Comparison of three risk stratification rules for predicting patients with acute coronary syndrome presenting to an Australian emergency department

Objectives: To compare the predictive ability of three risk stratification tools used to assess patients presenting to the ED with potential acute coronary syndrome.

Design: Pre-planned analysis of an observational study.

Setting: A single tertiary referral hospital.

Participants: 1495 patients presented with chest pain. 948 patients were screened and enrolled. Patients with at least 5 min of chest pain suggestive of ACS were eligible.

Interventions: Subjects were risk categorised using the Heart Foundation of Australia/Cardiac Society of Australia and New Zealand guidelines (HFA/CSANZ), the TIMI score and the GRACE score. Three strata of the TIMI and GRACE score were used to compare to the HFA/CSANZ risk categories.

Main outcome measurement: 30-Day cardiac event rates including cardiac death, acute myocardial infarction and unstable angina.

Results: There were 152 events in 91 patients (9.6%). The discriminatory ability of the scores determined by the AUC was 0.83 (95% CI 0.79-0.87) for the GRACE score, 0.79 (95% CI 0.74-0.83) for TIMI score and 0.75 (95% CI 0.70-0.80) for HFA/CSANZ. The AUCs with three strata of the GRACE and TIMI scores were 0.76 (95% CI 0.72-0.81) and 0.68 (95% CI 0.62-0.73) respectively.

Conclusions: All three scores were similar in performance in quantifying risk in ED patients with possible ACS. The GRACE score identified a sizable low risk cohort with high sensitivity and NPV but complexity of this tool may limit its utility. Improved scores are needed to allow early identification of low- and high-risk patients to support improvements in patient flow and ED overcrowding.