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2013 ACC/AHA Guideline on the Treatment of Blood Cholesterol to Reduce Atherosclerotic Cardiovascular Risk in Adults
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A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines
2.2. Initiation of Statin Therapy
The Expert Panel found extensive and consistent evidence supporting the use of statins for the prevention of ASCVD in many higher-risk primary- and all secondary-prevention individuals without New York Heart Association class II–IV heart failure who were not receiving hemodialysis. In the RCTs reviewed, initiation of moderate-intensity therapy (lowering LDL-C by approximately 30% to <50%) or high-intensity statin therapy (lowering LDL-C by approximately ≥50%) is a critical factor in reducing ASCVD events. Moreover, statin therapy reduces ASCVD events across the spectrum of baseline LDL-C levels ≥70 mg/dL. In addition, the relative reduction in ASCVD risk is consistent for primary and secondary prevention and for various patient subgroups. Of note, the absolute reduction in ASCVD events is proportional to baseline absolute ASCVD risk. Therefore, statin therapy is recommended for individuals at increased ASCVD risk who are most likely to experience a net benefit in terms of the potential for ASCVD risk reduction and the potential for adverse effects (Table 3; Figure 2).
4.5. Primary Prevention in Individuals With Diabetes
A high level of evidence supports the use of moderate-intensity statin therapy in persons with diabetes who are 40 to 75 years of age. The only trial of high-intensity statin therapy in primary prevention was performed in a population without diabetes. However, a high level of evidence existed for event reduction with statin therapy in individuals with a ≥7.5% estimated 10-year ASCVD risk (Section 4.6) who did not have diabetes to recommend high-intensity statin therapy preferentially for individuals with diabetes and a ≥7.5% estimated 10-year ASCVD risk (Section 4.7). This consideration for those with diabetes who are 40 to 75 years of age recognizes that these individuals are at substantially increased lifetime risk for ASCVD events and death. Moreover, individuals with diabetes experience greater morbidity and worse survival after the onset of clinical ASCVD. In persons with diabetes who are <40 years of age or >75 years of age, or whose LDL-C is <70 mg/dL, statin therapy should be individualized on the basis of considerations of ASCVD risk-reduction benefits, the potential for adverse effects and drug–drug interactions, and patient preferences (Figure 4).
CQ2: What is the evidence for LDL-C and non–HDL-C goals for the primary prevention of ASCVD?
The Expert Panel reviewed 6 RCTs. The 4 studies confirming the efficacy of cholesterol reduction in improving clinical outcomes in patients without ASCVD used fixed-dose statin therapy to lower LDL-C levels. In the AFCAPS-TEXCAPS (Air Force/Texas Coronary Atherosclerosis Prevention Study) trial,17 in 50% of participants, the lovastatin dose was raised from 20 mg to 40 mg to achieve an LDL-C level <110 mg/dL. In the MEGA (Management of Elevated Cholesterol in the Primary Prevention Group of Adult Japanese) trial,18 the dose of pravastatin could be uptitrated from 10 mg to 20 mg to achieve a total cholesterol level <220 mg/dL. The Expert Panel did not find any RCTs that evaluated titration of all individuals in a treatment group to specific LDL-C targets <100 mg/dL or <70 mg/dL, nor were any RCTs comparing 2 LDL-C treatment targets identified. No trials reported on-treatment non–HDL-C levels.
On the basis of this large and consistent body of evidence, 4 major statin benefit groups were identified for whom the ASCVD risk reduction clearly outweighs the risk of adverse events based on a strong body of evidence. These are 1) secondary prevention in individuals with clinical ASCVD, 2) primary prevention in individuals with primary elevations of LDL-C ≥190 mg/dL, 3) primary prevention in individuals with diabetes 40 to 75 years of age who have LDL-C 70 to 189 mg/dL, and 4) primary prevention in individual without diabetes and with estimated 10-year ASCVD risk ≥7.5%, 40 to 75 years of age who have LDL-C 70 to 189 mg/dL. Moderate evidence supports the use of statins for primary prevention in individuals with 5% to <7.5% 10-year ASCVD risk, 40 to 75 years of age with LDL-C 70 to 189 mg/dL. Selected individuals with <5% 10-year ASCVD risk, or <40 or >75 years of age may also benefit from statin therapy. Clinicians and patients should engage in a discussion of the potential for ASCVD risk-reduction benefits, adverse effects, drug–drug interactions, and consider patient preferences for treatment. This discussion also provides the opportunity to re-emphasize healthy-lifestyle habits and address other risk factors.
Clinical ASCVD is defined by the inclusion criteria for the secondary-prevention statin RCTs (acute coronary syndromes, a history of MI, stable or unstable angina, coronary or other arterial revascularization, stroke, transient ischemic attack, or peripheral arterial disease presumed to be of atherosclerotic origin). For primary prevention in individuals without clinical ASCVD or diabetes who have an LDL-C 70 to 189 mg/dL, the estimated absolute 10-year risk of ASCVD (defined as nonfatal MI, CHD death, or nonfatal and fatal stroke) should be used to guide the initiation of statin therapy. The 10-year ASCVD risk should be estimated with the Pooled Cohort Equations (Section 4.7). For the primary prevention of ASCVD in individuals with diabetes (diabetes mellitus type 1 and type 2), estimated 10-year ASCVD risk can also be used to guide the intensity of statin therapy. For those with clinical ASCVD or with LDL-C ≥190 mg/dL who are already in a statin benefit group, it is not appropriate to estimate 10-year ASCVD risk. In primary prevention, additional factors may influence ASCVD risk in those for whom a risk-based decision is unclear. These include a primary LDL-C ≥160 mg/dL or other evidence of genetic hyperlipidemias, family history of premature ASCVD with onset <55 years of age in a first-degree male relative or <65 years of age in a first-degree female relative, high-sensitivity C-reactive protein ≥2 mg/L, coronary artery calcium score ≥300 Agatston units or ≥75th percentile for age, sex, and ethnicity (for additional information, see http://www.mesa-nhlbi.org/CACReference.aspx.), ankle-brachial index <0.9, and elevated lifetime risk of ASCVD.
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