At what percentage of Atherosclerotic Cardiovascular Disease (ASCVD) risk score should a statin be prescribed?

Statin Prescription Based on ASCVD Risk Score

Statins should be prescribed for primary prevention when the 10-year ASCVD risk score is ≥7.5%, with consideration in borderline risk patients (5% to <7.5%) when risk-enhancing factors are present.

Risk Categories and Statin Recommendations

Primary Prevention Categories:

1. High Risk (≥20% 10-year ASCVD risk)

   • Moderate to high-intensity statin therapy
   • Goal: Reduce LDL-C by ≥50% 1

2. Intermediate Risk (≥7.5% to <20% 10-year ASCVD risk)

   • Moderate-intensity statin therapy recommended
   • Goal: Reduce LDL-C by ≥30% 1
   • Consider high-intensity statin if maximal risk reduction desired 1

3. Borderline Risk (5% to <7.5% 10-year ASCVD risk)

   • Statin therapy may be justified when risk-enhancing factors are present 1
   • Risk discussion essential for shared decision-making

4. Low Risk (<5% 10-year ASCVD risk)

   • Generally no statin therapy unless other indications present

Special Populations (Regardless of ASCVD Risk Score):

• Diabetes mellitus (age 40-75): Moderate-intensity statin regardless of 10-year risk 1

  • High-intensity statin reasonable with multiple risk factors 1

• LDL-C ≥190 mg/dL: High-intensity statin without calculating ASCVD risk 1

Risk-Enhancing Factors to Consider in Borderline/Intermediate Risk

• Family history of premature ASCVD
• Persistently elevated LDL-C ≥160 mg/dL
• Metabolic syndrome
• Chronic kidney disease
• History of preeclampsia or premature menopause
• Chronic inflammatory disorders (e.g., rheumatoid arthritis, psoriasis, HIV)
• High-risk ethnic groups (e.g., South Asian)
• Persistent elevations of triglycerides ≥175 mg/dL
• Elevated apolipoprotein B ≥130 mg/dL (if measured)
• Elevated Lp(a) ≥50 mg/dL (if measured)
• Elevated hs-CRP ≥2 mg/L 1

Using Coronary Artery Calcium (CAC) Score to Refine Decision-Making

For intermediate-risk or selected borderline-risk adults where decision remains uncertain:

• CAC = 0: Reasonable to withhold statin therapy and reassess in 5-10 years (unless diabetes, family history of premature CAD, or active smoking present) 1
• CAC = 1-99: Reasonable to initiate statin therapy, especially for patients ≥55 years 1
• CAC ≥100 or ≥75th percentile: Reasonable to initiate statin therapy 1

Clinical Considerations and Caveats

1. Benefit vs. Risk Assessment:

   • Statin therapy provides greater benefit with higher baseline risk
   • NNT to prevent one ASCVD event varies significantly by risk level and CAC score (NNT as low as 28 for CAC >100) 1

2. Common Pitfalls to Avoid:

   • Undertreating high-risk patients: Only 59.9% of patients with established ASCVD received statins by 2016, despite clear indications 2
   • Overreliance on LDL-C levels alone: ASCVD risk score provides better risk stratification than LDL-C alone
   • Neglecting non-CHD ASCVD: Patients with ischemic stroke/TIA (65.8%) and PAD (37.5%) are less likely to receive statins than those with CHD (80.9%) despite similar benefit 2
   • Ignoring residual risk: Even on statin therapy, residual ASCVD risk remains substantial, especially in high and very-high risk groups 3

3. Statin Intensity Selection:

   • High-intensity statin: Reduces LDL-C by ≥50%
   • Moderate-intensity statin: Reduces LDL-C by 30-49%
   • Low-intensity statin: Generally not recommended unless intolerance to higher doses 1

The evidence clearly supports using the 7.5% 10-year ASCVD risk threshold as the primary cutoff for statin therapy in primary prevention, with consideration of statin therapy at lower risk levels (5-7.5%) when risk-enhancing factors are present. Using CAC scoring can help refine decision-making in cases where risk status remains uncertain after traditional risk assessment.