COST-EFFECTIVENESS OF CAROTID ENDARTERECTOMY IN ASYMPTOMATIC PATIENTS

Purpose: The purpose of this study was to determine the cost-effective ness of carotid endarterectomy for treating asymptomatic patients with greater than or equal to 60% internal carotid stenosis, based on outc omes reported in the Asymptomatic Carotid Atherosclerosis Study (ACAS) . Methods: A cost-effectiveness analysis was performed using a Markov decision model in which the probabilities for base-case analysis (aver age age, 67 years; 66% male; perioperative stroke plus death rate, 2.3 %; ipsilateral stroke rate during medical management, 2.3% per year) w ere based on ACAS. The model assumed that patients who had TIAs or min or strokes during medical management crossed over to surgical treatmen t, and used the NASCET data to model the outcome of these now-symptoma tic patients. Average cost of surgery ($8500), major stroke ($34,000 p lus $18,000 per year), and other costs were based on local cost determ inations plus a review of the published literature. Cost-effectiveness was calculated as the incremental cost of surgery per quality-adjuste d life year (QALY) saved when compared with medical treatment, discoun ting at 5% per year. Sensitivity analysis was performed to determine t he impact of key variables on cost-effectiveness. Results: In the base -case analysis, surgical treatment improved quality-adjusted life expe ctancy from 7.87 to 8.12 QALYs, at an incremental lifetime cost of $20 41. This yielded an incremental cost-effectiveness ratio of $8,000 per QALY saved by surgical compared with medical treatment. The high cost of care after major stroke during medical management largely offset t he initial cost of endarterectomy in the surgical group. Furthermore, 26% of medically managed patients eventually underwent endarterectomy because of symptom development, which also decreased the cost differen tial. Sensitivity analysis demonstrated that the relative cost of surg ical treatment increased substantially with increasing age, increasing perioperative stroke rate, and decreasing stroke rate during medical management. Conclusion: For the typical asymptomatic patient in ACAS w ith greater than or equal to 60% carotid stenosis, our results indicat e that carotid endarterectomy is cost-effective when compared with oth er commonly accepted health care practices. Surgery does not appear co st-effective in very elderly patients, in settings where the operative stroke risk is high, or in patients with very low stroke risk without surgery.