European Heart Journal Advance Access published online on April 16, 2007
European Heart Journal, doi:10.1093/eurheartj/ehm004
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Risk scores for risk stratification in acute coronary syndromes: useful but simpler is not necessarily better
1 Canadian Heart Research Centre, Toronto, Ontario, Canada
2 Terrence Donnelly Heart Centre, Division of Cardiology, St Michael's Hospital, University of Toronto, 30 Bond Street, Room 6-034 Queen, Toronto, Ontario, Canada, M5B 1W8
3 University of Ottawa Heart Institute, University of Ottawa, Ottawa, Ontario, Canada
4 London Health Sciences Centre, London, Ontario, Canada
Received 7 November 2006; revised 15 January 2007; accepted 9 February 2007.
* Corresponding author. Tel: +1 416 864 5722; fax: +1 416 864 5407. E-mail address: goodmans{at}smh.toronto.on.ca
 |
Abstract |
|---|
 Top Abstract IntroductionMethodsResultsDiscussionConclusionAppendixAcknowledgementsReferences |
|---|
Aims: Our objectives were (i) to compare the discriminatory performance of the Thrombolysis in Myocardial Infarction risk score (TIMI RS), Platelet glycoprotein IIb/IIIa in Unstable angina: Receptor Suppression Using Integrilin Therapy risk score (PURSUIT RS), and Global Registry of Acute Cardiac Events risk score (GRACE RS) for in-hospital and 1 year mortality across the broad spectrum of non-ST-elevation acute coronary syndromes (ACS) and (ii) to determine their incremental prognostic utility beyond overall risk assessment by physicians.
Methods and results: We calculated the TIMI RS, PURSUIT RS, and GRACE RS for 1728 patients with non-ST-elevation ACS in the prospective, multicentre, Canadian ACS II Registry. Discriminatory performance was measured by the c-statistic (area under receiver-operating characteristic curve) and compared by the method described by DeLong. TIMI RS, PURSUIT RS, and GRACE RS all demonstrated good discrimination for in-hospital death (c-statistics = 0.68, 0.80, 0.81, respectively, all P < 0.001) and 1 year mortality (c-statistics = 0.69, 0.77, 0.79, respectively, all P < 0.0001). However, PURSUIT RS and GRACE RS performed significantly better than the TIMI RS in predicting in-hospital (P = 0.036 and 0.02, respectively) and 1 year (P = 0.006 and 0.001, respectively) outcomes. In multivariable analysis adjusting for the use of in-hospital revascularization, stratification by tertiles of risk scores (into low, intermediate, and high-risk groups) furnished independent and greater prognostic information compared with risk assessment by treating physicians for 1 year outcome.
Conclusion: Compared with TIMI RS, both PURSUIT RS and GRACE RS allow better discrimination for in-hospital and 1 year mortality in patients presenting with a wide range of ACS. All three risk scores confer additional important prognostic value beyond global risk assessment by physicians. These validated risk scores may refine risk stratification, thereby improving patient care in routine clinical practice.
Key Words: Acute coronary syndromes • Risk scores • Risk stratification • Prognosis
|
Introduction |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionConclusionAppendixAcknowledgementsReferences |
|---|
Early risk stratification plays a pivotal role in the optimal management of non-ST-elevation acute coronary syndromes (ACS), which represent a heterogeneous condition with variable short-term and long-term prognosis.1–3 Over the past decade, a multitude of risk scores have been proposed to facilitate risk assessment.4–8 For example, the Platelet glycoprotein IIb/IIIa in Unstable angina: Receptor Suppression Using Integrilin Therapy (PURSUIT RS) and Thrombolysis in Myocardial Infarction (TIMI RS) risk scores were derived from clinical trial populations,6,7 and the Global Registry of Acute Cardiac Events risk score (GRACE RS) was developed from an international registry.8 Although these risk scores have been externally validated,6–13 their comparative performance in representative patient populations has not been well studied.12,13 Furthermore, it is not known whether application of these risk scores can refine risk assessment by physicians in routine clinical practice.
Using data from the prospective Canadian ACS II Registry, we sought to (i) compare the in-hospital and 1 year prognostic accuracy of the PURSUIT RS, TIMI RS, and GRACE RS and (ii) determine their incremental prognostic value beyond patient risk assessment by treating physicians.
|
Methods |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionConclusionAppendixAcknowledgementsReferences |
|---|
Study design and population
The study design of the Canadian ACS Registry has been described.14 The Canadian ACS II Registry, which included only patients with non-ST-elevation ACS, was an extension of the ACS Registry. In brief, patients were eligible if they were (i)
18 years old on presentation; (ii) admitted to hospital with a suspected ACS (defined by symptoms consistent with acute cardiac ischaemia within 24 h of onset); and (iii) there was no serious concurrent illness such as trauma or gastrointestinal bleeding. To reduce patient selection bias, there were no other specific exclusion criteria, and we encouraged all participating hospitals to enrol consecutive patients. At each site, the designated physician or study coordinator recorded demographic and clinical data, in-hospital treatment, and outcome on standardized case report forms, which were then forwarded to the Canadian Heart Research Centre and scanned into an electronic database (TeleformTM, Version 7.0, Cardiff, San Diego, CA, USA). A brief summary of the contemporary Canadian practice guidelines on management of ACS was appended in the case report form (Appendix).15 Treating physicians were asked to categorize their patients into low, intermediate, and high-risk groups on the basis of overall risk assessment of medical history (e.g. age), physical examination (e.g. heart failure or haemodynamic instability), and laboratory investigations (e.g. ST-segment deviation on ECG). This approach was similar to the American College of Cardiology/American Heart Association (ACC/AHA) and the European Society of Cardiology (ESC) consensus guidelines.1,2 Central data checks were performed and queries were sent to sites for data correction. The local research ethics board approved the study, and all patients who were followed after discharge provided informed consent.
Risk score calculation
All three risk scores were calculated on the basis of clinical features at presentation. The TIMI RS (range 0–7) was the sum of seven dichotomous variables (1 point for each variable if present): age 65 years, 3 risk factors for coronary artery disease, use of aspirin within the past 7 days, known coronary artery stenosis 50%, 2 episodes of angina within the past 24 h, ST-segment deviation, and elevated cardiac biomarker.7 For patients without prior coronary angiography, we assigned 1 point if there was a history of myocardial infarction or coronary revascularization, in accordance with the suggestion by the authors of TIMI RS.9,10 In contrast, the PURSUIT RS and GRACE RS included both dichotomous and continuous variables, and published nomograms were available to convert the latter into points, which were then summed.6,8 The PURSUIT RS (range 0–25) comprised age, gender, worst Canadian Cardiovascular Society angina class in previous 6 weeks, heart rate, systolic blood pressure, signs of heart failure, and ST-depression (different points for age and heart rate variables were computed in patients with unstable angina vs. myocardial infarction).6 The components of the GRACE RS (range 1–372) were age, heart rate, systolic blood pressure, Killip class, cardiac arrest, serum creatinine, ST-segment deviation, and cardiac biomarker status.8
Between October 2002 and December 2003, the ACS II Registry recruited 2359 patients with suspected ACS from 36 participating hospitals in Canada; of these patients, 1956 (82.9%) had a final diagnosis of ACS. Compared with those given a final non-ACS diagnosis, patients with confirmed ACS had significantly higher TIMI RS, PURSUIT RS, and GRACE RS on presentation (all P < 0.001). Owing to missing data (which constituted <2% of cases for all variables, except 8.7% for Killip class), we could not calculate one or more risk scores for 228 patients (11.7%). These patients were excluded from the analysis; they did not differ significantly in most baseline characteristics and in-hospital mortality (1.8 vs. 1.8%, P = 0.97) from the remaining cohort. Thus, 1728 patients constituted the study cohort.
Outcome
Death included all-cause mortality. We focused on all-cause mortality because it was the most robust endpoint and had not been evaluated in a prior comparative study.13 Both PURSUIT RS and GRACE RS predict all-cause mortality.6,8 Although the TIMI RS was designed to predict the composite endpoint of death, myocardial (re-)infarction, or urgent revascularization [c-statistic (area under the receiver-operating characteristic curve) = 0.63], it demonstrated better discrimination for death alone in the original derivation and validation cohorts (c-statistic = 0.74).7
In-hospital outcome data were complete for all patients. At 1 year after discharge, follow-up data were collected via standardized telephone. Vital status could not be ascertained for 165 patients (9.5%); their TIMI RS, PURSUIT RS, and GRACE RS were similar (all P > 0.50) compared with patients with follow-up data.
Statistical analysis
Continuous data are summarized as medians and interquartile ranges (IQR), and categorical data as percentages. Group differences in continuous and categorical variables were compared by the Kruskal–Wallis test and chi-square test, respectively. We used Kendall's 
–b test to examine correlations. The discriminatory abilities of the risk scores for in-hospital and 1 year mortality were measured by c-statistics, with standard errors estimated by a non-parametric method.16 We generated receiver-operating characteristic curves for each of the three risk scores and compared their areas according to the non-parametric method described by DeLong.17
To directly compare the utility of risk scores with global risk assessment by physicians (low, intermediate, and high risk, as recorded on the case report form) in predicting 1 year outcome, we categorized the study population into low, intermediate, and high-risk groups by ascending tertiles of risk scores. We then assessed the independent prognostic value of each risk score by entering it as categorical variable (tertiles) into separate multivariable logistic regression models, which adjusted for the global risk category according to treating physicians. Because patients deemed to be at high risk might have received more intensive treatment, which might impact on 1 year outcome and thereby negate the prognostic significance of physicians' risk assessment, we also controlled for the use of in-hospital revascularization in multivariable analysis. Interaction terms were not significant and were not retained in the final model. The relative prognostic importance of each covariate was evaluated by the change in –2 log likelihood when the covariate was removed from the multivariable model.18 We analysed data using SPSS version 12.0 (SPSS Inc., Chicago, IL, USA) and considered two-sided P-values <0.05 to be statistically significant.
|
Results |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionConclusionAppendixAcknowledgementsReferences |
|---|
Table 1 presents the baseline characteristics of the study population. The median TIMI RS was 3 (IQR 2–4); median PURSUIT RS was 7 (IQR 4–10); and median GRACE RS was 117 (IQR 95–143). There were moderate-to-strong positive correlations among the three risk scores, with the following Kendall's
–b correlation coefficients: 0.32 for TIMI RS and GRACE RS (P < 0.0001), 0.40 for TIMI RS and PURSUIT RS (P < 0.0001), and 0.66 for PURSUIT RS and GRACE RS (P < 0.0001). For classifying patients into low, intermediate, and high-risk groups, the kappa values were 0.27 for TIMI RS and PURSUIT RS (P < 0.0001), 0.19 for GRACE RS and TIMI RS (P < 0.0001), and 0.54 for PURSUIT RS and GRACE RS (P < 0.0001). According to the treating physicians, 16.4, 40.8, and 42.8% of patients were categorized as low, intermediate, and high risk, respectively. There were significant but only weak correlations between physicians' assessment and TIMI RS (correlation coefficient = 0.09), PURSUIT RS (0.14), and GRACE RS (0.14) (all P < 0.0001).
|
Table 2 summarizes the in-hospital management of patients by risk groups. Patients considered to be at high risk by their physicians were more likely to undergo cardiac catheterization and coronary revascularization during index hospitalization. In contrast, there was a consistent inverse relationship between risk and early invasive management whether patients were stratified by the TIMI RS, PURSUIT RS, or GRACE RS.
|
Overall, in-hospital mortality rate was 1.8%. Of the 1563 patients with known vital status at 1 year, cumulative mortality rate was 6.8%. Figures 1
–4 illustrate the in-hospital and 1 year outcomes by patient risk groups.
|
|
|
|
Prognostic accuracy of the risk scores
Figures 5 and 6 display the receiver-operating characteristic curves for the three risk scores in predicting in-hospital and 1 year death, respectively. For in-hospital mortality, the c-statistics (areas under the curves) were 0.68 [95% confidence interval (CI) 0.59–0.77, P < 0.001] for TIMI RS, 0.80 (95% CI 0.71–0.88, P < 0.0001) for PURSUIT RS, and 0.81 (95% CI 0.73–0.89, P < 0.0001) for GRACE RS. Both PURSUIT RS and GRACE RS demonstrated better discrimination than TIMI RS in predicting in-hospital death (P = 0.036 and 0.02, respectively), but there was no significant difference between PURSUIT RS and GRACE RS (P = 0.69). For 1 year mortality, the c-statistics were 0.69 (95% CI 0.64–0.74, P < 0.0001) for TIMI RS, 0.77 (95% CI 0.72–0.81, P < 0.0001) for PURSUIT RS, and 0.79 (95% CI 0.74–0.83, P < 0.0001) for GRACE RS. The PURSUIT RS and GRACE RS showed similar predictive accuracy (P = 0.34), but were more accurate than the TIMI RS (P = 0.006 and 0.001, respectively) in predicting death at 1 year.
|
|
Comparison of risk scores and risk assessment by physicians
As shown in Figures 1–4, higher risk categories as per treating physicians or any of the risk score tertiles were associated with adverse outcome both during index hospitalization and at 1 year. However, for 1 year outcome, the risk gradient was steeper when patients were stratified by risk scores. Patients considered to be high risk by their physicians were three times more likely to die compared with those at low risk. The c-statistic for physicians' risk assessment in predicting 1 year mortality was 0.59 (95% CI 0.54–0.64, P = 0.002). In comparison, patients at the highest tertile of TIMI RS had a five-fold increased risk of death compared with those at the lowest tertile. Similarly, patients at high risk by virtue of their PURSUIT or GRACE risk scores had a 10 to 15-fold higher mortality rate than the low-risk group.
In multivariable analysis (Table 3), all three risk scores (by tertiles) were independently associated with 1 year mortality even after adjusting for risk assessment by physicians and the use of revascularization during index admission. Moreover, the greater changes in –2 log likelihood indicate that all three risk scores consistently provided more prognostic information compared with risk assessment by physicians. Similar results were obtained after further adjustment for discharge use of evidence-based medical therapies among hospital survivors, and for the composite endpoint of death or myocardial infarction at 1 year. Finally, when PURSUIT RS and GRACE RS were analysed as continuous variables (instead of tertiles), risk assessment by physicians failed to confer any incremental prognostic value and was no longer an independent predictor of outcome.
|
|
Discussion |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionConclusionAppendixAcknowledgementsReferences |
|---|
Across the broad spectrum of non-ST-elevation ACS, the TIMI RS, PURSUIT RS, and GRACE RS all demonstrated significant discriminatory ability for in-hospital and 1 year mortality. However, PURSUIT RS and GRACE RS were more accurate than TIMI RS in predicting these outcomes. Furthermore, to the best of our knowledge, the present study is the first to show that these risk scores confer additional prognostic value beyond risk assessment by physicians.
In an attempt to simplify and improve risk stratification, researchers have focused their attention on the development and validation of various risk scores over the past decade.3,19,20 To date, there are only limited data on the comparative accuracy of these risk scores,11–13 despite substantial differences in their complexity, derivation cohorts, and predicted endpoints. Singh et al.11 showed that the TIMI RS was inferior to the PREDICT score in forecasting death alone and the combined endpoint of death or re-infarction among 717 patients with non-ST-elevation myocardial infarction in Olmsted County. In the Canadian ACS I Registry, the GRACE RS and modified PURSUIT RS demonstrated similar discriminatory performance for in-hospital death, although model calibration was better for the former.12 Recently, de Araújo Gonçalves et al.13 compared the predictive accuracy of TIMI RS, PURSUIT RS, and GRACE RS among 460 ACS patients admitted to their coronary care unit. Both PURSUIT RS and GRACE RS demonstrated stronger discrimination than TIMI RS for death or myocardial infarction at 1 year. The c-statistic for 1 month outcome was also lower for TIMI RS, although this difference did not reach statistical significance, plausibly due to inadequate power. Moreover, the generalizability of this single-centre study requires confirmation in other patient populations. The present study extends previous work by showing that PURSUIT RS and GRACE RS performed better than TIMI RS in identifying patients with poor outcome both in the short term and long term across the wide range of ACS.
A number of reasons may account for the differences in discriminatory capacities of TIMI RS, PURSUIT RS, and GRACE RS. Although advanced age, ST-segment deviation, and biomarker status are common components of all three risk scores, PURSUIT RS and GRACE RS incorporate haemodynamic variables also, whereas renal dysfunction is included in GRACE RS only. These clinical characteristics, which have been shown to be powerful independent prognosticators,21–25 were not evaluated as candidate variables when TIMI RS was initially developed.7 Exclusion of patients with these high-risk features from clinical trials might also have diminished the prognostic significance of these variables,20 which were therefore eliminated during model development. Furthermore, the TIMI RS, composed of dichotomous variables only and with a limited range of 0–7, likely incurred a trade-off between its ease of use and predictive accuracy.19
Despite the proven utility of risk scores in prognostication and guidance of treatment strategies,4–13,26,27 it is not known how often they are actually used in routine practice. Physicians may be reluctant to use risk scores at the bedside because they find it inconvenient and time-consuming. Others believe that they can readily discern and integrate high-risk features into overall risk estimation without the aid of risk scores. Lack of definitive data demonstrating the incremental prognostic utility of risk scores beyond global risk assessment by physicians may have also contributed to their underuse. Although there are numerous established prognostic markers, they usually co-exist and their importance hinges on the inter-relationship of many factors.18 Because patients often present with complex risk profiles, assimilation of all the relevant information from history, physical examination, and laboratory investigations is a highly complicated process and a daunting task for a busy clinician.1,19 Consistent with this notion, our data show that there was poor correlation between risk assessment by treating physicians and all three risk scores. Using tertiles rather than the full range of risk scores in our main analysis, their prognostic utility was likely underestimated. Nevertheless, these risk scores still confer independent and greater prognostic information compared with physicians' risk assessment after adjusting for treatment differences. Importantly, we observed the selective targeting of more aggressive therapies towards patients considered as high risk by their physicians, but a treatment-risk paradox became evident when patients were objectively stratified by risk scores. Although we realize that many other factors might have appropriately influenced management decisions, our findings offer a possible explanation for the documented treatment-risk paradox and the apparent lack of measurable benefit despite the proliferative use of invasive cardiac procedures in recent years.28–32 Therefore, dedicated efforts to improve risk stratification may enhance the overall care process and resource utilization. Yet, it should be emphasized that risk scores are clinical tools that can supplement but not replace sound clinical judgment—the astute clinician is well aware that none of the risk scores will necessarily encompass all the high-risk features. For instance, a high-risk patient with known three-vessel coronary artery disease and left ventricular systolic dysfunction presenting with crescendo angina may be haemodynamically stable without ECG changes or abnormal biomarker, and yet would be deemed to be at low risk on the basis of the calculated risk score.
Clinical implications
The ACC/AHA and the ESC consensus guidelines of 2002 recognize the importance of early risk stratification in the management of non-ST-elevation ACS and recommend an integrated approach to risk assessment.1,2 In addition, ACC/AHA guidelines state that ‘estimation of the level of risk is a multivariable problem that cannot be accurately quantified with a simple table’.1 Accordingly, both ACC/AHA and ESC guidelines contain a list of high-risk clinical features to facilitate categorization of patients into low, intermediate, and high-risk groups.1,2 Since these risk scores had not been well validated in large external data sets when these guidelines were published, there were no explicit recommendations about their use.
With the subsequent external validation of several risk scores in representative patient populations,6–13 and their demonstrated superiority to subjective global risk assessment in the present study, risk scores should prove to be useful for risk stratification in clinical practice. Although the more sophisticated PURSUIT RS and GRACE RS may be more difficult to calculate than the TIMI RS, with wide availability of hand-held computer devices and access to websites, these clinical tools can be easily employed at the point of care.19
Study limitations
Several study limitations should be discussed in the interpretation of our results. We encouraged but could not verify consecutive patient enrolment at all sites. The relatively low in-hospital mortality rate suggests that early deaths after presentation were likely excluded, although risk stratification is least applicable for these patients. Because of missing data, 11.7% of patients were excluded from the analysis, although their baseline characteristics and in-hospital outcome did not differ from the remaining cohort. At 1 year after index admission, 9.5% of patients were lost to follow-up. Despite their similar risk scores on presentation compared with patients with follow-up data, we could not rule out any potential bias. Since the three risk scores were originally developed to predict outcome at different time points, we could not assess calibration by comparing observed with predicted event rates. Physicians' ability to risk-stratify patients may depend on their knowledge and experience, and this individual variability could not be determined in the present study. Nevertheless, more widespread and systematic application of a validated risk score will likely improve the process of risk stratification overall in the ‘real world’. Although our findings suggest that validated risk scores may improve risk assessment by physicians, it remains unclear whether they will ultimately result in better treatment decisions, resource allocation, and patient outcome. Finally, we did not collect data to evaluate other existing risk scores which were beyond the scope of our study.
|
Conclusion |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionConclusionAppendixAcknowledgementsReferences |
|---|
Compared with the simpler TIMI RS, both PURSUIT RS and GRACE RS provide better discrimination for in-hospital and 1 year mortality among patients presenting with a wide spectrum of non-ST-elevation ACS. These validated risk scores are easy to use at the bedside and afford incremental prognostic value beyond global risk assessment by physicians. Because risk scores can refine risk stratification and inform therapeutic decision-making, they have the potential to improve patient care. We therefore advocate more wide-scale adoption of validated risk scores in routine clinical practice.
|
Appendix |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionConclusionAppendixAcknowledgementsReferences |
|---|
Case report form.
|
Acknowledgements |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionConclusionAppendixAcknowledgementsReferences |
|---|
We thank Sue Francis for her secretarial assistance, and all the study investigators, coordinators, and patients who participated in the Canadian ACS II Registry.
Conflict of interest: none declared.
|
References |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionConclusionAppendixAcknowledgementsReferences |
|---|
- Braunwald E, Antman EM, Beasley JW, Califf RM, Cheitlin MD, Hochman JS, Jones RH, Kereiakes D, Kupersmith J, Levin TN, Pepine CJ, Schaeffer JW, Smith EE III, Steward DE, Theroux P, Gibbons RJ, Alpert JS, Faxon DP, Fuster V, Gregoratos G, Hiratzka LF, Jacobs AK, Smith SC Jr. (2002) ACC/AHA 2002 guideline update for the management of patients with unstable angina and non-ST-segment elevation myocardial infarction: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on the Management of Patients with Unstable Angina). Circulation 106:1883–1890.
[Free Full Text] - Bertrand ME, Simoons ML, Fox KA, Wallentin LC, Hamm CW, McFadden E, De Feyter PJ, Specchia G, Ruzyllo W. (2002) Management of acute coronary syndromes in patients presenting without persistent ST-segment elevation. Eur Heart J 23:1809–1840.
[Free Full Text] - Fitchett DH, Borgundvaag B, Cantor W, Cohen E, Dhingra S, Fremes S, Gupta M, Heffernan M, Kertland H, Husain M, Langer A, Letovsky E, Goodman SG. (2006) Non ST segment elevation acute coronary syndromes: a simplified risk-orientated algorithm. Can J Cardiol 22:663–677.[Web of Science][Medline]
- Calvin JE, Klein LW, VandenBerg BJ, Meyer P, Condon JV, Snell RJ, Ramirez-Morgen LM, Parrillo JE. (1995) Risk stratification in unstable angina. Prospective validation of the Braunwald classification. JAMA 273:136–141.
[Abstract/Free Full Text] - Jacobs DR Jr, Kroenke C, Crow R, Deshpande M, Gu DF, Gatewood L, Blackburn H. (1999) PREDICT: a simple risk score for clinical severity and long-term prognosis after hospitalization for acute myocardial infarction or unstable angina: the Minnesota heart survey. Circulation 100:599–607.
[Abstract/Free Full Text] - Boersma E, Pieper KS, Steyerberg EW, Wilcox RG, Chang WC, Lee KL, Akkerhuis KM, Harrington RA, Deckers JW, Armstrong PW, Lincoff AM, Califf RM, Topol EJ, Simoons ML. (2000) Predictors of outcome in patients with acute coronary syndromes without persistent ST-segment elevation. Results from an international trial of 9461 patients. Circulation 101:2557–2567.
[Abstract/Free Full Text] - Antman EM, Cohen M, Bernink PJ, McCabe CH, Horacek T, Papuchis G, Mautner B, Corbalan R, Radley D, Braunwald E. (2000) The TIMI risk score for unstable angina/non-ST elevation MI: a method for prognostication and therapeutic decision making. JAMA 284:835–842.
[Abstract/Free Full Text] - Granger CB, Goldberg RJ, Dabbous O, Pieper KS, Eagle KA, Cannon CP, Van De Werf F, Avezum A, Goodman SG, Flather MD, Fox KA. (2003) Predictors of hospital mortality in the Global Registry of Acute Coronary Events. Arch Intern Med 163:2345–2353.
[Abstract/Free Full Text] - Scirica BM, Cannon CP, Antman EM, Murphy SA, Morrow DA, Sabatine MS, McCabe CH, Gibson CM, Braunwald E. (2002) Validation of the Thrombolysis in Myocardial Infarction (TMI) risk score for unstable angina pectoris and non-ST-elevation myocardial infarction in the TIMI III Registry. Am J Cardiol 90:303–305.[CrossRef][Web of Science][Medline]
- Morrow DA, Antman EM, Snapinn SM, McCabe CH, Theroux P, Braunwald E. (2002) An integrated clinical approach to predicting the benefit of tirofiban in non-ST-elevation acute coronary syndromes: application of the TIMI risk score for UA/NSTEMI in PRISM-PLUS. Eur Heart J 23:223–229.
[Abstract/Free Full Text] - Singh M, Reeder GS, Jacobsen SJ, Weston S, Killian J, Roger VL. (2002) Scores for post-myocardial infarction risk stratification in the community. Circulation 106:2309–2314.
[Abstract/Free Full Text] - Yan AT, Jong P, Yan RT, Tan M, Fitchett D, Chow CM, Roe MT, Pieper KS, Langer A, Goodman SG. (2004) Clinical trial-derived risk model may not generalize to real-world patients with acute coronary syndromes. Am Heart J 148:1020–1027.[CrossRef][Web of Science][Medline]
- de Araujo Goncalves P, Ferreira J, Aguiar C, Seabra-Gomes R. (2005) TIMI, PURSUIT, and GRACE risk scores: sustained prognostic value and interaction with revascularization in NSTE-ACS. Eur Heart J 26:865–872.
[Abstract/Free Full Text] - Yan AT, Tan M, Fitchett D, Chow CM, Fowlis RA, McAvinue TG, Roe MT, Peterson ED, Tu JV, Langer A, Goodman SG. (2004) One-year outcome of patients after acute coronary syndromes (from the Canadian Acute Coronary Syndromes Registry). Am J Cardiol 94:25–29.[CrossRef][Web of Science][Medline]
- Fitchett D. (2000) Guidelines for the early management of acute coronary syndromes: focus on antithrombotic and antiplatelet therapy. Can J Cardiol 16:1423–1432.[Web of Science][Medline]
- Hanley JA and McNeil BJ. (1982) The meaning and use of the area under a receiver operating characteristic curve. Radiology 143:29–36.
[Abstract/Free Full Text] - DeLong ER, DeLong DM, Clarke-Pearson DL. (1988) Comparing the areas under two or more correlated receiver operating characteristic curves: a nonparametric approach. Biometrics 44:837–845.[CrossRef][Web of Science][Medline]
- Harrell FE Jr, Califf RM, Pryor DB, Lee KL, Rosati RA. (1982) Evaluating the yield of medical tests. JAMA 247:2543–2546.
[Abstract/Free Full Text] - Weintraub W. (2002) Prediction scores after myocardial infarction. Value, limitations, and future directions. Circulation 106:2292–2293.
[Free Full Text] - Wong CK and White HD. (2005) Value of community-derived risk models for stratifying patients with non-ST elevation acute coronary syndromes. Eur Heart J 26:851–852.
[Free Full Text] - Gibson CM, Dumaine RL, Gelfand EV, Murphy SA, Morrow DA, Wiviott SD, Giugliano RP, Cannon CP, Antman EM, Braunwald E. (2004) Association of glomerular filtration rate on presentation with subsequent mortality in non-ST-segment elevation acute coronary syndrome; observations in 13,307 patients in five TIMI trials. Eur Heart J 25:1998–2005.
[Abstract/Free Full Text] - Gibson CM, Pinto DS, Murphy SA, Morrow DA, Hobbach HP, Wiviott SD, Giugliano RP, Cannon CP, Antman EM, Braunwald E. (2003) Association of creatinine and creatinine clearance on presentation in acute myocardial infarction with subsequent mortality. J Am Coll Cardiol 42:1535–1543.
[Abstract/Free Full Text] - Freeman RV, Mehta RH, Al Badr W, Cooper JV, Kline-Rogers E, Eagle KA. (2003) Influence of concurrent renal dysfunction on outcomes of patients with acute coronary syndromes and implications of the use of glycoprotein IIb/IIIa inhibitors. J Am Coll Cardiol 41:718–724.
[Abstract/Free Full Text] - Khot UN, Jia G, Moliterno DJ, Lincoff AM, Khot MB, Harrington RA, Topol EJ. (2003) Prognostic importance of physical examination for heart failure in non-ST-elevation acute coronary syndromes. The enduring value of Killip classification. JAMA 290:2174–2181.
[Abstract/Free Full Text] - Steg PG, Dabbous OH, Feldman LJ, Cohen-Solal A, Aumont MC, Lopez-Sendon J, Budaj A, Goldberg RJ, Klein W, Anderson FA Jr. (2004) Determinants and prognostic impact of heart failure complicating acute coronary syndromes: observations from the Global Registry of Acute Coronary Events (GRACE). Circulation 109:494–499.
[Abstract/Free Full Text] - Yan AT, Yan RT, Tan M, Eagle KA, Granger CB, Dabbous OH, Fitchett D, Grima E, Langer A, Goodman SG. (2005) In-hospital revascularization and one-year outcome of acute coronary syndrome patients stratified by the GRACE risk score. Am J Cardiol 96:913–916.[CrossRef][Web of Science][Medline]
- Cannon CP, Weintraub WS, Demopoulos LA, Vicari R, Frey MJ, Lakkis N, Neumann FJ, Robertson DH, DeLucca PT, DiBattiste PM, Gibson CM, Braunwald E. (2001) Comparison of early invasive and conservative strategies in patients with unstable coronary syndromes treated with glycoprotein IIb/IIIa inhibitor tirofiban. N Engl J Med 344:1879–1887.
[Abstract/Free Full Text] - Roe MT, Peterson ED, Newby LK, Chen AY, Pollack CV Jr, Brindis RG, Harrington RA, Christenson RH, Smith SC Jr, Califf RM, Braunwald E, Gibler WB, Ohman EM. (2006) The influence of risk status on guideline adherence for patients with non-ST-segment elevation acute coronary syndromes. Am Heart J 151:1205–1213.[CrossRef][Web of Science][Medline]
- Yan AT, Yan RT, Tan M, Fung A, Cohen EA, Fitchett DH, Langer A, Goodman SG. (2007) Management patterns in relation to risk stratification among patients with non-ST elevation acute coronary syndromes. Arch Intern Med in press.
- Krumholz HM, Chen J, Murillo JE, Cohen DJ, Radford MJ. (1998) Admission to hospitals with on-site cardiac catheterization facilities: impact on long-term costs and outcomes. Circulation 98:2010–2016.
[Abstract/Free Full Text] - Alter DA, Naylor CD, Austin PC, Tu JV. (2001) Long-term MI outcomes at hospitals with or without on-site revascularization. JAMA 285:2101–2108.
[Abstract/Free Full Text] - Van de Werf F, Gore JM, Avezum A, Gulba DC, Goodman SG, Budaj A, Brieger D, White K, Fox KA, Eagle KA, Kennelly BM. (2005) Access to catheterisation facilities in patients admitted with acute coronary syndrome: multinational registry study. BMJ 330:441.
[Abstract/Free Full Text]
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  A. T. Yan, R. T. Yan, and S. G. Goodman Is Concentration on More Intensive Treatment for Younger Patients More Rational and Humane Than Ignorant?--Reply Arch Intern Med, August 10, 2009; 169(15): 1442 - 1443. [Full Text] [PDF]
|
|
|
|
 |
|
 A T Yan, R T Yan, S Jedrzkiewicz, and S G Goodman Evaluation of risk scores for risk stratification of acute coronary syndromes Heart, June 15, 2009; 95(12): 1019 - 1019. [Full Text] [PDF]
|
|
|
|
 |
|
 J. A. Wong, S. G. Goodman, R. T. Yan, R. Wald, A. J. Bagnall, R. C. Welsh, G. C. Wong, J. Kornder, K. A. Eagle, P. G. Steg, et al. Temporal management patterns and outcomes of non-ST elevation acute coronary syndromes in patients with kidney dysfunction Eur. Heart J., March 1, 2009; 30(5): 549 - 557. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. T. Yan, R. T. Yan, T. Huynh, A. Casanova, F. E. Raimondo, D. H. Fitchett, A. Langer, S. G. Goodman, and for the Canadian Acute Coronary Syndrome Registry Understanding Physicians' Risk Stratification of Acute Coronary Syndromes: Insights From the Canadian ACS 2 Registry Arch Intern Med, February 23, 2009; 169(4): 372 - 378. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C P Gale, S O M Manda, C F Weston, J S Birkhead, P D Batin, and A S Hall Evaluation of risk scores for risk stratification of acute coronary syndromes in the Myocardial Infarction National Audit Project (MINAP) database Heart, February 1, 2009; 95(3): 221 - 227. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. S. Alpert A Plethora of Prognostic Pearls Circulation, September 23, 2008; 118(13): 1312 - 1313. [Full Text] [PDF]
|
|
|
|
 |
|
 M. M. Henneman, J. D. Schuijf, G. Pundziute, J. M. van Werkhoven, E. E. van der Wall, J. W. Jukema, and J. J. Bax Noninvasive evaluation with multislice computed tomography in suspected acute coronary syndrome plaque morphology on multislice computed tomography versus coronary calcium score. J. Am. Coll. Cardiol., July 15, 2008; 52(3): 216 - 222. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. H. Lee, M. Tan, A. T. Yan, R. T. Yan, D. Fitchett, E. A. Grima, A. Langer, S. G. Goodman, and for the Canadian Acute Coronary Syndromes (ACS) Re Use of Cardiac Catheterization for Non-ST-Segment Elevation Acute Coronary Syndromes According to Initial Risk: Reasons Why Physicians Choose Not to Refer Their Patients Arch Intern Med, February 11, 2008; 168(3): 291 - 296. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. T. Yan, R. T. Yan, and S. G. Goodman Are acute coronary syndromes risk models too complex? reply Eur. Heart J., September 1, 2007; 28(17): 2176 - 2177. [Full Text] [PDF]
|
|
|
|
|
|
C. P. Gale, S. O. Manda, and A. S. Hall Are acute coronary syndromes risk models too complex? Eur. Heart J., September 1, 2007; 28(17): 2175 - 2176. [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||