Cost efficiency of anticoagulation with warfarin to prevent stroke in medicare beneficiaries with nonvalvular atrial fibrillation.
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2011-01
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Abstract
Background and purpose
in controlled trials, anticoagulation with warfarin reduces stroke risk by nearly two thirds, but the benefit has been less pronounced in clinical practice. This report describes the extent of warfarin use, its effectiveness, and its impact on medical costs among Medicare patients with nonvalvular atrial fibrillation.Methods
using claims from >2 million beneficiaries in the Centers for Medicare and Medicaid Services 5% Sample Standard Analytic Files, we identified patients with nonvalvular atrial fibrillation from 2004 to 2005. Warfarin use was inferred from 3 or more tests of the international normalized ratio within 1 year. Incidence of ischemic/hemorrhagic stroke and major bleeding was evaluated. Adjusted risk was calculated by Cox proportional-hazards regression. Medical costs (reimbursed amounts in 2006 US dollars) were estimated by multivariate linear regression.Results
of patients with nonvalvular atrial fibrillation (N=119 764, mean age=79.3 years), 58.5% were categorized as warfarin users based on the study definition. During an average of 2.1 years' follow-up, the rate of ischemic stroke was 3.9 per 100 patient-years. After multivariate adjustment, ischemic stroke incidence was 27% lower in patients taking warfarin than in patients not taking warfarin (P<0.0001), with no increase in hemorrhagic stroke and a slightly elevated risk of a major bleed. Use of warfarin was independently associated with lower total medical costs, averaging $9836 per patient per year.Conclusions
these results indicate that 41.5% of Medicare patients with nonvalvular atrial fibrillation are not anticoagulated with warfarin. The incidence of stroke and overall medical costs were significantly lower in patients treated with warfarin.Type
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Mercaldi, Catherine J, Mike Ciarametaro, Beth Hahn, George Chalissery, Matthew W Reynolds, Stephen D Sander, Gregory P Samsa, David B Matchar, et al. (2011). Cost efficiency of anticoagulation with warfarin to prevent stroke in medicare beneficiaries with nonvalvular atrial fibrillation. Stroke, 42(1). pp. 112–118. 10.1161/strokeaha.110.592907 Retrieved from https://hdl.handle.net/10161/22909.
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Scholars@Duke
Gregory P. Samsa
Greg Samsa is an applied statistician whose primary interests are in study design, instrument development, information synthesis, practice improvement, effective communication of statistical results, and teaching. He is a believer in the power of statistical thinking, as broadly defined.
David Bruce Matchar
My research relates to clinical practice improvement - from the development of clinical policies to their implementation in real world clinical settings. Most recently my major content focus has been cerebrovascular disease. Other major clinical areas in which I work include the range of disabling neurological conditions, cardiovascular disease, and cancer prevention.
Notable features of my work are: (1) reliance on analytic strategies such as meta-analysis, simulation, decision analysis and cost-effectiveness analysis; (2) a balancing of methodological rigor the needs of medical professionals; and (3) dependence on interdisciplinary groups of experts.
This approach is best illustrated by the Stroke Prevention Patient Outcome Research Team (PORT), for which I served as principal investigator. Funded by the AHCPR, the PORT involved 35 investigators at 13 institutions. The Stroke PORT has been highly productive and has led to a stroke prevention project funded as a public/private partnership by the AHCPR and DuPont Pharma, the Managing Anticoagulation Services Trial (MAST). MAST is a practice improvement trial in 6 managed care organizations, focussing on optimizing anticoagulation for individuals with atrial fibrillation.
I serve as consultant in the general area of analytic strategies for clinical policy development, as well as for specific projects related to stroke (e.g., acute stroke treatment, management of atrial fibrillation, and use of carotid endarterectomy.) I have worked with AHCPR (now AHRQ), ACP, AHA, AAN, Robert Wood Johnson Foundation, NSA, WHO, and several pharmaceutical companies.
Key Words: clinical policy, disease management, stroke, decision analysis, clinical guidelines
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