Evaluation of the safety and efficacy of enoxaparin and warfarin for prevention of deep vein thrombosis after total knee arthroplasty

Is chemoprophylaxis required after total knee and total hip arthroplasty in the Asian population? A systematic review and network meta-analysis

INTRODUCTION

Although chemoprophylaxis against venous thromboembolism (VTE) after Total Joint Arthroplasty (TJA) is commonly practiced, epidemiology studies have shown Asians have a much lower incidence of VTE. The authors aim to investigate if chemoprophylaxis is really necessary in the Asian population undergoing TJA.

MATERIAL AND METHODS

Literature searched was conducted for randomized controlled trials or quasi-experimental studies investigating efficacy and/or safety of chemoprophylaxis for TJA without language restrictions. Network meta-analysis, comparing the incidence of 'VTE to be treated', 'VTE not to be treated', 'Minor bleeding', and 'Major bleeding' amongst the different interventions was performed using multivariate meta-regression model.

RESULTS

38 studies (11,769 patients) were included. Total incidence of deep vein thrombosis (DVT) and pulmonary embolism (PE) were 14.2% and 0.73% respectively. For outcome on efficiency, edoxaban, low-molecular-weight-heparin (LMWH), fondaparinux, and enoxaparin showed significantly lower Risk Ratio (RR) for 'VTE to be treated' compared to Control/Placebo. Although no interventions showed increased incidence of major bleeding, LMWH and fondaparinux showed higher RR for minor bleeding. Enoxaparin displayed the best efficacy and safety profile. Total incidence of symptomatic DVT in studies involving enoxaparin was 1.98% (1.07% in patients who received enoxaparin, 2.92% in Control/Placebo). Total incidence of proximal DVT was 2.93% (2.67% in patients who received enoxaparin, 3.11% in Control/Placebo).

CONCLUSION

Asian population has a much lower incidence of VTE events after TJA compared to the Western population. Although Enoxaparin is still efficacious in reducing symptomatic and proximal DVT after TJA, its benefit-to-risk ratio is much lower than described in the Western literature.

Postoperative Deep Vein Thrombosis, Pulmonary Embolism, and Myocardial Infarction: Complications After Therapeutic Anticoagulation in the Patient With Spine Trauma

STUDY DESIGN

A retrospective review (2001-2014) was conducted using prospectively collected data at a level I trauma center.

OBJECTIVE

We sought to determine the incidence and characteristics of complications occurring secondary to therapeutic anticoagulation in adult spine trauma patients.

SUMMARY OF BACKGROUND DATA

Numerous studies have assessed prophylactic anticoagulation after spine surgery, but none has investigated the risks of therapeutic doses of anticoagulation for treatment of postoperative thromboembolic events.

METHODS

Patients were included if they sustained a postoperative thromboembolic event (deep venous thrombosis, pulmonary embolism, or myocardial infarction). Patients were excluded if anticoagulation was subtherapeutic. Of 1712 patients, 62 who received therapeutic anticoagulation and 174 propensity-matched control patients who did not receive therapeutic anticoagulation were included in the study.

RESULTS

Initial anticoagulation was obtained by heparin infusion (51%), low-molecular-weight heparin (LMWH, 46%), and warfarin (3%). Complications requiring unplanned reoperation occurred in 18% of anticoagulated patients and 10% of nonanticoagulated patients (P = 0.17). The reoperation rate after heparin infusion was 31% and after LMWH was 6.5% (P = 0.02). Epidural hematoma occurred in 3% and 1% of anticoagulated and nonanticoagulated patients, respectively. Multivariate logistic regression analysis of the two groups showed a trend toward increased risk of reoperation in the anticoagulation group. Analysis of the heparin infusion subgroup separate from the LMWH subgroup compared with the control group showed an increased risk of reoperation for any complication (odds ratio, 3.57; P = 0.01) and for bleeding complications (odds ratio, 43.1; P = 0.01).

CONCLUSION

This is the first study to quantify complications secondary to postoperative therapeutic anticoagulation in spine patients. Postoperative spine trauma patients who underwent therapeutic anticoagulation experienced an unplanned reoperation rate of 18%, including a 3% incidence of spinal epidural hematoma. Therapeutic anticoagulation using heparin infusion seems to drive the overall rate of reoperation (31%) compared with LMWH.

LEVEL OF EVIDENCE

3.

Can enoxaparin reduce thromboembolism related events after primary TKA in Asian patients?

The purpose of this study was to investigate the efficacy and safety of enoxaparin in preventing venous and arterial thromboembolism related events after primary total knee arthroplasty (TKA) in Asian patients. Four hundred twenty nine patients (621 TKAs) did not receive thromboprophylaxis after TKA and 907 patients (1,336 TKAs) received enoxaparin after the procedure. We assessed clinically significant venous and arterial thromboembolism related events and bleeding complications. Total thromboembolism related events occurred in 13 patients (3.03%) without thromboprophylaxis and 17 patients (1.87%) with enoxaparin (P = 0.183). Our study showed that the incidence of clinically significant thromboembolism related events after TKA was very low in Asian patients. Enoxaparin had no benefits in reducing thromboembolism related events in Asian patients.

Thromboembolism prophylaxis with dabigatran leads to lower perioperative blood loss than with dalteparin in primary knee arthroplasty

INTRODUCTION

Low-molecular-weight heparins (LMWH) are commonly used in thrombosis prophylaxis after total knee arthroplasty. In contrast to LMWH, dabigatran etexilate is an oral and direct acting anticoagulant. The hypothesis of the present study was that blood loss occurring in total knee arthroplasty (TKA) is not greater after dabigatran etexilate than after dalteparin.

METHOD

All patients suffering from primary arthrosis of knee joint that had received a total knee arthroplasty were included in this retrospective case-control study. Two groups were formed (dalteparin versus dabigatran etexilate) and the perioperative blood loss was compared using the formula of Nadler (V = EBV × ln (Hct(0)/Hct(1)) [V = blood loss (l); EBV = blood volume (l); Hct(0) = preoperative haematocrit; Hct(1) = haematocrit on the first postoperative day].

PATIENTS

A total of 155 patients, 61 men and 94 women, were included. The calculated blood loss differed significantly between the two groups. The blood loss was on average 1.5 ± 0.58 l [0.32-2.9 l] in the dalteparin group, compared with 1.3 ± 0.63 l [0.29-4.31 l] in the dabigatran etexilate group (p < 0.01). None of the patients of both observed groups showed clinical signs of thrombosis or pulmonary artery embolism.

RESULTS

Dabigatran etexilate showed a lower perioperative blood loss than dalteparin by comparable safety of both drugs.

CONCLUSION

Whether the timing of administration or pharmacological factors were responsible for this cannot be explained by our study.

The monitoring of heparin induced thrombocytopenia following surgery: an audit and international survey

Heparin-induced thrombocytopenia (HIT) is a serious postoperative complication of low-molecular-weight heparin (LWMH) prescribed following surgery and recent evidence based guidelines recommend routine platelet count monitoring for all at-risk patients. With the implementation of these guidelines this clinical study demonstrated a significant improvement (2-56% p < 0.05) in HIT diagnosis in postoperative patients receiving LMWH. An international survey showed a lack of awareness of heparin-induced thrombocytopenia and its management.

Monitoring and management of heparin-induced thrombocytopenia

Low molecular weight heparins have been used to reduce thromboembolic risk for at least 20 years, but their use is not without risk. This article considers the incidence, monitoring, treatment and lack of insight about heparin-induced thrombocytopenia - a potentially fatal complication of low molecular weight heparin use.

Thromboembolic prophylaxis for total knee arthroplasty in Asian patients: a randomised controlled trial

PURPOSE

To compare the efficacy and safety of different modes of thromboembolic prophylaxis for elective total knee arthroplasty (TKA) in Asian patients.

METHODS

440 low-risk patients undergoing TKA were randomised into 4 equal groups: (1) no prophylaxis (control), (2) graduated compression stockings (GCS), (3) intermittent pneumatic compression (IPC), and (4) low-molecular-weight heparin (enoxaparin). Duplex ultrasonography was used as an assessment tool.

RESULTS

The deep vein thrombosis point prevalence was highest in the control group (22%), which was significantly higher than in patients receiving IPC (8%, p=0.032) or enoxaparin (6%, p=0.001). One patient each in the control and GCS groups developed a non-fatal pulmonary embolism. Patients on enoxaparin received more blood transfusions and 2 of them had major bleeding complications.

CONCLUSION

IPC is the preferred method of thromboprophylaxis for TKA in Asian patients.

Early return to surgery for evacuation of a postoperative hematoma after primary total knee arthroplasty

BACKGROUND

Development of a postoperative hematoma is a reported complication after primary total knee arthroplasty. However, little is known about the clinical outcomes in patients who require surgical evacuation of an acute hematoma. The purpose of this study was to determine the incidence, risk factors, and long-term sequelae of postoperative hematomas requiring surgical evacuation.

METHODS

From 1981 to 2004, 17,784 primary total knee arthroplasties were performed at our institution. Forty-two patients (forty-two knees) returned to the operating room within thirty days of the index arthroplasty for evacuation of a postoperative hematoma. A case-control study, with forty-two patients matched one-to-one with forty-two control subjects, was performed to attempt to identify risk factors for the development of postoperative hematoma requiring surgical evacuation.

RESULTS

The rate of return to surgery within thirty days for evacuation of a postoperative hematoma was 0.24% (95% confidence interval, 0.17% to 0.32%). For patients undergoing postoperative hematoma evacuation, the two-year cumulative probabilities of undergoing subsequent major surgery (component resection, muscle flap coverage, or amputation) or having a deep infection develop were 12.3% (95% confidence interval, 1.6% to 22.4%) and 10.5% (95% confidence interval, 0.2% to 20.2%), respectively. In contrast, for knees without early hematoma evacuation, the two-year cumulative probabilities were 0.6% (95% confidence interval, 0.5% to 0.7%) and 0.8% (95% confidence interval, 0.6% to 0.9%), respectively (p < 0.001 for both outcomes). A history of a bleeding disorder was identified as having a significant association with the development of a hematoma requiring surgical evacuation (p = 0.046).

CONCLUSIONS

Patients who return to the operating room within thirty days after the index total knee arthroplasty for evacuation of a postoperative hematoma are at significantly increased risk for the development of deep infection and/or undergoing subsequent major surgery. These results support all efforts to minimize the risk of postoperative hematoma formation.

Thromboembolic risk assessment and the efficacy of enoxaparin prophylaxis in excisional body contouring surgery

BACKGROUND

There is a paucity of evidence within the plastic surgery literature concerning risk stratification and management of patients with respect to thromboembolic disease. A retrospective chart review was conducted to examine whether the Davison-Caprini risk-assessment model could stratify patients undergoing excisional body contouring surgery, allowing prophylaxis to be managed in an evidence-based manner.

METHODS

Three hundred sixty excisional body contouring patients at the University of Texas Southwestern Medical Center in Dallas, Texas, under the senior authors' (J.M.K. and R.J.R.) care were reviewed. Patients were stratified into groups according to the risk-assessment model and into groups based on procedure. Patient characteristics were investigated for their effects on thromboembolic risk. Complications of enoxaparin administration were analyzed. The data were analyzed using appropriate statistical procedures.

RESULTS

The highest risk patients had a significantly increased rate of venous thromboembolism when compared with lower risk patients. Body mass index greater than 30 and hormone therapy use were associated with a significantly increased venous thromboembolism rate. Enoxaparin administration was associated with a statistically significant decrease in deep venous thrombosis in circumferential abdominoplasty patients. Enoxaparin administration was associated with higher bleeding rates.

CONCLUSIONS

Low-molecular-weight heparin may affect the incidence of postoperative thrombotic complications in some surgical populations. In this study, patients who scored greater than four risk factors were at significant risk for venous thromboembolism. Enoxaparin significantly decreased deep venous thrombosis risk in patients undergoing circumferential abdominoplasty. This demonstrates the need for a multicenter, prospective, randomized study to examine various thromboembolic therapies and associated possible complications in these patients.

VenaFlow plus Lovenox vs VenaFlow plus aspirin for thromboembolic disease prophylaxis in total knee arthroplasty

Two hundred seventy-five patients undergoing unilateral total knee arthroplasty were prospectively randomized to receive spinal epidural anesthesia (SEA), a VenaFlow calf compression device, and enoxaparin (group A) or SEA, VenaFlow, and aspirin (group B). Aspirin was started on the day of surgery, whereas enoxaparin was started 48 hours after surgery. Anticoagulants were continued for 4 weeks after surgery. All patients had an in-hospital ultrasound screening test on postoperative days 3 to 5 and a second follow-up ultrasound 4 to 6 weeks after surgery. The overall deep venous thrombosis rates in groups A and B were 14.1% and 17.8% (P = not significant), respectively. When used in combination with pneumatic compression devices and SEA, enoxaparin was not superior to aspirin in preventing deep venous thrombosis after total knee arthroplasty.

Deep venous thrombosis prophylaxis: better living through chemistry--in opposition

The best prophylactic regimens for thromboembolic disease continue to be debated despite years of investigation. The surgeon must balance the clinical risks and benefits. A decision depends on accurate data and our ability to balance the risks of fatal pulmonary embolism (PE) to the risk of bleeding. The current risk for fatal PE is 0.1% with most current prophylactic regimes. The risk of perioperative bleeding increases 1.8% to 5.2% with low molecular weight heparins or warfarin and generally is dose dependent. Most of the current prophylactic recommendations are based on the presence or absence of deep venous thrombosis (DVT). However, the correlation between the presence of a DVT and the risk of PE is low and inconsistent. Therefore, DVT may not be an accurate surrogate marker for the patient at risk after total joint surgery. Our experience with 2800 consecutive total knee arthroplasty patients, using aspirin as our principle agent, shows a fatal PE risk of 0.1% and a low risk of bleeding. Therefore, our current recommendation is aspirin.

Selective factor Xa inhibition improves efficacy of venous thromboembolism prophylaxis in orthopedic surgery

Venous thromboembolism is a serious, frequent, and potentially fatal complication of major orthopedic surgery. Currently available pharmacologic agents for the prevention of venous thromboembolism in this high-risk population consist of the oral anticoagulants and the heparin family of antithrombotic agents (unfractionated heparin, low-molecular-weight heparin, heparinoids). These classes of agents interfere with the activity of both thrombin and factor Xa (or their respective zymogens) to varying degrees. Newer antithrombotic agents in various stages of development exert their antithrombotic effect through a more targeted mechanism of action. Direct factor Xa inhibitors and the newest class of antithrombotic agents, the indirect factor Xa inhibitors, the prototype of which is the synthetic pentasaccharide fondaparinux sodium, limit fibrin formation through their exclusive inactivation of factor Xa. Clinical data from venous thromboembolism prophylaxis trials in hip and knee replacement and hip fracture surgeries, including the recently completed fondaparinux phase II and phase III trials, indicate that selective antifactor Xa activity may improve the efficacy:safety ratio of antithrombotic therapies for the prevention of venous thromboembolism in high-risk major orthopedic surgery.

The effect of anticoagulation on the restoration of range of motion after total knee arthroplasty: enoxaparin versus aspirin

Anticoagulation used for thromboembolic prophylaxis following total knee arthroplasty (TKA) could interfere with movement. This study compares the effect of 2 anticoagulants, enoxaparin and aspirin, on restoration of range of motion (ROM) after TKA. Two groups of 75 consecutive patients, matched for age, arthritic severity, and preoperative ROM, underwent TKA. Flexion and extension milestone measures were recorded daily. Results show a highly statistically significant difference (P<.001) between the 2 groups when comparing the days on which these milestones were achieved. Group 1 (enoxaparin) reached 90 degrees, 100 degrees and 110 degrees of flexion in 8.4, 10.4, and 12.4 days, respectively. Group 2 (aspirin) reached the same goals in 6.8, 8.5, and 10.6 days, respectively. At 15 months after surgery, no statistically significant difference in flexion was seen between the groups (122 degrees vs 121 degrees ). Enoxaparin delayed the return of early but not long-term flexion after TKA.

A comparison of heparin/warfarin and enoxaparin thromboprophylaxis in spinal cord injury: the Sheffield experience

OBJECTIVES

To compare the safety and effectiveness of two different thromboprophylactic protocols in the management of patients with spinal cord injury - one using heparin/warfarin and the other using enoxaparin.

STUDY DESIGN

Retrospective.

SETTING

Princess Royal Spinal Injuries Unit, Sheffield, UK.

METHODS

Retrospective review of two cohorts of patients with acute spinal injury admitted to a supra-regional spinal injuries centre and treated with different pharmacological agents. One group received heparin/warfarin in combination with antiembolism stockings and mechanical measures for thromboprophylaxis whereas the second group received enoxaparin in combination with the other measures. Patients who developed clinical symptoms suggestive of deep vein thrombosis or pulmonary embolism were investigated as appropriate.

RESULTS

Four of the 101 patients on heparin/warfarin developed symptoms of venous thromboembolism compared to 13 of the 72 who were on enoxaparin. Of the 13, three had been on 40 mg of enoxaparin daily and 10 on 20 mg enoxaparin daily. Six patients on enoxaparin and one patient on warfarin developed thromboembolic complications after they had been mobilised and the anticoagulant discontinued. Eight patients on warfarin prophylaxis and three patients on enoxaparin developed haemorrhagic complications necessitating cessation of therapy.

CONCLUSION

This study suggests that the traditional protocol of warfarin/heparin for thromboprophylaxis in spinal cord injury patients remains a safer option than enoxaparin.

Surveillance for venous thromboembolic disease after total knee arthroplasty

The value of deep venous thrombosis screening after total knee arthroplasty is controversial. The purpose of the current study was to examine the value of routine surveillance for venous thrombosis after total knee arthroplasty done with modern operative and perioperative treatment. Computerized search engines were used to identify papers published between 1985 and July 2000 relevant to the purpose of the study. Papers that met the inclusion criteria for review were categorized as follows: the frequency of deep venous thrombosis; the natural history of deep venous thrombosis; the accuracy of screening methods for venous thrombosis; and efficacy of screening in reducing morbidity attributable to venous thromboembolism after total knee arthroplasty. Several studies have shown a low complication rate related to venous thromboembolic disease when compression ultrasound is used for screening as part of a clinical algorithm after knee arthroplasty. However, the only large prospective randomized trial evaluating ultrasound screening failed to show a reduction in morbidity with a surveillance protocol. The benefits of surveillance depend on factors specific to each surgeon's practice including the type and duration of venous prophylaxis, the rate of symptomatic and asymptomatic thromboembolic disease associated with that protocol, and the accuracy of screening tests used for surveillance.