This presentation is part of: Poster Session - Clinical Strategies; Judgment and Decison Making
COST-EFFECTIVENESS OF DALTEPARIN VERSUS WARFARIN FOR ACUTE VENOUS THROMBOEMBOLISM IN PATIENTS WITH CANCER
Drahomir A. Aujesky, MD, MS, VA Pittsburgh Healthcare System, Center for Health Equity Research and Promotion, Pittsburgh, PA, Kenneth J. Smith, MD, University of Pittsburgh, Section of Decision Sciences and Clinical Systems Modeling, Pittsburgh, PA, Jacques Cornuz, MD, MPH, University Hospital of Lausanne, Department of Medicine, Lausanne, Switzerland, and Mark S. Roberts, MD, MPP, University of Pittsburgh, Section of Decision Sciences and Clinical Systems Managment, Pittsburgh, PA.
PURPOSE: Although dalteparin has been shown to be more effective than warfarin in preventing recurrent venous thromboembolism (VTE) in cancer patients with acute VTE, its cost-effectiveness is uncertain. We constructed a decision analytic model to calculate quality-adjusted life-years (QALYs) and lifetime costs for treatment with these drugs to compare their cost-effectiveness. METHODS: Using a societal perspective, our model compared two strategies to treat acute VTE in 65-year-old patients with cancer. In the dalteparin strategy, the daily dalteparin dosage was 200 IU/kg during month 1 and 150 IU/kg during months 2 to 6. In the warfarin strategy, warfarin was given for 6 months at a target international normalized ratio of 2.5 and dalteparin was given for the first 5 days at a dosage of 200 IU/kg. Our model incorporated probability estimates and utilities reported in the literature and published cost data. We conducted multiple one-way and probabilistic (Monte-Carlo) sensitivity analyses to assess the effect of varying baseline estimates on cost-effectiveness. RESULTS: The incremental cost-effectiveness ratio of dalteparin compared with warfarin was $192,726 per QALY gained. Dalteparin yielded a quality-adjusted life expectancy of 1.270 QALYs at the cost of $13,481. Although the dalteparin strategy achieved a slightly higher incremental quality-adjusted life expectancy than the warfarin strategy (difference of 0.034 QALYs), this small clinical benefit was offset by a substantial cost increment of $6,580. Cost-effectiveness results were sensitive to variation of the overall mortality associated with dalteparin and warfarin and the pharmacy costs for dalteparin. Dalteparin cost <$50,000 per QALY only if the pharmacy costs for dalteparin were <$17 per day (26% of the drug’s 2002 US wholesale price). In probabilistic sensitivity analysis, the warfarin strategy was considered cost-effective in 97% of Monte Carlo iterations and the dalteparin strategy in 3% at a willingness-to-pay ceiling of $50,000 per QALY gained. If the willingness-to-pay ceiling was increased to $100,000 per QALY gained, the warfarin strategy was optimal in 78% of Monte Carlo iterations and the dalteparin strategy was preferred in 22%. CONCLUSIONS: Based on the best available evidence, a 6-month course of dalteparin is slightly more effective than a 6-month course with warfarin. However, because of the high pharmacy costs of dalteparin, this drug is very unfavorable economically compared with warfarin.
