Underlying risk factors incrementally add to the standard risk estimate in detecting subclinical atherosclerosis in low- and intermediate-risk middle-aged asymptomatic individuals.

BACKGROUND: Traditional risk factors predict the 10-year risk of developing coronary heart disease (CHD). Underlying risk factors like physical inactivity, obesity (BMI >30 kg/m2), and family history of premature CHD are independently associated with CHD. High burden of coronary artery calcification (CAC) on electron beam tomography (EBT) is a CHD risk equivalent. GOALS: To determine the association between CAC and traditional risk assessment and whether the presence of added underlying risk factors is associated with advanced CAC in low- and intermediate-risk individuals. METHODS: After excluding patients with CHD, we studied 8549 asymptomatic individuals referred for EBT for cardiac risk assessment. Traditional myocardial infarction risk score was estimated according to Framingham criteria, and individuals were divided into 3 groups: low-risk (< or =9% MI risk over the next 10 years), intermediate-risk (10%-20% risk), and high-risk (>20 % risk). Advanced CAC was defined as a calcium score > or =75th percentile based on sex and age. RESULTS: The prevalence of advanced CAC was 20% in low-risk, 27% in intermediate-risk, and 31% in high-risk individuals (P < .001). Underlying risk factors were incrementally associated with advanced CAC in low- and intermediate-risk individuals (P < .001). A receiver operating characteristic curve analysis revealed that addition of underlying risk factors to traditional risk assessment increased the area under the curve significantly from 0.56 to 0.62 (P < .001). CONCLUSION: A substantial proportion of low- and intermediate-risk individuals have advanced CAC. Adding family history, obesity, and physical inactivity to traditional risk assessment improves prediction of advanced CAC, which may lead these individuals to be treated more aggressively at an earlier age.