Primary Prevention of ASCVD: Engage in shared decision making when testing and treating
EBM Focus - Volume 13, Issue 40
Reference: J Am Coll Cardiol 2018 Nov 8 early online
The 2018 AHA Guideline for Management of Blood Cholesterol was recently released. This week’s EBM Focus is about primary prevention. After the 2013 American Heart Association (AHA) cholesterol guidelines were issued, many clinicians focused primarily on just initiating statin therapy for the treatment of hyperlipidemia, happy to forgo the previously recommended low density lipoprotein (LDL) targets. Five years later, clinicians better hang on; it appears the pendulum is swinging back towards LDL goals and the use of non-statin therapies if needed to help get there. In addition, there is an emphasis on shared decision making when considering statins for primary prevention in patients with borderline- or intermediate-risk classification.
For primary prevention, the guideline recommends earlier screening and earlier treatment. Screening for hypercholesterolemia is recommended for children as young as 9 years old, even in the absence of a strong family history of cardiovascular disease (CVD). The guideline also recommends that adults aged 20 years and older should have lipid panels every 4-6 years, beginning at age 21. The pooled cohort equation (PCE) is recommended to be used to estimate lifetime atherosclerotic cardiovascular disease risk (ASCVD) risk, despite minimal data demonstrating accuracy in people < 40 years old. The guideline recommends high intensity statin therapy for those aged 20 to 75 years with LDL 190 mg/dL or greater. For adults aged 20 to 39 years with an LDL over 160 mg/dL and a strong family history of premature CVD, the guideline recommends consideration of statin therapy, although no randomized controlled trials have been conducted that demonstrate benefit.
For patients aged 40 to 75 with diabetes and an LDL ≥70 mg/dL, immediate therapy with a moderate intensity statin is recommended regardless of calculated 10-year risk. For adults with diabetes and other ASCVD risk factors, initiation of high intensity statin therapy is recommended, aiming to reduce LDL by greater than 50%. If this target is not met, the guideline suggests addition of ezetimibe to further lower LDL. Similarly, for patients with severe hypercholesterolemia (defined as LDL greater than 190 mg/dL), the guideline recommends high intensity statin followed by ezetimibe therapy if LDL is reduced by less than 50% with statin therapy alone despite a paucity of evidence for ezetimibe for primary prevention.
For adults aged 40 to 75 without diabetes mellitus, consideration of statin therapy is now recommended for those with borderline-risk, an estimated 10-year ASCVD risk of 5%-7.4% (despite the vast majority of evidence demonstrating benefit of statin therapy only after a 10% 10-year risk in most populations, a threshold reflected in most other international guidelines).This updated AHA guideline also recommends evaluating these patients for ‘risk enhancers’ which include traditional risk factors such as family history of premature ASCVD as well as certain non-traditional risk factors such as inflammatory conditions, history of preeclampsia, South Asian ethnicity, and several biomarkers. However, these ‘risk enhancing’ biomarkers are predicted to lead to a net cardiovascular risk reclassification improvement of <1%. For those patients with intermediate-risk (10-year risk of 7.5 to 20%), the guideline also recommends consideration of risk enhancers when counseling patients. It goes on to suggest obtaining a coronary artery calcium score if uncertainty remains about whether or not to start statin therapy. Most studies show that coronary artery calcium scores increase statin prescriptions.
Focus Point: The updated AHA cholesterol guideline emphasizes a shared decision making model but at its core is suggesting more testing and treatment without much high quality data demonstrating benefit. As these recommendations shift towards more intervention, look for minimalists and evidence-gurus jumping off of this swinging pendulum. Next week’s EBM Focus will take a closer look at the guideline’s recommendations for secondary prevention.
DynaMed Plus EBM Focus Editorial Team
This EBM Focus was written by Carina Brown, MD, Faculty Development and Information Mastery Fellow and Clinical Instructor at the University of Virginia. Edited by Alan Ehrlich, MD, Executive Editor at DynaMed Plus and Associate Professor in Family Medicine at the University of Massachusetts Medical School and Katharine DeGeorge, MD, MS, Assistant Professor in Family Medicine at the University of Virginia and Clinical Editor at DynaMed Plus.