RESUMEN
BACKGROUND: Major orthopaedic surgery, such as total hip replacement (THR) and total knee replacement (TKR), is associated with an increased risk of venous thromboembolism (VTE). OBJECTIVE: Clinical trials have demonstrated the efficacy of rivaroxaban, a once-daily, orally administered Factor Xa inhibitor, for the prevention of VTE in patients undergoing THR or TKR. This analysis evaluated the cost effectiveness of rivaroxaban compared with enoxaparin, from a U.S. payer's perspective. METHODS: A decision-analytic model was developed to compare the costs and outcomes associated with rivaroxaban and enoxaparin for the prevention of VTE. The model replicated short-term clinical outcomes from the phase III RECORD trials. RECORD1 and RECORD2 compared rivaroxaban 10 mg daily (qd), given for 35 days, with enoxaparin 40 mg qd, given for 35 days or 10 to 14 days, respectively, in patients undergoing THR. RECORD3 compared 10 mg of rivaroxaban qd for 10 to 14 days versus 40 mg of enoxaparin qd for 10 to 14 days in patients undergoing TKR. The decision-analytic model also included data on long-term complications and sequelae as captured in observational studies and databases. It also included direct year 2010 medical costs over 1-year and 5-year time horizons. A series of sensitivity analyses were performed to determine the impact of different factors on the results of the model. Results of the cost-effectiveness analysis were reported in terms of symptomatic VTE events avoided. RESULTS: Rivaroxaban was associated with cost savings of $US 511.93 per patient and prevented an average of 0.0145 symptomatic VTE events per patient in the THR population, compared with enoxaparin. For a TKR population, 10 to 14 days of rivaroxaban prophylaxis was associated with cost savings of $US 465.74 and prevented an average 0.0193 symptomatic VTE events per patient. Sensitivity analysis suggested that the results of the model were robust, with cost savings ranging from $US 133.96-629.57 in the THR population and $US 293.01-848.68 in the TKR population, depending on the variables used. Sensitivity analysis also suggested that the economic profile of rivaroxaban is improved when the time horizon of the model is extended from 1 year to 5 years. A probabilistic sensitivity analysis confirmed the findings of baseline results, showing that rivaroxaban was less costly and more effective in all model simulations for both populations. CONCLUSIONS: This decision-analytic model analysis, from the U.S. payer's perspective, concluded that rivaroxaban may be cost saving in both the THR and the TKR populations, when compared with enoxaparin in the U.S.