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05-12-2010 | Cardiology | Article

Aspirin thromboprophylaxis feasible following total knee arthroplasty


Free abstract

MedWire News: Thromboprophylaxis with aspirin is associated with a lower risk for venous thromboembolism (VTE) than warfarin in patients undergoing total knee arthroplasty (TKA), US study findings indicate.

Patients given aspirin had similar rates of surgical site bleeding, infection, and mortality to those in patients who received warfarin or injectable thromboprophylaxis strategies such as low-molecular-weight heparin (LMWH) or synthetic pentasaccharides, report Kevin Bozic (University of California, San Francisco) and colleagues.

The American College of Chest Physicians does not currently recommend aspirin as a first-line agent for VTE prophylaxis in TKA patients because it has been reported to be less effective at preventing deep vein thrombosis (DVT) than warfarin or injectable VTE prophylaxis strategies, explain the researchers.

However, many changes have occurred in the perioperative management of TKA patients in recent years, and as a result, the perioperative risk for VTE is likely to be lower than it was when aspirin was originally studied as a prophylaxis agent, they add.

To assess the safety and effectiveness of aspirin, warfarin, and injectable VTE prophylaxis in the current era, Bozic and team analyzed clinical and administrative data from 93,840 patients who underwent primary TKA at 307 US hospitals over a 24-month period.

Of the patients, 51,923 (55%) received warfarin, 37,198 (40%) received injectable agents, and 4719 (5%) received aspirin.

The rate of VTE (DVT or pulmonary embolism) among patients treated with aspirin was 2.3%, compared with 3.1% for injectable agents, and 4.0% for warfarin.

After adjustment for patient and hospital factors, the researchers found that patients who received warfarin were 1.36 times more likely to have VTE than patients who received aspirin. In contrast, the odds were similar when injectable agents were compared with aspirin (odd ratio=1.03).

The rates of bleeding (0.6%-1.2%), infection (12% in all groups), and mortality (0.1-0.2%) did not differ between the groups.

"Our findings suggest that aspirin, when used in conjunction with other modern clinical care protocols, may be effective VTE prophylaxis for certain TKA patients," write the researchers in the Journal of Arthroplasty.

"However, given the observational retrospective design of our study, our conclusions should be considered hypothesis generating rather than conclusive evidence of the comparative safety and efficacy of aspirin for use in VTE prophylaxis after TKA," they conclude.

MedWire ( is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010

By Laura Dean

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