Thromboprophylaxis with enoxaparin and direct oral anticoagulants in major orthopedic surgery and acutely ill medical patients: a meta-analysis

Direct Oral Anticoagulants: How Do These Drugs Work, How to Monitor, and What Is Their Role in Orthopaedic Surgery

Postoperative venous thromboembolism is a major adverse event associated with orthopaedic surgery. With the addition of perioperative anticoagulation and antiplatelet therapy, the rates of symptomatic venous thromboembolism have dropped to 1% to 3%, and as such, practicing orthopaedic surgeons must be familiar with these medications, including aspirin, heparin, or warfarin, and the use of direct oral anticoagulants (DOACs). DOACs are increasingly being prescribed due to their predictable pharmacokinetics and increased convenience, as they do not require routine monitoring, and 1% to 2% of the general population is currently anticoagulated. Although the introduction of DOACs has yielded additional treatment options, this has also led to confusion and uncertainty regarding treatment, specialized testing, and when and what reversal agents are appropriate. This article provides a basic overview of DOAC medications, their suggested use in the perioperative setting, effects on laboratory testing, and consideration for when and how to use reversal agents in orthopaedic patients.

Prevention of Deep Vein Thrombosis by Panax Notoginseng Saponins Combined with Low-Molecular-Weight Heparin in Surgical Patients

OBJECTIVE

To evaluate the efficacy of deep vein thrombosis (DVT) prevention among real-world surgical inpatients who received panax notoginseng saponins (PNS) combined with low-molecular-weight heparin (LMWH).

METHODS

A prospective cohort study was conducted among surgical patients between January 2016 and November 2018 in Xuanwu Hospital, Capital Medical University, Beijing, China. Participants received LMWH alone or PNS combined with LMWH for preventing DVT. The primary outcome was incidence of lower extremity DVT, which was screened once a week. Participants in the LMWH group were given LMWH (enoxaparin) via hypodermic injection, 4000-8000 AxalU once daily. Participants in the exposure group received PNS (Xuesaitong oral tablets, 100 mg, 3 times daily) combined with LMWH given the same as LMWH group.

RESULTS

Of the 325 patients screened for the study, 281 participants were included in the final analysis. The cohort was divided into PNS + LMWH group and LMWH group with 134 and 147 participants, respectively. There was a significant difference of DVT incidence between two groups (P=0.01), with 21 (15.7%) incident DVT in the PNS + LMWH group, and 41 (27.9%) incident DVT in the LMWH group. Compared with participants without DVT, the participants diagnosed with DVT were older and had higher D-dimer level. The multivariate logistic regression model showed a significant lower risk of incident DVT among participants in the PNS + LMWH group compared with the LMWH group (odds ratio 0.46, 95% confidence interval, 0.25-0.86). There were no significant differences in thromboelaslography values (including R, K, Angle, and MA) and differences in severe bleeding between two groups. No symptomatic pulmonary embolism occurred during the study.

CONCLUSION

Combined application of PNS and LMWH can effectively reduce the incidence of DVT among surgical inpatients compared with LMWH monotherapy, without increased risk of bleeding.

Venous thromboembolism in orthopaedic oncology

AIMS

Malignancy and surgery are risk factors for venous thromboembolism (VTE). We undertook a systematic review of the literature concerning the prophylactic management of VTE in orthopaedic oncology patients.

METHODS

MEDLINE (PubMed), EMBASE (Ovid), Cochrane, and CINAHL databases were searched focusing on VTE, deep vein thrombosis (DVT), pulmonary embolism (PE), bleeding, or wound complication rates.

RESULTS

In all, 17 studies published from 1998 to 2018 met the inclusion criteria for the systematic review. The mean incidence of all VTE events in orthopaedic oncology patients was 10.7% (1.1% to 27.7%). The rate of PE was 2.4% (0.1% to 10.6%) while the rate of lethal PE was 0.6% (0.0% to 4.3%). The overall rate of DVT was 8.8% (1.1% to 22.3%) and the rate of symptomatic DVT was 2.9% (0.0% to 6.2%). From the studies that screened all patients prior to hospital discharge, the rate of asymptomatic DVT was 10.9% (2.0% to 20.2%). The most common risk factors identified for VTE were endoprosthetic replacements, hip and pelvic resections, presence of metastases, surgical procedures taking longer than three hours, and patients having chemotherapy. Mean incidence of VTE with and without chemical prophylaxis was 7.9% (1.1% to 21.8%) and 8.7% (2.0% to 23.4%; p = 0.11), respectively. No difference in the incidence of bleeding or wound complications between prophylaxis groups was reported.

CONCLUSION

Current evidence is limited to guide clinicians. It is our consensus opinion, based upon logic and deduction, that all patients be considered for both mechanical and chemical VTE prophylaxis, particularly in high-risk patients (pelvic or hip resections, prosthetic reconstruction, malignant diagnosis, presence of metastases, or surgical procedures longer than three hours). Additionally, the surgeon must determine, in each patient, if the risk of haemorrhage outweighs the risk of VTE. No individual pharmacological agent has been identified as being superior in the prevention of VTE events. Cite this article: Bone Joint J 2020;102-B(12)1743:-1751.

Risk of Pulmonary Embolism More Than 6 Weeks After Surgery Among Cancer-Free Middle-aged Patients

Importance

The risk of postoperative pulmonary embolism has been reported to be highest during the first 5 weeks after surgery. However, how long the excess risk of postoperative pulmonary embolism persists remains unknown.

Objective

To assess the duration and magnitude of the late postoperative risk of pulmonary embolism among cancer-free middle-aged patients by the type of surgery.

Design, Setting, and Participants

Case-crossover analysis to compute the respective risks of pulmonary embolism after 6 types of surgery using data from a French national inpatient database, which covers a total of 203 million inpatient stays over an 8-year period between 2007 and 2014. Participants were cancer-free middle-aged adult patients (aged 45 to 64) with a diagnosis of a first pulmonary embolism.

Exposures

Hospital admission for surgery. Surgical procedures were classified into 6 types: (1) vascular surgery, (2) gynecological surgery, (3) gastrointestinal surgery, (4) hip or knee replacement, (5) fractures, and (6) other orthopedic operations.

Main Outcomes and Measures

Diagnosis of a first pulmonary embolism.

Results

A total of 60 703 patients were included (35 766 [58.9%] male; mean [SD] age, 56.6 [6.0] years). The risk of postoperative pulmonary embolism was elevated for at least 12 weeks after all types of surgery and was highest during the immediate postoperative period (1 to 6 weeks). The excess risk of postoperative pulmonary embolism ranged from odds ratio (OR), 5.24 (95% CI, 3.91-7.01) for vascular surgery to OR, 8.34 (95% CI, 6.07-11.45) for surgery for fractures. The risk remained elevated from 7 to 12 weeks, with the OR ranging from 2.26 (95% CI, 1.81-2.82) for gastrointestinal operations to 4.23 (95% CI, 3.01-5.92) for surgery for fractures. The risk was not clinically significant beyond 18 weeks postsurgery for all types of procedures.

Conclusions and Relevance

The risk of postoperative pulmonary embolism is elevated beyond 6 weeks postsurgery regardless of the type of procedure. The persistence of this excess risk suggests that further randomized clinical trials are required to evaluate whether the duration of postoperative prophylactic anticoagulation should be extended and to define the optimal duration of treatment with regard to both the thrombotic and bleeding risks.

Therapeutic Anticoagulation with Argatroban and Heparins Reduces Granulocyte Migration: Possible Impact on ECLS-Therapy?

Introduction

Anticoagulants such as argatroban and heparins (low-molecular-weight and unfractionated) play an immense role in preventing thromboembolic complications in clinical practice. Nevertheless, they can also have a negative effect on the immune system. This study is aimed at investigating the influence of these substances on polymorphonuclear neutrophils (PMNs), whose nonspecific defense mechanisms can promote thrombogenesis.

Methods

Blood samples from 30 healthy volunteers were investigated, whereby PMNs were isolated by density gradient centrifugation and incubated with 0.8 μg/mL of argatroban, 1.0 U/mL of low-molecular-weight heparin (LMWH), 1.0 U/mL of unfractionated heparin (UFH), or without drug (control). A collagen-cell mixture was prepared and filled into 3D μ-slide chemotaxis chambers (IBIDI® GmbH, Germany). Stimulation was initiated by using a chemokine gradient of n-formyl-methionine-leucyl-phenylalanine (fMLP), and microscopic observation was conducted for 4.5 hours. The cells' track length and track straightness, as well as the number of attracted granulocytes, level of ROS (reactive oxygen species) production, and NET (neutrophil extracellular traps) formation, were analyzed and categorized into migration distances and time periods.

Results

All three anticoagulants led to significantly reduced PMN track lengths, with UFH having the biggest impact. The number of tracks observed in the UFH group were significantly reduced compared to the control group. Additionally, the UFH group demonstrated a significantly lower track straightness compared to the control. ROS production and NET formation were unaffected.

Conclusion

Our data provide evidence that anticoagulants have an inhibitory effect on the extent of PMN migration and chemotactic migration efficiency, thus indicating their potential immune-modulatory and prothrombotic effects.

Extended anticoagulation after venous thromboembolism: should it be done?

Most physicians understand venous thromboembolism (VTE) to be an acute and time-limited disease. However, pathophysiological and epidemiological data suggest that in most patients VTE recurrence risk is not resolved after the first 6 months of anticoagulation. Recurrence rates are high and potentially life-threatening. In these cases, it would make sense to prolong anticoagulation for an undetermined length of time. However, what about the bleeding rates, induced by prolonged anticoagulation? Would they not outweigh the benefit of reducing the VTE recurrent risk? How long should anticoagulation be continued, and should all patients suffering from VTE be provided with extended anticoagulation? This review will address the most recent data concerning extended anticoagulation in VTE secondary prophylaxis.

The reviews of this paper are available via the supplementary material section.

CRISTAL: protocol for a cluster randomised, crossover, non-inferiority trial of aspirin compared to low molecular weight heparin for venous thromboembolism prophylaxis in hip or knee arthroplasty, a registry nested study

INTRODUCTION

Venous thromboembolism (VTE) is a serious complication following hip arthroplasty (HA) and knee arthroplasty (KA). This study aims to determine whether aspirin is non-inferior to low molecular weight heparin (LMWH) in preventing symptomatic VTE following HA and KA.

METHODS AND ANALYSIS

This is a cluster randomised, crossover, non-inferiority, trial nested within the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR). The clusters will consist of Australian hospitals performing at least 250 HA and/or KA procedures per annum. All adult patients undergoing HA or KA will be included. The intervention will be aspirin, orally, 85-150 mg daily. The comparator will be LMWH (enoxaparin) 40 mg, subcutaneously, daily. Both drugs will commence within 24 hours postoperatively and continue for 35 days after HA and 14 days after KA. Each hospital will be randomised to commence with aspirin or LMWH and then crossover to the alternative treatment after meeting the recruitment target. Data will be collected through the AOANJRR via patient-reported surveys. The primary outcome is symptomatic VTE within 90 days post surgery, verified by AOANJRR staff. The primary analysis will include only patients undergoing elective primary total hip arthroplasty and total knee arthroplasty for osteoarthritis. Secondary outcomes will include symptomatic VTE for all HA and KA (including partial and revision) within 90 days, readmission, reoperation, major bleeding and death within 90 days and reoperation, death and patient-reported pain, function and health status at 6 months. If aspirin is found to be inferior, a cost-effectiveness analysis will be conducted. The study will aim to recruit 15 562 patients from 31 hospitals.

ETHICS AND DISSEMINATION

Ethics approval has been granted. Trial results will be submitted for publication. The trial is registered with the Australian New Zealand Clinical Trials Registry (ACTRN12618001879257, pre-results) and is endorsed by the Australia and New Zealand Musculoskeletal Clinical Trials Network.

Enoxaparin Dosing for Venous Thromboembolism Prophylaxis in Low Body Weight Patients

Background:

The appropriate dose of enoxaparin for venous thromboembolism (VTE) prophylaxis in low body weight patients is unknown.

Objective:

The aim of this study is to evaluate the impact of enoxaparin dosing on major and minor bleeding events in low body weight patients.

Methods:

This was a retrospective cohort study of patients weighing less than 45 kg receiving subcutaneous (SC) enoxaparin for VTE prevention. The primary objective was to determine whether enoxaparin dose was associated with major and minor bleeding. The secondary objective was to determine the incidence of VTE by enoxaparin dose.

Results:

There were 173 patients included in the study, of which 37 patients received 2 different courses of enoxaparin during hospitalization, resulting in 210 enoxaparin courses. Among all enoxaparin courses, 16.2% were associated with major bleeding and 5.2% with minor bleeding. There was no difference in the incidence of major bleeding by dose (enoxaparin 30 mg SC daily, 30 mg SC twice daily, or 40 mg SC daily; P = .409). Patients who experienced major bleeding were older (54.9 ± 16.1 years) than patients who did not (48.4 ± 18.4 years) (P = .043). There was no difference in the incidence of minor bleeding by dosing schedule (P = .14). No patients experienced a VTE.

Conclusion and Relevance:

The risk of bleeding was similar by enoxaparin dose but increased with age in low body weight patients. Given the low incidence of VTE in this study, it is reasonable to consider decreasing the prophylactic enoxaparin dose in low body weight patients, especially in the elderly population.

Comparative effectiveness of direct oral anticoagulants versus low-molecular weight heparins for the prevention of venous thromboembolism after total hip or knee replacement: A nationwide database cohort study

BACKGROUND

Venous thromboembolism (VTE) after total knee or hip replacement (TKR, THR) is usually prevented with low-molecular weight heparin (LMWH), and increasingly by direct oral anticoagulants (DOAC). The aim of the present study was to compare the benefit-risk and medical costs of DOAC vs. LMWH in a real-life setting.

METHODS

All patients with THR or TKR in France between Jan-1st 2013 and Sep-30th 2014, discharged to home, were identified and followed-up for 3 months in the French nationwide claims database, SNDS. DOAC users were 1:1 matched with LWMH users on gender, age and propensity score. Relative risks (RR) of hospitalized VTE, hospitalized bleeding and death were estimated using quasi-Poisson models. Medical costs were calculated according to the societal perspective, including total cost for outpatient claims and national DRG costs for hospitalisations.

RESULTS

Most DOAC users (≥ 98.8%) were matched to a LMWH patient. For the 63,238 matched THR patients, the 3-month absolute risk of VTE was 0.9‰ with DOAC and 2.5‰ with LMWH (RR = 0.35 [0.23 to 0.54]), of bleeding 1.8‰ and 2.1‰ (0.88 [0.62-1.25]), death 0.7‰ and 1.1‰ (0.68 [0.40-1.15]). For the 31,440 matched TKR patients, risks were 1.6‰ and 2.3‰ (0.69 [0.42-1.16]) for VTE, 2.4‰ and 3.8‰ (0.64 [0.43 to 0.97]) for bleeding, and 0.6‰ and 0.8‰ (0.69 [0.30-1.62]) for all-cause death. Mean medical costs were 28% and 21% lower with DOAC than LMWH for THR and TKR, respectively. This nationwide study found a very low risk of VTE, hospitalized bleeding and death after THR or TKR discharge in patients with VTE prevention in real-life setting, with better benefit-risk profiles of DOAC compared to LMWH, and associated cost savings.

Direct Oral Anticoagulants vs Low-Molecular-Weight Heparin for Thromboprophylaxis in Nonoperative Pelvic Fractures

BACKGROUND

Patients with pelvic fractures are prone to venous thromboembolic (VTE) complications. Recent literature shows superiority of direct oral anticoagulants (DOACs) over low-molecular-weight heparin (LMWH) for thromboprophylaxis in patients undergoing orthopaedic operations. The aim of our study was to compare in-hospital outcomes for DOACs vs LMWH in patients with nonoperative pelvic fractures.

STUDY DESIGN

We performed a 2-year (2015 to 2016) analysis of the American College of Surgeons-Trauma Quality Improvement Program (ACS-TQIP) database. We included all adult patients with isolated blunt pelvic fractures who were managed nonoperatively and received thromboprophylaxis with either LMWH or DOACs (Factor-Xa inhibitor or direct thrombin inhibitor). Patients were divided into 2 groups based on receipt of DOACs vs LMWH and were propensity-score-matched in a 1:2 ratio to control for possible confounding factors. Primary outcomes were deep venous thrombosis (DVT) and/or pulmonary embolism (PE). Secondary outcomes were pRBC transfusions, intervention for hemorrhage control, and in-hospital mortality after initiation of thromboprophylaxis.

RESULTS

We identified 20,692 patients with pelvic fractures. There were 7,312 patients with isolated pelvic fractures included, 852 of whom were matched (DOACs: 284; LMWH: 568). Mean age was 43.2 ± 15 years, median Injury Severity Score was 14 (range 10 to 18). Matched groups were similar in demographics, vital signs, injury parameters, and timing of initiation of thromboprophylaxis. Overall, 5.2% of patients had DVT, 1.4% PE, and 1.3% died. Patients who received DOACs were less likely to develop DVT (1.8% vs 6.9%, p < 0.01) compared with LMWH. There was no difference in PE (p = 0.85) or in-hospital mortality (p = 0.79) between the 2 groups. Similarly, there was no difference in post-prophylaxis blood transfusion, and post-prophylaxis intervention for hemorrhage control.

CONCLUSIONS

In patients with nonoperative pelvic fractures, DOACs were associated with a reduced rate of DVT vs LMWH without increasing the risk of bleeding complications. No association was found between the type of thromboprophylactic agent and rates of PE or in-hospital mortality.

Oral Xa Inhibitors Versus Low Molecular Weight Heparin for Thromboprophylaxis After Nonoperative Spine Trauma

BACKGROUND

Thromboprophylaxis with oral Xa inhibitors (Xa-Inh) are recommended after major orthopedic operation; however, its role in spine trauma is not well-defined. The aim of our study was to assess the impact of Xa-Inh in spinal trauma patients managed nonoperatively.

METHODS

A 4-y (2013-2016) review of the Trauma Quality Improvement Program database. We included all patients with an isolated spine trauma (Spine-abbreviated injury scale ≥3 and other-abbreviated injury scale <3) who were managed nonoperatively and received thromboprophylaxis with either low molecular weight heparin (LMWH) or Xa-Inh. Patients were divided into two groups based on the thromboprophylactic agent received: Xa-Inh and LMWH and were matched in a 1:2 ratio using propensity score matching for demographics, vitals and injury parameters, and level of spine injury. Outcomes were rates of deep venous thrombosis, pulmonary embolism, and mortality.

RESULTS

We analyzed a total of 58,936 patients, of which 1056 patients (LMWH: 704, Xa-Inh: 352) were matched. Matched groups were similar in demographics, vital and injury parameters, length of hospital stay (P = 0.31), or time to thromboprophylaxis (P = 0.79). Patients who received Xa-Inh were less likely to develop a deep venous thrombosis (2.3% versus 5.7%, P < 0.01). There were no differences in the rate of pulmonary embolism (P = 0.73), postprophylaxis packed red blood cells transfusions (P = 0.79), postprophylaxis surgical decompression of spinal column (P = 0.75), and mortality rate (P = 0.77).

CONCLUSIONS

Oral Xa-Inh seems to be more effective as prophylactic pharmacologic agent for the prevention of deep venous thrombosis in patients with nonoperative spinal trauma compared to LMWH. The two drugs had similar safety profile. Further prospective trials should be performed to change current guidelines.

Prophylaxis of Postoperative Venous Thromboembolism Using Enoxaparin After Esophagectomy: A Prospective Observational Study of Effectiveness and Safety

BACKGROUND

The incidence of venous thromboembolism (VTE) after esophagectomy is higher than in other gastroenterological cancer surgery. Although the effectiveness and safety of thromboprophylaxis using enoxaparin have been established in orthopedic, abdominal, and pelvic surgeries, no studies regarding esophagectomy are available.

METHODS

A prospective observational study was conducted to elucidate the usefulness of enoxaparin for VTE prophylaxis after esophagectomy. The study enrolled 30 patients who underwent elective esophagectomy for esophageal cancer between April 2015 and October 2016. During postoperative days 2-11, the patients received a subcutaneous injection of enoxaparin (2000 IU) twice daily. The primary end point for the study was the incidence of postoperative VTE. In addition, the incidence of all enoxaparin treatment- and operation-related adverse events was investigated. The study identified VTE by VTE protocol-enhanced computed tomography, performed routinely during and after enoxaparin treatment.

RESULTS

One pulmonary embolism (PE) (3.3%) and two deep vein thromboses (DVTs) (6.7%) were observed during enoxaparin treatment. In addition, one PE (3.6%) and four DVTs (14.3%) (one patient experienced both) were observed after treatment. All VTEs were asymptomatic. Regarding enoxaparin-related adverse events, four minor bleeds occurred but did not require discontinuation of enoxaparin. The incidence of postoperative morbidity was acceptable. In blood tests related to coagulation, no significant differences were observed between patients with and without VTE.

CONCLUSIONS

The authors believe that thromboprophylaxis using enoxaparin is safe and can prevent VTE after esophagectomy. However, its effectiveness is limited to the period of treatment, so additional prophylaxis may be recommended.