Prevention of venous thromboembolism after hip and knee replacement among older adults
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BACKGROUND: Venous thromboembolism (VTE) after total hip and knee replacement is a major patient safety threat, and pharmacologic prophylaxis is generally recommended. However, clinicians disagree on the optimal prophylaxis agent. OBJECTIVE: We sought to compare effectiveness and safety of aspirin versus anticoagulants for VTE prophylaxis after hip and knee replacement. METHODS: We identified patients aged ≥ 65 years undergoing elective hip and knee replacement during 2011–2013 in 59 hospitals nationwide and included in the Institute for Health Metrics clinical database. We limited our analysis to the patients with electronic medical record of discharge prophylaxis medication. Patients were categorized into either anticoagulant or aspirin only group. VTE, major hemorrhage, cardiovascular event, and death were identified from electronic databases and validated by physician review of the source documents. We compared the 90-day risk of VTE and the composite outcome (VTE, cardiovascular events, major hemorrhage, and death) in the anticoagulant group to the aspirin group using Cox proportional hazards analysis. RESULTS: Study sample included 5648 patients with mean age 73 years. The overall number of outcome events was low. There were 35 VTE events (0.61%), 15 (0.26%) cardiovascular events, 17 major hemorrhages (0.30%), and 18 deaths (0.31%). In multivariable analysis adjusting for patient demographics and cardiovascular disease and risk factors, anticoagulation therapy was associated with decreased risk of VTE (HR 0.76, 95% CI 0.35–1.68) and the composite outcome (HR 0.80, 95% CI 0.48–1.32) although not statistically significant. CONCLUSION: Among older adults undergoing elective total hip and knee replacement in community hospitals, the 90-day risk of VTE and the composite outcome was low. We did not find any statistical difference in the risk of the outcomes between anticoagulation and aspirin. Future studies with a larger sample size and different patient population are needed to validate our results.