# Risk Assessment for Primary Prevention -- ACC/AHA 2018

## 10-Year ASCVD Risk Categories

In adults aged 40--75 years without clinical ASCVD or diabetes, the 10-year ASCVD risk (estimated by the Pooled Cohort Equations) guides statin therapy initiation (Class I, Level of Evidence B-NR):

| Risk Category | 10-Year ASCVD Risk | Statin Recommendation |
|---|---|---|
| **Low** | < 5% | Emphasize lifestyle modifications; statin generally not indicated |
| **Borderline** | 5% to < 7.5% | If risk-enhancing factors present, consider moderate-intensity statin (Class IIb, Level of Evidence B-NR) |
| **Intermediate** | 7.5% to < 20% | Moderate-intensity statin to reduce LDL-C by >= 30% after clinician--patient risk discussion (Class I, Level of Evidence A) |
| **High** | >= 20% | High-intensity statin to reduce LDL-C by >= 50% (Class I, Level of Evidence A) |

> **OpenMedicine Calculator:** `calculate_ascvd` -- available via MCP for automated 10-year ASCVD risk scoring.

> **OpenMedicine Calculator:** `calculate_framingham` -- available via MCP for automated 10-year general CVD risk scoring.

## Risk-Enhancing Factors

In adults at borderline (5% to < 7.5%) or intermediate (7.5% to < 20%) 10-year ASCVD risk, the presence of risk-enhancing factors favors initiation of statin therapy (Class IIa, Level of Evidence B-NR):

### Demographic and Family History
- Family history of premature ASCVD (males < 55 years; females < 65 years)
- High-risk race/ethnicity (e.g., South Asian ancestry)

### Reproductive History (Women)
- History of premature menopause (before age 40 years)
- History of pregnancy-associated conditions: preeclampsia, gestational diabetes

### Metabolic and Lipid Factors
- Primary hypercholesterolemia: LDL-C 160--189 mg/dL (4.1--4.8 mmol/L)
- Persistently elevated primary hypertriglyceridemia: >= 175 mg/dL (>= 2.0 mmol/L)
- Metabolic syndrome (increased waist circumference, elevated triglycerides [>= 150 mg/dL], elevated blood pressure, elevated fasting glucose [>= 100 mg/dL], and low HDL-C [< 40 mg/dL in men, < 50 mg/dL in women])

### Chronic Inflammatory and Systemic Conditions
- Chronic inflammatory conditions: psoriasis, rheumatoid arthritis, or HIV/AIDS
- Chronic kidney disease (eGFR 15--59 mL/min/1.73 m2)

### Biomarkers (If Measured)
- Elevated high-sensitivity C-reactive protein (hs-CRP): >= 2.0 mg/L
- Elevated lipoprotein(a) [Lp(a)]: >= 50 mg/dL or >= 125 nmol/L
- Elevated apolipoprotein B (apoB): >= 130 mg/dL
- Ankle-brachial index (ABI): < 0.9

## Coronary Artery Calcium (CAC) Scoring

When risk-based decisions for statin therapy are uncertain in intermediate-risk adults (7.5% to < 20% 10-year ASCVD risk), CAC scoring may be used to refine the decision (Class IIa, Level of Evidence B-NR):

| CAC Score | Clinical Action |
|---|---|
| **0** | Treatment with statin therapy may be withheld or delayed, except in cigarette smokers, those with diabetes mellitus, and those with a strong family history of premature ASCVD. Reassess in 5--10 years. |
| **1--99** | Favors statin therapy, especially in patients >= 55 years of age |
| **>= 100 or >= 75th percentile** | Statin therapy is indicated unless otherwise deferred by clinician--patient risk discussion |

## Lipid Measurement

- Fasting or nonfasting plasma lipid levels are effective for estimating ASCVD risk in adults >= 20 years not on lipid-lowering therapy (Class I, Level of Evidence B-NR).
- When nonfasting triglycerides are >= 400 mg/dL, obtain a fasting lipid profile (Class IIa, Level of Evidence C-EO).
- In adults aged 20--39 years, assessment of lifetime risk is reasonable to encourage intensive lifestyle efforts (Class IIa, Level of Evidence B-NR).

## Clinician--Patient Risk Discussion

Before initiating statin therapy for primary prevention, a clinician--patient risk discussion should address (Class I, Level of Evidence B-NR):

1. Assessment of major risk factors using the ASCVD Risk Estimator Plus
2. Presence of risk-enhancing factors
3. Potential benefits of lifestyle modifications and statin therapy
4. Potential for adverse effects and drug interactions
5. Costs of statin therapy
6. Patient preferences and shared decision-making

## Limitations

- The Pooled Cohort Equations are validated for adults aged 40--79 years in non-Hispanic White and non-Hispanic African American populations. They may over- or underestimate risk in other racial/ethnic groups (e.g., Hispanic, Asian American); clinical judgment is required.
- CAC scoring involves radiation exposure and should not be repeated more frequently than every 5 years.
- Risk-enhancing factors are qualitative considerations that do not modify the quantitative risk estimate.
