Number Needed to Treat with Statins to Prevent Heart Attack or Stroke

NNT Values from Major Statin Trials

The American Heart Association recommends that treating 258 patients with atorvastatin 80mg daily for one year would prevent one recurrent stroke, based on the Stroke Prevention by Aggressive Reduction in Cholesterol Levels (SPARCL) trial 1, 2
In the same population, treating 288 patients with atorvastatin for one year would prevent one nonfatal myocardial infarction, with a strength of evidence based on multiple clinical trials 2, 3
The 5-year absolute risk reduction for major cardiovascular events was 3.5% in the SPARCL trial, with a hazard ratio of 0.80 (95% CI, 0.69 to 0.92; p=0.002), indicating a moderate to high strength of evidence 4, 5

The American College of Cardiology states that the NNT varies significantly based on patient risk factors, with an NNT of 64 for intermediate-risk patients with coronary artery calcium score (CACS) = 0, and an NNT of 28 for patients with CACS > 100, indicating a high strength of evidence 6
Greater LDL-C reduction correlates with improved outcomes, with patients achieving ≥50% reduction in LDL-C having a 35% reduction in combined risk of fatal and nonfatal stroke, based on moderate to high strength of evidence 2, 7
Achieving an LDL-C level of <70 mg/dL was associated with a 28% reduction in risk of stroke without increasing hemorrhagic stroke risk, with a moderate strength of evidence 2, 3

The American Heart Association recommends statin therapy for patients with established cardiovascular disease, with a reduction in overall incidence of strokes by 16% compared to placebo over 4.9 years, based on high strength of evidence 4
The reduction in ischemic strokes was 37% (HR, 0.63; 95% CI, 0.49 to 0.81) in patients achieving significant LDL-C reduction, indicating a high strength of evidence 2, 3

There was a slightly higher incidence of hemorrhagic stroke in the atorvastatin treatment arm in SPARCL (2.3% vs 1.4% for placebo), with a moderate strength of evidence 1, 4
Increased risk of hemorrhagic stroke was associated with previous hemorrhagic stroke (HR, 5.65; 95% CI, 2.82 to 11.30), male sex (HR, 1.79, 95% CI, 1.13 to 2.84), advanced age (10-year increments; HR, 1.42; 95% CI, 1.16 to 1.74), and stage 2 hypertension, based on moderate to high strength of evidence 3, 7

The American College of Cardiology recommends statin therapy with intensive lipid-lowering effects for patients with ischemic stroke or TIA who have evidence of atherosclerosis, an LDL-C level >100 mg/dL, and who are without known coronary heart disease, based on high strength of evidence 7, 8
Targeting a reduction of at least 50% in LDL-C or a target LDL-C level of <70 mg/dL is recommended to obtain maximum benefit, with a moderate to high strength of evidence 7, 8, 9