How is 10-year Cardiovascular Disease (CVD) risk calculated?

10-Year CVD Risk Calculation

The ACC/AHA Pooled Cohort Equations should be used to calculate 10-year ASCVD risk in adults aged 40-79 years, incorporating age, sex, race, total cholesterol, HDL cholesterol, systolic blood pressure, hypertension treatment status, diabetes, and smoking status. 1

Primary Risk Calculator: ACC/AHA Pooled Cohort Equations

The ACC/AHA Pooled Cohort Equations represent the current standard for 10-year cardiovascular disease risk assessment in the United States. 1 These equations were developed from pooled data from multiple large, racially diverse NHLBI-sponsored cohort studies including ARIC, Cardiovascular Health Study, CARDIA, and Framingham cohorts. 1

Required Input Variables

The calculator requires the following specific parameters: 1

• Age (40-79 years)
• Sex (male or female)
• Race (non-Hispanic White or non-Hispanic African American)
• Total cholesterol (mg/dL)
• HDL cholesterol (mg/dL)
• Systolic blood pressure (mmHg)
• Antihypertensive treatment status (yes/no)
• Diabetes mellitus (yes/no)
• Current smoking status (yes/no)

Predicted Outcomes

The equations estimate 10-year risk of hard ASCVD events, specifically: 1

• Nonfatal myocardial infarction
• Death from coronary heart disease
• Fatal or nonfatal stroke

Risk Categorization Thresholds

Risk stratification using the Pooled Cohort Equations defines: 1, 2

• Low risk: <7.5% 10-year ASCVD risk
• Borderline risk: 5-7.5% 10-year ASCVD risk
• Intermediate risk: 7.5-10% 10-year ASCVD risk
• High risk: ≥10% 10-year ASCVD risk OR established CVD

The USPSTF uses slightly different thresholds, with ≥10% defining higher risk and 7.5-10% representing an intermediate category requiring shared decision-making. 1

Race-Specific Application

For non-Hispanic African Americans and non-Hispanic Whites aged 40-79 years, use the race- and sex-specific Pooled Cohort Equations. 1 For Hispanic Americans, Asian Americans, and other ethnic groups, the equations for non-Hispanic Whites may be considered, though this represents expert opinion rather than validated data. 1 The calculator generally underestimates risk in American Indian populations and overestimates risk in Asian American and Hispanic populations. 1

Important Caveats and Limitations

Age heavily influences calculated risk—41% of men and 27% of women aged 60-69 years without CVD will have calculated 10-year risk ≥10% even without traditional risk factors like dyslipidemia, diabetes, hypertension, or smoking. 1 This age-driven risk elevation means many older adults may meet treatment thresholds based solely on age, despite lacking other modifiable risk factors. 1

The Pooled Cohort Equations have been criticized for overestimating risk when applied to contemporary US cohorts, particularly at the lower end of the risk spectrum. 1 External validation studies suggest the calculator may overestimate actual event rates, though it remains the only US-based CVD risk prediction tool with published external validation in diverse US populations. 1

Alternative Risk Calculator: PREVENT Equations (2023 Update)

The 2023 PREVENT equations represent the most recent update to ASCVD risk assessment, removing race as a variable and adding kidney function (eGFR and urine albumin-creatinine ratio) and statin use. 3 These equations estimate lower 10-year ASCVD risk compared to the Pooled Cohort Equations (mean 4.3% vs 8.0%), with the largest differences in Black adults (5.1% vs 10.9%) and individuals aged 70-75 years (10.2% vs 22.8%). 3 However, the ACC/AHA guidelines have not yet formally adopted PREVENT as the primary risk calculator, so the Pooled Cohort Equations remain the guideline-recommended tool. 1

European Alternative: SCORE System

The European Society of Cardiology uses the SCORE (Systematic Coronary Risk Evaluation) system, which estimates 10-year CVD mortality risk rather than total ASCVD events. 1 SCORE incorporates age, sex, total cholesterol (or total and HDL cholesterol), smoking status, and systolic blood pressure, but notably excludes diabetes as a direct input variable. 1 This fundamental difference in outcome (mortality vs. total events) makes SCORE estimates substantially lower than ACC/AHA calculations and not directly comparable. 1

Implementation in Clinical Practice

Downloadable spreadsheets and web-based calculators are available at http://my.americanheart.org/cvriskcalculator and http://www.cardiosource.org/science-and-quality/practice-guidelines-and-quality-standards/2013-prevention-guideline-tools.aspx. 1

Periodic reassessment is recommended: 1

• Blood pressure: annually
• Lipid levels: every 5 years (shorter intervals for borderline values, longer for consistently normal values)
• Smoking status: annually

Age-Specific Considerations

For adults <40 years old, lifetime CVD risk assessment is recommended rather than 10-year risk calculation. 1, 2 The Pooled Cohort Equations are not validated for this age group. 1

For adults ≥76 years old, evidence is insufficient to guide risk assessment and statin initiation decisions. 1 No trial data evaluated statin use in this age group without existing CVD risk factors. 1

Risk Refinement Beyond the Calculator

For patients with borderline or intermediate risk (5-10%), additional risk-enhancing factors can refine assessment: 2

• Family history of premature ASCVD
• Chronic inflammatory conditions
• South Asian ancestry
• Coronary artery calcium (CAC) scoring

CAC scoring is particularly useful for reclassifying intermediate-risk patients and selected borderline-risk patients. 2, 4