GRACE Score: Definition and Clinical Application in Acute Coronary Syndrome
The GRACE (Global Registry of Acute Coronary Events) score is a validated risk stratification tool that predicts in-hospital and long-term mortality (up to 6 months, 1 year, and 3 years) in patients with acute coronary syndrome, demonstrating superior discriminative ability (C-statistic 0.83) compared to subjective physician assessment and other risk models. 1, 2
What the GRACE Score Measures
The GRACE score uses 8 specific variables collected at hospital admission to calculate risk across all forms of ACS (STEMI, NSTEMI, and unstable angina): 1, 2
- Age (odds ratio 1.7 per 10 years) 1
- Killip class (OR 2.0 per class) 1
- Systolic blood pressure (OR 1.4 per 20 mm Hg decrease) 1
- Heart rate (OR 1.3 per 30-beat per min increase) 1
- ST-segment deviation on ECG (OR 2.4) 1
- Cardiac arrest during presentation (OR 4.3) 1
- Serum creatinine level (OR 1.2 per 1-mg per dL increase) 1
- Positive initial cardiac biomarkers (OR 1.6) 1
How to Use the GRACE Score Clinically
Calculate the GRACE score immediately at hospital admission for all confirmed ACS patients using the online calculator at www.outcomes-umassmed.org/grace or downloadable handheld device application. 1, 3 The sum of individual variable scores is applied to a reference nomogram to determine predicted mortality risk. 1
Risk Stratification Categories
High-risk patients (GRACE score >140) require: 2, 3
- Early invasive strategy with urgent coronary angiography
- Intensive antiplatelet therapy
- Close hemodynamic monitoring during hospitalization
Intermediate and low-risk patients (GRACE score ≤140) can be managed with: 2
- Initial conservative strategy with medical therapy
- Selective invasive evaluation only if recurrent ischemia develops
- Noninvasive stress testing before discharge
Predictive Performance Across Time Points
The GRACE score accurately predicts mortality at multiple clinically relevant time points: 1, 4, 5
- In-hospital mortality: C-statistic 0.83 1
- 6-month mortality: C-statistic 0.81 4, 5
- 1-year mortality: C-statistic 0.82 4
- 3-year mortality: C-statistic 0.81 4
- 4-year mortality: C-statistic 0.80 4
The discrimination remains excellent across all ACS subtypes (STEMI, NSTEMI, unstable angina) and is maintained despite advances in contemporary treatment. 6, 7
Advantages Over Alternative Risk Scores
The GRACE score demonstrates superior discriminative ability compared to TIMI and PURSUIT risk scores for predicting death and myocardial infarction at 1 year. 1 While all three scores show good predictive accuracy, the GRACE model's C-statistic of 0.83 exceeds that of competing models. 1, 2
The GRACE score captures both hemodynamic instability (through Killip class, blood pressure, heart rate, cardiac arrest) and underlying disease severity (through age, creatinine, biomarkers, ECG changes), providing a more comprehensive risk assessment. 2
Updated GRACE 2.0 Model
An updated version (GRACE 2.0) employs non-linear algorithms for age, systolic blood pressure, heart rate, and creatinine, which improved model discrimination beyond the original linear associations. 8 This updated score maintains excellent discrimination (C-index >0.82 for 1-year and 3-year mortality) and performs equally well acutely and over the longer term. 8
Critical Clinical Considerations
The GRACE score applies across the entire ACS spectrum, but STEMI patients warrant special attention due to higher early mortality risk and the particular importance of the creatinine component—in-hospital mortality in STEMI patients with stage 4-5 chronic kidney disease approaches 30%. 3
Renal impairment represents an additional high-risk feature in ACS patients, with mild-to-moderate dysfunction associated with moderately increased risk and severe dysfunction associated with severely increased short- and long-term risks. 1
Practical Implementation Pitfalls
While the GRACE score demonstrates excellent discrimination, calibration may require adjustment in specific healthcare settings and with treatment advances. 6 The predicted probability of in-hospital mortality showed suboptimal calibration in some Canadian populations despite excellent discrimination. 6
There is insufficient evidence that routine use of risk scores translates into reduced cardiovascular events. 2 The Australian GRACE Risk Score Intervention Study failed to demonstrate added value with routine GRACE implementation, largely because control hospitals performed better than expected. 2
Risk scores are not diagnostic tools—they stratify risk only in suspected or confirmed ACS and must be used alongside clinical judgment, serial ECGs, and cardiac biomarkers. 2, 9