COST-EFFECTIVENESS OF SCREENING FOR ASYMPTOMATIC CAROTID ATHEROSCLEROTIC DISEASE

Background and Purpose The value of screening for asymptomatic carotid stenosis has become an important issue with the recently reported ben eficial effect of endarterectomy. The purpose of this study is to eval uate the cost-effectiveness of using Doppler ultrasound as a screening tool to select subjects for arteriography and subsequent surgery. Met hods A computer model was developed to simulate the cost-effectiveness of screening a cohort of 1000 men during a 20-year period. The primar y outcome measure was incremental present-value dollar expenditures fo r screening and treatment per incremental present-value quality-adjust ed life-year (QALY) saved. Estimates of disease prevalence and arterio graphic and surgical complication rates were obtained from the literat ure. Probabilities of stroke and death with surgical and medical treat ment were obtained from published clinical trials. Doppler ultra soun d sensitivity and specificity were obtained through review of local ex perience. Estimates of costs were obtained from local Medicare reimbur sement data. Results A one-time screening program of a population with a high prevalence (20%) of greater than or equal to 60% stenosis cost $35 130 per incremental QALY gained. Decreased surgical benefit or in creased annual discount rate was detrimental, resulting in lost QALYs. Annual screening cost $457 773 per incremental QALY gained. In a low- prevalence (4%) population, one-time screening cost S52 588 per QALY g ained, while annual screening was detrimental, Conclusions The cost-ef fectiveness of a one-time screening program for an asymptomatic popula tion with a high prevalence of carotid stenosis may be cost-effective. Annual screening is detrimental. The most sensitive variables in this simulation model were long-term stroke risk reduction after surgery a nd annual discount rate for accumulated costs and QALYs.