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 FRS 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 CHD risk factors.
Design, Setting, and Participants Prospective observational population-based study, of 1461 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 CHD. 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 CHD death.
Results During a median of 7.0 years of follow-up, 84 patients experienced MI
or CHD 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 FRS of more than 20% predicted the risk of
MI or CHD 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 FRS, CACS was predictive of risk among patients with
an FRS higher than 10% (P<.001) but not with an
FRS less than 10%.
Conclusion These data support the hypothesis that high CACS can modify predicted
risk obtained from FRS alone, especially among patients in the intermediate-risk
category in whom clinical decision making is most uncertain.