Dabigatran versus enoxaparin for prevention of venous thromboembolism after hip or knee arthroplasty: A pooled analysis of three trials

Background

Three randomized, double-blind trials compared dabigatran, an oral direct thrombin inhibitor, with enoxaparin for the primary prevention of venous thromboembolism (VTE) in patients undergoing elective total hip and knee arthroplasty.

Objectives and Methods

We conducted a pre-specified pooled analysis of these trials. 8,210 patients were randomized, of whom 8,135 were treated (evaluable for safety) with dabigatran 220 mg or 150 mg once-daily, or subcutaneous enoxaparin (40 mg once-daily or 30 mg twice-daily). Efficacy analyses were based on the modified intention-to-treat population of 6,200 patients with an evaluable outcome. The common risk difference (RD) of treatment effect between each dabigatran dose and enoxaparin was estimated using fixed-effects models, and statistical heterogeneity was estimated using the I² statistic.

Results

The composite outcome of major VTE (proximal deep vein thrombosis and/or pulmonary embolism) and VTE-related mortality occurred in 3.3% of the enoxaparin group versus 3.0% of the dabigatran 220 mg group (RD vs. enoxaparin -0.2%, 95% CI -1.3% to 0.9%, I² = 37%) and 3.8% of the 150 mg group (RD vs. enoxaparin 0.5%, -0.6% to 1.6%, I² = 0%). Major bleeding occurred in 1.4% of the enoxaparin group versus 1.4% of the dabigatran 220 mg group (RD vs. enoxaparin -0.2%, -0.8% to 0.5%, I² = 40%) and 1.1% of the 150 mg group (RD vs. enoxaparin -0.4%, -1.0% to 0.2%, I² = 0%).

Conclusions

Oral dabigatran was as effective as subcutaneous enoxaparin in reducing the risk of major VTE and VTE-related mortality after hip or knee arthroplasty and has a similar bleeding profile.     

Apixaban versus enoxaparin in patients with total knee arthroplasty. A meta-analysis of randomised trials

It was the objective of this study to systematically compare the effects of apixaban versus enoxaparin in patients following total knee arthroplasty (TKA). A systematic search of Medline, EMBASE, Cochrane Central Register of Controlled Trials was conducted. Eligible studies were prospective, randomised control trials (RCT) of apixaban therapy, comparing with enoxaparin, in patients who have a high risk of venous thromboembolism (VTE) after TKA. Three RCTs involving 7,337 individuals were identified, of whom 4,057 were treated with apixaban 2.5 mg once daily, and 3280 were subcutaneous enoxaparin (40 mg once-daily or 30 mg twice-daily). Meta-analysis demonstrated the odds ratio (OR) for the composite of major VTE (proximal deep-vein thrombosis and pulmonary embolism) for apixaban versus enoxaparin was 0.47 (95% confidence interval [CI]: 0.27 to 0.82, 0.6% vs. 1.2%) and 2.09 (95%CI: 0.99 to 4.45, 0.6% vs. 0.3%), respectively. All-cause mortality occurred in 0.2% of the apixaban group versus 0.09% of the enoxaparin group (OR=1.74; 95%CI, 0.51 to 5.95). With respect to safety outcomes, apixaban was associated with a lower major bleeding rate than enoxaparin (OR=0.55, 95%CI: 0.32 to 0.96). No significant differences were detected between two strategies in other endpoints of safety profile analysed: clinically relevant non-major bleeding, raised hepatic transaminase enzyme or bilirubin concentrations and arterial thromboembolic events. In conclusion, apixaban is non-inferior to subcutaneous enoxaparin when used for the same duration, with considerable advantage regarding safety profile of major bleeding after TKA.     

Rivaroxaban for the prevention of venous thromboembolism after hip or knee arthroplasty. Pooled analysis of four studies

Four phase III studies compared oral rivaroxaban with subcutaneous enoxaparin for the prevention of venous thromboembolism (VTE) after total hip or knee arthroplasty (THA or TKA). A pooled analysis of these studies compared the effect of rivaroxaban with enoxaparin on symptomatic VTE plus all-cause mortality and bleeding events, and determined whether these effects were consistent in patient subgroups. Patients (N=12,729) aged ≥18 years and scheduled for elective THA or TKA received rivaroxaban 10 mg once daily or enoxaparin 40 mg once daily or 30 mg every 12 hours. The composite of symptomatic VTE and all-cause mortality, the prespecified primary efficacy endpoint and adjudicated bleeding events were analysed in the day 12± 2 active treatment pool. Subgroup analyses of these outcomes were performed over the total treatment period. In the day 12± 2 pool, the primary efficacy endpoint occurred in 29/6,183 patients receiving rivaroxaban (0.5%) versus 60/6,200 patients receiving enoxaparin (1.0%; p=0.001). Major bleeding occurred in 21 (0.3%) versus 13(0.2%) patients, p=0.23; major plus non-major clinically relevant bleeding in 176(2.8%) versus 152 (2.5%) patients, p=0.19; and any bleeding in 409 (6.6%) versus 384 (6.2%) patients, p=0.38, respectively. The reduction of symptomatic VTE plus all-cause mortality was consistent across prespecified subgroups (age, gender, body weight, creatinine clearance) in the total treatment period. Compared with enoxaparin regimens, rivaroxaban reduces the composite of symptomatic VTE and all-cause mortality after elective THA or TKA, with a small increase in bleeding, no signs of compromised liver safety and fewer serious adverse events.     

Direct thrombin inhibitor melagatran followed by oral ximelagatran in comparison with enoxaparin for prevention of venous thromboembolism after total hip or knee replacement

We evaluated whether a postoperative regimen with melagatran followed by oral ximelagatran, two new direct thrombin inhibitors, was an optimal regimen for thromboprophylaxis in major orthopaedic surgery. In a double-blind study, 2788 patients undergoing total hip or knee replacement were randomly assigned to receive for 8 to 11 days either 3 mg of subcutaneous melagatran started 4-12 h postoperatively, followed by 24 mg of oral ximelagatran twice-daily or 40 mg of subcutaneous enoxaparin once-daily, started 12 h preoperatively. Ximelagatran was to be initiated within the first two postoperative days. The primary efficacy endpoint was venous thromboembolism (deep-vein thrombosis detected by mandatory venography, pulmonary embolism or unexplained death). The main safety endpoint was bleeding. Venous thromboembolism occurred in 355/1146 (31.0%) and 306/1122 (27.3%) patients in the ximelagatran and enoxaparin group, respectively, a difference in risk of 3.7% in favour of enoxaparin (p = 0.053). Bleeding was comparable between the two groups.     

Dose-escalation study of rivaroxaban (BAY 59-7939)--an oral, direct Factor Xa inhibitor--for the prevention of venous thromboembolism in patients undergoing total hip replacement

INTRODUCTION: Rivaroxaban (BAY 59-7939) is a novel, oral, direct Factor Xa inhibitor in clinical development for the prevention of thromboembolic disorders. The aim of this study was to demonstrate proof-of-principle for rivaroxaban. MATERIALS AND METHODS: This was an open-label, dose-escalation study to assess the efficacy and safety of rivaroxaban, relative to enoxaparin, for the prevention of venous thromboembolism (VTE) after total hip replacement surgery. Patients were randomized in a 3:1 ratio to rivaroxaban (2.5, 5, 10, 20 and 30 mg twice daily [bid] or 30 mg once daily [od] starting 6-8 h after surgery) or enoxaparin (40 mg od starting the evening before surgery). Therapy continued until mandatory bilateral venography was performed 5-9 days after surgery. RESULTS: A total of 625 patients received therapy, of whom 466 patients were eligible for the per-protocol efficacy analysis. The primary efficacy endpoint - deep vein thrombosis (DVT), pulmonary embolism (PE) or all-cause mortality - occurred in 22.2%, 23.8%, 20.0%, 10.2%, 17.4%, 15.1% and 16.8% of patients receiving rivaroxaban 2.5, 5, 10, 20, 30 mg bid, 30 mg od and enoxaparin, respectively. The dose-response relationship with rivaroxaban for the primary efficacy endpoint was not statistically significant (p=0.0504), although major VTE (proximal DVT, PE and VTE-related death) decreased dose dependently with rivaroxaban (p=0.0108). Major, post-operative bleeding increased dose dependently with rivaroxaban (p=0.0008), occurring in 0-10.8% of patients, compared with 0% in patients receiving enoxaparin. CONCLUSIONS: This study demonstrated proof-of-principle for rivaroxaban for the prevention of VTE after total hip replacement surgery.     

A dose-finding study with TAK-442, an oral factor Xa inhibitor, in patients undergoing elective total knee replacement surgery

This multicentre dose-finding study compared TAK-442, an oral factor Xa inhibitor, with enoxaparin for thromboprophylaxis after knee arthroplasty. In this parallel group study, patients were randomised to oral TAK-442 (40 or 80 mg once-daily [QD] or 10, 20, 40, or 80 mg twice-daily [BID] started 6-8 hours postoperatively), which was blinded as to dose, or to open-label subcutaneous enoxaparin (30 mg BID starting 12-24 hours postoperatively) for 10 days. Treatments were continued until bilateral venography was performed (maximum of 14 days). The primary efficacy endpoint was the composite of any deep-vein thrombosis, non-fatal pulmonary embolism or all-cause mortality, while the primary safety endpoint was major bleeding. Of 1,038 patients randomised who received at least one dose of study drug, 949 completed the study and 730 (76.9%) were evaluable for the primary efficacy analysis. Recruitment into the 10 and 20 mg BID dose groups was stopped early because the incidences of the primary efficacy endpoint were significantly higher than that with enoxaparin. The primary efficacy endpoint occurred in 22.0% of patients given enoxaparin and in 39.0%, 38.4%, 23.5%, 21.4%, 26.8%, and 14.3% of those receiving TAK-442 10 mg BID, 20 mg BID, 40 mg QD, 40 mg BID, 80 mg QD, and 80 mg BID, respectively. The incidences of major and clinically relevant non-major bleeding with TAK-442 were not dose-dependent or different from that with enoxaparin. All TAK-442 doses except 10 and 20 mg BID displayed similar efficacy and safety profiles to enoxaparin.     

Dabigatran, rivaroxaban and apixaban versus enoxaparin for thomboprophylaxis after total knee or hip arthroplasty: pool-analysis of phase III randomized clinical trials

Objectives

To compare the main efficacy and safety endpoints of the pivotal randomised clinical trials (RCTs) on venous thromboembolism (VTE) prevention after total hip (THR) or knee (TKR) replacement with the new oral anticoagulants (NAs) versus enoxaparin.

Methods

A pool-analysis of 10 RCTs that included 32.144 randomised patients was performed. Efficacy outcomes were total VTE and all-cause mortality, major VTE, and proximal DVT. Safety outcomes were major bleeding, and clinically relevant (major or non-major) bleeding.

Results

Overall, a significant effect favouring NAs was found for the primary efficacy outcome (RR 0.71; 95%CI 0.56-0.90), major VTE (RR 0.59; 95%CI 0.41-0.84), and proximal DVT (RR 0.51; 95%CI 0.35-0.76). Compared to enoxaparin 40 mg QD, rivaroxaban showed superiority (RR 0.50; 95%CI 0.34-0.73), followed by apixaban (RR 0.63; 95%CI 0.36-1.01) and dabigatran (RR 1.02; 95%CI 0.86-1.20). There was significant heterogeneity among trials and subgroups analysed for these efficacy outcomes. Major bleeding (RR 1.04; 95% CI 0.74-1.46) and clinically relevant bleeding (RR 1.03; 95%CI 0.88-1.21) was similar with NAs or enoxaparin. Rivaroxaban showed a trend toward more major bleeding episodes than enoxaparin (RR 1.88; 95%CI 0.92-3.82) and apixaban showed the lowest clinically relevant bleeding risk (RR 0.81; 95%CI 0.64-1.01).

Conclusions

Overall, NAs showed more efficacy and same safety when compared to the recommended dose of enoxaparin after THR and TKR. There are little differences in efficacy and bleeding risk among NAs and the type of prophylaxis that should be analysed further.     

Safety and Efficacy of Edoxaban,an Oral Factor Xa Inhibitor,Versus Enoxaparin for Thromboprophylaxis After Total Knee Arthroplasty: The STARS E-3 Trial

Introduction

This phase 3 trial compared the safety and efficacy of edoxaban, an oral direct factor Xa inhibitor, with enoxaparin sodium (enoxaparin) for thromboprophylaxis after total knee arthroplasty (TKA) in patients in Japan and Taiwan.

Materials and methods

In this randomized, double-blind, double-dummy study, patients received oral edoxaban 30 mg once daily beginning 6 to 24 hours postsurgery or enoxaparin 2000 IU (equivalent to 20 mg) subcutaneously twice daily beginning 24 to 36 hours postsurgery for 11 to 14 days. The primary efficacy endpoint was the composite of symptomatic pulmonary embolism and symptomatic and asymptomatic deep vein thrombosis. Safety endpoints included the incidence of major bleeding, clinically relevant non-major (CRNM) bleeding, major bleeding or CRNM bleeding, all bleeding events, adverse events, and adverse drug reactions.

Results

Of 716 patients enrolled, 360 and 356 were randomized to receive edoxaban or enoxaparin, respectively. The primary efficacy outcome occurred in 22/299 (7.4%) and 41/295 (13.9%) patients in the edoxaban and enoxaparin groups, respectively (relative risk reduction = 46.8%), indicating non-inferiority (P < 0.001) and superiority (P = 0.010) of edoxaban versus enoxaparin. In the edoxaban and enoxaparin groups, major bleeding occurred in 4/354 (1.1%) versus 1/349 (0.3%) patients (P = 0.373); major or CRNM bleeding occurred in 22/354 (6.2%) versus 13/349 (3.7%) patients (P = 0.129), respectively.

Conclusions

Edoxaban 30 mg once daily was more effective for thromboprophylaxis than subcutaneous enoxaparin 2000 IU twice daily following TKA and demonstrated a similar incidence of bleeding events.     

Rivaroxaban for thromboprophylaxis after orthopaedic surgery: pooled analysis of two studies

Rivaroxaban (BAY 59-7939) is an oral, direct factor Xa inhibitor in clinical development for the prevention and treatment of venous thromboembolism (VTE). This analysis of pooled results from two phase II studies of rivaroxaban for VTE prevention after major orthopaedic surgery aimed to strengthen the conclusions of the individual studies. One study was conducted in patients undergoing total hip replacement (THR; N = 722), and one in patients undergoing total knee replacement (TKR; N = 621). In both studies, patients were randomized, doubleblind, to oral, twice-daily (bid) rivaroxaban beginning after surgery, or subcutaneous enoxaparin (40 mg once daily beginning before THR, and 30 mg bid beginning after TKR). Treatment continued until mandatory bilateral venography was performed 5-9 days after surgery. Total VTE (deep vein thrombosis, pulmonary embolism, and all-cause mortality) occurred in 16.1-24.4% of per-protocol patients receiving rivaroxaban 5-60 mg, and 27.8% receiving enoxaparin (n = 914). There was a flat dose response relationship between rivaroxaban and total VTE (p = 0.39). Major bleeding (safety population, n = 1,317) increased dose-dependently with rivaroxaban (p < 0.001), occurring in 0.9%, 1.3%, 2.1%, 3.9%, and 7.0% of patients receiving rivaroxaban total daily doses of 5, 10, 20, 40, and 60 mg, respectively, versus 1.7% of patients receiving enoxaparin. No routine coagulation monitoring was performed, and there were no significant differences between dose response relationships with rivaroxaban after THR and TKR. Overall, rivaroxaban total daily doses of 5-20 mg had the most favorable balance of efficacy and safety, relative to enoxaparin, for the prevention of VTE after major orthopaedic surgery.     

Dabigatran etexilate and concomitant use of non-steroidal anti-inflammatory drugs or acetylsalicylic acid in patients undergoing total hip and total knee arthroplasty: no increased risk of bleeding

Patients undergoing total hip or knee arthroplasty should receive anticoagulant therapy because of the high risk of venous thromboembolism. However, many are already taking non-steroidal anti-inflammatory drugs (NSAIDs) or acetylsalicylic acid (ASA) that can have antihaemostatic effects. We assessed the bleeding risk in patients treated with thromboprophylactic dabigatran etexilate, with and without concomitant NSAID or ASA. A post-hoc analysis was undertaken of the pooled data from trials comparing dabigatran etexilate (220 mg and 150 mg once daily) and enoxaparin. Major bleeding event (MBE) rates were determined and odds ratios (ORs) generated for patients who received study treatment plus NSAID (half-life ≤12 hours) or ASA (≤160 mg/day) versus study treatment alone. Relative risks were calculated for comparisons between treatments. Overall, 4,405/8,135 patients (54.1%) received concomitant NSAID and 386/8,135 (4.7%) received ASA.ORs for the comparison with/without concomitant NSAID were 1.05 (95% confidence interval [CI] 0.55-2.01) for 220 mg dabigatran etexilate; 1.19 (0.55-2.55) for 150 mg; and 1.32 (0.67-2.57) for enoxaparin. ORs for the comparison with/without ASA were 1.14 (0.26-5.03); 1.64 (0.36-7.49); and 2.57 (0.83-7.94), respectively. For both NSAIDs and ASA there was no significant difference in bleeding between patients with and without concomitant therapy in any treatment arm. Patients concomitantly taking NSAIDs or ASA have a similar risk of MBE to those taking dabigatran etexilate alone. No significant differences in MBE were detected between dabigatran etexilate and enoxaparin within co-medication subgroups, suggesting that no increased major bleeding risk exists when dabigatran etexilate is administered with NSAID or ASA.     

Safety and efficacy of edoxaban in patients undergoing hip fracture surgery

Introduction

Edoxaban is an oral, direct, once-daily factor Xa inhibitor. This study evaluated the safety and efficacy of edoxaban compared to subcutaneous enoxaparin in Japanese patients undergoing hip fracture surgery.

Materials and methods

In this multicenter, randomized, open-label, active-comparator, phase 3 trial, 92 patients were randomized 2:1 to receive edoxaban 30 mg once daily (n = 62) or enoxaparin sodium (enoxaparin) 2000 IU (equivalent to 20 mg) twice daily (n = 30) for 11 to 14 days. The primary endpoints were the incidence of major or clinically relevant non-major (CRNM) bleeding and incidence of any bleeding events (major, CRNM, or minor bleeding). Secondary efficacy endpoints included the incidence of thromboembolic events, venous thromboembolism-related deaths, and all-cause deaths. Additional adverse events were recorded throughout the study.

Results

In the edoxaban and enoxaparin treatment groups, the incidence of major or CRNM bleeding was 3.4% and 6.9%, respectively, while any bleeding event occurred in 25.4% and 17.2% of patients, respectively. The incidence of thromboembolic events was 6.5% in the edoxaban group and 3.7% in the enoxaparin group. All events were asymptomatic deep vein thrombosis. The incidence of adverse events was 72.9% and 82.8% in the edoxaban and enoxaparin groups, respectively.

Conclusions

Compared to subcutaneous enoxaparin 2000 IU twice daily, oral edoxaban 30 mg once daily demonstrated similar safety and efficacy in the prevention of thromboembolic events in Japanese patients undergoing hip fracture surgery.Clinical trials registration number: NCT01181141.     

An open-label, comparative study of the efficacy and safety of once-daily dose of enoxaparin versus unfractionated heparin in the treatment of proximal lower limb deep-vein thrombosis

BACKGROUND: Treatment of deep-vein thrombosis (DVT) with a once-daily regimen of enoxaparin, rather than a continuous infusion of unfractionated heparin (UFH) is more convenient and allows for home care in some patients. This study was designed to compare the efficacy and safety of these two regimens for the treatment of patients with proximal lower limb DVT. METHODS: 201 patients with proximal lower limb DVT from 13 centers in Brazil were randomized in an open manner to receive either enoxaparin [1.5 mg/kg subcutaneous (s.c.) OD] or intravenous (i.v.) UFH (adjusted to aPTT 1.5-2.5 times control) for 5-10 days. All patients also received warfarin (INR 2-3) for at least 3 months. The primary efficacy endpoint was recurrent DVT (confirmed by venography or ultrasonography), and safety endpoints included bleeding and serious adverse events. The rate of pulmonary embolism (PE) was also collected. Hospitalization was at the physician's discretion. RESULTS: Baseline patient characteristics were comparable between groups. The duration of hospital stay was significantly shorter with enoxaparin than with UFH (3 versus 7 days). In addition, 36% of patients receiving enoxaparin did not need to be hospitalized, whereas all of the patients receiving UFH were hospitalized. The treatment duration was slightly longer with enoxaparin (8 versus 7 days). There was a nonsignificant trend toward a reduction in the rate of recurrent DVT with enoxaparin versus UFH, and similar safety. CONCLUSIONS: A once-daily regimen of enoxaparin 1.5 mg/kg subcutaneous is at least as effective and safe as conventional treatment with a continuous intravenous infusion of UFH. However, the once daily enoxaparin regimen is easier to administer (subcutaneous versus intravenous), does not require aPTT monitoring, and leads to both a reduced number of hospital admissions and an average 4-day-shorter hospital stay.     

Reduction of ischemic sequelae following spontaneous subarachnoid hemorrhage: a double-blind, randomized comparison of enoxaparin versus placebo

BACKGROUND: Cerebral vasospasm, including its ischemic sequelae, remains a leading cause of death and disability following subarachnoid hemorrhage (SAH). This study was designed to evaluate whether the low-molecular-weight heparin (LMWH) enoxaparin reduces the occurrence of cerebral vasospasm and ischemia following spontaneous SAH. METHODS: A prospective, double-blind, randomized study was conducted in 120 consecutive patients with SAH (Hunt Hess Scale (HHS) I-III). Patients received one subcutaneous injection per day of either 20mg enoxaparin or placebo for 3 weeks following SAH. Efficacy endpoints were the occurrence of cerebral vasospasm, delayed ischemic deficit (DID), cerebral infarction, and overall outcome at 1 year following SAH. RESULTS: At 1-year follow-up, enoxaparin significantly reduced DID and cerebral infarction. Delayed ischemic deficit occurred in 8.8% of the enoxaparin group versus 66.7% of the placebo group (P<0.001), while 3.5% of vasospasm-related cerebral infarctions occurred in enoxaparin-treated patients and 28.3% in placebo-treated patients (P<0.001). Severe shunt-dependent hydrocephalus was significantly lower in the enoxaparin group (1.8% versus 16.7%; P=0.019). Compared with the placebo group, the enoxaparin group had fewer intracranial bleeding events and better overall outcomes at 1-year follow-up. Although there was potential bias as a result of patients in the placebo group being more severely affected (in terms of HHS), treatment with enoxaparin for 3 weeks improved long-term outcome following SAH. CONCLUSIONS: Enoxaparin is safe and effective in reducing cerebral vasospasm and ischemia following SAH (Hunt Hess grades I-III), resulting in a better long-term outcome for the patient.     

Efficacy and safety of enoxaparin in Japanese patients undergoing curative abdominal or pelvic cancer surgery: Results from a multicenter, randomized, open-label study

Background

Enoxaparin sodium (enoxaparin) is used worldwide for the prevention of venous thromboembolism (VTE). Registration trials of enoxaparin have been conducted primarily in Caucasian populations, and its preventive use in Japanese patients has yet to be established. To address this, we evaluated the efficacy and safety of postoperative enoxaparin in Japanese patients undergoing surgery for abdominal cancer.

Methods

This multicenter, open-label study randomized 151 Japanese patients undergoing curative surgery for abdominal cancer to enoxaparin 20 mg twice daily for 14 days, started 24-36 hours after surgery (n = 113) or intermittent pneumatic compression (IPC) as a reference (n = 38). IPC was performed at least once in both groups between randomization and surgery. The primary efficacy endpoint was the incidence of VTE in the modified intention-to-treat (mITT) population. The primary safety outcome was the incidence of any bleeding during treatment and follow-up.

Results

Incidence of VTE was 1.2% (95% CI, 0.03-6.53%) (1/83 patients) in the enoxaparin group and 19.4% (95% CI, 7.45-37.47%) (6/31 patients) in the IPC group. In the safety population, 10/109 patients in the enoxaparin group (9.2%; 95% CI, 4.49-16.23%) and 3/38 patients in the IPC group (7.9%; 95% CI, 1.66-21.38%) experienced a bleeding event. There were no cases of fatal bleeding or bleeding into any critical organ.

Conclusions

These favorable efficacy and safety data support the use of enoxaparin (20 mg twice daily for 14 days started 24-36 hours after surgery) in Japanese patients undergoing abdominal or pelvic cancer surgery.     

A comparative double-blind, randomised trial of a new second generation LMWH (bemiparin) and UFH in the prevention of post-operative venous thromboembolism. The Bemiparin Assessment group

A randomised, prospective, double-blind trial was performed, to compare the safety and efficacy of a new low-molecular-weight heparin (LMWH) Bemiparin and standard unfractionated heparin (UFH), for the prophylaxis of postoperative venous thromboembolism. 300 patients scheduled to undergo elective hip arthroplasty were included. The principal outcome measures were the incidence of thromboembolic events and bleeding complications. 149 patients received 3,500 anti-Xa IU of bemiparin plus a placebo injection daily and 149 patients received 5,000 IU of UFH twice a day. The two groups were similar with respect to factors likely to affect the risk of developing post-operative venous thromboembolism (VTE) and risk of bleeding events. During the post-operative period, 34 patients developed VTE complications; 9 (7.2%) in the bemiparin group and 25 (18.7%) in the UFH group. VTE in the two groups was statistically significant (OR of 2.96; 95% CI 1.32-6.62 and p = 0.01). There were no significant differences in the frequency of bleeding complications: major bleeding requiring discontinuation of prophylaxis, (OR 1.21; 95% CI 0.36-4.05; p = 1.00), the measured median operative blood loss (p = 0.77) or the median postoperative drain loss (p = 0.97), and the number of patients who developed wound haematoma (OR 0.87; 95% CI 0.31-2.46; p = 1.00). A comparison of coagulation parameters on the preoperative day with post-operative day 2 +/- 1, day 6 +/- 1 and day of discharge showed a significantly higher AT concentration, anti-factor Xa activity and TFPI levels in the bemiparin group when compared with UFH. This study demonstrates that bemiparin, in a single daily subcutaneous dose of 3,500 anti-Xa IU in high risk patients undergoing hip arthroplasty is more effective than UFH administered twice daily at a dose of 5,000 IU in the prevention of postoperative VTE. Both agents are equally safe.     

Warfarin prophylaxis and venous thromboembolism in the first 5 days following hip and knee arthroplasty

Many orthopaedic surgeons use warfarin to prevent venous thromboembolism (VTE) following hip or knee arthroplasty. Since warfarin's antithrombotic effects are delayed, we hypothesized that early VTE (occurring within 5 days post-operatively) would be more common in arthroplasty patients receiving warfarin monotherapy compared to those receiving enoxaparin. We performed a secondary analysis of a case-control study examining risk factors for post-operative thrombosis in postmenopausal women. We defined cases as patients who were diagnosed with thrombosis within 5 days of surgery. Controls without thrombosis were matched with cases by age, surgeon, year of surgery and surgical joint. 84 women with early post-operative thrombosis (cases) were matched with 206 controls. 18 cases (21.4%) had been prescribed warfarin mono-therapy, compared with 7 controls (3.4%). 58 (69.1%) cases and 195 (94.7%) controls had been prescribed subcutaneous enoxaparin 30 mg twice daily, starting 12-24 hours after surgery. The odds ratio for any early thrombosis in patients receiving warfarin as opposed to enoxaparin 30 mg twice daily was 8.6 (p<0.0001). For proximal thrombosis, the odds ratio was 11.3 (p<0.0001). Multivariate analysis did not alter these findings. Warfarin's delayed antithrombotic effects may not provide adequate VTE prophylaxis in the immediate post-operative setting. We suggest caution in employing warfarin monotherapy following joint arthroplasty.     

Venous thromboembolism prevention with fondaparinux 1.5 mg in renally impaired patients undergoing major orthopaedic surgery. A real-world, prospective, multicentre, cohort study

Despite the need for effective and safe thromboprophylactic drugs for patients with renal impairment, clinical trial data on anticoagulant agents are limited in this population. The study aim was to assess in the real-world setting the use of the once-daily 1.5 mg reduced dosage regimen of fondaparinux available for this context. In this prospective cohort study, patients with a creatinine clearance (CrCl) of 20-50 ml/minute, undergoing total hip (THR) or knee (TKR) replacement or hip fracture surgery (HFS) received fondaparinux thromboprophylaxis. Main clinical outcomes were bleeding (major/clinically relevant non-major), symptomatic venous thromboembolism (VTE) and death. Overall, 442 patients (353 women; median age: 82 years; 39.4% in ASA class ≥3; mean ± SD CrCl: 39.0 ± 8.0 ml/minute; 78% with additional risk factors for bleeding), undergoing THR (43.7%), TKR (27.6%), or HFS (28.7%) received fondaparinux 1.5 mg for a mean ± SD duration of 16.0 ± 12.5 days. At postoperative day 10, the rates (95% confidence interval) of major bleeding, clinically relevant bleeding and symptomatic VTE were 4.5% (2.8-6.9), 0.5% (0.1-1.6) and 0.5% (0.05-1.62), respectively; no fatal bleeding, bleeding into a critical organ, pulmonary embolism or proximal deep-vein thrombosis occurred. Corresponding rates at one month were 5.2%, 0.7% and 0.7%. One-month mortality was 2.3% (0.9-3.6). This large clinical prospective study provides for the first time, under conditions reflecting "real-world" routine clinical practice, data on the bleeding and VTE risks of thromboprophylaxis with fondaparinux 1.5 mg after major orthopaedic surgery in renally impaired patients. It shows that these patients constitute a very elderly and fragile population.     

Enoxaparin vs heparin for prevention of deep-vein thrombosis in acute ischaemic stroke: a randomized,double-blind study

OBJECTIVES: To compare the efficacy, safety, and overall risk-benefit profile of enoxaparin and unfractionated heparin (UFH) prophylaxis of venous thromboembolic complications in patients with acute ischaemic stroke. METHODS: Patients with ischaemic stroke resulting in lower-limb paralysis lasting for at least 24 h and necessitating bedrest, were randomized within 48 h of the onset of stroke, and treated with enoxaparin (40 mg subcutaneously once daily) or UFH (5000 IU subcutaneously thrice daily) for 10 +/- 2 days. Main outcome measures were deep-vein thrombosis, pulmonary embolism (PE), death from any cause, intracranial haemorrhage including haemorrhagic infarction, or any other major bleeding. RESULTS: Outcome events occurred within 3 months of stroke in 40/106 patients treated with enoxaparin (37.7%) and 52/106 patients treated with UFH (49.1%, P=0.127). Fewer patients treated with enoxaparin (14, 13.2%) than with UFH (20, 18.9%) had evidence of haemorrhagic transformation of ischaemic stroke. CONCLUSIONS: Enoxaparin administered subcutaneously once daily was as safe and effective as subcutaneous UFH given thrice daily in the prevention of thromboembolic events in patients with lower limb paralysis caused by acute ischaemic stroke.     

Do women bleed more than men when prescribed novel oral anticoagulants for venous thromboembolism? A sex-based meta-analysis

Introduction

Bleeding complications occur more frequently in women than men in clinical trials of warfarin and thrombolytics. It is unknown whether these sex-related differences exist for new oral anticoagulants, including dabigatran, rivaroxaban, and apixaban. To determine whether women suffer more bleeding complications with these agents, we conducted a systematic review and meta-analysis of randomized controlled trials on new oral anticoagulants for venous thromboembolism (VTE).

Materials and Methods

Medline, Embase, and the Cochrane-controlled trial register on the Cochrane library were searched to identify studies that evaluated novel oral anticoagulants versus any comparator, and reported outcomes, including major bleeding and recurrent VTE, stratified by sex. No language restrictions were applied. Studies were evaluated according to a priori inclusion criteria and critically appraised using established internal validity criteria. Pooled relative risk was estimated using a random effects model.

Results

Eight studies were eligible, comprising 9417 patients. There was no difference in the primary efficacy outcome of recurrent VTE between men and women [Relative Risk (RR) 1.02, 95% confidence interval (CI) 0.74-1.39]. However, men had less major bleeding with novel oral anticoagulants compared to women [RR 0.79, 95% CI 0.66-0.97, p = 0.03]. All-cause mortality was not reported by sex in any of the studies.

Conclusion

Women suffer more bleeding complications than men when receiving novel oral anticoagulants for VTE. Future clinical trials should report outcomes stratified by sex, and further studies are needed to investigate the clinical impact of this sex-related safety difference.     

An indirect comparison of dabigatran, rivaroxaban and apixaban for atrial fibrillation

New oral anticoagulant drugs are emerging as alternatives to warfarin for the prevention of stroke in patients with non-valvular atrial fibrillation. Two agents are direct factor Xa inhibitors (rivaroxaban and apixaban), and the third is a direct thrombin inhibitor (dabigatran). They have been separately compared to warfarin in large randomised trials. Our objective was to indirectly compare the three agents to each other for major efficacy and safety outcomes. Studies were assessed for comparability and the odds ratios of selected outcomes for each anticoagulant versus one another were estimated indirectly. The three cohorts differed significantly in terms of CHADS2 score and the number of individuals with a past history of stroke, transient ischemic attack or systemic embolism. The estimated odds ratio of stroke or systemic embolism was 1.35 for rivaroxaban vs dabigatran 150 mg (p=0.04), 0.97 for rivaroxaban versus dabigatran 110 mg (p=0.81), 1.22 for apixaban versus dabigatran 150 mg (p=0.18), 0.88 for apixaban versus dabigatran 110 mg (p=0.34) and 0.90 for apixaban versus rivaroxaban (p=0.43). The estimated odds ratio of major bleeding was 1.10 for rivaroxaban versus dabigatran 150 mg (p=0.36), 1.28 for rivaroxaban versus dabigatran 110 mg (p=0.02), 0.74 for apixaban versus dabigatran 150 mg (p=0.004), 0.87 for apixaban versus dabigatran 110 mg (p=0.17) and 0.68 for apixaban versus rivaroxaban (p<0.001). In conclusion, the available data indicate no significant difference in efficacy between dabigatran 150 mg and apixaban for the prevention of stroke or systemic embolism in patients with non-valvular atrial fibrillation. It appears however that apixaban is associated with less major bleeding than dabigatran 150 mg or rivaroxaban and that rivaroxaban is less effective than dabigatran 150 mg in preventing stroke or systemic embolism. Such an indirect comparison should be used only to generate hypotheses which need to be tested in a dedicated randomised trial comparing the three drugs directly.