At what point should a patient with a history of cardiovascular disease or high low-density lipoprotein (LDL) cholesterol start taking a statin?

When to Start a Statin

For patients with established cardiovascular disease, start a high-intensity statin immediately—this is secondary prevention and requires no risk calculation. 1 For primary prevention, the decision depends on specific clinical criteria outlined below.

Immediate Statin Initiation (No Risk Calculation Needed)

Start statin therapy immediately in these three groups:

• LDL-C ≥190 mg/dL: Initiate high-intensity statin therapy without calculating 10-year ASCVD risk 1, 2
• Diabetes mellitus (ages 40-75) with LDL-C ≥70 mg/dL: Start at least moderate-intensity statin therapy; consider high-intensity if multiple risk factors present 1
• Established ASCVD (secondary prevention): Begin high-intensity statin therapy targeting ≥50% LDL-C reduction 1, 3

Risk-Based Statin Initiation (Ages 40-75, Primary Prevention)

Calculate 10-year ASCVD risk using the Pooled Cohort Equations for all patients ages 40-75 with one or more CVD risk factors (dyslipidemia, diabetes, hypertension, or smoking) and LDL-C 70-189 mg/dL. 1

High Risk (≥20% 10-year ASCVD risk)

• Initiate high-intensity statin therapy targeting ≥50% LDL-C reduction 1, 2

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

• Start moderate-intensity statin therapy after clinician-patient risk discussion, targeting ≥30% LDL-C reduction 1, 2
• This is a Class I recommendation with Level A evidence 1
• The USPSTF recommends statin initiation at ≥10% risk (B recommendation), while ACC/AHA guidelines recommend starting at ≥7.5% 1, 4
• The more recent 2019 ACC/AHA guideline threshold of ≥7.5% should guide practice 1

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

• Consider moderate-intensity statin therapy if risk-enhancing factors are present 1, 2
• This is a Class IIb recommendation 1

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

• Statin therapy generally not indicated unless other specific indications present 2

Risk-Enhancing Factors That Favor Statin Initiation

In patients with borderline or intermediate risk, the presence of these factors strengthens the indication for statin therapy: 1, 2

• Family history of premature ASCVD (male <55 years, female <65 years) 1, 2
• Persistently elevated LDL-C ≥160 mg/dL 1, 2
• Metabolic syndrome 1, 2
• Chronic kidney disease 1, 2
• History of preeclampsia or premature menopause (age <40 years) 1, 2
• Chronic inflammatory disorders (rheumatoid arthritis, psoriasis, HIV) 1, 2
• High-risk ethnic groups (e.g., South Asian) 1, 2
• Persistent triglycerides ≥175 mg/dL 1, 2
• High-sensitivity C-reactive protein ≥2.0 mg/L 1, 2
• Ankle-brachial index <0.9 1, 2
• Lipoprotein(a) ≥50 mg/dL or 125 nmol/L 1

Using Coronary Artery Calcium (CAC) Score When Decision Is Uncertain

For intermediate-risk patients (7.5% to <20%) or selected borderline-risk patients (5% to <7.5%) when the statin decision remains uncertain after risk discussion, measure CAC score: 1, 2

• CAC = 0: Reasonable to withhold statin therapy and reassess in 5-10 years, except in patients with diabetes, cigarette smoking, or strong family history of premature CHD 1, 2
• CAC 1-99: Favors statin initiation, especially in patients ≥55 years 1, 2
• CAC ≥100 Agatston units or ≥75th percentile: Statin therapy indicated 1, 2

The CAC score is particularly useful because it reclassifies 6.8% of patients with initial risk <7.5% to statin-eligible status, with these patients having an observed event rate of 13.3% and a number needed to screen of only 14.7 5

Special Populations

Adults ≥76 Years

• Insufficient evidence to recommend routine statin initiation for primary prevention 1, 4
• For secondary prevention (established CAD), moderate-intensity statin therapy is reasonable (Class IIa) 6
• Clinical judgment based on life expectancy, functional status, and patient preferences should guide decisions 1

Young Adults (20-39 Years)

• Statin therapy generally reserved for LDL-C ≥190 mg/dL or very high-risk conditions 1
• Focus on lifetime risk reduction through lifestyle modifications 1

Mandatory Clinician-Patient Risk Discussion

Before prescribing any statin for primary prevention, conduct a structured discussion addressing: 1, 2

• Review of major risk factors (smoking, blood pressure, LDL-C, hemoglobin A1C if indicated, calculated 10-year ASCVD risk) 1, 2
• Presence of risk-enhancing factors 1, 2
• Potential benefits: 20-30% relative risk reduction in cardiovascular events 2
• Potential adverse effects: myalgias (most common), new-onset diabetes (number needed to harm = 100), drug interactions 2, 3
• Cost considerations 1
• Patient preferences and values 1, 2
• Emphasis that heart-healthy lifestyle remains the foundation of ASCVD prevention 1, 2

Statin Intensity Definitions

Moderate-intensity statins (30-50% LDL-C reduction): 1

• Atorvastatin 10-20 mg daily 7
• Rosuvastatin 5-10 mg daily 1
• Simvastatin 20-40 mg daily 1
• Pravastatin 40-80 mg daily 1

High-intensity statins (≥50% LDL-C reduction): 1

• Atorvastatin 40-80 mg daily 7
• Rosuvastatin 20-40 mg daily 1

Monitoring After Initiation

Assess adherence and LDL-C response 4-12 weeks after statin initiation or dose adjustment 1, 2

Repeat lipid measurement every 3-12 months as needed 1, 2

Define treatment response by percentage LDL-C reduction from baseline, not absolute LDL-C targets 1

Critical Pitfalls to Avoid

• Do not rely on risk calculation alone—the clinician-patient discussion is mandatory before initiating statin therapy 1, 2
• Do not let age alone drive decisions—consider the complete risk profile, life expectancy, and functional status 2
• Do not dismiss statin therapy in patients with favorable lipid profiles if their calculated risk is elevated—overall risk score determines benefit 8
• Do not forget that 57% of ASCVD events occur in patients with calculated risk <7.5%—this highlights the importance of risk-enhancing factors and CAC scoring in borderline cases 5
• Do not overlook that the Pooled Cohort Equations may overestimate risk in some populations—use CAC scoring when uncertainty exists 1