Coronary artery calcium score combined with Framingham score for risk prediction in asymptomatic individuals

Context Guidelines advise that all adults undergo coronary heart disease (CHD) risk assessment to guide preventive treatment intensity. Although the Framingham Risk Score (FRS) is often recommended for this, it has been suggested that risk assessment may be improved by additional tests such as coronary artery calcium scoring (CACS). Objectives To determine whether CACS assessment combined with FIRS in asymptomatic adults provides prognostic information superior to either method alone and whether the combined approach can more accurately guide primary preventive strategies in patients with CHID risk factors. Design, Setting, and Participants Prospective observational population-based study, of 146 asymptomatic adults with coronary risk factors. Participants with at least 1 coronary risk factor (>45 years) underwent computed tomography (CT) examination, were screened between 1990-1992, were contacted yearly for up to 8.5 years after CT scan, and were assessed for CHID. This analysis included 1312 participants with CACS results; excluded were 269 participants with diabetes and 14 participants with either missing data or had a coronary event before CACS was performed. Main Outcome Measure Nonfatal myocardial infarction (MI) or CHID death. Results During a median of 7.0 years of follow-up, 84 patients experienced MI or CHID death; 70 patients died of any cause. There were 291 (28%) participants with an FRS of more than 20% and 221 (21%) with a CACS of more than 300. Compared with an FRS of less than 10%, an FIRS of more than 20% predicted the risk of MI or CHID death (hazard ratio [HR], 14.3; 95% confidence interval [CI]; 2.0-104; P=.009). Compared with a CACS of zero, a CACS of more than 300 was predictive (HR, 3.9; 95% CI, 2.1-7.3; P<.001). Across categories of FIRS, CACS was predictive of risk among patients with an FRS higher than 10% (P<.001) but not with an FIRS less than 10%. Conclusion These data support the hypothesis that high CACS can modify predicted risk obtained from FIRS alone, especially among patients in the intermediate-risk category in whom clinical decision making is most uncertain.