Aspirin for the prophylaxis of venous thromboembolic events in orthopedic surgery patients: a comparison of the AAOS and ACCP guidelines with review of the evidence.

BACKGROUND: The American Academy of Orthopaedic Surgeons (AAOS) and the American College of Chest Physicians (ACCP) have both developed evidence-based guidelines to prevent venous thromboembolism (VTE) in high-risk orthopedic surgery patients. Recent changes to these documents have brought them into agreement as to the inclusion of aspirin as an appropriate option for VTE prophylaxis in this patient population.
OBJECTIVE: To evaluate the appropriateness of aspirin to prevent VTE in high-risk orthopedic surgery patients. DATA SOURCES: Guidelines published by the AAOS in 2011 and the ACCP in 2012 were compared regarding their recommendations on the use of aspirin for the prevention of VTE. A literature search was also conducted to identify clinical trials that evaluated the use of aspirin for the prevention of VTE in this patient population. Search terms included the MeSH terms venous thromboembolism; venous thrombosis; pulmonary embolism; aspirin; arthroplasty, replacement, knee; arthroplasty, replacement, hip; and hip fractures/surgery. STUDY SELECTION AND DATA EXTRACTION: Any study that evaluated aspirin, even in combination with another method of prophylaxis (such as pneumatic compression devices), and had been published during or after 1985 was included. DATA SYNTHESIS: Randomized controlled trials, meta-analyses, and other large pooled and retrospective reviews have failed to consistently arrive at similar conclusions regarding the efficacy and safety of aspirin as an option for VTE prophylaxis in patients undergoing total knee arthroplasty (TKA), total hip arthroplasty (THA), or hip fracture surgery (HFS). Disagreements in the appropriateness of surrogate markers for safety and efficacy have resulted in differing recommendations from the ACCP and AAOS. The primary argument lies in the appropriateness of deep vein thrombosis as a surrogate marker for more serious outcomes such as pulmonary emboli.
CONCLUSIONS: Recent changes to both the ACCP and AAOS guidelines are in agreement for those who choose to use aspirin for chemoprophylaxis of VTE. Current surgical care improvement project measures do not include aspirin as an appropriate sole option for the prevention of VTE, but in patients undergoing elective TKA or who have a contraindication to pharmacologic prophylaxis and undergo a THA or HFS, aspirin in conjunction with compression devices as part of a multimodal approach would meet these measures. Data do not support the hypothesis that aspirin is less likely to cause adverse bleeding events than more potent anticoagulants.