and a clinical diagnosis of acute myocardial principal investigator. If all 3 disagreed, the final outcome was infarction; or (5) death with no other definite cause found in Clinical Prediction Rule for Early Discharge of Chest Pain Patients Figure 3. Chest pain early discharge rule.
Investigators reviewed all ECGs in a structured format to predictors were chosen initially by the algorithm and then identify T-wave flattening, T-inversion in 2 contiguous leads, rounded to convenient values by the investigators, and the ST depression (R0.05 mV) in 2 contiguous leads, ST-elevation patients were reclassified based on rounded values. Predictor (R0.1 mV in limb leads or R0.2 mV in precordial leads), and variables were allowed in the model if they were univariately the presence of left bundle-branch block, paced rhythm, or left associated with the primary outcome (P\.2). In addition, ventricular hypertrophy. In addition, investigators blinded to variables subjected to interpretation (medical history and final outcome reviewed all ECGs for each patient and recorded physical examination findings) were included if they were their impression of the likelihood of ischemia. Evaluation of all reliable (lower bound of confidence [95%] was at least 0.4 for available ECGs was used for outcome determination.
the reliability measure; prevalence and bias adjusted k Evaluation of ECGs up to 2 hours was used as predictors coefficient for dichotomous variables and intraclass correlation coefficient for continuous variables).
Investigators reviewed each derived rule for clinical relevance.
Nodes with small numbers of patients were reaggregated and Data were collected on specific study data forms and entered recursive partitioning was reinstituted to simplify the branch into an Oracle database (Oracle Corporation, Redwood City, points. This modification, although not previously described, CA, USA). Proportions, medians, means, and SDs were makes clinical sense and reduces the chance of selecting a calculated and multiple clinical prediction rules were derived nonoptimal splitting variable when partitioning groups with using the S-Plus (Insightful Corp., Seattle, WA) ‘‘rpart’’ smaller sample sizes. The simplest, most specific prediction recursive partitioning module. The algorithm was run using all rule that met the goal of sensitivity greater than 98% was of the default options except that a 10:1 loss was specified for missed acute coronary syndrome patients versus missed non- We do not report confidence intervals (CI) around the acute coronary syndrome patients. This higher penalty on sensitivity and specificity values, because these values arise as a missed acute coronary syndrome patients encouraged the consequence of the rule development process, not as an algorithm to choose splits that maximized sensitivity and so evaluation of a fixed rule. Specifically, the sampling variability reduce the complexity of the model. Cut points for continuous in the estimated sensitivity cannot be assessed because different Clinical Prediction Rule for Early Discharge of Chest Pain Patients samples lead to different rules (all of which are forced to satisfy the ‘‘at least 98% sensitive’’ criterion). Meaningful CIs will be The sample size of 800 patients was chosen so that equal numbers would be used in rule development and in subsequent rule validation. In the validation phase, the aim is to confirm that the sensitivity of the rule exceeds current practice (ie, to obtain a lower bound on the 95% CI for sensitivity of acute coronary syndrome detection that is no less than 0.95).
Assuming that the true sensitivity is of the rule is 0.98, roughly *Sensitivity 98.8%; specificity 32.5%; positive predictive value 28.5%; negative 187 positive cases (800 patients in total) are needed to achieve this lower bound with 90% probability.
allows the early discharge process to be divided into We enrolled 819 patients and subsequently excluded The 2 missed patients were subsequently diagnosed with 50 patients from analysis, 31 who met exclusion criteria and 19 unstable angina. A 66-year-old woman was diagnosed 8 days who were lost to follow-up. Of the 19 lost to follow-up, 14 were later by outpatient nuclide stress testing, with no subsequent known to be alive at subsequent hospital visits, and the other 5 admission or adverse event. The other was a 52-year-old patient did not appear in the provincial death registry. with a clear history of new and accelerating angina before rest summarizes baseline characteristics and outcomes for the 769 pain who was treated medically for a single critical lesion not patients analyzed showing 30-day diagnosis was acute amenable to intervention. During validation, we will clarify the myocardial infarction in 77 (10.0%) and definite unstable definition of past angina to include a recent history of typical angina in 88 (11.4%). Documented adverse events related or angina of effort whether diagnosed or not.
unrelated to acute coronary syndrome included tachycardia(35), bradycardia (14), assisted ventilations (4), proven pulmonary thromboembolism (5), proven thoracic aortic Although we used accepted and validated methodology, aneurysm or dissection (0), new congestive heart failure the Vancouver Chest Pain Prediction Rule was developed in requiring intravenous therapy (12), hypotension requiring 1 cohort of patients in a single center. We are currently intervention (9), and chest compressions (2). Eighty-three beginning validation of the rule, and it will subsequently patients had percutaneous intervention and 31 had coronary require evaluation of implementation in multiple centers. Our artery bypass grafting within 30 days.
criterion standard for definite acute coronary syndrome was Of the 123 possible predictor variables screened, 48 were not based on mandated investigations but on a careful retained for entry into the recursive partitioning algorithm.
evaluation of all tests and visits during 30 days. It is possible that lists the variables selected for the rule by diagnostic we missed some patients with silent events. The cohort was groups with respective univariate statistics and P values. These collected during day and evening hours and will require variables include a normal ECG result (which could include validation in patients presenting at all hours of the day. The rule T-wave flattening but no ST deviation or T-wave inversion), age, is modestly complex and may be difficult to remember, which previous ischemic pain, 3 pain descriptors, 1 physical finding, could limit its use by clinicians. However, the rule is largely and both CK-MB and troponin results. Reliability measures intuitive, and simple memory aids (eg, pocket cards or PDA (95% CI) for clinical subjective variables were pain radiates to algorithms) will enhance implementation once the rule is neck, 0.68 (95% CI 0.54 to 0.83); pain radiates to jaw, 0.81 validated. It is important to note that although our focus was on (95% CI 0.69 to 0.93); pain radiates to left arm, 0.79 (95% CI identifying patients with very low risk of acute coronary 0.67 to 0.91); and chest tenderness reproduces pain, 0.63 (95% syndrome, no patients were missed with pulmonary embolism or aortic dissection. Suspicion of other life-threatening outlines the classification tree, and is a conditions requires appropriate, independent investigations.
simplified clinical algorithm of the chest pain prediction rule.
In retrospect, this rule development should have included In this development cohort, the rule is 98.8% sensitive, patients 24 hours per day. Ideally, the study would be identifying all but 2 patients with unstable angina, and would strengthened by mandating initial and 30-day imaging have allowed the appropriate discharge of 32.5% of patients studies to improve the criterion standard of acute coronary without acute coronary syndrome using data collected within 2 syndrome. The cost implications of the Vancouver Chest hours of arrival (Of those identified for discharge, 89.4% would be determined with information available atpresentation, most without any laboratory testing, and the remainder would be determined safe for discharge based on Patients who present to the ED with chest pain fall into repeat ECG, CK-MB, and troponin at 2 hours. This potentially 3 categories: those with objective ischemia who need admission Clinical Prediction Rule for Early Discharge of Chest Pain Patients and treatment, those with a clear noncardiac cause, and those Recent American College of Cardiology/American Heart who require a diagnostic process to rule out acute coronary Associationguidelines recommend that all patients with a syndrome and other life-threatening conditions. The Vancouver compatible history have serial marker testing until 9 hours after Chest Pain Rule identifies 32.5% of patients who do not have symptom onset, followed by provocative testing. Applying this acute coronary syndrome using information available in the guideline in the ED, where most patients have ill-defined first 2 hours of the ED visit. These very-low-risk patients are chest discomfort, could greatly increase diagnostic and ED bed identified with minimal error, in fact including only 1.2% of utilization without a corresponding improvement in patient those who do have unstable angina or acute myocardial outcomes. The ED/AHCPR guidelines and the Toronto Heart infarction. This information can be integrated into the decision Centre ACS Guidelinesrecommend excluding patients with framework of the emergency physician who continually discomfort because of other causes from the diagnostic pathway, evaluates patients for safe and appropriate disposition.
but neither suggests a process for identifying these patients.
This prediction rule is different from previous risk The Vancouver Chest Pain Rule is unique in its ability to stratification tools. In 1988, Goldman et aldeveloped a identify very-low-risk patients who are suitable for early clinical/ECG algorithm that identified patients with less than discharge. It is also unique in that it identifies patients in a 7% risk of acute myocardial infarction. This was not designed clinically logical stepwise process with a minimum of to detect patients with unstable angina and it did not improve investigations. First, age, initial history, and ECG findings disposition decisions relative to experienced clinician judgment identified 56 of 198 patients who ultimately meet rule criteria.
alone. Limkakeng et allater reported that 4.9% of patients A further 121 patients were identified based on initial CK-MB with low-risk Goldman criteria and a negative initial troponin and low-risk pain characteristics. The last 21 patients were I level experienced death, acute myocardial infarction, and identified by the absence of changes in the ECG or serum revascularization within 30 days. Lee et aland Goldman et al markers during 2 hours. If disposition according to the rule was subsequently developed a strategy to identify patients implemented in this stepwise manner, ED lengths of stay and unlikely to have acute myocardial infarction and criteria to investigational costs could be reduced substantially in many identify patients who need coronary care unit admission. These criteria required 12 to 24 hours of observation and did not Some would argue that the age criteria might result in facilitate early ED disposition decPozen et al missing younger patients with myocardial infarction, but age is developed and tested a predictive equation using 7 clinical in fact a powerful predictor, and the low-risk group younger and ECG variables. After application of this instrument, than 40 years is also defined by a near-normal ECG and the inappropriate coronary care unit admissions fell from 24% to absence of past myocardial infarction or angina. Marsan et al 17%, but the 3% inappropriate discharge rate was unchanged.
recently studied 1032 patients younger than 40 years and Selker et almodified the Pozen et alequation and linked presenting with chest pain and found that those with no it to ECG findings, creating an electronic tool called the cardiac history and either no cardiac risk factors or a normal ACI-TIPI. This tool increased the rate of appropriate ECG result had less than 0.5% 30-day risk of acute coronary discharges by unsupervised residents but did not change the performance of attending physicians. Of note, We found that CK-MB at a low threshold was consistently a ACI-TIPI defines low risk as less than 10% chance of acute better discriminator than any level of troponin, surprising myocardial infarction or unstable angina, and few clinicians will because many studies suggest troponin is the superior marker.
Our findings are not unique, and at least 1 other investigator In 1992, Baxtand Baxt and Skora‘‘trained’’ neural has reported that CK-MB was more predictive of acute coronary networks to recognize acute myocardial infarction and, in 1993, syndrome than troponin early in the patient’s presentati Jonsbu et developed a sensitive computer-derived Laboratory technicians used the Triage (Biosite) point-of-care algorithm. Doyle et studied 9 algorithms but found none device, and we attribute the greater discriminatory power of that improved clinical decisionmaking. The recently described CK-MB over troponin to its better analytic performance within Thrombolysis in Myocardial Infarction (TIMI) Risk scoreis the normal range. The reported 99th percentile for troponin an excellent stratification tool but was derived from studies of on the Triage point-of-care device is actually the detection patients with objective evidence of acute coronary syndrome limit (0.19 mg/L), whereas the 95th percentile for CK-MB and has not been validated in undifferentiated ED patients with (usual cutoff) is well above the detection limit (0.75 mg/L).
chest discomfort. The Erlanger protocolis an intense 2-hour de Winter et determined that an increase in CK-MBmass assessment that includes serial ECGs, 2 CK-MB and troponin greater than 2 mg/L represents the critical difference between measurements, clinical judgment, and nuclear stress testing.
2 results for the detection of myocardial damage. We It is the most detailed published protocol designed to facilitate hypothesize that it is the absence of a critical increase over early discharge but requires nuclear imaging to increase baseline value (median 1.5 mg/L) that underlies the sensitivity from 80% to 99%. None of the above stratification discriminatory power of a CK-MB level less than 3 mg/L. In tools help clinicians identify patients who are safe to discharge comparison, present troponin methods do not permit the detection of a change within the normal range.
Clinical Prediction Rule for Early Discharge of Chest Pain Patients An early discharge strategy such as the one developed here 6. Goldman L, Cook E, Brand D. A computer protocol to predict defines patients safe for early discharge and reduces the number myocardial infarction in emergency department patients with chestpain. N Engl J Med. 1988;318:797-803.
who require more definitive testing but also defines the 7. Limkakeng A Jr, Gibler WB, Pollack C, et al. Combination of companion group of patients who are not clearly ‘‘safe’’ and Goldman risk and initial cardiac troponin I for emergency require further investigations. To maximize diagnostic department chest pain patient risk stratification. Acad Emerg Med.
efficiency, a more prolonged ‘‘chest pain unit’’ rule-out strategy should be applied to patients without objective ischemia who do 8. Pozen MW, D’Agostino RB, Selker HP, et al. A predictive instrument to improve coronary-care-unit admission practices in acute ischemic heart disease: a prospective multicenter clinical trial. N Engl J In summary, the Vancouver Chest Pain Rule defines a group of chest pain patients who can be safely discharged from the 9. Pozen MW, D’Agostino RB, Mitchell JB, et al. The usefulness of a ED in the first few hours after arrival. If validated in an predictive instrument to reduce inappropriate admissions to the independent cohort, it will improve the process of diagnostic coronary care unit. Ann Intern Med. 1980;92:238-242.
10. Selker HP, Beshansky JR, Griffith JL, et al. Use of the acute cardiac decisionmaking in patients presenting with chest pain.
ischemia time-insensitive predictive instrument (ACI-TIPI) to assistwith triage of patients with chest pain or other symptoms The authors are grateful for the support and data supplied by the suggestive of acute cardiac ischemia: a multicenter, controlled physicians and nurses at St. Paul’s Hospital, Vancouver, Canada, clinical trial. Ann Intern Med. 1998;129:845-855.
and for the dedication of Patti Lawson, BA, and Courtney Barker.
11. Selker H, D’Agostino R, Laks M. A predictive instrument for acute ischemic heart disease to improve coronary care unit admissionpractices: a potential on-line tool in a computerized Supervising editor: Judd E. Hollander, MD electrocardiograph. J Electrocardiol. 1988;(21 suppl):S11-S17.
12. Selker H, Griffith J, Patil S, et al. A comparison of performance of Author contributions: DM, HR, EY, EG, FR, AA, and JS helped mathematical predictive methods for medical diagnosis: identifying design the study, analyzed the data, and reviewed the acute cardiac ischemia among emergency department patients.
manuscript. BB helped design the study, collected data, and reviewed the manuscript. JMC, GI, and CRT conceived and 13. Fesmire FM, Hughes AD, Fody EP, et al. The Erlanger chest pain helped design the study, collected data, and wrote the evaluation protocol: a one-year experience with serial 12-lead ECG manuscript. JMC takes responsibility for the paper as a whole.
monitoring, two-hour delta serum marker measurements, andselective nuclear stress testing to identify and exclude acute Funding and support: Canadian Institutes of Health research coronary syndromes. Ann Emerg Med. 2002;40:584-594.
grant MOP 53102 and Heart and Stroke Foundation of British 14. Braunwald E, Antman E, Beasley J, et al. ACC/AHA: a guideline Columbia and Yukon Grant. Materials for analysis of some update for the management of patients with unstable angina and laboratory testing were donated by Biosite.
non-ST-elevation myocardial infarction: a report of the AmericanCollege of Cardiology/American Heart Association task force on Publication dates: Received for publication March 17, 2005.
practice guidelines (committee on the management of patients Revision received June 13, 2005. Accepted for publication July 13, 2005. Available online October 19, 2005.
15. Laupacis A, Sekar N, Stiell IG. Clinical prediction rules: a review and Reprints not available from the authors.
suggested modifications of methodological standards. JAMA.
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Street, Vancouver, British Columbia V6Z 1Y6, Canada; 604- 17. Stiell IG, Wells GA. Methodologic standards for the development of clinical decision rules in emergency medicine. Ann Emerg Med.
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strategy for patients at low risk. N Engl J Med. 1991;324: 3. Anderson HJ. Hospitals battle heart attacks with new chest pain 20. Goldman L, Cook EF, Johnson PA, et al. Prediction of the need for intensive care in patients who come to the emergency departments 4. Zalenski RJ, Rydman RJ, Ting S, et al. A national survey of with acute chest pain. N Engl J Med. 1996;334:1498-1504.
emergency department chest pain centers in the United States.
21. Reilly B, Durairaj L, Husain S, et al. Performance and potential impact of a chest pain decision prediction rule in a large public 5. Graff L, Joseph T, Andelman R, et al. American College of hospital. Am J Med. 1999;106:285-291.
Emergency Physicians information paper: chest pain units in 22. Davis MA, Keerbs A, Hoffman JR, et al. Admission decisions emergency departments: a report from the Short-Term in emergency department chest pain patients at low risk for Observation Services Section. Am J Cardiol. 1995;76: myocardial infarction: patient versus physician preferences.
Clinical Prediction Rule for Early Discharge of Chest Pain Patients 23. Baxt WG. Analysis of the clinical variables driving decision in 28. Fesmire F, Hughes A, Fody E, et al. The Erlanger chest pain an artificial neural network trained to identify the presence of evaluation protocol: a one-year experience with serial 12-lead ECG myocardial infarction. Ann Emerg Med. 1992;21:1439-1444.
monitoring, two-hour delta serum marker measurements, and 24. Baxt WG, Skora J. Prospective validation of artificial neural network selective nuclear stress testing to identify and exclude acute trained to identify acute myocardial infarction. Lancet. 1996;347: coronary syndromes. Ann Emerg Med. 2002;40:584-594.
29. Fitchett D, Goodman S, Langer A. New advances in the management 25. Jonsbu J, Aase O, Rollag A, et al. Prospective evaluation of of acute coronary syndromes. CMAJ. 2001;164:1309-1316.
an EDB-based diagnostic program to be used in patients 30. Marsan R, Shaver K, Sease K, et al. Validation of a clinical decision admitted to hospital with acute chest pain. Eur Heart J. 1993; rule for young adult chest pain patients. Acad Emerg Med. 2004; 26. Doyle Y, Conroy R, Mulcahy R. Can we improve on the diagnostic 31. Svensson L, Isaksson L, Axelsson C, et al. Predictors of myocardial accuracy of chest pain in accident and emergency departments? damage prior to hospital admission among patients with acute chest pain or other symptoms raising a suspicion of acute coronary 27. Holper E, Antman E, McCabe C, et al. A simple, readily available syndrome. Coron Artery Dis. 2003;14:225-231.
method for risk stratification of patients with unstable angina and 32. de Winter RJ, Koster RW, van Straalen JP, et al. Critical difference non-ST elevation myocardial infarction. Am J Cardiol. 2001;87: between serial measurements of CK-MB mass to detect myocardial

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