Use of Risk Assessment Tools to Guide Decision-Making in ASCVD Prevention

Lloyd-Jones DM, Braun LT, Ndumele CE, et al.
Use of Risk Assessment Tools to Guide Decision-Making in the Primary Prevention of Atherosclerotic Cardiovascular Disease: A Special Report From the American Heart Association and American College of Cardiology. J Am Coll Cardiol 2018;Nov 10:[Epub ahead of print].

The following are key points to remember from this Special Report on the Use of Risk Assessment Tools to Guide Decision-Making in the Primary Prevention of Atherosclerotic Cardiovascular Disease (ASCVD):

  1. This Special Report summarizes the rationale and evidence base for quantitative risk assessment, reviews strengths and limitations of existing risk score tools, discusses approaches for refining individual risk estimates for patients, and provides practical advice regarding implementation of risk assessment and decision-making strategies in clinical practice. It is intended to serve as a companion to the 2018 American College of Cardiology/American Heart Association (ACC/AHA) Guideline on the Management of Blood Cholesterol and the 2017 ACC/AHA Guideline for the Prevention, Detection, Evaluation, and Management of High Blood Pressure in Adults.
  2. How and why to use risk estimates for events when deciding treatment options? Clinicians are often influenced by the term "relative risk" when making decisions regarding treatment options. Placebo-controlled studies generally describe comparative benefits of an active treatment (lifestyle or pharmacologic) using relative risk estimates for future events or incidence rates. But these have little clinical usefulness even if relative risk is 10- to 20-fold when the risk in the reference group is low. In contrast, absolute risk estimation allows direct understanding of prognosis and identification of patients with certain risk factors and at sufficient risk to merit treatment with higher likelihood of net benefit to the individual or society. There is substantial observational evidence to support this approach in terms of patient selection for medical therapy (maximizing net benefit and minimizing number-needed-to-treat to prevent one event in 5-10 years) for both statins and antihypertensive therapy.
  3. Health care providers can readily obtain estimates of absolute risk in patients without known heart or vascular disease using internet-based applications, and similar tools are often available within electronic health records, each of which can provide advice regarding long-term utility of treatment (usually event rate over 10 years). The most recent ACC ASCVD Risk Estimator Plus calculator provides the 10-year risk (also life-time risk for persons ages 40-59 years). It provides therapy impact with expected change in risk with statins, blood pressure therapy, aspirin, and cigarette smoking. It also provides the rationale and advice with actual treatment suggestions (e.g., combination antihypertensive versus single drug).
  4. Both the 2018 Cholesterol and 2017 High Blood Pressure Guidelines recommend the US-derived Pooled Cohort Equation (PCE) to estimate 10-year risk for ASCVD events (including stroke). While useful for the general US population and specific for ethnic groups, PCE is less accurate in certain groups known as a miscalibration or a mismatch between predicted and observed events. PCE may overestimate risk in groups with 10-year risk >10%, older persons without long-standing risk factors, and those with higher socioeconomic status who are more likely to have a healthy lifestyle and be on preventive drug therapy. In contrast, it may underestimate risk in persons with a family history of premature vascular disease, varying degrees of chronic kidney disease, and chronic inflammatory diseases.
  5. The tools for risk estimation should not be used in persons with known clinical ASCVD, or in confirmed familial hypercholesterolemia or when baseline LDL-C is ≥190 mg/dl. The latter require statin therapy regardless of age, gender, and other risk factors. While most diabetics require statin therapy, the PCE risk calculator provides additional data for deciding blood pressure treatment and targets and intensity of statin dosing. PCE applies to adults ages 40-75 years. It is reasonable to consider 30-year or lifetime risk estimation in younger adults to inform intensity of prevention efforts (see ASVD Risk Estimator Plus). More than half of the US adult population has a 10-year risk estimate <10% and a lifetime risk estimate ≥39%. There are data from the HOPE-3 trial that men and women with 10-year risk <10% but a lifetime risk of ≥40% had a significant reduction in CVD events with low-dose rosuvastatin.
  6. After using the tools for quantitative risk assessment, clinical judgment should be based on the individual patient's preferences, and presence of other risk enhancers including LDL-C 160-189 mg/dl, triglycerides 175-500 mg/dl, high-sensitivity C-reactive protein >2 mg/dl, Lp(a) >50 mg/dl, apo B >130 mg/dl, metabolic syndrome, history of pre-eclampsia, and particularly family history of premature vascular disease. Adding these variables and selective use of coronary artery calcium scoring (CAC score), can help to overcome most issues of miscalibration for each of the many risk prediction equations. Alternatives to the ACC/AHA PCE include the Framingham General CVD Risk Profile, which predicts more ASCVD events including unstable angina/coronary insufficiency, transient ischemic attack, claudication, and heart failure. The Reynolds Risk Score performs better than the PCE in some higher socioeconomic and lower risk cohorts and includes coronary revascularization as an endpoint. Some features of the Framingham and Reynolds risk assessment tools may limit their implementation in clinical practice with regard to alignment with recommendations in ACC/AHA guidelines, including utility in nonwhites, calibration to the hard ASCVD endpoint, and reclassification by CAC scoring. Another user-friendly tool to assist in deciding statin use is available from the Mayo Clinic (see Mayo Clinic's Shared Decision Making Cardiovascular Primary Prevention Choice tool).
  7. Recognizing the imprecision of multivariable CVD risk prediction scores, as well as the uncertainty clinicians and patients may encounter regarding the potential benefits of drug therapy for an individual patient at borderline or intermediate 10-year ASCVD risk, additional testing for assessment of the presence of subclinical atherosclerosis with CAC score (patient pay) is reasonable and preferable to serum biomarkers and other modalities to detect subclinical atherosclerosis, which are weaker predictors of ASCVD events than the CAC score. The addition of the CAC score to the advanced Framingham General CVD Risk Profile provides additional information that improves discrimination (see MESA CHD Risk Calculator), and influences patient decisions and compliance with treatments.
  8. Summary of using CAC score in patients undecided or clinical uncertainty regarding net benefit of statin therapy:
    • CAC = 0: Below threshold for statin benefit. Consider avoiding or postponing drug therapy with exceptions being diabetes, heavy current smokers, or strong family history of premature ASCVD.
    • CAC 1-99 and <75th percentile score for age/sex/race: Subclinical atherosclerosis present; risk estimate similar. Repeat discussion with patient regarding new information. Consider beginning statin or postpone statin and consider repeat CAC score in 5 years (see #7 re using MESA Risk Score with CAC).
    • CAC ≥100 or ≥75th percentile for age/sex/race. Above threshold for statin benefit. Recommend statin therapy.

Perspective: As a preventive cardiologist, I find this summary and guide to risk assessment for decision-making in primary prevention for ASCVD outstanding and a must-read for all health care providers responsible for primary prevention. However, it is important that clinicians realize the tools that recommend specific therapies based on risk estimates are vulnerable to the ever-changing recommendations based on new studies (e.g., aspirin).

Keywords: Antihypertensive Agents, Apolipoproteins B, Aspirin, Atherosclerosis, Blood Pressure, Cholesterol, LDL, C-Reactive Protein, Decision Making, Electronic Health Records, Heart Failure, Hydroxymethylglutaryl-CoA Reductase Inhibitors, Ischemic Attack, Transient, Life Style, Metabolic Syndrome, Pre-Eclampsia, Primary Prevention, Renal Insufficiency, Chronic, Risk Assessment, Risk Factors, Smoking, Stroke, Triglycerides, Vascular Diseases

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