To evaluate the cost-effectiveness of prolonged (35-day) and standard-duration (14-day) anticoagulation therapy following total knee arthroplasty (TKA).
Using Markov modeling, we assessed clinical and economic outcomes of 14-day and 35-day anticoagulation therapy following TKA with rivaroxaban, low molecular weight heparin (LMWH), fondaparinux, warfarin, and aspirin. Incidence of complications of TKA and anticoagulation therapy (deep vein thrombosis [DVT], pulmonary embolism [PE], prosthetic joint infection [PJI], and bleeding) were derived from published literature. Daily costs ranged from $1 (aspirin) to $43 (fondaparinux). Primary outcomes included quality-adjusted life years (QALYs), direct medical costs, and incremental cost-effectiveness ratios (ICERs) at 1 year post-TKA. The preferred regimen was the regimen with highest QALYs maintaining an ICER below the willingness-to-pay threshold ($100,000/QALY). We conducted probabilistic sensitivity analyses, varying complication incidence and anticoagulation efficacy, to evaluate the impact of parameter uncertainty on model results.
Aspirin resulted in the highest cumulative incidence of DVT and PE, while prolonged fondaparinux led to the largest reduction in DVT incidence (15% reduction compared to no prophylaxis). Despite differential bleeding rates (ranging from 3% to 6%), all strategies had similar incidence of PJI (1% to 2%). Prolonged rivaroxaban was the least costly strategy ($3,300 at 1 year post-TKA) and the preferred regimen in the base case. In sensitivity analyses, prolonged rivaroxaban and warfarin had similar likelihoods of being cost-effective.
Extending postoperative anticoagulation therapy to 35 days increases QALYs compared to standard 14-day prophylaxis. Prolonged rivaroxaban and prolonged warfarin are most likely to be cost-effective post-TKA; the costs of fondaparinux and LMWH precluded their being preferred strategies.