When to Start Statin Therapy Based on ASCVD Risk Score
For adults 40-75 years of age without diabetes mellitus and with LDL-C levels ≥70 mg/dL, statin therapy should be initiated at a 10-year ASCVD risk of ≥7.5% after a clinician-patient risk discussion. 1
Primary Prevention Recommendations Based on Risk Categories
Definite Statin Indications (No ASCVD Risk Calculation Needed)
- Adults with LDL-C ≥190 mg/dL should receive high-intensity statin therapy without calculating 10-year ASCVD risk 1
- Adults 40-75 years with diabetes mellitus and LDL-C ≥70 mg/dL should receive moderate-intensity statin therapy without calculating 10-year ASCVD risk 1
- Adults with diabetes at higher risk (multiple risk factors or age 50-75) should receive high-intensity statin therapy to reduce LDL-C by ≥50% 1
Risk-Based Statin Recommendations
- 10-year ASCVD risk ≥7.5% to <20% (Intermediate risk): Start moderate-intensity statin therapy after clinician-patient risk discussion 1
- 10-year ASCVD risk ≥20% (High risk): High-intensity statin therapy to reduce LDL-C by ≥50% 1
- 10-year ASCVD risk 5% to <7.5% (Borderline risk): Consider moderate-intensity statin therapy if risk-enhancing factors are present 1
- 10-year ASCVD risk <5% (Low risk): Generally, statin therapy not recommended unless other indications present 1
Risk-Enhancing Factors to Consider
Risk-enhancing factors that may favor statin initiation, particularly in borderline or intermediate risk patients include:
- Family history of premature ASCVD 1
- Persistently elevated LDL-C ≥160 mg/dL 1
- Metabolic syndrome 1
- Chronic kidney disease 1
- History of preeclampsia or premature menopause (age <40 years) 1
- Chronic inflammatory disorders (e.g., rheumatoid arthritis, psoriasis, HIV) 1
- High-risk ethnic groups (e.g., South Asian) 1
- Persistent elevations of triglycerides ≥175 mg/dL 1
- If measured: apolipoprotein B ≥130 mg/dL, high-sensitivity C-reactive protein ≥2.0 mg/L, ankle-brachial index <0.9, or lipoprotein(a) ≥50 mg/dL 1
Using Coronary Artery Calcium (CAC) Score for Decision-Making
In intermediate-risk (7.5% to <20%) or selected borderline-risk (5% to <7.5%) adults where the decision about statin therapy is uncertain:
- CAC score = 0: May withhold or delay statin therapy (except in smokers, those with diabetes, or strong family history of premature ASCVD) 1
- CAC score 1-99: Favors statin therapy, especially in those ≥55 years of age 1
- CAC score ≥100 or ≥75th percentile: Statin therapy is indicated 1
Monitoring and Follow-up
- Assess adherence and percentage response to LDL-C-lowering medications 4-12 weeks after statin initiation or dose adjustment 1
- For patients on statin therapy, aim for LDL-C reduction of ≥30% for moderate-intensity statins and ≥50% for high-intensity statins 1
Clinical Considerations and Caveats
- The clinician-patient risk discussion is essential before starting statin therapy and should include review of major risk factors, risk-enhancing factors, potential benefits, adverse effects, drug interactions, costs, and patient preferences 1
- Despite statin therapy, residual ASCVD risk remains, especially in those with multiple risk factors 2
- Recent evidence suggests that intensive risk factor management provides additional benefit in patients with ASCVD risk ≥7.5% 3
- There are significant treatment gaps in statin therapy, particularly in women and patients with non-coronary forms of ASCVD 4
- The number needed to treat (NNT) to prevent one ASCVD event over 10 years ranges from 18-32 depending on risk level and statin intensity 5
Comparison of Guidelines
While this guidance is based primarily on the 2018/2019 ACC/AHA guidelines, it's worth noting that different guidelines have varying thresholds for statin initiation:
- ACC/AHA (2018): ≥7.5% 10-year ASCVD risk 1
- USPSTF (2016): ≥10% 10-year ASCVD risk 1, 5
- ESC/EAS (2019): Uses risk categories rather than specific percentage thresholds 1
The ACC/AHA approach has been shown to correctly identify more individuals who will develop ASCVD compared to some other guidelines, while maintaining similar NNT values 5.