Pharmaceutical Research

Both aspirin and extended release dipyridamole/aspirin are cost-effective anticoagulant agents to prevent second strokes

Options for preventing a second stroke, heart attack, and premature death among patients who have suffered a stroke include anticoagulant agents such as aspirin (ASA), a combination of extended release dipyridamole/aspirin (DP/A), and clopidogrel (CLO). Both ASA and DP/A are cost-effective compared to placebo, but there is no clear winner between the two, concludes a study supported by the Agency for Healthcare Research and Quality (HS11746).

David Matchar, M.D., of Duke University Medical Center, and colleagues used the Duke Stroke Policy Model (DSPM), a simulation model of the natural history of stroke and the impact of various prevention strategies, to compare four strategies of secondary stroke prevention. They examined the impact of ASA, DP/A, CLO, and placebo on quality-adjusted-life-years (QALYs), costs, and costs per QALY for 70-year-old men who had suffered a first, nondisabling stroke. The researchers modified model inputs to reflect the cost of the drugs, as well as their relative ability to prevent subsequent ischemic stroke (based on published reports) compared with placebo.

In large part because of its low drug cost, ASA led to modest improvements in outcome at minimal costs compared to placebo, and it is cost-effective using the cost-effectiveness benchmark of $50,000 per QALY. DP/A led to additional improvements in outcome compared with ASA, at additional cost. However, the comparison between ASA and DP/A was not definitive. In some simulations, when accounting for uncertainty due to the limits of available evidence, ASA resulted in slightly more QALYs than DP/A. More often, DP/A resulted in better quality-adjusted life expectancy. However, the additional benefits of DP/A in some cases were worth the cost, and sometimes not. CLO was seldom judged to be the optimal strategy, and was dominated by DP/A and ASA in several simulations.

See "Cost-effectiveness of antiplatelet agents in secondary stroke prevention: The limits of certainty," by Dr. Matchar, Gregory P. Samsa, Ph.D., and Suping Liu, M.S., in the September/October 2005 Value In Health 8(5), pp. 572-580.

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