Cost-effectiveness of using electron beam computed tomography to identify patients at risk for clinical coronary artery disease

Background The use of electron beam computed tomography (EBCT) to screen for coronary artery calcification (CAC) has been widely promulgated, although the cost effectiveness of this practice is unknown. Methods We constructed a decision tree to determine the marginal cost per additional patient who was “at risk” (>10% 10-year risk of coronary heart disease) identified with the addition of EBCT to the Framingham Risk Index (FRI) in a screening population with no cardiac symptoms. We also determined the marginal cost per quality adjusted life year (QALY) saved, assuming a 30% improvement in life expectancy associated with primary prevention. A consecutive screening cohort of 39- to 45-year-old men and women was used for demographic and risk factor data. Estimates of the relevant input costs were made on the basis of published literature when available. Results Compared with using FRI alone, the strategy of incorporating EBCT detects patients who are “at risk” at a cost of $9789/additional case and a marginal cost of $86,752/QALY. The marginal cost per QALY is highly sensitive to the gain in life expectancy from early intervention ($10,000–1,700,000/QALY for a relative risk reduction in mortality of 50% or 25%, respectively), the utility of being “at risk” ($18,000/QALY to dominated for a utility of 1.0–<0.98, similar to other asymptomatic chronic illnesses), and the added prognostic value of EBCT ($60,000/QALY to dominated in a wide range). Conclusion The use of EBCT to improve cardiovascular risk prediction in a population with no cardiac symptoms who are at low absolute risk is expensive, even using favorable assumptions. If the utility of being “at risk” is comparable with other asymptomatic disease states, EBCT may in aggregate have a detrimental effect on the quality of life of screening populations.