Anticoagulation Prophylaxis in Orthopedic Surgery: An Efficiency Frontier Approach

This study assesses the use of new anticoagulants for the prevention of venous thromboembolism (VTE) in patients undergoing elective orthopedic surgery using traditional cost-effectiveness analysis and efficiency frontier methodology. Rationale: Efficiency frontier methodology has the potential to systematically improve the information used in policy and decision making, though it is still relatively uncommon in health economics. Anticoagulation in elective orthopedic surgery provides a fitting and timely case study for examining the influence of choosing one methodology over another. Methods: An economic model was developed to capture the relative benefits and consequences of choosing one anticoagulation strategy over another in the context of orthopedic surgery. Three novel oral anticoagulants (apixaban, rivaroxaban, dabigatran) are compared with enoxaparin 40 mg daily from the UK National Health Service perspective using traditional cost-effectiveness estimates (cost/quality-adjusted life years, cost/life years gained) and the efficiency frontier. The latter explicitly includes embolic and bleeding events as outcomes. A 5-year time horizon was adopted. Results: Total discounted costs ranged from about 200 000 to 431 000 over 5 years per 1000 patients undergoing elective total hip arthroplasty, and from 243 000 to 463 000 per 1000 patients for elective total knee arthroplasty. Analysis of the efficiency frontier demonstrates that apixaban and rivaroxaban are the preferred choices, depending on the outcome examined and the type of surgery. In terms of safety, apixaban is associated with more bleeding events avoided; yet, rivaroxaban demonstrated better VTE outcomes. Conclusion: Traditional cost-effectiveness analysis systematically excludes information related to the safety profiles of these anticoagulants. The efficiency frontier approach presented in this study provides critical information, without substantial effort, to permit a fully informed decision by taking into account all relevant outcomes as they relate to the costs associated with treatment choice.