RESUMO
Anticoagulant plasma concentrations and patient characteristics might affect the benefit-risk balance of therapy. This study assessed the impact of model-predicted rivaroxaban exposure and patient characteristics on outcomes in patients receiving rivaroxaban for venous thromboembolism treatment (VTE-T) using data from the phase 3 EINSTEIN-DVT and EINSTEIN-PE studies. In the absence of measured rivaroxaban exposure, exposure estimates were predicted based on individual increases in prothrombin time (PT) and the known correlation between rivaroxaban plasma concentrations and PT dynamics. The composite efficacy outcomes evaluated were recurrent deep-vein thrombosis (DVT) and pulmonary embolism (PE) and recurrent DVT, PE and all-cause death; safety outcomes were major bleeding and the composite of major or non-major clinically relevant (NMCR) bleeding. Exposure-response relationships were evaluated using multivariate logistic and Cox regression for the twice-daily (BID) and once-daily (OD) dosing periods, respectively. Predicted rivaroxaban exposure and CrCl were significantly associated with both efficacy outcomes in the BID period. In the OD period, exposure was significantly associated with recurrent DVT and PE but not recurrent DVT, PE and all-cause death. The statistically significant exposure-efficacy relationships were shallow. Exposure-safety relationships were absent within the investigated exposure range. During both dosing periods, low baseline hemoglobin and prior bleeding were associated with the composite of major or NMCR bleeding. In conclusion, based on the underlying data and analysis, no reliable target window for exposure with improved benefit-risk could be identified within the investigated exposure range. Therefore, monitoring rivaroxaban levels is unlikely to be beneficial in VTE-T.
Assuntos
Monitoramento de Medicamentos , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos , Risco Ajustado/métodos , Rivaroxabana , Tromboembolia Venosa , Anticoagulantes/administração & dosagem , Anticoagulantes/efeitos adversos , Anticoagulantes/sangue , Biomarcadores Farmacológicos/análise , Monitoramento de Medicamentos/métodos , Monitoramento de Medicamentos/estatística & dados numéricos , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos/diagnóstico , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos/prevenção & controle , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Modelos Estatísticos , Prognóstico , Tempo de Protrombina/métodos , Medição de Risco , Rivaroxabana/administração & dosagem , Rivaroxabana/efeitos adversos , Rivaroxabana/sangue , Índice Terapêutico , Resultado do Tratamento , Tromboembolia Venosa/sangue , Tromboembolia Venosa/diagnóstico , Tromboembolia Venosa/tratamento farmacológicoRESUMO
OBJECTIVES: This study investigated the effects of a mid-trial protocol amendment requiring elevated natriuretic peptides for inclusion in the COMMANDER-HF (A Study to Assess the Effectiveness and Safety of Rivaroxaban in Reducing the Risk of Death, Myocardial Infarction, or Stroke in Participants with Heart Failure and Coronary Artery Disease Following an Episode of Decompensated Heart Failure) trial. BACKGROUND: Heart failure (HF) trials that select patients based on history of HF hospitalization alone are susceptible to regional variations in event rates. Elevated plasma concentrations of natriuretic peptides (NPs) as selection criteria may help HF ascertainment and risk enrichment. In the COMMANDER-HF trial, B-type natriuretic peptide ≥200 ng/l or N-terminal pro-B-type natriuretic peptide ≥800 ng/l were added to inclusion criteria as a mid-trial protocol amendment, providing a unique case-study of NP-based inclusion criteria. METHODS: We compared the baseline characteristics, event rates, and treatment effects for patients enrolled before and after the NP protocol amendment. The primary endpoint was all-cause death, myocardial infarction, or stroke. Secondary endpoints included HF rehospitalization and cardiovascular death. RESULTS: A total of 5,022 patients with left ventricular ejection fraction ≤40% and coronary artery disease were included. Compared to patients enrolled before the NP protocol amendment, those enrolled post-amendment (n = 3,867, 77%) were older, more often had diabetes, and had lower values for body mass index, left ventricular ejection fraction, and estimated glomerular filtration rate, higher heart rate, and higher event rates: primary endpoint (hazard ratio [HR]: 1.32; 95% confidence interval [CI]: 1.16 to 1.50), cardiovascular death (HR: 1.29; 95% CI: 1.11 to 1.50), HF rehospitalization (HR: 1.31; 95% CI: 1.15 to 1.49), and major bleeding (HR: 1.71; 95% CI: 1.11 to 2.65). Differences between pre- and post-amendment rates were confined to and driven by Eastern Europe. This protocol amendment did not modify the neutral effect of rivaroxaban on the primary endpoint (p interaction = 0.36) or secondary endpoints. CONCLUSIONS: In a global event-driven trial of rivaroxaban in HF, requiring elevated NPs for inclusion increased event rates allowing earlier completion of the trial but did not modify treatment effect. These data inform future HF trials regarding the expected impact of NP-based inclusion criteria on patient characteristics and event rates. (COMMANDER HF [A Study to Assess the Effectiveness and Safety of Rivaroxaban in Reducing the Risk of Death, Myocardial Infarction, or Stroke in Participants With Heart Failure and Coronary Artery Disease Following an Episode of Decompensated Heart Failure] NCT01877915).
Assuntos
Insuficiência Cardíaca/tratamento farmacológico , Peptídeos Natriuréticos/sangue , Seleção de Pacientes , Rivaroxabana/uso terapêutico , Volume Sistólico/fisiologia , Função Ventricular Esquerda/fisiologia , Idoso , Biomarcadores/sangue , Método Duplo-Cego , Inibidores do Fator Xa/uso terapêutico , Feminino , Saúde Global , Insuficiência Cardíaca/sangue , Insuficiência Cardíaca/mortalidade , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico , Taxa de Sobrevida/tendênciasRESUMO
Patients with renal impairment are at higher risk of thrombosis and bleeding than those with normal renal function. The optimal rivaroxaban dose for thromboprophylaxis in acutely ill medical patients with renal impairment is unknown. MARINER and MAGELLAN were multicenter, randomized clinical trials of rivaroxaban in acutely ill medical patients. Efficacy and safety outcomes in patients with renal impairment in MARINER (7.5 mg once daily) were compared with those in patients with normal renal function in MARINER (10 mg once daily) and in a subpopulation of MAGELLAN that excluded patients at high risk for bleeding at baseline (10 mg once daily). Compared with enoxaparin/placebo in the MAGELLAN subpopulation, the relative risk (RR) of symptomatic venous thromboembolism (VTE) and VTE-related death with rivaroxaban 10 mg in patients with renal impairment (RR = 0.62; 95% confidence interval [CI] 0.27-1.44) was similar to that in those with normal renal function (RR = 0.78; 95% CI 0.44-1.40), while in MARINER, the 7.5 mg dose did not reduce the risk in patients with renal impairment (hazard ratio = 1.00; 95% CI 0.52-1.92). Major bleeding with rivaroxaban 10 mg once daily was higher in patients with renal impairment than in those with normal renal function in MAGELLAN (1.54% vs. 0.98%) and in the MAGELLAN subpopulation (0.94% vs. 0.61%). At a dose of 10 mg once daily, rivaroxaban is effective for thromboprophylaxis in acutely ill medical patients with impaired or normal renal function. The safety of this regimen is enhanced without loss of efficacy by excluding patients at high risk for bleeding, but not by using a reduced-dose strategy. TRIAL REGISTRATION: ClinicalTrials.gov identifiers: NCT00571649 for the MAGELLAN trial, NCT02111564 for the MARINER trial.
Assuntos
Nefropatias/sangue , Nefropatias/complicações , Rivaroxabana/uso terapêutico , Trombose/prevenção & controle , Doença Aguda , Idoso , Anticoagulantes , Método Duplo-Cego , Enoxaparina/uso terapêutico , Feminino , Hemorragia , Humanos , Incidência , Testes de Função Renal , Masculino , Pessoa de Meia-Idade , Fatores de Risco , Resultado do Tratamento , Tromboembolia Venosa/tratamento farmacológicoRESUMO
Acutely ill medical patients are at risk of venous thromboembolism (VTE) and VTE-related mortality during hospitalization and posthospital discharge, but widespread adoption of extended thromboprophylaxis has not occurred. We analyzed a subpopulation within the MAGELLAN study of extended thromboprophylaxis with rivaroxaban to reevaluate the benefit risk profile. We identified 5 risk factors for major and fatal bleeding after a clinical analysis of the MAGELLAN study and analyzed efficacy and safety with these patients excluded (n = 1551). Risk factors included: active cancer, dual antiplatelet therapy at baseline, bronchiectasis/pulmonary cavitation, gastroduodenal ulcer, or bleeding within 3 months before randomization. We evaluated efficacy, safety, and benefit risk using clinically comparable endpoints in the subpopulation. At day 10, rivaroxaban was noninferior to enoxaparin (relative risk [RR] = 0.82, 95% confidence interval [CI] = 0.58-1.15) and at day 35 rivaroxaban was significantly better than enoxaparin/placebo (RR = 0.68, 95% CI = 0.53-0.88) in reducing VTE and VTE-related death. Major bleeding was reduced at day 10 (RR = 2.18, 95% CI = 1.07-4.44 vs 1.19, 95% CI = 0.54-2.65) and at day 35 (2.87, 95% CI = 1.60-5.15 vs 1.48, 95% CI = 0.77-2.84) for MAGELLAN versus this subpopulation, respectively. The benefit risk profile was favorable in this subpopulation treated for 35 days, with the number needed to treat ranging from 55 to 481 and number needed to harm from 455 to 1067 for all pairwise evaluations. Five exclusionary criteria defined a subpopulation of acutely ill medical patients with a positive benefit risk profile for in-hospital and extended thromboprophylaxis with rivaroxaban.
Assuntos
Anticoagulantes/uso terapêutico , Inibidores do Fator Xa/uso terapêutico , Rivaroxabana/uso terapêutico , Tromboembolia Venosa/tratamento farmacológico , Administração Oral , Idoso , Anticoagulantes/farmacologia , Método Duplo-Cego , Inibidores do Fator Xa/farmacologia , Feminino , Humanos , Pessoa de Meia-Idade , Fatores de Risco , Rivaroxabana/farmacologiaRESUMO
AIMS: Stroke is often a devastating event among patients with heart failure with reduced ejection (HFrEF). In COMMANDER HF, rivaroxaban 2.5 mg b.i.d. did not reduce the composite of first occurrence of death, stroke, or myocardial infarction compared with placebo in patients with HFrEF, coronary artery disease (CAD), and sinus rhythm. We now examine the incidence, timing, type, severity, and predictors of stroke or a transient ischaemic attack (TIA), and seek to establish the net clinical benefit of treatment with low-dose rivaroxaban. METHODS AND RESULTS: In this double-blind, randomized trial, 5022 patients who had HFrEF(≤40%), elevated natriuretic peptides, CAD, and who were in sinus rhythm were treated with rivaroxaban 2.5 mg b.i.d. or placebo in addition to antiplatelet therapy, after an episode of worsening HF. The primary neurological outcome for this post hoc analysis was time to first event of any stroke or TIA. Over a median follow-up of 20.5 (25th-75th percentiles 20.0-20.9) months, 150 all-cause stroke (127) or TIA (23) events occurred (ischaemic stroke in 82% and haemorrhagic stroke in 11% of stroke events). Overall, 47.5% of first-time strokes were either disabling (16.5%) or fatal (31%). Prior stroke, low body mass index, geographic region, and the CHA2DS2-VASc score were predictors of stroke/TIA. Rivaroxaban significantly reduced the primary neurological endpoint of all-cause stroke or TIA compared with placebo by 32% (1.29 events vs. 1.90 events per 100 patient-years), adjusted for the time from index HF event to randomization and stratified by geographic region (adjusted hazard ratio 0.68, 95% confidence interval 0.49-0.94), with a number needed to treat of 164 patients per year to prevent one stroke/TIA event. The principal safety endpoint of fatal bleeding or bleeding into a critical space, occurred at a similar rate on rivaroxaban and placebo (0.44 events vs. 0.55 events per 100 patient-years). CONCLUSIONS: Patients with HFrEF and CAD are at risk for stroke or TIA in the period following an episode of worsening heart failure in the absence of atrial fibrillation. Most strokes are of ischaemic origin and nearly half are either disabling or fatal. Rivaroxaban at a dose of 2.5 mg b.i.d. reduced rates of stroke or TIA compared with placebo in this population. TRIAL REGISTRATION: COMMANDER HF (A Study to Assess the Effectiveness and Safety of Rivaroxaban in Reducing the Risk of Death, Myocardial Infarction, or Stroke in Participants with Heart Failure and Coronary Artery Disease Following an Episode of Decompensated Heart Failure); ClinicalTrials.gov NCT01877915.
Assuntos
Inibidores do Fator Xa/uso terapêutico , Insuficiência Cardíaca/tratamento farmacológico , Ataque Isquêmico Transitório/prevenção & controle , Rivaroxabana/uso terapêutico , Acidente Vascular Cerebral/prevenção & controle , Idoso , Isquemia Encefálica/induzido quimicamente , Estudos de Casos e Controles , Doença da Artéria Coronariana/tratamento farmacológico , Método Duplo-Cego , Quimioterapia Combinada , Inibidores do Fator Xa/administração & dosagem , Feminino , Insuficiência Cardíaca/complicações , Insuficiência Cardíaca/fisiopatologia , Hemorragia/induzido quimicamente , Humanos , Incidência , Ataque Isquêmico Transitório/epidemiologia , Masculino , Pessoa de Meia-Idade , Infarto do Miocárdio/tratamento farmacológico , Infarto do Miocárdio/epidemiologia , Placebos/administração & dosagem , Inibidores da Agregação Plaquetária/uso terapêutico , Rivaroxabana/administração & dosagem , Acidente Vascular Cerebral/epidemiologia , Acidente Vascular Cerebral/mortalidade , Acidente Vascular Cerebral/patologia , Volume Sistólico/fisiologiaRESUMO
Importance: Whether anticoagulation benefits patients with heart failure (HF) in sinus rhythm is uncertain. The COMMANDER HF randomized clinical trial evaluated the effects of adding low-dose rivaroxaban to antiplatelet therapy in patients with recent worsening of chronic HF with reduced ejection fraction, coronary artery disease (CAD), and sinus rhythm. Although the primary end point of all-cause mortality, myocardial infarction, or stroke did not differ between rivaroxaban and placebo, there were numerical advantages favoring rivaroxaban for myocardial infarction and stroke. Objective: To examine whether low-dose rivaroxaban was associated with reduced thromboembolic events in patients enrolled in the COMMANDER HF trial. Design, Setting, and Participants: Post hoc analysis of the COMMANDER HF multicenter, randomized, double-blind, placebo-controlled trial in patients with CAD and worsening HF. The trial randomized 5022 patients postdischarge from a hospital or outpatient clinic after treatment for worsening HF between September 2013 and October 2017. Patients were required to be receiving standard care for HF and CAD and were excluded for a medical condition requiring anticoagulation or a bleeding history. Patients were randomized in a 1:1 ratio. Analysis was conducted from June 2018 and January 2019. Intervention: Patients were randomly assigned to receive 2.5 mg of rivaroxaban given orally twice daily or placebo in addition to their standard therapy. Main Outcomes and Measures: For this post hoc analysis, a thromboembolic composite was defined as either (1) myocardial infarction, ischemic stroke, sudden/unwitnessed death, symptomatic pulmonary embolism, or symptomatic deep venous thrombosis or (2) all of the previous components except sudden/unwitnessed deaths because not all of these are caused by thromboembolic events. Results: Of 5022 patients, 3872 (77.1%) were men, and the overall mean (SD) age was 66.4 (10.2) years. Over a median (interquartile range) follow-up of 19.6 (11.7-30.8) months, fewer patients assigned to rivaroxaban compared with placebo had a thromboembolic event including sudden/unwitnessed deaths: 328 (13.1%) vs 390 (15.5%) (hazard ratio, 0.83; 95% CI, 0.72-0.96; P = .01). When sudden/unwitnessed deaths were excluded, the results analyzing thromboembolic events were similar: 153 (6.1%) vs 190 patients (7.6%) with an event (hazard ratio, 0.80; 95% CI, 0.64-0.98; P = .04). Conclusions and Relevance: In this study, thromboembolic events occurred frequently in patients with HF, CAD, and sinus rhythm. Rivaroxaban may reduce the risk of thromboembolic events in this population, but these events are not the major cause of morbidity and mortality in patients with recent worsening of HF for which rivaroxaban had no effect. While consistent with other studies, these results require confirmation in prospective randomized clinical trials. Trial Registration: ClinicalTrials.gov identifier: NCT01877915.
Assuntos
Doença da Artéria Coronariana/tratamento farmacológico , Inibidores do Fator Xa/uso terapêutico , Insuficiência Cardíaca/tratamento farmacológico , Infarto do Miocárdio/epidemiologia , Embolia Pulmonar/epidemiologia , Rivaroxabana/uso terapêutico , Acidente Vascular Cerebral/epidemiologia , Trombose Venosa/epidemiologia , Idoso , Aspirina/uso terapêutico , Doença Crônica , Morte Súbita/epidemiologia , Progressão da Doença , Método Duplo-Cego , Quimioterapia Combinada , Feminino , Insuficiência Cardíaca/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Mortalidade , Inibidores da Agregação Plaquetária/uso terapêutico , Modelos de Riscos Proporcionais , Volume Sistólico , Tienopiridinas/uso terapêutico , Tromboembolia/epidemiologiaRESUMO
BACKGROUND: Heart failure is associated with activation of thrombin-related pathways, which predicts a poor prognosis. We hypothesized that treatment with rivaroxaban, a factor Xa inhibitor, could reduce thrombin generation and improve outcomes for patients with worsening chronic heart failure and underlying coronary artery disease. METHODS: In this double-blind, randomized trial, 5022 patients who had chronic heart failure, a left ventricular ejection fraction of 40% or less, coronary artery disease, and elevated plasma concentrations of natriuretic peptides and who did not have atrial fibrillation were randomly assigned to receive rivaroxaban at a dose of 2.5 mg twice daily or placebo in addition to standard care after treatment for an episode of worsening heart failure. The primary efficacy outcome was the composite of death from any cause, myocardial infarction, or stroke. The principal safety outcome was fatal bleeding or bleeding into a critical space with a potential for causing permanent disability. RESULTS: Over a median follow-up period of 21.1 months, the primary end point occurred in 626 (25.0%) of 2507 patients assigned to rivaroxaban and in 658 (26.2%) of 2515 patients assigned to placebo (hazard ratio, 0.94; 95% confidence interval [CI], 0.84 to 1.05; P=0.27). No significant difference in all-cause mortality was noted between the rivaroxaban group and the placebo group (21.8% and 22.1%, respectively; hazard ratio, 0.98; 95% CI, 0.87 to 1.10). The principal safety outcome occurred in 18 patients who took rivaroxaban and in 23 who took placebo (hazard ratio, 0.80; 95% CI, 0.43 to 1.49; P=0.48). CONCLUSIONS: Rivaroxaban at a dose of 2.5 mg twice daily was not associated with a significantly lower rate of death, myocardial infarction, or stroke than placebo among patients with worsening chronic heart failure, reduced left ventricular ejection fraction, coronary artery disease, and no atrial fibrillation. (Funded by Janssen Research and Development; COMMANDER HF ClinicalTrials.gov number, NCT01877915 .).
Assuntos
Doença da Artéria Coronariana/tratamento farmacológico , Inibidores do Fator Xa/uso terapêutico , Insuficiência Cardíaca/tratamento farmacológico , Rivaroxabana/uso terapêutico , Idoso , Doença da Artéria Coronariana/complicações , Método Duplo-Cego , Quimioterapia Combinada , Inibidores do Fator Xa/efeitos adversos , Feminino , Seguimentos , Insuficiência Cardíaca/complicações , Insuficiência Cardíaca/mortalidade , Insuficiência Cardíaca/fisiopatologia , Humanos , Estimativa de Kaplan-Meier , Masculino , Pessoa de Meia-Idade , Infarto do Miocárdio/epidemiologia , Infarto do Miocárdio/prevenção & controle , Peptídeo Natriurético Encefálico/sangue , Readmissão do Paciente/estatística & dados numéricos , Inibidores da Agregação Plaquetária/uso terapêutico , Rivaroxabana/efeitos adversos , Acidente Vascular Cerebral/epidemiologia , Acidente Vascular Cerebral/prevenção & controle , Volume Sistólico , Falha de TratamentoRESUMO
BACKGROUND: Patients who are hospitalized for medical illness remain at risk for venous thromboembolism after discharge, but the role of extended thromboprophylaxis in the treatment of such patients is a subject of controversy. METHODS: In this randomized, double-blind trial, medically ill patients who were at increased risk for venous thromboembolism on the basis of a modified International Medical Prevention Registry on Venous Thromboembolism (IMPROVE) score of 4 or higher (scores range from 0 to 10, with higher scores indicating a higher risk of venous thromboembolism) or a score of 2 or 3 plus a plasma d-dimer level of more than twice the upper limit of the normal range (defined according to local laboratory criteria) were assigned at hospital discharge to either once-daily rivaroxaban at a dose of 10 mg (with the dose adjusted for renal insufficiency) or placebo for 45 days. The primary efficacy outcome was a composite of symptomatic venous thromboembolism or death due to venous thromboembolism. The principal safety outcome was major bleeding. RESULTS: Of the 12,024 patients who underwent randomization, 12,019 were included in the intention-to-treat analysis. The primary efficacy outcome occurred in 50 of 6007 patients (0.83%) who were given rivaroxaban and in 66 of 6012 patients (1.10%) who were given placebo (hazard ratio, 0.76; 95% confidence interval [CI], 0.52 to 1.09; P=0.14). The prespecified secondary outcome of symptomatic nonfatal venous thromboembolism occurred in 0.18% of patients in the rivaroxaban group and 0.42% of patients in the placebo group (hazard ratio, 0.44; 95% CI, 0.22 to 0.89). Major bleeding occurred in 17 of 5982 patients (0.28%) in the rivaroxaban group and in 9 of 5980 patients (0.15%) in the placebo group (hazard ratio, 1.88; 95% CI, 0.84 to 4.23). CONCLUSIONS: Rivaroxaban, given to medical patients for 45 days after hospital discharge, was not associated with a significantly lower risk of symptomatic venous thromboembolism and death due to venous thromboembolism than placebo. The incidence of major bleeding was low. (Funded by Janssen Research and Development; MARINER ClinicalTrials.gov number, NCT02111564 .).
Assuntos
Inibidores do Fator Xa/uso terapêutico , Hospitalização , Rivaroxabana/uso terapêutico , Tromboembolia Venosa/prevenção & controle , Assistência ao Convalescente , Idoso , Método Duplo-Cego , Esquema de Medicação , Inibidores do Fator Xa/administração & dosagem , Inibidores do Fator Xa/efeitos adversos , Feminino , Hemorragia/induzido quimicamente , Humanos , Estimativa de Kaplan-Meier , Masculino , Pessoa de Meia-Idade , Alta do Paciente , Rivaroxabana/administração & dosagem , Rivaroxabana/efeitos adversos , Resultado do Tratamento , Tromboembolia Venosa/epidemiologia , Tromboembolia Venosa/mortalidade , Trombose Venosa/prevenção & controleRESUMO
BACKGROUND: The clinically appropriate duration of thromboprophylaxis in hospitalized patients with acute medical illnesses is unknown. In this multicenter, randomized, double-blind trial, we evaluated the efficacy and safety of oral rivaroxaban administered for an extended period, as compared with subcutaneous enoxaparin administered for a standard period, followed by placebo. METHODS: We randomly assigned patients 40 years of age or older who were hospitalized for an acute medical illness to receive subcutaneous enoxaparin, 40 mg once daily, for 10±4 days and oral placebo for 35±4 days or to receive subcutaneous placebo for 10±4 days and oral rivaroxaban, 10 mg once daily, for 35±4 days. The primary efficacy outcomes were the composite of asymptomatic proximal or symptomatic venous thromboembolism up to day 10 (noninferiority test) and up to day 35 (superiority test). The principal safety outcome was the composite of major or clinically relevant nonmajor bleeding. RESULTS: A total of 8101 patients underwent randomization. A primary efficacy outcome event occurred in 78 of 2938 patients (2.7%) receiving rivaroxaban and 82 of 2993 patients (2.7%) receiving enoxaparin at day 10 (relative risk with rivaroxaban, 0.97; 95% confidence interval [CI], 0.71 to 1.31; P=0.003 for noninferiority) and in 131 of 2967 patients (4.4%) who received rivaroxaban and 175 of 3057 patients (5.7%) who received enoxaparin followed by placebo at day 35 (relative risk, 0.77; 95% CI, 0.62 to 0.96; P=0.02). A principal safety outcome event occurred in 111 of 3997 patients (2.8%) in the rivaroxaban group and 49 of 4001 patients (1.2%) in the enoxaparin group at day 10 (P<0.001) and in 164 patients (4.1%) and 67 patients (1.7%) in the respective groups at day 35 (P<0.001). CONCLUSIONS: In acutely ill medical patients, rivaroxaban was noninferior to enoxaparin for standard-duration thromboprophylaxis. Extended-duration rivaroxaban reduced the risk of venous thromboembolism. Rivaroxaban was associated with an increased risk of bleeding. (Funded by Bayer HealthCare Pharmaceuticals and Janssen Research and Development; MAGELLAN ClinicalTrials.gov number, NCT00571649.).