Efficacy and safety of factor Xa inhibitors in low body weight patients.

STUDY OBJECTIVE: The purpose of this study is to provide evidence for the safety and efficacy of factor Xa inhibitors in patients with a weight ≤60 kg or BMI < 18.5 kg/m2 . DESIGN: Multicenter, retrospective, cohort study. SETTING: Twenty-two Ascension Health hospitals. PATIENTS: Low-body-weight adult patients (weight ≤ 60 kg or BMI < 18.5 kg/m2 ) receiving treatment for atrial fibrillation or venous thromboembolism. INTERVENTION: Factor Xa inhibitors (apixaban or rivaroxaban) or warfarin. MEASUREMENTS AND MAIN RESULTS: This study included 2538 patients between the factor Xa inhibitors (n = 1695) and warfarin (n = 843) groups with a mean weight of 53.5 ± 5.5 kg and BMI of 20.7 ± 3.1 kg/m2 . No significant difference in time to major bleeding was noted after controlling for potential confounders (HR 1.03, 95% CI 0.70-1.53, p = 0.87); similar results were seen following propensity score matching. Thromboembolism (5.3% vs. 6.2%, p = 0.38), composite major + clinically relevant nonmajor bleeding (9.8% vs. 11.5%, p = 0.18), and all-cause mortality (10.7% vs. 12.8%, p = 0.12) were similar between patients receiving factor Xa inhibitors versus warfarin. CONCLUSION: No differences in safety or effectiveness were noted between factor Xa inhibitors versus warfarin. These findings provide encouraging evidence to support the use of factor Xa inhibitors in low-body-weight patients.

Management of Venous Thromboembolism in Morbid Obesity With Rivaroxaban or Warfarin.

BACKGROUND: Rivaroxaban is a first-line option for the management of venous thromboembolism (VTE). However, limited data are available regarding its effectiveness in morbidly obese patients. OBJECTIVE: To evaluate rates of thrombosis and bleeding in morbidly obese patients receiving rivaroxaban or warfarin for VTE. METHODS: A multicenter, retrospective cohort study was conducted to compare rates of bleeding and thrombosis in patients receiving rivaroxaban versus warfarin for acute VTE. Patients were included if they were older than 18 years and had a body mass index (BMI) greater than 40 kg/m2 or weight greater than 120 kg. The primary effectiveness outcome was hazard of VTE recurrence; the primary safety outcome was hazard of major bleeding. Patients were followed for up to 12 months. RESULTS: A total of 1281 patients were identified for acute VTE and were included in this study with 487 patients receiving rivaroxaban and 785 receiving warfarin. The average cohort age was 57.6 ± 14.6 years, and the average weight was 136.4 ± 27.2 kg. After controlling for confounding factors, the use of rivaroxaban was not associated with an increased hazard of VTE events when compared with warfarin (hazard ratio [HR] = 0.69, 95% confidence interval [CI]: 0.42-1.08, P = 0.12) or major bleeding (HR = 1.29, 95% CI: 0.66-2.30, P = 0.52). CONCLUSION AND RELEVANCE: No difference was observed in obese patients with weight >120 kg or BMI >40 kg/m2 receiving rivaroxaban or warfarin for VTE treatment in hazard of VTE or major bleeding. Either agent may be considered an appropriate treatment option in this population.