How do I calculate the STS (Society of Thoracic Surgeons) score?

How to Calculate the STS (Society of Thoracic Surgeons) Score

The STS score can be calculated using the online STS Adult Cardiac Surgery Risk Calculator available at http://riskcalc.sts.org/stswebriskcalc/calculate, which provides individualized risk assessment for patients undergoing cardiac surgery. 1

Overview of the STS Score

• The STS score is a validated risk prediction tool that calculates the predicted risk of mortality (PROM) and morbidity for patients undergoing cardiac surgical procedures 1
• It serves as a benchmark for cardiac surgery reporting and is widely used for preoperative risk assessment, patient selection, and shared decision-making 1
• The score is regularly updated and calibrated annually to ensure the predicted rates equal the observed rates across the entire STS database 2, 3

Accessing the STS Calculator

• The official STS Adult Cardiac Surgery Risk Calculator is available online at: http://riskcalc.sts.org/stswebriskcalc/calculate 1
• For TAVR-specific risk assessment, a separate tool is available at: http://tools.acc.org/TAVRRisk/#!/content/evaluate/ 1

Key Variables Required for Calculation

The STS score incorporates approximately 70 clinical variables including:

• Demographics: Age, gender, height, weight 4
• Cardiac status: Ejection fraction, heart failure classification (NYHA class), prior myocardial infarction 4
• Comorbidities: Renal function, pulmonary function, cerebrovascular disease, peripheral vascular disease 1, 4
• Cardiac anatomy and pathology: Coronary disease extent, valve pathology 1
• Procedural factors: Type of procedure (isolated CABG, valve surgery, combined procedures) 1
• Urgency of procedure: Elective, urgent, or emergent status 4

Interpretation of STS Score Results

• Low risk: STS-PROM <3% 1
• Intermediate risk: STS-PROM between 3% and 8% 1
• High risk: STS-PROM ≥8% 1
• Extreme risk: STS-PROM ≥15% 1

Clinical Applications

• The STS score helps determine surgical risk and guides decision-making for various cardiac procedures 1
• It's used in heart team discussions to choose between surgical (SAVR) and transcatheter (TAVR) approaches for aortic valve replacement 1
• An STS-PROM score >15% may indicate futility of TAVR, as these patients showed no appreciable benefit in all-cause mortality compared to medical therapy in clinical trials 1
• The score is also used to calculate risk for specific procedures, with median operative mortality rates varying by procedure type (e.g., 2.2% for isolated AVR, 9% for AVR plus mitral valve replacement) 1

Important Considerations

• The uncalibrated STS risk scores provided by the online calculator are typically higher than the calibrated values used in the STS database 2, 3
• The current STS calculator produces significantly lower predicted risk of mortality than earlier versions, particularly for patients with certain comorbidities like atrial fibrillation and heart failure 5
• When comparing with other risk scores (like EuroSCORE), be aware that the STS score tends to be more accurate but less inclusive for complex procedures 6
• The STS score demonstrates strong predictive accuracy for postoperative stroke risk and other complications in addition to mortality 4

Practical Steps for Calculation

1. Visit the official STS calculator website: http://riskcalc.sts.org/stswebriskcalc/calculate 1
2. Enter all required patient data accurately
3. The calculator will provide risk estimates for mortality and major morbidities
4. Use these risk estimates as part of a shared decision-making process with patients 1
5. Consider the results in the context of a heart team discussion for complex cases 1

Remember that while the STS score is valuable for risk stratification, it should be considered alongside clinical judgment and other factors when making treatment decisions 1.