Inclusion of Stroke as an Outcome and Risk Equivalent in Risk Scores for Primary and Secondary Prevention of Vascular Disease

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Current guideline statements for primary and secondary prevention of cardiovascular disease (CVD) rely on estimates of absolute risk of coronary events. For example, the American Heart Association guidelines on primary prevention state that persons with ≥10% risk over 10 years of myocardial infarction (MI) or coronary death should be considered for antiplatelet therapy with aspirin.1 Similarly, the National Cholesterol Education Program Adult Treatment Panel III (ATP III) guidelines2 state that target low-density lipoprotein level should be based on projected absolute risk of future coronary events rather than on presence or absence of specific risk factors. These guidelines state that patients at high risk of MI and coronary death, defined as an absolute 10-year risk of ≥20%, should have a target low-density lipoprotein level <100 mg/dL and should receive statin therapy if needed to achieve this goal. Stroke, however, is not included as one of the outcomes contributing to these absolute risk levels. Included in the group of patients with elevated risk, moreover, are those who already have ischemic heart disease, as well as patients deemed to be “coronary heart disease (CHD) risk equivalents,” indicating those at the same elevated risk as patients with ischemic heart disease. CHD risk equivalents include patients with diabetes mellitus, those with multiple risk factors that put them at elevated risk based on calculation of their Framingham Score, and patients with “other forms of symptomatic atherosclerotic disease.” The latter group is further defined to include those with peripheral arterial disease (PAD), abdominal aortic aneurysm (AAA), and carotid artery disease. The category of “risk equivalents” in the ATP III guidelines, however, does not include the vast majority (≈80%3) of ischemic stroke patients without carotid artery disease as cause of their stroke. Ischemic stroke is therefore notably excluded from the list of outcomes contributing to …