AJR:194, May 2010
Kevin M.Johnson, David A. Dowe
OBJECTIVE. The Framingham risk score is often recommended as the starting point for coronary disease screening. We compared the sensitivity of the Framingham risk score for moderate or greater degrees of atherosclerosis to the sensitivity achieved by simple observation of whether any coronary calcium is present. The reference standard was plaque burden as determined by coronary CT angiography.
MATERIALS AND METHODS. Of 1,416 men (mean age, 51.4± 9.9 [SD] years) and 707 women (56.9 ± 10.6 years), most were asymptomatic. Plaque burden (segment plaque score) and stenoses burden (Duke prognostic score) were estimated. A segment plaque score > 4 or a Duke prognostic score > 3 indicated moderate or greater disease burden.
RESULTS. For a segment plaque score > 4, the presence of any calcium was 98% sensitive in men and 97% sensitive in women, whereas a Framingham risk score > 10% was 74% sensitive in men and 36% sensitive in women. The negative likelihood ratio for the presence of calcium was 0.04 in subjects of either sex, whereas, for a Framingham risk score < 10%, the negative likelihood ratio was 0.38 in men and 0.71 in women. For a Duke prognostic score > 3, calcium was 97% sensitive in men and 92% sensitive in women, whereas a Framingham risk score > 10% was 88% sensitive in men and 35% sensitive in women. The negative likelihood ratio of calcium presence was 0.05 in men and 0.13 in women, whereas the negative likelihood ratio for a Framingham risk score < 10% was 0.20 in men and 0.75 in women.
CONCLUSION. If subjects are excluded from further screening because they are in the Framingham low-risk category, almost two thirds of women and a quarter of men with substantial atherosclerosis will be missed. In contrast, the simple observation of any coronary calcium is highly sensitive and moderately specific.