We determined the distribution of three risk strata in the U.S. population: low 10-year/low lifetime, low 10-year/high lifetime, and high 10-year predicted risk, as defined below. For the main analysis, we calculated 10-year predicted risk for hard CHD (myocardial infarction or coronary death) for all participants using the ATP III risk assessment tool,10 (link) and we defined a calculated risk of ≥10% or diagnosed diabetes as “high 10-year predicted risk,” since individuals with this level of predicted risk would potentially be eligible for intensive preventive measures, including drug therapy.7 (link) Among the participants with low (<10%) 10-year predicted risk (and no diabetes), we assigned lifetime predicted risk for CVD (myocardial infarction, coronary insufficiency, angina, atherothrombotic stroke, intermittent claudication, or CVD death) using our previously published algorithm,4 (link), 6 (link) as shown in Table 1 . We defined “low lifetime predicted risk” as the two lower risk strata (“all optimal” or “≥1 not optimal” risk factors), which according to our prior work have predicted lifetime risk <39%,4 (link) and “high lifetime predicted risk” as the three higher risk strata (“≥1 elevated,” “1 major” or “≥2 major” risk factors), which have predicted lifetime risk ≥39%.4 (link) This stratification was chosen a priori based on the previously observed apparent natural separation in lifetime risks of these two groups in the Framingham cohorts4 (link) as well as in a large pooled sample of U.S. multi-ethnic cohorts.5 It has been further justified with recent work demonstrating differential burden and progression of subclinical atherosclerosis in younger adults using the identical stratification algorithm.6 (link)
In further analyses, we also included obesity (BMI ≥30kg/m2) and low HDL cholesterol (<40 mg/dL for men, <50 mg/dL for women) as major risk factors. To examine whether a more stringent definition of low short-term risk would weaken the distinction of different lifetime predicted risk groups among those at low-short term predicted risk, we also repeated the primary stratification described above using two additional definitions of short-term risk. For the first, we defined low short-term risk as <6% predicted 10-year risk for hard CHD (and absence of diabetes) using the ATP III risk assessment tool.10 (link) For the second, we defined low short-term risk as <20% predicted 10-year risk for total CVD (coronary death, myocardial infarction, coronary insufficiency, angina, ischemic stroke, hemorrhagic stroke, transient ischemic attack, intermittent claudication, or heart failure) (and absence of diabetes) using the risk functions published by D’Agostino et al.11 (link)
In further analyses, we also included obesity (BMI ≥30kg/m2) and low HDL cholesterol (<40 mg/dL for men, <50 mg/dL for women) as major risk factors. To examine whether a more stringent definition of low short-term risk would weaken the distinction of different lifetime predicted risk groups among those at low-short term predicted risk, we also repeated the primary stratification described above using two additional definitions of short-term risk. For the first, we defined low short-term risk as <6% predicted 10-year risk for hard CHD (and absence of diabetes) using the ATP III risk assessment tool.10 (link) For the second, we defined low short-term risk as <20% predicted 10-year risk for total CVD (coronary death, myocardial infarction, coronary insufficiency, angina, ischemic stroke, hemorrhagic stroke, transient ischemic attack, intermittent claudication, or heart failure) (and absence of diabetes) using the risk functions published by D’Agostino et al.11 (link)
