Cost effectiveness of new antiplatelet agents in secondary stroke prevention
Objective. To determine the cost effectiveness of new antiplatelet agents. Methods. From a payor perspective, we performed cost-effectiveness and cost-utility analyses of ticlopidine, clopidogrel, or combination aspirin/dipyridamole, each compared with aspirin alone for secondary prevention of stroke. Our target population was men and women with cerebrovascular disease, divided into 4 groups by severity of baseline symptoms. Simulation models incorporated data on drug effectiveness, drug and stroke treatment costs, and quality of life for stroke survivors. Cost effectiveness was expressed as cost/stroke averted and cost utility as cost/quality-adjusted life year (QALY). Results. The average annual cost effectiveness over 2 years for patients with TIA, mild, moderate, or severe stroke was $170,188, $177,304, $206,245, and $220,716, respectively, for clopidogrel; $59,131, $66,247, $95,188, and $109,659 for ticlopidine; and $22,080, $29,196, $58,137, and $72,608 for aspirin/dipyridamole. The annual cost utility for patients with TIA, mild, moderate, or severe stroke was $113,620, $187,421, $436,027, and $933,240, respectively, for clopidogrel; $39,477, $70,027, $201,239, and $463,664 for ticlopidine; and $14,741, $30,862, $122,909, and $307,004 for aspirin/dipyridamole. To fall below the threshold of $50,000, the relative risk reduction among TIA patients would need to increase from 8.7% to 15.1% for clopidogrel. For the cost utility of ticlopidine or aspirin/dipyridamole to rise above $50,000, effectiveness among TIA patients would need to fall from 21.0% to 18.5% and 23.1% to 13.8%, respectively. Conclusion. According to criteria of <50,000/QALY, both aspirin/dipyridamole and ticlopidine are cost effective compared to aspirin alone for secondary stroke prevention among patients with TIA. Aspirin/dipyridamole is also cost effective in mild stroke. No agent had a cost utility ratio <$100,000 for moderate or severe stroke. Our findings are limited by the absence of research directly comparing the effectiveness of new antiplatelet agents; conclusions about the relative cost effectiveness of new agents should, therefore, be made cautiously.