Milvexian for the Prevention of Venous Thromboembolism.

BACKGROUND: Factor XIa inhibitors for the prevention and treatment of venous and arterial thromboembolism may be more effective and result in less bleeding than conventional anticoagulants. Additional data are needed regarding the efficacy and safety of milvexian, an oral factor XIa inhibitor. METHODS: In this parallel-group, phase 2 trial, we randomly assigned 1242 patients undergoing knee arthroplasty to receive one of seven postoperative regimens of milvexian (25 mg, 50 mg, 100 mg, or 200 mg twice daily or 25 mg, 50 mg, or 200 mg once daily) or enoxaparin (40 mg once daily). The primary efficacy outcome was venous thromboembolism (which was a composite of asymptomatic deep-vein thrombosis, confirmed symptomatic venous thromboembolism, or death from any cause). The principal safety outcome was bleeding. RESULTS: Among the patients receiving milvexian twice daily, venous thromboembolism developed in 27 of 129 (21%) taking 25 mg, in 14 of 124 (11%) taking 50 mg, in 12 of 134 (9%) taking 100 mg, and in 10 of 131 (8%) taking 200 mg. Among those receiving milvexian once daily, venous thromboembolism developed in 7 of 28 (25%) taking 25 mg, in 30 of 127 (24%) taking 50 mg, and in 8 of 123 (7%) taking 200 mg, as compared with 54 of 252 patients (21%) taking enoxaparin. The dose-response relationship with twice-daily milvexian was significant (one-sided P<0.001), and the 12% incidence of venous thromboembolism with twice-daily milvexian was significantly lower than the prespecified benchmark of 30% (one-sided P<0.001). Bleeding of any severity occurred in 38 of 923 patients (4%) taking milvexian and in 12 of 296 patients (4%) taking enoxaparin; major or clinically relevant nonmajor bleeding occurred in 1% and 2%, respectively; and serious adverse events were reported in 2% and 4%, respectively. CONCLUSIONS: Postoperative factor XIa inhibition with oral milvexian in patients undergoing knee arthroplasty was effective for the prevention of venous thromboembolism and was associated with a low risk of bleeding. (Funded by Bristol Myers Squibb and Janssen Research and Development; AXIOMATIC-TKR ClinicalTrials.gov number, NCT03891524.).

Effect of Osocimab in Preventing Venous Thromboembolism Among Patients Undergoing Knee Arthroplasty: The FOXTROT Randomized Clinical Trial.

Importance: The efficacy of factor XIa inhibition for thromboprophylaxis is unknown. Osocimab is a long-acting, fully human monoclonal antibody that inhibits factor XIa. Objective: To compare different doses of osocimab with enoxaparin and apixaban for thromboprophylaxis in patients who have undergone knee arthroplasty. Design, Setting, and Participants: Randomized, open-label, adjudicator-blinded, phase 2 noninferiority trial with observer blinding for osocimab doses, conducted at 54 hospitals in 13 countries. Adult patients undergoing unilateral knee arthroplasty were randomized from October 2017 through August 2018 and followed up until January 2019. Interventions: Single intravenous osocimab postoperative doses of 0.3 mg/kg (n = 107), 0.6 mg/kg (n = 65), 1.2 mg/kg (n = 108), or 1.8 mg/kg (n = 106); preoperative doses of 0.3 mg/kg (n = 109) or 1.8 mg/kg (n = 108); or 40 mg of subcutaneous enoxaparin once daily (n = 105) or 2.5 mg of oral apixaban twice daily (n = 105) for at least 10 days or until venography. Main Outcomes and Measures: The primary outcome was venous thromboembolism incidence between 10 and 13 days postoperatively (assessed by mandatory bilateral venography performed 10 to 13 days after surgery or confirmed symptomatic deep vein thrombosis or pulmonary embolism). A 5% noninferiority margin compared with enoxaparin was chosen. The primary safety outcome of major or clinically relevant nonmajor bleeding was assessed until 10 to 13 days postoperatively. Results: Of 813 randomized participants (mean [SD] age, 66.5 years [8.2 years]; body mass index, 32.7 [5.7]; and 74.2% women), 600 were included in the per-protocol population used for the primary analysis. The primary outcome occurred in 18 patients (23.7%) receiving 0.3 mg/kg, 8 (15.7%) receiving 0.6 mg/kg, 13 (16.5%) receiving 1.2 mg/kg, and 14 (17.9%) receiving 1.8 mg/kg of osocimab postoperatively; 23 (29.9%) receiving 0.3 mg/kg and 9 (11.3%) receiving 1.8 mg/kg of osocimab preoperatively; 20 (26.3%) receiving enoxaparin; and 12 (14.5%) receiving apixaban. Osocimab given postoperatively met criteria for noninferiority compared with enoxaparin with risk differences (1-sided 95% CIs) of 10.6% (95% CI, -1.2% to ∞) at the 0.6-mg/kg dose; 9.9% (95% CI, -0.9% to ∞) at the 1.2-mg/kg dose, and 8.4% (95% CI, -2.6 to ∞) at the 1.8-mg/kg dose. The preoperative dose of 1.8 mg/kg of osocimab met criteria for superiority compared with enoxaparin with a risk difference of 15.1%; 2-sided 90% CI, 4.9% to 25.2%). Postoperative and preoperative doses of 0.3 mg/kg of osocimab did not meet the prespecified criteria for noninferiority, with risk differences (1-sided 95% CIs) of 2.6% (95% CI, -8.9% to ∞) and -3.6% (95% CI, -15.5% to ∞), respectively. Major or clinically relevant nonmajor bleeding was observed in up to 4.7% of those receiving osocimab, 5.9% receiving enoxaparin, and 2% receiving apixaban. Conclusions and Relevance: Among patients undergoing knee arthroplasty, postoperative osocimab 0.6 mg/kg, 1.2 mg/kg, and 1.8 mg/kg met criteria for noninferiority compared with enoxaparin, and the preoperative 1.8-mg/kg dose of osocimab met criteria for superiority compared with enoxaparin for the primary outcome of incidence of venous thromboembolism at 10 to 13 days postoperatively. Further studies are needed to establish efficacy and safety of osocimab relative to standard thromboprophylaxis. Trial Registration: ClinicalTrials.gov Identifier: NCT03276143.

Rivaroxaban compared with standard thromboprophylaxis after major orthopaedic surgery: co-medication interactions.

AIM: The aim of the present study was to analyse concomitant drug use and its association with outcome in patients (N = 17 701) receiving rivaroxaban or standard of care (SOC) for the prevention of venous thromboembolism after major orthopaedic surgery in the non-interventional, phase IV XAMOS (Xarelto® in the prophylaxis of post-surgical venous thromboembolism after elective major orthopaedic surgery of hip or knee) study. METHODS: Concomitant drug use was at the discretion of the treating physician. Prespecified co-medications of interest were cytochrome P450 (CYP) 3A4/P-glycoprotein inhibitors/inducers, platelet aggregation inhibitors (PAIs) and nonsteroidal anti-inflammatory drugs (NSAIDs). Crude event incidences were compared between rivaroxaban and SOC groups. RESULTS: CYP3A4/P-glycoprotein inhibitor/inducer use was infrequent, in contrast to PAI (~7%) and NSAID (~52%) use. Rivaroxaban was associated with a lower incidence of overall symptomatic thromboembolic events compared with SOC, regardless of co-medication use. In both treatment groups, PAI users, with higher age and prevalence of cardiovascular co-morbidities, had similar higher (>7-fold) incidences of symptomatic arterial but not venous thromboembolic events compared with non-users. NSAID use had no influence on thromboembolic events. However, odds ratios (ORs) for major bleeding events (European Medicines Agency definition) were higher in NSAID users compared with non-users in rivaroxaban [OR = 1.50; 95% confidence interval (CI) 1.06, 2.13] and SOC (OR = 1.70; CI 1.16, 2.49) groups. In PAI users, ORs for major bleeding events were no different from those of non-users in both the rivaroxaban (OR = 1.49; CI 0.84, 2.65) and SOC (OR = 1.46; CI 0.82, 2.62) groups. CONCLUSIONS: Use of NSAIDs in XAMOS was frequent and associated with a higher frequency of bleeding events in patients receiving rivaroxaban or SOC, although the benefit-risk profile of rivaroxaban compared with SOC was maintained.

Semuloparin for thromboprophylaxis in patients receiving chemotherapy for cancer.

BACKGROUND: Patients receiving chemotherapy for cancer are at increased risk for venous thromboembolism. Limited data support the clinical benefit of antithrombotic prophylaxis. METHODS: In this double-blind, multicenter trial, we evaluated the efficacy and safety of the ultra-low-molecular-weight heparin semuloparin for prevention of venous thromboembolism in patients receiving chemotherapy for cancer. Patients with metastatic or locally advanced solid tumors who were beginning to receive a course of chemotherapy were randomly assigned to receive subcutaneous semuloparin, 20 mg once daily, or placebo until there was a change of chemotherapy regimen. The primary efficacy outcome was the composite of any symptomatic deep-vein thrombosis, any nonfatal pulmonary embolism, and death related to venous thromboembolism. Clinically relevant bleeding (major and nonmajor) was the main safety outcome. RESULTS: The median treatment duration was 3.5 months. Venous thromboembolism occurred in 20 of 1608 patients (1.2%) receiving semuloparin, as compared with 55 of 1604 (3.4%) receiving placebo (hazard ratio, 0.36; 95% confidence interval [CI], 0.21 to 0.60; P<0.001), with consistent efficacy among subgroups defined according to the origin and stage of cancer and the baseline risk of venous thromboembolism. The incidence of clinically relevant bleeding was 2.8% and 2.0% in the semuloparin and placebo groups, respectively (hazard ratio, 1.40; 95% CI, 0.89 to 2.21). Major bleeding occurred in 19 of 1589 patients (1.2%) receiving semuloparin and 18 of 1583 (1.1%) receiving placebo (hazard ratio, 1.05; 95% CI, 0.55 to 1.99). Incidences of all other adverse events were similar in the two study groups. CONCLUSIONS: Semuloparin reduces the incidence of thromboembolic events in patients receiving chemotherapy for cancer, with no apparent increase in major bleeding. (Funded by Sanofi; ClinicalTrials.gov number, NCT00694382.).

Preoperative enoxaparin versus postoperative semuloparin thromboprophylaxis in major abdominal surgery: a randomized controlled trial.

OBJECTIVE: To compare efficacy and safety of thromboprophylaxis with semuloparin started postoperatively versus enoxaparin started preoperatively in major abdominal surgery. BACKGROUND: Venous thromboembolism is an important complication following major abdominal surgery. Semuloparin is a novel ultra-low-molecular-weight heparin with high antifactor Xa and minimal antifactor IIa activity. METHODS: In this double-blind noninferiority trial, adult patients undergoing major abdominal or pelvic operation under general anesthesia lasting more than 45 minutes were assigned to either daily enoxaparin 40 mg commenced preoperatively or daily semuloparin 20 mg commenced postoperatively, for 7 to 10 days. Patients underwent bilateral leg venography between 7 and 11 days postsurgery. The primary efficacy end point was the composite of any deep vein thrombosis, nonfatal pulmonary embolism, or all-cause death. The primary safety outcome was bleeding. Both were independently adjudicated. RESULTS: In total, 4413 patients were randomized; 3030 (1499 in the enoxaparin and 1531 in the semuloparin groups) were evaluable for the primary efficacy end point, which occurred in 97 patients (6.3%) in the semuloparin group and 82 patients (5.5%) in the enoxaparin group [odds ratio (OR) = 1.16, 95% confidence interval (CI): 0.84-1.59]. On the basis of a noninferiority margin of 1.25, postoperative semuloparin did not demonstrate noninferiority to preoperative enoxaparin. Major bleeding occurred in 63 of 2175 patients (2.9%) in the semuloparin group and 98 of 2177 patients (4.5%) in the enoxaparin group (OR = 0.63, 95% CI: 0.46-0.87). CONCLUSIONS: Semuloparin commenced postoperatively did not demonstrate noninferiority to enoxaparin initiated preoperatively for thromboprophylaxis after major abdominal surgery. Study registered with clinicaltrials.gov: NCT00679588.

Rivaroxaban versus enoxaparin for thromboprophylaxis after total knee arthroplasty.

BACKGROUND: We investigated the efficacy of rivaroxaban, an orally active direct factor Xa inhibitor, in preventing venous thrombosis after total knee arthroplasty. METHODS: In this randomized, double-blind trial, 2531 patients who were to undergo total knee arthroplasty received either oral rivaroxaban, 10 mg once daily, beginning 6 to 8 hours after surgery, or subcutaneous enoxaparin, 40 mg once daily, beginning 12 hours before surgery. The primary efficacy outcome was the composite of any deep-vein thrombosis, nonfatal pulmonary embolism, or death from any cause within 13 to 17 days after surgery. Secondary efficacy outcomes included major venous thromboembolism (i.e., proximal deep-vein thrombosis, nonfatal pulmonary embolism, or death related to venous thromboembolism) and symptomatic venous thromboembolism. The primary safety outcome was major bleeding. RESULTS: The primary efficacy outcome occurred in 79 of 824 patients (9.6%) who received rivaroxaban and in 166 of 878 (18.9%) who received enoxaparin (absolute risk reduction, 9.2%; 95% confidence interval [CI], 5.9 to 12.4; P<0.001). Major venous thromboembolism occurred in 9 of 908 patients (1.0%) given rivaroxaban and 24 of 925 (2.6%) given enoxaparin (absolute risk reduction, 1.6%; 95% CI, 0.4 to 2.8; P=0.01). Symptomatic events occurred less frequently with rivaroxaban than with enoxaparin (P=0.005). Major bleeding occurred in 0.6% of patients in the rivaroxaban group and 0.5% of patients in the enoxaparin group. The incidence of drug-related adverse events, mainly gastrointestinal, was 12.0% in the rivaroxaban group and 13.0% in the enoxaparin group. CONCLUSIONS: Rivaroxaban was superior to enoxaparin for thromboprophylaxis after total knee arthroplasty, with similar rates of bleeding. (ClinicalTrials.gov number, NCT00361894.)

Rivaroxaban versus enoxaparin for thromboprophylaxis after total knee arthroplasty (RECORD4): a randomised trial.

BACKGROUND: Prophylaxis for venous thromboembolism is recommended for at least 10 days after total knee arthroplasty; oral regimens could enable shorter hospital stays. We aimed to test the efficacy and safety of oral rivaroxaban for the prevention of venous thromboembolism after total knee arthroplasty. METHODS: In a randomised, double-blind, phase III study, 3148 patients undergoing knee arthroplasty received either oral rivaroxaban 10 mg once daily, beginning 6-8 h after surgery, or subcutaneous enoxaparin 30 mg every 12 h, starting 12-24 h after surgery. Patients had mandatory bilateral venography between days 11 and 15. The primary efficacy outcome was the composite of any deep-vein thrombosis, non-fatal pulmonary embolism, or death from any cause up to day 17 after surgery. Efficacy was assessed as non-inferiority of rivaroxaban compared with enoxaparin in the per-protocol population (absolute non-inferiority limit -4%); if non-inferiority was shown, we assessed whether rivaroxaban had superior efficacy in the modified intention-to-treat population. The primary safety outcome was major bleeding. This trial is registered with ClinicalTrials.gov, number NCT00362232. FINDINGS: The primary efficacy outcome occurred in 67 (6.9%) of 965 patients given rivaroxaban and in 97 (10.1%) of 959 given enoxaparin (absolute risk reduction 3.19%, 95% CI 0.71-5.67; p=0.0118). Ten (0.7%) of 1526 patients given rivaroxaban and four (0.3%) of 1508 given enoxaparin had major bleeding (p=0.1096). INTERPRETATION: Oral rivaroxaban 10 mg once daily for 10-14 days was significantly superior to subcutaneous enoxaparin 30 mg given every 12 h for the prevention of venous thromboembolism after total knee arthroplasty. FUNDING: Bayer Schering Pharma AG, Johnson & Johnson Pharmaceutical Research & Development.

Prevention of venous thromboembolism: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition).

This article discusses the prevention of venous thromboembolism (VTE) and is part of the Antithrombotic and Thrombolytic Therapy: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Grade 1 recommendations are strong and indicate that the benefits do or do not outweigh risks, burden, and costs. Grade 2 suggestions imply that individual patient values may lead to different choices (for a full discussion of the grading, see the "Grades of Recommendation" chapter by Guyatt et al). Among the key recommendations in this chapter are the following: we recommend that every hospital develop a formal strategy that addresses the prevention of VTE (Grade 1A). We recommend against the use of aspirin alone as thromboprophylaxis for any patient group (Grade 1A), and we recommend that mechanical methods of thromboprophylaxis be used primarily for patients at high bleeding risk (Grade 1A) or possibly as an adjunct to anticoagulant thromboprophylaxis (Grade 2A). For patients undergoing major general surgery, we recommend thromboprophylaxis with a low-molecular-weight heparin (LMWH), low-dose unfractionated heparin (LDUH), or fondaparinux (each Grade 1A). We recommend routine thromboprophylaxis for all patients undergoing major gynecologic surgery or major, open urologic procedures (Grade 1A for both groups), with LMWH, LDUH, fondaparinux, or intermittent pneumatic compression (IPC). For patients undergoing elective hip or knee arthroplasty, we recommend one of the following three anticoagulant agents: LMWH, fondaparinux, or a vitamin K antagonist (VKA); international normalized ratio (INR) target, 2.5; range, 2.0 to 3.0 (each Grade 1A). For patients undergoing hip fracture surgery (HFS), we recommend the routine use of fondaparinux (Grade 1A), LMWH (Grade 1B), a VKA (target INR, 2.5; range, 2.0 to 3.0) [Grade 1B], or LDUH (Grade 1B). We recommend that patients undergoing hip or knee arthroplasty or HFS receive thromboprophylaxis for a minimum of 10 days (Grade 1A); for hip arthroplasty and HFS, we recommend continuing thromboprophylaxis > 10 days and up to 35 days (Grade 1A). We recommend that all major trauma and all spinal cord injury (SCI) patients receive thromboprophylaxis (Grade 1A). In patients admitted to hospital with an acute medical illness, we recommend thromboprophylaxis with LMWH, LDUH, or fondaparinux (each Grade 1A). We recommend that, on admission to the ICU, all patients be assessed for their risk of VTE, and that most receive thromboprophylaxis (Grade 1A).

Use of the low-molecular-weight heparin reviparin to prevent deep-vein thrombosis after leg injury requiring immobilization.

BACKGROUND: Deep-vein thrombosis is a well-recognized complication after trauma to the legs and subsequent immobilization, but there are no generally accepted approaches to preventing this complication. METHODS: We performed a prospective, double-blind, placebo-controlled trial to evaluate the efficacy and safety of subcutaneous reviparin (1750 anti-Xa units given once daily) in 440 patients who required immobilization in a plaster cast or brace for at least five weeks after a leg fracture or rupture of the Achilles tendon. The study drug was given throughout the period of immobilization. Venography of the injured leg was performed within one week after removal of the plaster cast or brace, or earlier if there were symptoms suggesting deep-vein thrombosis. RESULTS: Data on efficacy and end points were available for 371 patients. Deep-vein thrombosis was diagnosed in 17 of the 183 patients randomly assigned to receive reviparin (9 percent) and in 35 of the 188 patients randomly assigned to receive placebo (19 percent) (odds ratio, 0.45; 95 percent confidence interval, 0.24 to 0.82). Most of the thromboses were distal (14 in the reviparin group and 25 in the placebo group). There were two cases of pulmonary embolism, both in patients in the placebo group who also had proximal deep-vein thrombosis. There were no differences between the two groups with respect to bleeding or other adverse events. CONCLUSIONS: Deep-vein thrombosis is common in persons with leg injury requiring prolonged immobilization. Reviparin given once daily appears to be effective and safe in reducing the risk of this complication.

Prothrombin fragment 1+2 in urine as an indicator of sustained coagulation activation after total hip arthroplasty.

PURPOSE: Prothrombin fragment 1+2 measured in spot urine (uF1+2) is an indicator of thrombin generation. We examined whether measured levels of uF1+2 can be used to differentiate between patients who do and do not acquire sustained coagulation activation after total hip arthroplasty (THA). METHODS: We performed two separate studies in patients undergoing THA. Study 1 was a prospective pilot study aiming to roughly estimate the extent of pre- and postoperative fluctuations in the uF1+2 concentration. Study 2 was a larger prospective cohort study aiming to verify the findings of Study 1 and to examine the association between the uF1+2 concentrations and risk of vascular thrombotic complications (VTC) or death. Finally, we sought to define a cut-off concentration value that could be used to identify patients with a sustained uF1+2 elevation after the first postoperative week. The urine samples were analysed by ELISA. In both studies thromboprophylaxis was used for at least 7 days after the operation. RESULTS: The operative trauma resulted in elevation of the uF1+2 level in all patients compared with the preoperative level and levels in the healthy volunteers. Ten out of 113 patients (8.8%) in the second study suffered VTC or death, assumed to be caused by a coagulation problem. Analysis of variance revealed the following statistically significant associations: pre- vs. postoperative log uF1+2 levels (P<0.0001), log uF1+2 levels comparing patients with and without events (P=0.004); and the individual log uF1+2 levels (P<0.0001). A cut-off value of uF1+2 concentration between 0.3 and 0.5 nmol/l had a sensitivity and a negative predictive value between100% and 90%, and specificity between 45% and 63% and overall accuracy between 50% and 65%. This value was obtained by the analysis of a receiver operating characteristic curve with the purpose of identifying patients with sustained coagulation activation on day 5 after operation. CONCLUSION: Our studies suggest that measured levels of uF1+2 can be potentially used to assess the individual risk of VTC after THA and to test for non-invasive detection of sustained coagulation activation.

Rivaroxaban for Thromboprophylaxis After Fracture-Related Orthopedic Surgery in Routine Clinical Practice.

BACKGROUND: The risk of venous thromboembolism is high in patients undergoing fracture-related major orthopedic surgery, but data on pharmacological thromboprophylaxis are limited. This analysis evaluated the effectiveness and safety of rivaroxaban after fracture-related orthopedic surgery in routine care compared with other pharmacological thromboprophylaxis (standard of care [SOC]). METHODS: The study population comprised a subset of patients with lower-limb fracture from XArelto in the prophylaxis of post-surgical venous thromboembolism after elective Major Orthopaedic Surgery of hip or knee (XAMOS; a phase IV noninterventional study) and a XAMOS extension study (XAMOS-Extra). The study participants included patients who underwent surgery for hip/femur or lower-leg fractures (below-knee lower-leg fractures, eg, the tibia or foot). All adverse events were recorded, including symptomatic thromboembolic events and bleeding events. RESULTS: Data from 790 patients were available for analysis (n = 350 for rivaroxaban and n = 440 for SOC). The incidence of symptomatic thromboembolic events 3 months postsurgery was 0.57% (2 of the 350) in the rivaroxaban group and 1.14% (5 of the 440) in the SOC group (odds ratio [OR]: 0.50; 95% confidence interval [CI]: 0.10-2.59). Treatment-emergent major bleeding events occurred in 0.29% (1 of the 350) of patients receiving rivaroxaban and 0.45% (2 of the 440) of patients receiving SOC (OR: 0.63; 95% CI: 0.06-6.95). There were no cases of fatal or critical bleeding in either treatment group. The incidences of wound complications and any other adverse events were numerically lower with rivaroxaban compared with SOC. CONCLUSIONS: These data from routine practice demonstrate that rivaroxaban can provide effective thromboprophylaxis after fracture-related orthopedic surgery of the lower limb with a favorable safety profile.

Duration of prophylaxis against venous thromboembolism with fondaparinux after hip fracture surgery: a multicenter, randomized, placebo-controlled, double-blind study.

BACKGROUND: The benefit of thromboprophylaxis for 1 month has never been evaluated in patients undergoing hip fracture surgery, a setting in the highest risk category for postoperative venous thromboembolism (VTE). METHODS: In a double-blind multicenter trial, 656 patients undergoing hip fracture surgery were randomly assigned to receive prophylaxis with a once-daily subcutaneous injection of either 2.5 mg of fondaparinux sodium or placebo for 19 to 23 days. Before randomization, all patients had received fondaparinux for 6 to 8 days. The primary efficacy outcome was VTE occurring during the double-blind period (deep vein thrombosis detected by mandatory bilateral venography or documented symptomatic deep vein thrombosis or pulmonary embolism). The main safety outcome was major bleeding. RESULTS: The primary efficacy outcome was assessed in 428 patients. Fondaparinux reduced the incidence of VTE compared with placebo from 35.0% (77/220) to 1.4% (3/208), with a relative reduction in risk of 95.9% (95% confidence interval, 87.2%-99.7%; P<.001). Similarly, the incidence of symptomatic VTE was significantly lower with fondaparinux (1/326; 0.3%) than with placebo (9/330; 2.7%). The relative reduction in risk was 88.8% (P =.02). Although there was a trend toward more major bleeding in the fondaparinux group than in the placebo group (P =.06), there were no differences between the 2 groups in the incidence of clinically relevant bleeding (leading to death, reoperation, or critical organ bleeding). CONCLUSIONS: Extended prophylaxis with fondaparinux for 3 weeks after hip fracture surgery reduced the risk of VTE by 96% and was well tolerated.

Fondaparinux vs enoxaparin for the prevention of venous thromboembolism in major orthopedic surgery: a meta-analysis of 4 randomized double-blind studies.

BACKGROUND: Orthopedic surgery remains a condition at high risk of venous thromboembolism (VTE). Fondaparinux, the first of a new class of synthetic selective factor Xa inhibitors, may further reduce this risk compared with currently available thromboprophylactic treatments. METHODS: A meta-analysis of 4 multicenter, randomized, double-blind trials in patients undergoing elective hip replacement, elective major knee surgery, and surgery for hip fracture (N = 7344) was performed to determine whether a subcutaneous 2.5-mg, once-daily regimen of fondaparinux sodium starting 6 hours after surgery was more effective and as safe as approved enoxaparin regimens in preventing VTE. The primary efficacy outcome was VTE up to day 11, defined as deep vein thrombosis detected by mandatory bilateral venography or documented symptomatic deep vein thrombosis or pulmonary embolism. The primary safety outcome was major bleeding. RESULTS: Fondaparinux significantly reduced the incidence of VTE by day 11 (182 [6.8%] of 2682 patients) compared with enoxaparin (371 [13.7%] of 2703 patients), with a common odds reduction of 55.2% (95% confidence interval, 45.8% to 63.1%; P<.001); this beneficial effect was consistent across all types of surgery and all subgroups. Although major bleeding occurred more frequently in the fondaparinux-treated group (P =.008), the incidence of clinically relevant bleeding (leading to death or reoperation or occurring in a critical organ) did not differ between groups. CONCLUSION: In patients undergoing orthopedic surgery, 2.5 mg of fondaparinux sodium once daily, starting 6 hours postoperatively, showed a major benefit over enoxaparin, achieving an overall risk reduction of VTE greater than 50% without increasing the risk of clinically relevant bleeding.

New pentasaccharides for the prophylaxis of venous thromboembolism: clinical studies.

Fondaparinux, a selective inhibitor of factor Xa, is the first of a new class of antithrombotic compounds, the synthetic pentasaccharides. Its benefit-to-risk ratio in preventing venous thromboembolism after major orthopedic surgery was investigated in four randomized, double-blind international phase III trials in patients undergoing surgery for hip fracture, elective hip replacement, and major knee surgery. Compared to enoxaparin, fondaparinux administered at a subcutaneous dose of 2.5 mg qd, starting postoperatively, reduced the overall incidence of venous thromboembolism up to day 11 by 55.2% (p < 0.001). The incidence of clinically relevant bleeding was low and did not differ between the two groups. Overall, fondaparinux achieved optimal efficacy and safety when treatment was initiated > or =6 h after the surgical procedure. In a further randomized double-blind trial, 4 weeks of prophylaxis with fondaparinux after hip fracture surgery reduced the risk of venous thromboembolism by 96% as compared to 1 week of prophylaxis, and was well tolerated. Fondaparinux has been recently approved for use in thromboprophylaxis after major orthopedic surgery. The clinical development of fondaparinux in other thromboprophylactic indications is ongoing.

Superiority of fondaparinux over enoxaparin in preventing venous thromboembolism in major orthopedic surgery using different efficacy end points.

STUDY OBJECTIVES: To assess the relevance of various efficacy end points established for thromboprophylaxis trials, we compared the results of the fondaparinux phase III program in major orthopedic surgery using the original primary efficacy end point with those obtained when the efficacy end points recently suggested by the American College of Chest Physicians (ACCP) Consensus Conference on Antithrombotic Therapy and the European Committee for Proprietary Medicinal Products (CPMP) were used. SETTING AND PATIENTS: Fondaparinux was compared with enoxaparin in four multicenter, randomized, double-blind trials of major orthopedic surgery. The original primary efficacy end point consisted of a composite of deep-vein thrombosis detected by mandatory bilateral venography, documented symptomatic deep-vein thrombosis, or pulmonary embolism up to day 11. The efficacy end point established by the ACCP Consensus Conference on Antithrombotic Therapy comprises any proximal deep-vein thrombosis, symptomatic proven deep-vein thrombosis or pulmonary embolism, or fatal pulmonary embolism, and that established by the European CPMP comprises any proximal deep-vein thrombosis, symptomatic proven pulmonary embolism, or death from any cause. INTERVENTIONS: Patients were randomized to receive either subcutaneous fondaparinux (2.5 mg once daily) starting postoperatively or approved enoxaparin regimens. RESULTS: Using the original end point of the fondaparinux studies, the incidence of venous thromboembolism was 13.7% (371 of 2,703 patients) in the enoxaparin group compared with 6.8% (182 of 2,682 patients) in the fondaparinux group, with a common odds reduction of 55.2% (p = 10(-17); 95% confidence interval, 45.8% to 63.1%) in favor of fondaparinux. The respective incidences of efficacy end points with enoxaparin and fondaparinux were 3.3% and 1.7%, respectively, according to the ACCP definition, and 3.9% and 2.1%, respectively, according to the CPMP definition. The common odds reduction in favor of fondaparinux was 49.6% (p < 0.001) and 48.0% (p < 0.001), respectively. CONCLUSIONS: Fondaparinux was consistently more effective than enoxaparin in preventing venous thromboembolism in patients undergoing major orthopedic surgery, irrespective of the established composite outcomes used.

Prevention of venous thromboembolism: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy.

This article discusses the prevention of venous thromboembolism (VTE) and is part of the Seventh American College of Chest Physicians Conference on Antithrombotic and Thrombolytic Therapy: Evidence-Based Guidelines. Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh risks, burden, and costs. Grade 2 suggests that individual patients' values may lead to different choices (for a full understanding of the grading see Guyatt et al, CHEST 2004; 126:179S-187S). Among the key recommendations in this chapter are the following. We recommend against the use of aspirin alone as thromboprophylaxis for any patient group (Grade 1A). For moderate-risk general surgery patients, we recommend prophylaxis with low-dose unfractionated heparin (LDUH) (5,000 U bid) or low-molecular-weight heparin (LMWH) [< or = 3,400 U once daily] (both Grade 1A). For higher risk general surgery patients, we recommend thromboprophylaxis with LDUH (5,000 U tid) or LMWH (> 3,400 U daily) [both Grade 1A]. For high-risk general surgery patients with multiple risk factors, we recommend combining pharmacologic methods (LDUH three times daily or LMWH, > 3,400 U daily) with the use of graduated compression stockings and/or intermittent pneumatic compression devices (Grade 1C+). We recommend that thromboprophylaxis be used in all patients undergoing major gynecologic surgery (Grade 1A) or major, open urologic procedures, and we recommend prophylaxis with LDUH two times or three times daily (Grade 1A). For patients undergoing elective total hip or knee arthroplasty, we recommend one of the following three anticoagulant agents: LMWH, fondaparinux, or adjusted-dose vitamin K antagonist (VKA) [international normalized ratio (INR) target, 2.5; range, 2.0 to 3.0] (all Grade 1A). For patients undergoing hip fracture surgery (HFS), we recommend the routine use of fondaparinux (Grade 1A), LMWH (Grade 1C+), VKA (target INR, 2.5; range, 2.0 to 3.0) [Grade 2B], or LDUH (Grade 1B). We recommend that patients undergoing hip or knee arthroplasty, or HFS receive thromboprophylaxis for at least 10 days (Grade 1A). We recommend that all trauma patients with at least one risk factor for VTE receive thromboprophylaxis (Grade 1A). In acutely ill medical patients who have been admitted to the hospital with congestive heart failure or severe respiratory disease, or who are confined to bed and have one or more additional risk factors, we recommend prophylaxis with LDUH (Grade 1A) or LMWH (Grade 1A). We recommend, on admission to the intensive care unit, all patients be assessed for their risk of VTE. Accordingly, most patients should receive thromboprophylaxis (Grade 1A).

Prothrombin fragment 1+2 in urine as a marker on coagulation activity in patients with suspected pulmonary embolism.

INTRODUCTION: We have recently reported that increased levels of urine prothrombin fragment 1+2 reflected radiologically verified deep vein thrombosis. In this study we evaluated whether urine prothrombin fragment 1+2 was associated with pulmonary embolism in non-selected patients. MATERIALS AND METHODS: Patients with clinical suspected pulmonary embolism were interviewed on comorbidities and medications. Urine was collected from each patient before radiological examination and snap frozen until analysed on urine prothrombin fragment 1+2 with an ELISA kit. Imaging of the pulmonary arteries were conducted with contrast enhanced computer tomography. RESULTS: Pulmonary embolism was diagnosed in 44/197 patients. Non-significantly higher urine prothrombin fragment 1+2 levels were found in non-selected patients with pulmonary embolism vs. those without (p=0.324). Significantly higher urine prothrombin fragment 1+2 levels were found in the pulmonary embolism positive patients without comorbidities (n=13) compared to the control group (n=28) (p=0.009). The calculated sensitivity, specificity and negative predictive value using the lowest detectable urine prothrombin fragment 1+2 level was 82%, 34% and 87%, respectively. CONCLUSIONS: There was no significant urine prothrombin fragment 1+2 level difference in patients with and without pulmonary embolism. In non-comorbide pulmonary embolism positive patients the urine prothrombin fragment 1+2 levels were significantly higher compared to the control group. The negative predictive value found in this study indicates that uF1+2 has the potential to identify patients with a low risk of PE.

Darexaban (YM150) versus enoxaparin for the prevention of venous thromboembolism after total hip arthroplasty: a randomised phase IIb dose confirmation study (ONYX-3).

This double-blind, double-dummy, randomised, phase IIb study (NCT00902928) evaluated different dosing regimens of darexaban compared with enoxaparin (randomised 1:1:1:1:1 to 15 mg twice daily [bid], 30 mg once daily [qd], 30 mg bid or 60 mg qd or enoxaparin 40 mg qd) in patients undergoing elective total hip arthroplasty. Patients, investigators, pharmacists and sponsor were all blinded to treatment allocation. Darexaban administration started 6-10 hours (h) post-surgery. Enoxaparin 40 mg qd administration started 12 ± 2 h before surgery. Treatment continued for 35 days. Bilateral venography was performed on Day 10 ± 2. The primary efficacy outcome was total VTEs (composite of proximal/distal deep-vein thrombosis, pulmonary embolism) or death, at Day 12. Total VTE rates were similar across all groups. There was no apparent difference in efficacy between once- and twice-daily darexaban (odds ratio [OR] 1.00; 95% confidence interval [CI] 0.71-1.42; p=0.988), or total daily dose (30 mg/day vs 60 mg/day; OR 0.81; 95% CI 0.57-1.15; p=0.244). There was no significant difference in major and/or clinically relevant non-major bleeding between darexaban qd or bid, or between total daily doses of 30 mg or 60 mg, and also for any dosing regimen of darexaban vs enoxaparin. Darexaban was well tolerated, without signs of liver toxicity. In conclusion, darexaban, administered qd or bid, and at total daily doses of 30 mg or 60 mg, appears to be effective for VTE prevention and was well tolerated. Data suggest no significant differences between a once- or twice-daily dosing regimen.

Sustained release of tissue factor following thrombosis of lower limb trauma.

This study was undertaken to provide evidence for the mechanism of venous thromboembolism (VTE) in healthy patients with minor lower limb injury (fracture; Achilles tendon rupture) that was medically managed with plaster cast/brace immobilization. The Plaster Cast clinical trial provided a unique opportunity to identify the natural history of VTE using placebo-controlled patients (n = 183) with validation of the mechanism using the low-molecular-weight heparin (LMWH; reviparin)-treated patients (n = 182). Confirmed VTE in this population was associated with a burst of tissue factor release (and a minor fibrinolytic deficit) leading to thrombin generation that was sustained at least 5 weeks, greater with fractures than with soft-tissue injuries and greater with surgery than with conservative treatment. The root cause likely involves platelet/leukocyte activation (inflammation) rather than endothelial cell injury. Thromboprophylaxis with a low dose of LMWH reduced thrombin generation, with patients undergoing surgery benefitting the most.

A non-interventional comparison of rivaroxaban with standard of care for thromboprophylaxis after major orthopaedic surgery in 17,701 patients with propensity score adjustment.

Rivaroxaban demonstrated superior efficacy and a similar safety profile to enoxaparin for the prevention of venous thromboembolism in the phase III RECORD programme in patients undergoing elective hip or knee replacement surgery. The XAMOS study investigated adverse events, including bleeding and thromboembolic events, in patients receiving rivaroxaban for thromboprophylaxis in routine clinical practice. XAMOS was a non-interventional, open-label cohort study in patients undergoing major orthopaedic surgery of the hip or knee (predominantly elective arthroplasty), in which rivaroxaban was compared with other pharmacological thromboprophylaxis. All adverse events were documented, including symptomatic thromboembolic and bleeding events. Crude and adjusted incidences based on propensity score subclasses were calculated and compared between the rivaroxaban and standard-of-care groups. A total of 17,701 patients were enrolled from 252 centres in 37 countries. Crude incidences of symptomatic thromboembolic events three months after surgery in the safety population were 0.89% in the rivaroxaban group (n=8,778) and 1.35% in the standard-of-care group (n=8,635; odds ratio [OR] 0.65; 95% confidence interval [CI] 0.49-0.87), and 0.91% and 1.31% (weighted) in the propensity score-adjusted analysis (OR 0.69; 95% CI 0.56-0.85), respectively. Treatment-emergent major bleeding events (as defined in the RECORD studies) occurred in 0.40% and 0.34% of patients in the rivaroxaban and standard-of-care groups in the safety population (OR 1.19; 95% CI 0.73-1.95), and in 0.44% versus 0.33% (weighted) in the propensity score-adjusted analysis (OR 1.35; 95% CI 0.94-1.93), respectively.This study in unselected patients confirmed the favourable benefit-risk profile of rivaroxaban seen in the RECORD programme.