HEALTH ECONOMIC EVALUATION OF ANTIPLATELET THERAPY IN THE SECONDARY PREVENTION OF STROKE

Purpose: Stroke is a major cause of mortality and severe disability and accounts for considerable amounts of healthcare resources. Antiplatelet therapy has demonstrated efficacy in preventing serious vascular events. The most well known antiplatelet drug is acetylsalicylic acid (ASA). Recently, newer antiplatelet drug therapies, such as clopidogrel and the combination of ASA and dipyridamole have been suggested as possible alternative prophylactic treatments. However, there is no guideline for using one of these therapies over the other in the secondary stroke prevention.The aim of this study was to assess the cost-effectiveness of antiplatelet therapy with either ASA alone, ASA combined with dipyridamole and clopidogrel monotherapy in secondary prevention of stroke.

Method: Analyses were done in NorCaD, a Markov-model based on Norwegian incidence data and treatment costs. The model was run for 70-year-old men with average risk of further cardiovascular diseases. The patients were followed until death or 100 years of age. Effectiveness of the strategies was based on meta-analyses of published RCTs identified by a systematic literature search. Quality of life data were extracted from published literature. The model calculated quality-adjusted life years (QALYs) and life years gained with different strategies and life time costs related to stroke. We also analysed data for women and other age groups. In addition, we performed sensitivity analyses to get an impression of uncertainty surrounding our analyses.

Result: Combination of ASA and dipyridamole provided 0.13 additional QALYs and reduced lifetime costs for the health care system with USD 7,152 compared with ASA monotherapy. Hence, the combination therapy is dominant relative to ASA alone in secondary prevention of stroke. The use of ASA combined with dipyridamole for patients of 70 years resulted in a QALY gain of 0.09 and reduced lifetime costs (USD 5,012) compared with clopidogrel in secondary prevention of stroke, and hence combination therapy is a dominant strategy. Sensitivity analyses showed that cost per QALY gained was dependent on health effect and drug costs. The results also showed little sensitivity with gender variation, but the conclusions may change with age variation. With regards to life year, the main results did not change and both comparisons are dominant.

Conclusion: Combination of ASA and dipyridamole offers a cost-effective alternative to ASA and clopidogrel monotherapy in the secondary prevention of stroke.