Added value of CAC in risk stratification for cardiovascular events: a systematic review

Abstract

Identification of individuals at high risk for cardiovascular disease (CVD) is important to initiate adequate treatment and to prevent future events. Moreover, identification of low-risk individuals is important to refrain from unneeded therapy. Current risk prediction models do not accurately predict the risk of CVD in individuals, and new markers have been sought to improve the risk assessment in individuals. Coronary artery calcification (CAC) is a marker of atherosclerosis that might improve current risk assessment when added to traditional risk factors. We performed a systematic review on PubMed search (1 February 2011) on studies reporting on the added value of CAC in risk prediction in asymptomatic individuals. Of 39 publications on CAC and CVD, nine studies were carried out in asymptomatic individuals. All studies showed an increase in area under the curve ranging from 0.05 to 0.20 when CAC was added to the risk model. Four studies reported on improvements of individuals in low-, intermediate-, and high-risk categories. Addition of CAC to the risk model resulted in a net reclassification improvement ranging from 14% to 30%, meaning that CAC measurement reclassified a substantial proportion of individuals into correct risk categories. This improvement was most pronounced in those at intermediate Framingham risk. The available studies consistently showed that CAC scoring improves risk stratification in CVD risk categories when added to traditional risk factors only, especially among individuals at intermediate risk for CVD. Cost-effectiveness analyses together with a randomized controlled trial are needed before widespread introduction of CAC in clinical care.