Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


Aspirin vs. Low Molecular Weight Heparin for Prophylaxis Against Venous Thromboembolism after Total Knee or Hip Replacement in Lower Risk Individuals: A Cost-Utility Analysis.

Schousboe1,  John T., Brown2,  Gregory A.

Park Nicollet Institute, Minneapolis, St Louis Park, MN
Park Nicollet Institute, Minneapolis, MN

Introduction:

Venous thromboembolism (VTE) is common following total joint replacement (TJA) surgery, but there is substantial disagreement as to the best way to prevent VTE events. The American Academy of Orthopedic Surgeons guideline recommends aspirin after TJA for patients at average or lower risk of VTE or at high risk of bleeding. The American College of Chest Physicians guideline recommends stronger anticoagulants (adjusted dose warfarin, low molecular weight heparin, or fondiparinux) for VTE prophylaxis after TJA, and specifically recommends against aspirin. Our objective was to estimate the lifetime incremental costs per quality adjusted life year gained for 10 days of low molecular weight heparin (LMWH) vs. aspirin 160 mg daily following joint replacement surgery.

Methods:

A Markov cohort model allowing 6 transient events following TJA (deep vein thrombosis, pulmonary embolism, operative site hemorrhage, non-operative site major hemorrhage, intracranial hemorrhage, and thrombocytopenia), and 5 chronic health states (healthy post TJA, post TJA VTE without post-phlebitic syndrome, post TJA VTE with post-phlebitic syndrome, post intracranial hemorrhage, prosthetic joint infection). Costs and loss of quality of life associated with each event and chronic health state were derived from the medical literature. The absolute risks of VTE and bleeding events on LWMH following TJA were derived from a pooled analysis of clinical trials, and the relative risks of VTE and major bleeding on aspirin vs. LMWH were derived from literature estimates of each drug vs placebo. LMWH and aspirin were compared for four sets of individuals; those without any additional risks for VTE (non-obese, no personal or family history of VTE), obese individuals but without additional risk factors, and those with a family history of VTE.

Results:

The costs (2008 U.S. $) per QALY gained for LMWH compared to aspirin prophylaxis post TJA for those age 55 to 85 are as follows:

  Scenario 
AgeNo Added VTE RisksObese (BMI >30 mg/kg2)Family History of VTE
55Aspirin Dominant$35,762$1,850
65$635,488$31,644LMWH Dominant
75$326,842$31,819LMWH Dominant
85$246,044$27,310LMWH Dominant

Results were highly sensitive to the relative risks of VTE and major bleeding events on aspirin vs LMWH, modestly sensitive to the risks of and quality of life loss associated with post-phlebitic syndrome.

Conclusion:

Aspirin may be a cost-effective reasonable choice for VTE prophylaxis following TJA for those individuals with no additional risk factors for VTE events, based on currently available data. For those with one or more additional VTE risk factor, LMWH is preferred over aspirin. A randomized controlled trial of aspirin vs LMWH post TJA might clarify the relative risks and benefits of these two strategies.

To cite this abstract, please use the following information:
Schousboe, John T., Brown, Gregory A.; Aspirin vs. Low Molecular Weight Heparin for Prophylaxis Against Venous Thromboembolism after Total Knee or Hip Replacement in Lower Risk Individuals: A Cost-Utility Analysis. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :1539
DOI: 10.1002/art.29305

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