A comparison of subcutaneous low-molecular-weight heparin with warfarin sodium for prophylaxis against deep-vein thrombosis after hip or knee implantation

Venous Thromboembolism in Outpatient Elective Foot and Ankle Procedure Patients Who Is at Risk?

BACKGROUND

Venous thromboembolism (VTE) is a rare but potentially serious complication following elective foot and ankle (F&A) procedures. The absence of guidelines for thromboprophylaxis in elective procedures underscores the importance of identifying patients at risk. This study aimed to identify key risk factors of VTE in patients who underwent elective foot and ankle (F&A) operations.

METHODS

Data was collected from the IBM MarketScan Database (2009-2019) for patients >18 years old without prior VTE who underwent elective F&A procedures. Patients were divided into 3 groups based on region of operation (forefoot, mid/hindfoot, lower leg/ankle). VTE incidence (including deep vein thrombosis and/or pulmonary embolism) was recorded 30 and 90 days postprocedure. Risk factors for VTE were identified through multivariate logistic regression.

RESULTS

Among the 301 256 patients who underwent elective F&A procedures, the overall 90-day incidence of VTE was 0.95%. The findings revealed that 31.9% of VTE incidents occurred within the first 2 weeks after operation, and 29.2% still occurred after 6 weeks. Analysis of the anatomical region of operation demonstrated that the lowest rate of 90-day VTE was amongst patients undergoing forefoot procedures (0.70%). There was a higher risk for VTE in patients undergoing midfoot/hindfoot procedures (1.22%, OR = 1.81) and lower leg/ankle procedures (1.76%, OR = 2.31). Additional risk factors for VTE included thrombophilia (4.02%, OR = 3.37), male sex (1.30%, OR = 1.47), increasing age (1.02% age 65+, OR = 1.41), and a high Charlson Comorbidity Index (1.12%, OR < 0.82 for scores <5).

CONCLUSION

This study identifies the incidence and timing for VTE after elective F&A procedures. Furthermore, this study defines the risk factors associated with increased odds of VTE after elective F&A procedures. These findings are helpful in educating patients about a continued risk for VTE throughout the 90-day postoperative period and beyond. These results can also be utilized to stratify patients who need thromboprophylaxis based on the individual risk level.

LEVEL OF EVIDENCE

Level III: Retrospective cohort study.

Trends in Venous Thromboembolism and Chemoprophylaxis Utilization in Elective Total Knee Arthroplasty From 2011 to 2020

BACKGROUND

Venous thromboembolism (VTE) is a feared complication of joint arthroplasty, leading to recent clinical practice guidelines aimed at VTE prevention and prophylaxis. However, limited studies have examined national changes in practice regarding chemoprophylaxis and the resultant changes in VTE rates. The purpose of this study was to identify: (1) the temporal trends in thrombotic complications; and (2) changes in chemoprophylaxis utilization in patients undergoing elective total knee arthroplasty (TKA).

METHODS

A retrospective study was conducted using a large all-payer claims dataset. Patients who underwent osteoarthritis-indicated TKA between 2011 and 2020 were identified. Annual rates of VTE, including deep vein thrombosis and pulmonary embolism, within 90 days of TKA were determined. Utilization patterns for postoperative aspirin and anticoagulant medications were observed. Temporal trends were analyzed with linear regression and the calculation of the cumulative annual growth rate. Multivariable logistic regression was conducted to account for the effects of age and comorbidities.

RESULTS

A total of 1,263,351 TKA patients were identified between 2011 and 2020. There were significant reductions in VTE rates (2.9% in 2011 to 1.8% in 2020), deep vein thrombosis rates (2.0% in 2011 to 1.3% in 2020), and pulmonary embolism rates (1.1% in 2011 to 0.6% in 2020). Postoperative utilization of aspirin increased from 5.9% in 2011 to 53.2% in 2020, whereas utilization of anticoagulants decreased from 94.1% in 2011 to 46.8% in 2020. Among anticoagulants, direct factor Xa inhibitors had the greatest increase in utilization (4.6 to 69.7%). The average reimbursement associated with VTE after TKA decreased from $18,061 in 2011 to $7,835 in 2020.

CONCLUSIONS

The incidence rate and economic burden of VTE after TKA have significantly declined since 2011. There has been a trend toward increased aspirin and direct oral anticoagulant utilization for postoperative chemoprophylaxis.

LEVEL OF EVIDENCE

Level III.

Risk Factors Associated with Thromboembolic Complications After total Hip Arthroplasty: An Analysis of 1,129 Pulmonary Emboli

INTRODUCTION

Venous thromboembolism (VTE) remains a dangerous complication after total hip arthroplasty (THA), despite advances in chemoprophylactic measures. This study aimed to identify risk factors of developing pulmonary embolism (PE) and deep vein thrombosis (DVT) after THA using a modern cohort of patients reflecting contemporary practices.

METHODS

The Premier Healthcare Database was queried for primary, elective THAs from January 1st, 2015, to December 31st, 2021. Patients who developed PE or DVT within 90 days of THA were compared with patients who did not develop any postoperative VTE. Differences in patient demographics, comorbidities, hospital factors, perioperative medications, chemoprophylactic agents, and allogeneic blood transfusion were compared between cohorts. Multivariable logistic regression models were used to identify independent risk factors of PE and DVT. In total, 544,298 THAs were identified, of which 1,129 (0.21%) developed a PE and 1,799 (0.33%) developed a DVT.

RESULTS

Patients diagnosed with a PE had significantly higher rates of in-hospital death (2.6% vs 0.1%, P < 0.001) compared with those without a PE. Age (adjusted odds ratio: 1.02 per year, 95% confidence interval [CI]: 1.01 to 1.03) and Black race (aOR: 1.52, 95% CI: 1.24 to 1.87) were associated with an increased risk of PE. Comorbidities associated with increased risk of PE included chronic pulmonary disease (aOR: 1.58, 95% CI: 1.36 to 1.84), pulmonary hypertension (aOR: 2.06, 95% CI: 1.39 to 3.04), and history of VTE (aOR: 2.38, 95% CI: 1.98 to 2.86). Allogeneic blood transfusion (aOR: 2.40, 95% CI: 1.88 to 3.06) was also associated with an increased risk of PE while dexamethasone utilization was associated with a reduced risk (aOR: 0.83, 95% CI: 0.73 to 0.95).

DISCUSSION

Increasing age; Black race; allogeneic blood transfusion; and comorbidities, including chronic pulmonary disease, pulmonary hypertension, and history of VTE, were independent risk factors of PE after THA. Given the increased mortality associated with PE, patients should be carefully evaluated for these factors and managed with an appropriate chemoprophylactic regimen.

Clinical guidelines for prevention and treatment of CAT in Japan and other countries

Cancer-associated thrombosis (CAT) is an important prognostic factor for an increasing number of cancer patients. Understanding of CAT among cancer care providers has grown in recent years, and guidelines for the prevention and treatment of CAT have been published in Japan and around the world. In this article, we introduce these major guidelines and discuss differences we identified between the Japanese guidelines and those of other countries, with a focus on problems and issues. Insurance coverage of low-molecular-weight heparin and indications for primary prevention with direct oral anticoagulants in particular require urgent consideration.

Venous Thromboembolism Prophylaxis in Major Orthopedic Surgeries and Factor XIa Inhibitors

Venous thromboembolism (VTE), comprising pulmonary embolism (PE) and deep vein thrombosis (DVT), poses a significant risk during and after hospitalization, particularly for surgical patients. Among various patient groups, those undergoing major orthopedic surgeries are considered to have a higher susceptibility to PE and DVT. Major lower-extremity orthopedic procedures carry a higher risk of symptomatic VTE compared to most other surgeries, with an estimated incidence of ~4%. The greatest risk period occurs within the first 7-14 days following surgery. Major bleeding is also more prevalent in these surgeries compared to others, with rates estimated between 2% and 4%. For patients undergoing major lower-extremity orthopedic surgery who have a low bleeding risk, it is recommended to use pharmacological thromboprophylaxis with or without mechanical devices. The choice of the initial agent depends on the specific surgery and patient comorbidities. First-line options include low-molecular-weight heparins (LMWHs), direct oral anticoagulants, and aspirin. Second-line options consist of unfractionated heparin (UFH), fondaparinux, and warfarin. For most patients undergoing knee or hip arthroplasty, the initial agents recommended for the early perioperative period are LMWHs (enoxaparin or dalteparin) or direct oral anticoagulants (rivaroxaban or apixaban). In the case of hip fracture surgery, LMWH is recommended as the preferred agent for the entire duration of prophylaxis. However, emerging factor XI(a) inhibitors, as revealed by a recent meta-analysis, have shown a substantial decrease in the occurrence of VTE and bleeding events among patients undergoing major orthopedic surgery. This discovery poses a challenge to the existing paradigm of anticoagulant therapy in this specific patient population and indicates that factor XI(a) inhibitors hold great promise as a potential strategy to be taken into serious consideration.

Trends of Venous Thromboembolism After Total Hip Arthroplasty in the United States: Analysis From 2011 to 2019

BACKGROUND

In 2011, the American Academy of Orthopaedic Surgeons released a Clinical Practice Guideline` that recommended routine venous thromboembolism (VTE) prophylaxis after total joint arthroplasty. The purpose of this study was to examine (1) the change in the incidence of 90-day VTE, deep vein thrombosis, and pulmonary embolism, (2) the change in the utilization of antithrombotic agents; and (3) the change in the economic burden associated with VTE after total hip arthroplasty (THA) from 2011 to 2019.

METHODS

National, administrative claims data from 2011 to 2019 were used to identify patients who underwent primary THA for osteoarthritis. Exclusions entailed liver pathology, coagulopathy, malignancy, or those on prior prescribed blood thinners before THA. Multivariable regression was used, controlling for age and Charlson Comorbidity Index for all years, with 2011 as the reference year.

RESULTS

From 2011 to 2019, there was a significant reduction in 90-day VTE rates after THA, with a significant reduction in deep vein thrombosis and pulmonary embolism during this time frame as well. Of the antithrombotic agents prescribed after THA, the utilization of prescribed aspirin significantly increased and that of nonaspirin anticoagulants significantly decreased. Among nonaspirin anticoagulants, the utilization of direct factor Xa inhibitors and direct thrombin inhibitors significantly increased. The added reimbursements associated with VTE after THA significantly decreased during this period.

CONCLUSION

Since 2011, the incidence and economic burden associated with VTE after THA have significantly declined. In addition, there has been an increase in prescription aspirin and direct oral anticoagulants.

LEVEL OF EVIDENCE

Therapeutic, III.

Global Research Status and Trends in Venous Thromboembolism After Hip or Knee Arthroplasty From 1990 to 2021: A Bibliometric Analysis

Background

Venous thromboembolism (VTE) after hip or knee arthroplasty has attracted increasing attention over the past few decades. However, there is no bibliometric report on the publications in this field. The purpose of this study was to analyze the global research status, hotspots, and trends in VTE after arthroplasty.

Methods

All articles about VTE research after hip or knee arthroplasty from 1990 to 2021 were retrieved from the Web of Science Core Collection database. The information of each article including citation, title, author, journal, country, institution, keywords, and level of evidence was extracted for bibliometric analysis.

Results

A total of 1,245 original articles from 53 countries and 603 institutions were retrieved. The USA contributed most with 457 articles, followed by England and Canada. McMaster University in Canada was the leading institution for publications. The journals with the highest output and citation were the Journal of Arthroplasty and the Thrombosis and Haemostasis, respectively. The median number of citations was significantly different among the levels of evidence (F = 128.957, P < 0.001). The research hotspots switched from VTE diagnosis and heparin to factor Xa inhibitors (fondaparinux, rivaroxaban, apixaban) and direct thrombin inhibitors (dabigatran etexilate, ximelagatran), and finally to aspirin, risk factor studies, which can be observed from the keyword analysis and co-cited reference cluster analysis.

Conclusions

This study observed an increasing trend of research articles on VTE after arthroplasty. Publications with higher levels of evidence gained further popularity among researchers and orthopedic surgeons. Additionally, individualized VTE prevention and the development of new, safe, effective, and inexpensive oral agents would be emerging trends in the future.

Deep Vein Thrombosis in Intravenous Drug Users: An Invisible Global Health Burden

The prevalence of intravenous drug use has increased in the past decade and it represents an important risk factor for deep vein thrombosis. Intravenous drug use is a global problem, with the main culprit being heroin. Peer pressure and poverty in high-risk groups such as sex workers, females, and young adults raise the risk of intravenous drug use, which expresses itself in the form of venous thromboembolism eventually. Deep vein thrombosis typically manifests itself eight years after the initial intravenous drug administration, rendering it a silent killer. Aiming to review and summarize existing articles in this context, we performed an exhaustive literature search online on PubMed and Google Scholar indexes using the keywords "Deep Venous Thrombosis (DVT)" and "Intravenous Drug Users (IVDU)." English articles that addressed epidemiology, pathogenesis, clinical manifestations, diagnosis, differential diagnosis, management, and outcomes of DVT, including those in IVDU, were selected and analyzed. The pathogenesis of DVT development in IVDU is mainly attributed to the interplay of trauma to the vessel by repeated injection and the injected drug itself. The right-sided femoral vein is the most common vein affected. Prevalent clinical presentations include local pain, swelling, and redness with typical systemic symptoms including fever, cough, dyspnea, and chest pain on top of addiction features. There appeared to be a delay in reporting symptoms, which was most likely due to the social stigma attached to IVDU. There are over 50 conditions that present with swollen and painful limbs comparable to DVT in IVDU, making precise diagnosis critical for timely treatment. Venous ultrasound is the method of choice for diagnosing DVT. Extended anticoagulant therapy with low-molecular-weight heparin combined with warfarin is the recommended treatment. Intravenous drug abusers having DVT are affected by multiple complications and poorer outcomes such as slower recovery, recurrent venous thromboembolism (VTE), and a longer hospital stay, which put them at higher risk of morbidity, mortality, reduced productivity, and economic burden.

A risk-stratified approach to venous thromboembolism prophylaxis with aspirin or warfarin following total hip and knee arthroplasty: A cohort study

INTRODUCTION

Venous thromboembolism (VTE) and bleeding events following total knee and hip arthroplasty (TKA/THA) are associated with significant morbidity. Clinical guidelines recommend administration of pharmacologic VTE prophylaxis post-operatively, although controversy exists regarding optimal prophylactic strategies.

METHODS

We performed a retrospective cohort study in patients who underwent elective TKA/TKA in an academic medical center. Patients were stratified by surgery type (TKA/THA) and VTE risk determined by a novel risk stratification protocol and compared pre- and post-protocol implementation. Patients received warfarin pre-protocol and either aspirin or warfarin post-protocol for VTE prophylaxis. Natural language processing identified VTE events and ICD codes were used to identify bleeding events, with all events validated manually.

RESULTS

A total of 1379 surgeries were included for analysis, 839 TKAs and 540 THAs. Post-protocol implementation, 445 (94.1%) patients following TKA and 294 (97.4%) patients following THA received aspirin for VTE prophylaxis. A significant reduction in bleeding events (hazard ratio [HR] = 0.19, p = 0.048) was observed in low-risk THA patients treated with aspirin (post-protocol) compared patients treated with warfarin (pre-protocol). Bleeding events did not differ significantly between low-risk TKA patients treated with aspirin or warfarin. No significant differences in VTE events were observed following the protocol implementation.

CONCLUSIONS

The use of a novel risk stratification system to guide VTE prophylaxis selection between aspirin or warfarin following TKA and THA appears safe and effective. Among low-risk patients, aspirin use was associated with fewer bleeding events following THA, without an observed increase in VTE events.

Venous Thromboembolic Prophylaxis After Total Hip and Knee Arthroplasty

➤

The selection of an agent for prophylaxis against venous thromboembolism (VTE) is a balance between efficacy and safety. The goal is to prevent symptomatic VTE while limiting the risk of bleeding.

➤

The optimal agent for VTE prophylaxis has not been identified. The American College of Chest Physicians guidelines recommend that, after total hip or total knee arthroplasty, patients receive at least 10 to 14 days of 1 of the following prophylaxis agents: aspirin, adjusted-dose vitamin K antagonist, apixaban, dabigatran, fondaparinux, low-molecular-weight heparin, low-dose unfractionated heparin, rivaroxaban, or portable home mechanical compression.

➤

The use of aspirin for VTE prophylaxis has increased in popularity over the past decade because it is effective, and it is an oral agent that does not require monitoring. The true efficacy of aspirin needs to be determined in multicenter randomized clinical trials.

➤

Validated risk stratification protocols are essential to identify the safest and most effective regimen for VTE prophylaxis for individual patients. There is no consensus regarding the optimal method for risk stratification; the selection of a prophylaxis agent should be determined by shared decision-making with the patient to balance the risk of thrombosis versus bleeding.

➤

Patients with atrial fibrillation being treated with chronic warfarin therapy or direct oral anticoagulants should stop the agent 3 to 5 days prior to surgery. Patients do not typically require bridging therapy prior to surgery.

Ranking the efficacy of anticoagulants for the prevention of venous thromboembolism after total hip or knee arthroplasty: A systematic review and a network meta-analysis

BACKGROUND

Anticoagulants are essential in the prevention of venous thromboembolism. However, the effectiveness and safety of different anticoagulants have always been controversial. Therefore, we aimed to expand the sample of anticoagulant results and rank the efficacy and safety of 19 anticoagulants in the prevention of venous thromboembolism when total knee or total hip arthroplasty procedure is performed.

METHODS

A systematic review and network meta-analysis of randomized trials of adult patients undergoing total hip or knee arthroplasty were conducted. The trials were identified from PubMed, Web of Science, Cochrane Library, and Embase databases, in which anticoagulants were used as interventions randomized controlled trial. The incidence of venous embolism and bleeding are the key outcomes of assessing the efficacy of intervention drugs. We used the Physical Therapy Evidence Database (PEDro) to assess risk bias and used pairwise comparison and network meta-analysis with random effects to estimate the summary relative risk. The study has been registered with PROSPERO, number CRD42020200747.

RESULTS

From the 4083 identified manuscripts, 45,067 participants from 53 randomized trials were included in the analysis and randomly assigned to 19 anticoagulants. With Enoxaparin as a control, Rivaroxaban (risk difference 0.07, 95 % credible interval 0.06 to 0.08), Edoxaban (RD 0.09, 95 % CrI 0.08 to 0.11), and Apixaban (RD 0.05, 95 % CrI 0.04 to 0.06) had the best effect in preventing VTE. However, in terms of comprehensive bleeding rate, Apixaban, Edoxaban, and Darexaban were the most effective and stable. Although effective in preventing VTE, bleeding remains relatively high in Rivaroxaban. Enoxaparin is low-molecular-weight heparin that is widely used in clinics, and although its overall efficacy is not the best, its efficacy and safety are very stable.

CONCLUSION

According to the available data, Apixaban, Edoxaban, and Darexaban are better than any anticoagulants in the prevention of VTE and bleeding during total knee or total hip arthroplasty. In our study, Fondaparinux, Eribaxaban, Dalteparin, Betrixaban, Bemiparin, Reviparin, Acenocoumarol, and Tinzaparin were scarce in the included studies, therefore, more evidence is needed to prove their efficacy and safety.

A Prospective Cohort Comparative Study of Rivaroxaban, Dabigatran, and Apixaban Oral Thromboprophylaxis in 2431 Hip and Knee Arthroplasty Patients: Primary Efficacy Outcomes and Safety Profile

BACKGROUND

Direct oral anticoagulants (DOACs) have promised superior efficacy to low molecular weight heparins in the prevention of venous thromboembolism (VTE) in total hip and knee arthroplasty. However, there are concerns about raised associated bleeding and wound problems with these agents. This study aims to evaluate and compare the efficacy and safety of the 3 DOAC drugs: rivaroxaban, dabigatran and apixaban.

METHODS

The primary outcome measures were rate of symptomatic VTE and major bleeding. Secondary outcome measures were wound healing problems and requirement for return to theater. A total of 2431 patients received one of the DOAC drugs as thromboprophylaxis following total hip arthroplasty (35 days) or total knee arthroplasty (14 days) between 2011 and 2015. Binary variables were compared between the 3 groups by using the chi-squared test or Fisher's exact test. Relative risks of selected primary and secondary end points were also calculated for the prespecified pairwise comparison.

RESULTS

The overall symptomatic VTE rate was 2%. Rivaroxaban had a statistically significant superior efficacy for overall VTE prevention (0.8% vs 2.6%) compared with dabigatran (P < .01) and apixaban (P < .01), and deep vein thrombosis prevention (0.3% vs 2.2%) over dabigatran (P < .01). The overall rate of major bleeding was 1.2% with no significant difference observed between the 3 studied drugs.

CONCLUSION

All 3 drugs had symptomatic VTE rates comparable with low molecular weight heparin from the published literature. Rivaroxaban appears to have superior efficacy in VTE prevention over apixaban and dabigatran. No statistical difference was observed for major bleeding with any of the 3 agents.

Temporal trends in pharmacologic prophylaxis for venous thromboembolism after hip and knee replacement in older adults

Trends in prescription for venous thromboembolism (VTE) prophylaxis following total hip (THR) and knee replacement (TKR) since the approval of direct oral anticoagulants (DOACs) and the 2012 guideline endorsement of aspirin are unknown, as are the risks of adverse events. We examined practice patterns in the prescription of prophylaxis agents and the risk of adverse events during the in-hospital period (the 'in-hospital sample') and 90 days following discharge (the 'discharge sample') among adults aged ⩾ 65 undergoing THR and TKR in community hospitals in the Institute for Health Metrics database over a 30-month period during 2011 to 2013. Eligible medications included fondaparinux, DOACs, low molecular weight heparin (LMWH), other heparin products, warfarin, and aspirin. Outcomes were validated by physician review of source documents: VTE, major hemorrhage, cardiovascular events, and death. The in-hospital and the discharge samples included 10,503 and 5722 adults from 65 hospitals nationwide, respectively (mean age 73, 74 years; 61%, 63% women). Pharmacologic prophylaxis was near universal during the in-hospital period (93%) and at discharge (99%). DOAC use increased substantially and was the prophylaxis of choice for nearly a quarter (in-hospital) and a third (discharge) of the patients. Aspirin was the sole discharge prophylactic agent for 17% and 19% of patients undergoing THR and TKR, respectively. Warfarin remained the prophylaxis agent of choice for patients aged 80 years and older. The overall risk of adverse events was low, at less than 1% for both the in-hospital and discharge outcomes. The low number of adverse events precluded statistical comparison of prophylaxis regimens.

Stratifying Venous Thromboembolism Risk in Arthroplasty: Do High-Risk Patients Exist?

BACKGROUND

While there are many possible complications associated with total joint arthroplasty (TJA), venous thromboembolism (VTE) is both frequent and potentially severe. Despite this importance, there are inconsistent recommendations for prophylaxis based on patient risk factors.

METHODS

A predictive model was constructed to compare low-molecular-weight heparin(LMWH) and aspirin (ASA) for prevention of VTE-associated complications following TJA.The model used risks from prior prophylaxis studies to estimate the risk of developing a symptomatic deep vein thrombosis, pulmonary embolism, thrombocytopenia, and operative or nonoperative site bleeding. We also evaluated the progression to 4 possible final health states: postphlebitis syndrome, intracranial hemorrhage, death, or baseline health. Within published ranges, we selected assumptions that were favorable to LMWH such that these analyses represent a best case scenario for LMWH or an alternative more aggressive low-molecular-weight heparin alternative (LMWHA). Events and outcomes were assigned quality-adjusted life-year (QALY) losses according to prior studies to determine the effect on patients' outcomes for ASA and LMWHA prophylaxis.

RESULTS

Assessing VTE risk populations from 0.2% to 2% with life expectancies ranging from 5 to 40 years postoperatively, patients with a risk ratio less than 3.7 showed increased expected QALY with ASA compared to LMWHA. For patients with a baseline VTE risk of 1% and a 15 year life expectancy, a risk ratio of 13.4 was needed to identify patients that would benefit from LMWHA. With life expectancy increased to 30 years, the risk ratio needed to idetify these patients was 7.4.

CONCLUSION

Patients undergoing TJA should receive ASA chemoprophylaxis in nearly all situations, unless the patient has a significantly increased VTE risk compared to the baseline population and a long life expectancy.

American Society of Hematology 2019 guidelines for management of venous thromboembolism: prevention of venous thromboembolism in surgical hospitalized patients

BACKGROUND

Venous thromboembolism (VTE) is a common source of perioperative morbidity and mortality.

OBJECTIVE

These evidence-based guidelines from the American Society of Hematology (ASH) intend to support decision making about preventing VTE in patients undergoing surgery.

METHODS

ASH formed a multidisciplinary guideline panel balanced to minimize bias from conflicts of interest. The McMaster University GRADE Centre supported the guideline-development process, including performing systematic reviews. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used to assess evidence and make recommendations, which were subject to public comment.

RESULTS

The panel agreed on 30 recommendations, including for major surgery in general (n = 8), orthopedic surgery (n = 7), major general surgery (n = 3), major neurosurgical procedures (n = 2), urological surgery (n = 4), cardiac surgery and major vascular surgery (n = 2), major trauma (n = 2), and major gynecological surgery (n = 2).

CONCLUSIONS

For patients undergoing major surgery in general, the panel made conditional recommendations for mechanical prophylaxis over no prophylaxis, for pneumatic compression prophylaxis over graduated compression stockings, and against inferior vena cava filters. In patients undergoing total hip or total knee arthroplasty, conditional recommendations included using either aspirin or anticoagulants, as well as for a direct oral anticoagulant over low-molecular-weight heparin (LMWH). For major general surgery, the panel suggested pharmacological prophylaxis over no prophylaxis, using LMWH or unfractionated heparin. For major neurosurgery, transurethral resection of the prostate, or radical prostatectomy, the panel suggested against pharmacological prophylaxis. For major trauma surgery or major gynecological surgery, the panel suggested pharmacological prophylaxis over no prophylaxis.

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.

A prospective randomized comparative study to determine appropriate edoxaban administration period, to prevent deep vein thromboembolism in patients with total knee arthroplasty

BACKGROUND

This study aimed to determine the appropriate administration duration of edoxaban 15 mg (a factor Xa inhibitor) for the prevention of deep vein thrombosis (DVT) after total knee arthroplasty (TKA).

METHODS

Our study comprised 202 patients who underwent TKA (excluding bilateral TKA) at our institution between 2014 and 2015. The subjects received edoxaban 15 mg daily for 1 (n = 93) or 2 (n = 109) weeks; group assignment was random. B-mode ultrasonography was performed 7 and 14 days post-TKA for the detection of DVT. We compared the incidence of DVT between the groups and examined for side effects.

RESULTS

The demographic data of the patients in the 1- and 2-week administration groups were similar at baseline. DVT incidence did not differ significantly between the groups at 1 week post-TKA. However, it was significantly lower in the 2-week administration group (n = 0) than in the 1-week administration group (n = 7; p = 0.004) at 2 weeks post-DVT. Neither group exhibited symptomatic DVT. A total of six patients withdrew during the study period because of hepatic dysfunction.

CONCLUSIONS

Our results show that the administration of edoxaban 15 mg is more effective in preventing DVT after TKA when administered for 2 weeks than for 1 week.

Plasma D-dimer is not useful in the prediction of deep vein thrombosis after total knee arthroplasty in patients using rivaroxaban for thromboprophylaxis

Background

Venous thromboembolism (VTE) is a serious complication following total joint replacement. The use of rivaroxaban, a highly selective and direct factor Xa inhibitor, has been used widely as a safe and efficacious way to prevent VTE after total joint replacements. However, little is known about the diagnostic efficacy of plasma D-dimer test on deep vein thrombosis (DVT) in patients using rivaroxaban for thromboprophylaxis. The study is aimed to investigate the trend and the diagnostic efficacy of D-dimer test on DVT in patients with primary total knee arthroplasty (TKA) using rivaroxaban for thromboprophylaxis.

Methods

Two hundred TKA patients using rivaroxaban postoperatively as chemical prophylaxis were reviewed. D-dimer levels were checked at 4 h after the surgery and on postoperative days 1 and 4. Venography was used to document the presence of DVT. The Mann-Whitney U test was used to detect the differences in the D-dimer levels at different time points in patients with and without DVT, followed by Bonferroni corrections for p values. Receiver operating characteristics (ROC) curves were constructed to determine the best cutoff values of the D-dimer test at each time point after the surgery.

Results

Twenty-nine of the 200 patients were found to have deep vein thrombosis by venography, resulting in an incidence of 14.5%. All patients with DVTs occurred in the distal calf veins, and only one patient was symptomatic. We found significant differences in D-dimer concentration between patients with and without DVT at postoperative day 4. The best cutoff value determined by receiver operating characteristics analysis was 3.8 mg/L at postoperative day 4, with an AUC equal to 63.5%, and a sensitivity, specificity, PPV, and NPV of 58.6, 76, 29.3, and 91.5%, respectively.

Conclusions

Rivaroxaban was effective on reducing DVT in patients undergoing TKA. Because all the DVTs occurred in the leg veins, decreased thrombus volume and size might result in poor accuracy of plasma D-dimer test in prediction or diagnosis of postoperative DVT.

Venous Thromboembolism Prophylaxis in Total Hip Arthroplasty and Total Knee Arthroplasty Patients: From Guidelines to Practice

Venous thromboembolism (VTE) prophylaxis is recommended for all patients undergoing total hip arthroplasty or total knee arthroplasty. The selection of an appropriate prophylaxis regimen represents a balance between efficacy and safety. To help orthopaedic surgeons select an appropriate VTE prophylaxis regimen for their patients, the American Academy of Orthopaedic Surgeons and the American College of Chest Physicians have developed guidelines. These guidelines do not recommend an optimal regimen, however. Rather, an individualized prophylaxis regimen that balances efficacy and safety is recommended for each patient, based on various risk factors. Because of a paucity of data and a lack of adequately powered head-to-head trials, implementing these guidelines can be challenging for the orthopaedic surgeon. Knowledge of the prophylaxis options and the VTE risk factors is paramount for developing an effective VTE prophylaxis algorithm for the surgeon's practice.

Low-Molecular-Weight Heparin and the Relative Risk of Surgical Site Bleeding Complications: Results of a Systematic Review and Meta-Analysis of Randomized Controlled Trials of Venous Thromboprophylaxis in Patients After Total Joint Arthroplasty

BACKGROUND

Venous thromboembolism causes significant morbidity and mortality in patients after total joint arthroplasty. Although network meta-analyses have demonstrated a benefit of various thromboprophylactic agents, there remains a concern in the surgical community regarding the resulting wound complications. There is currently no systematic review of the surgical site bleeding complications of thromboprophylactic agents. The aim of this study was to systematically review the surgical site bleeding outcomes of venous thromboembolism prophylaxis in this population.

METHODS

A systematic review and meta-analysis was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Randomized controlled trials comparing more than one of low-molecular-weight heparin (LMWH), warfarin, rivaroxaban, apixaban, dabigatran, aspirin, or no pharmacologic treatment in patients after total hip or knee arthroplasty were selected for inclusion. Five meta-analyses were performed to compare LMWH with control, warfarin, apixaban, rivaroxaban, and dabigatran.

RESULTS

Forty-five randomized controlled trials of 56,730 patients were included. LMWH had a significantly increased relative risk of surgical site bleeding in comparison with control (relative risk, 2.32; 95% confidence interval, 1.40-3.85) and warfarin (1.54; 1.23-1.94). The relative risk of LMWH trended higher than apixaban (1.27; 1.00-1.63) and was similar to rivaroxaban (0.95; 0.74-1.23). Only 1 study reported the risk of surgical site bleeding in LMWH vs dabigatran (5.97; 2.08-17.11).

CONCLUSION

LMWH increased the risk of surgical site bleeding compared with control, warfarin. and dabigatran and trended toward an increased risk compared with apixaban. The risk of surgical site bleeding was similar with LMWH and rivaroxaban.

Low-Dose Warfarin for Prevention of Symptomatic Thromboembolism after Orthopedic Surgery

BACKGROUND:

Warfarin dosing with a target international normalized ratio (INR) range of 1.5–2.5 has not been reported as adequate for venous thromboembolism (VTE) prophylaxis after total knee (TKR) and total hip replacement (THR) surgery. OBJECTIVE: To evaluate the rate of symptomatic VTE after TKR and THR surgery using a low-dose (INR 1.5–2.5) warfarin protocol started the evening before surgery compared with a literature cohort treated with enoxaparin.

METHODS:

TKR/THR patients treated with a 21-day low-dose warfarin protocol were followed via a consecutive observational design. Main outcome measures were symptomatic VTE and pulmonary embolism (PE), with major bleeds and death as secondary outcomes. Low-dose warfarin was compared with a literature cohort of patients treated with enoxaparin who received enoxaparin for a similar length of time and was evaluated for the same outcomes. Cohort event rates were derived as a weighted average using the DerSimonian model.

RESULTS:

VTE, PE, bleeds, and deaths in the low-dose warfarin group were 8 (1.04%), 4 (0.52%), 8 (1.04%), and 4 (0.52%), respectively. The cohort weighted average values were 35 (1.33%), 19 (0.72%), 65 (2.46%), and 18 (0.67%), respectively. Odds ratios for low-dose warfarin for VTE, PE, and VTE plus PE were 0.778 (95% CI 0.36 to 1.68), 0.717 (0.24 to 2.11), and 0.754 (0.41 to 1.42), respectively, all nonsignificant. Odds ratios for bleeds and death were 0.420 (0.20 to 0.87; p = 0.02) and 0.756 (0.26 to 2.24; NS), respectively.

CONCLUSIONS:

For this evaluation, low-dose warfarin was comparable to the enoxaparin cohort for development of VTE, PE, and VTE+PE. Incidences of bleeds in the enoxaparin cohort were significantly higher than in patients receiving low-dose warfarin.

Choosing the Appropriate Antithrombotic Agent for the Prevention and Treatment of VTE: A Case-Based Approach

Objective:

To review the risk of venous thromboembolism (VTE) in various patient populations and evaluate the agents available for the prevention and treatment of VTE using a case-based approach.

Data Sources:

A MEDLINE search (1995–July 2006) was conducted to identify relevant literature. Additional references were reviewed from selected articles.

Study Selection and Data Extraction:

Articles related to the prevention of VTE in orthopedic surgery, general surgery, and medically ill patients, as well as the treatment of VTE, were reviewed.

Data Synthesis:

Pharmacologic options for the prevention and treatment of VTE include warfarin, unfractionated heparin (UFH), low-molecular-weight heparins (LMWH), and fondaparinux. Current guidelines support the use of warfarin, LMWH, or fondaparinux for VTE prophylaxis following lower limb major orthopedic surgery. For VTE prophylaxis in hospitalized medical patients or patients undergoing general surgery, use of UFH and LMWH is supported; however, recent data on fondaparinux suggest that it is also effective in these patient populations. The use of UFH or LMWH (both in conjunction with warfarin) for treatment of acute deep venous thrombosis or nonmassive pulmonary embolism is recommended. Recent data suggest that fondaparinux (in conjunction with warfarin) is also effective for the treatment of VTE. A variety of pharmacokinetic, pharmacodynamic, and pharmacoeconomic factors differentiate each agent for the various indications.

Conclusions:

Currently, a “one-size-fits-all” anticoagulant is not available for treatment of VTE. A variety of patient factors, including type of surgery, medical indication, thrombotic risk factors, bleeding risk, history of heparin-induced thrombocytopenia, and a variety of comorbid conditions can affect the safety, efficacy, and selection of appropriate VTE therapy.

Cost implications of low molecular weight heparins as prophylaxis following total hip and knee replacement

Deep venous thrombosis (DVT) and pulmonary embolism (PE) are serious and costly complications of total hip and knee replacement surgery. The risk of these complications is significantly reduced by prophylaxis. Low molecular weight heparins (LMWH) are being used for this indication with increased frequency. The objective of this study was to assess the cost implications of LMWH for the prevention of symptomatic DVT and PE complications following total hip and knee replacement surgery. The study design was cost analysis based on utilization and the costs of medical resources for prophylaxis and treatment of DVT/PE. A retrospective hospital data set was used to assess symptomatic DVT/PE complication rates and medical resource utilization in patients receiving warfarin, other, and no prophylaxis. The results of a clinical trial were used to estimate relative reductions in risk of symptomatic DVT/PE due to prophylaxis with LMWH. The 7721 total hip and knee replacement patients analyzed were admitted in 1992 in 57 acute-care non-federal hospitals. The measurements were of incremental costs or charges expected to be saved as a result of using LMWH prophylaxis instead of warfarin prophylaxis. Prophylaxis using LMWH rather than warfarin reduces the expected total costs (charges) of treatment by $50 ($193), not including the pharmaceutical costs associated with prophylaxis. The cost reduction in favor of LMWH was sensitive to several factors, including blood monitoring costs and DVT/PE complication rates. Where a reduction of one day in hospital stay could be realized from LMWH's early onset of action, the cost (charges) reduction increased to $226 ($624). In conclusion, LMWH has the potential to offer several short- and long-term cost advantages compared with warfarin, mostly due to lower test costs associated with prophylaxis and reduced complication rates.

Duplex Ultrasonography Has Limited Utility in Detection of Postoperative DVT After Primary Total Joint Arthroplasty

BACKGROUND

Duplex ultrasound is routinely used to evaluate suspected deep venous thrombosis after total joint arthroplasty. When there is a clinical suspicion for a pulmonary embolism, a chest angiogram (chest CTA) is concomitantly obtained.

QUESTIONS/PURPOSES

Two questions were addressed: First, for the population of patients who receive duplex ultrasound after total joint arthroplasty, what is the rate of positive results? Second, for these patients, how many of these also undergo chest CTA for clinical suspicion of pulmonary embolus and how many of these tests are positive? Furthermore, what is the correlation between duplex ultrasound results and chest CTA results?

METHODS

A retrospective chart review was conducted of total joint replacement patients in 2011 at a single institution. Inclusion criteria were adult patients who underwent a postoperative duplex ultrasonography for clinical suspicion of deep venous thrombosis (DVT). Demographic data, result of duplex scan, clinical indications for obtaining the duplex scan, and DVT prophylaxis used were recorded. Additionally, if a chest CTA was obtained for clinical suspicion for pulmonary embolus, results and clinical indication for obtaining the test were recorded. The rate of positive results for duplex ultrasonography and chest CTA was computed and correlated based on clinical indications.

RESULTS

Two hundred ninety-five patients underwent duplex ultrasonography of which only 0.7% were positive for a DVT. One hundred three patients underwent a chest CTA for clinical suspicion of a pulmonary embolism (PE) of which 26 revealed a pulmonary embolus, none of which had a positive duplex ultrasound.

CONCLUSION

Postoperative duplex scans have a low rate of positive results. A substantial number of patients with negative duplex results subsequently underwent chest CTA for clinical suspicion for which a pulmonary embolus was found, presumably resulting from a DVT despite negative duplex ultrasound result. A negative duplex ultrasonography should not rule out the presence of a DVT which can embolize to the lungs and thus should not preclude further workup when clinical suspicion exists for a pulmonary embolus.

Therapeutic Update on the Prevention and Treatment of Venous Thromboembolism

Venous thromboembolism (VTE) is a common condition that increases in incidence with age and risk factors. Therapies for VTE are aimed at either preventing the disease in high-risk individuals or treating patients who have developed VTE. Assessing risk and aggressively using the recommended therapies is primacy in preventing VTE in surgical and medical patients. Risk of VTE in medical patients has become more defined in recent years, and prophylaxis in this group can prevent scores of iatrogenic VTE. Treatment of VTE has evolved in the past decade from a condition that required hospitalization for 5 to 7 days to a disease state that can be conveniently and safely treated on an outpatient basis, largely due to the advent of low-molecular-weight heparins and patient self-directed treatment.

Minidose Warfarin and Failure to Prevent Deep Vein Thrombosis After Joint Replacement Surgery Despite Inhibiting the Postoperative Rise in Plasminogen Activator Inhibitor Activity

In a prospective randomised study in patients undergoing elective total hip or knee replacement surgery, the antithrombotic efficacy of fixed-minidose warfarin (1 mg daily commenced 7 days before surgery) was compared with that of subcutaneous calcium heparin (Calciparine, 5,000 IU t.d.s. commenced 2 h before surgery). Both regimens were continued until venography of the operated limb was performed 9-14 days postsurgery. Venographically detected deep vein thromboses (DVTs) occurred in 15 of the 31 patients (48.4%) in the minidose warfarin group and in eight of the 37 patients (21.6%) receiving heparin. The absolute difference in the incidence of DVT was 26.8% in favour of heparin (95%l confidence interval [CI] -4.&--48.8%; p = 0.039). Proximal DVTs were detected in three patients receiving minidose warfarin and in none of those on heparin (p = 0.09). Minidose warfarin appeared to prevent the postoperative rise in the activity of plasminogen activator inhibitor (PAI) that occurred with heparin, although preoperative PAI activity was greater in the warfarin group. The prothrombin time (PT) and activated partial thromboplastin time (APTT) were within the normal range on the day of surgery in both treatment groups. Postsurgery, the minidose warfarin regimen produced a small, but significant prolongation of the PT compared with the group receiving heparin, In contrast to heparin, 1 mg warfarin daily failed to prevent postoperative acceleration of the APTT. There was no significant difference between the two regimens in bleeding complications. In conclusion, the fixed-minidose warfarin regimen cannot be recommended for prevention of DVT after hip or knee replacement surgery. Inhibition of the postoperative rise in PAI activity appears not to protect against DVT after major joint replacement surgery. Key Words: Warfarin—Heparin—Deep vein thrombosis prophylaxis—Coagulation—Fibrinolysis— Plasminogen activator inhibitor.

Cost-Effectiveness of Venous Thromboembolism Prophylaxis after Total Hip Replacement

Objective:

To determine the cost-effectiveness of three strategies used for the prevention of venous thromboem-bolism (VTE) in patients undergoing total hip replace-ment (THR), and to perform a sensitivity analysis comparing VTE rates based on different methods of detection.

Methods:

In this cost-effectiveness analysis, three strategies of prophylaxis of postoperative VTE and THR were compared: (1) low-molecular-weight heparin (LMWH); Enoxaparin, (2) warfarin and (3) a combination of warfarin, heparin (UFH), graduated stockings and sequential long-leg pneumatic compression devices. The model estimates were based on pooled data from the published literature and from personal data in our series of hip replacement patients. Expected direct costs of VTE care, including prophylaxis, diagnosis and manage-ment of thromboembolic and hemorrhagic complications, were estimated for a hypothetical cohort of 100 patients in 2001 US dollars from data available for patients hospitalized at Evanston Northwestern Health-care. A sensitivity analysis was performed with different rates of VTE based on routine venography, routine duplex ultrasound, or selective diagnosis and treatment of symptomatic patients.

Results:

When venography was used to diagnose VTE, the cost of warfarin or LMWH treatment was $118 422 and $104 732 per 100 patients, respectively, providing cost savings of $ 13 690 per hundred patients for LMWH. When VTE rates were based on duplex ultrasound diagnoses, LMWH resulted in cost savings of $4602 and $1345 per 100 patients compared with the use of warfarin or the combined approach, respectively. However, when the rates of VTE were based on confirmed symptomatic cases, the use of LMWH resulted in an increased cost of $4486 and $10015 per 100 patients compared with warfarin and the combined approach, respectively.

Conclusions:

The use of LMWH for the prevention of VTE after THR was more cost-effective than using warfarin or the combined approach, when the VTE rate was based on routine venography or duplex ultrasound. However, the combined approach was more cost-effective than the use of warfarin or LMWH alone when only patients with confirmed, symptomatic VTE were treated.

Risk of and Prophylaxis for Venous Thromboembolism in Hospital Patients

Objective:

To review the published clinical data on prophylaxis for thromboembolism in order to develop general guidelines to encourage the establishment of local protocols for management.

Data sources:

Published papers on thromboembolism over the period 1991–1997 were identified by Medline search and/or from the authors' personal literature collections and reviewed.

Study selection:

A total of 981 studies were identified. Only those papers reporting randomized studies with clearly defined diagnostic methods and clear end-points were included in this review.

Data extraction:

The available evidence for each specialty was summarized and reviewed by the authors responsible for each specialty, prior to presentation and discussion of their findings within the group. Where a consensus opinion was achieved in a speciality, general guidelines for thromboprophylaxis were summarized. Where a consensus could not be agreed, recommendations for further work were made.

Data synthesis:

There is evidence to support the preferred use of low-molecular-weight heparins (LMWHs) over unfractionated heparin (UFH) in orthopaedic surgery, major trauma and general surgery. However, the ideal duration of thromboprophylaxis has yet to be defined. The use of once daily subcutaneous administration of LMWH offers major practical advantages and may have significant cost saving implications. Further work is required to investigate the use of thromboprophylaxis in minimal access surgery, trauma, elective lower limb surgery, hip fracture and pregnancy; to compare the efficacy of LMWH and mechanical prophylaxis; and to investigate extended prophylaxis after discharge.

Conclusions:

There is overwhelming evidence that thromboembolic prophylaxis reduces the incidence of postoperative deep vein thrombosis and pulmonary embolism. Recommendations concerning the management of these patients when stratified into low, moderate and high risk are made with the suggestion that hospitals develop their own guidelines for the treatment of these patients.

A novel sensitive and selective electrochemical sensor based on molecularly imprinted polymer on a nanoporous gold leaf modified electrode for warfarin sodium determination

A novel electrochemical sensor was facilely fabricated by coupling nanoporous gold leaf (NPGL) with molecularly imprinted polymer (MIP), and afforded ultrasensitive and selective determination of warfarin sodium (WFS).

Thromboprophylaxis with apixaban and the risk of pulmonary embolism in patients undergoing knee replacement surgery

Background

Apixaban, a novel oral anticoagulant, is also used for deep vein thrombosis (DVT) prophylaxis. In this study, we sought to critically evaluate the differences in the rates of symptomatic DVT and bleeding, and analyze the rates of pulmonary embolism (PE) in subgroups of patients from ADVANCE I and II trials given their similar indication and design.

Methods

Studies were identified through electronic literature searches of MEDLINE, clinicaltrial.gov, SCOPUS, and EMBASE up to January 2014. Phase III RCTs involving use of apixaban and enoxaparin for thromboprophylaxis in patients undergoing total knee or hip replacement were included. Study-specific odds ratios were calculated and between-study heterogeneity was assessed using the I² statistics.

Results

In three studies involving 11,659 patients, the risk of symptomatic DVT (pooled OR 0.38, 95% CI 0.16–0.90, I²=0%, p=0.03) and bleeding (pooled OR 0.87, 95% CI 0.77–0.99, I²=0%, p=0.03) was less in apixaban group compared to the enoxaparin group. However, it was interesting to note that on subgroup analysis, the risk of PE was higher with apixaban when used for thromboprophylaxis in knee replacement surgery (pooled OR 2.58, 95% CI 1.10–6.04, I²=0%, p=0.03).

Conclusion

Apixaban was found to be associated with lower risk of symptomatic DVT and bleeding compared to enoxaparin when used for thromboprophylaxis in patients undergoing knee and hip replacement surgeries. However, it was associated with higher risk of PE in patients undergoing knee replacement.

Lack of consistency in the relationship between asymptomatic DVT detected by venography and symptomatic VTE in thromboprophylaxis trials

Asymptomatic deep-vein thrombosis (DVT) detected by mandatory venography, a surrogate outcome, comprises most of the efficacy outcome events in recent thromboprophylaxis trials. The validity of this surrogate to estimate trade-off between thrombotic and bleeding events in these clinical trials requires a consistent relationship between asymptomatic DVT and symptomatic venous thromboembolism (VTE). In this systematic review of high quality VTE prevention trials, we examined the consistency of the ratios of asymptomatic DVT to symptomatic VTE across a broad range of indications. Studies were identified from citations listed in the chapters on VTE prevention in the antithrombotic guidelines by the American College of Chest Physicians, 2012. A study was eligible if it: 1) was a randomised trial comparing an anticoagulant with standard of care; 2) included at least 500 participants; 3) reported asymptomatic or all DVT rates; and 4) reported symptomatic VTE rates. Of the 26 eligible trials, 19 trials were conducted in orthopaedic patients, five in general surgery patients and two in general medical patients. The overall median rates (ranges) for asymptomatic DVT and symptomatic VTE were 9.11 % (0.75 to 54.87 %) and 0.49 % (0.00 to 3.10 %), respectively. The median ratio was 14.53, with a wide range (2.75 to 103.86). Wide variability in the ratios persisted despite indication- and anticoagulant-specific analyses. In VTE prevention trials of alternative anticoagulants, the wide variability in the ratios of asymptomatic DVT to symptomatic VTE precludes judging the trade-off between thrombotic and bleeding events on the basis of composite outcomes dominated by venographic DVT.

Using new oral anticoagulants in patients undergoing major orthopedic surgery

Four new oral anticoagulants (NOAC), apixaban, rivaroxaban, edoxaban, and dabigatran, are now available in the USA; however, only apixaban and rivaroxaban are FDA approved for the prevention of venous thromboembolism following orthopedic surgery. Apixaban, rivaroxaban, and edoxaban's anticoagulant activity can be measured using a chromogenic anti-factor Xa assay but there is no widely available means of measuring dabigatran blood levels. None of the NOAC has an antidote. Dabigatran is 80% renally excreted, and patients with atrial fibrillation taking dabigatran for stroke prevention should stop the drug 4-5 days prior to major orthopedic surgery. Apixaban, rivaroxaban, and edoxaban should be held for 48 h preoperatively in this setting.

Venous thromboembolism prophylaxis after total joint arthroplasty

Venous thromboembolism (VTE) prophylaxis after total joint arthroplasty is considered best practice. However, over the past 5 years, there has been considerable debate about the ideal prophylactic regimen or modality. The American Academy of Orthopaedic Surgeons and the American College of Chest Physicians published their most recent clinical practice guidelines about VTE prophylaxis in 2011 and 2012, respectively. In addition, the Surgical Care Improvement Project published their latest recommendations in 2014. In this review, commonly used VTE prophylaxis options and the latest clinical guidelines will be discussed.

Comparative lower limb hemodynamics using neuromuscular electrical stimulation (NMES) versus intermittent pneumatic compression (IPC)

Deep Vein Thrombosis (DVT) is a life threatening condition and a serious concern among hospitalised patients, with death occurring in approximately 6% of cases. Intermittent pneumatic compression (IPC) is commonly used for DVT prevention, however suffers from low compliance and issues of usability and portability. Neuromuscular electrical stimulation (NMES) has been shown to improve lower limb hemodynamics but direct comparison with IPC in terms of hemodynamics is rare but very important to determine the potential effectiveness of NMES in DVT prevention.Lower limb IPC was compared to calf NMES, in 30 healthy volunteers (18-23 years). Each intervention was carried out on each leg, on the popliteal vein measured using Doppler ultrasound. All interventions produced significantly greater haemodynamic responses compared to baseline. Calf-IPC and NMES produced significant increases in venous blood velocity (cm/s) and volume of blood ejected per cycle (1 cycle of NMES expels 23.22 ml compared to the baseline ejected volume of 2.52 ml, measured over 1 s (p < 0.001 versues baseline).Improving lower limb hemodynamics is vital in preventing DVT. NMES resulted in larger ejected volumes compared to IPC (x3 greater than foot-IPC and x1.7 greater than calf-IPC) more effectively emptying the veins and soleal sinuses. This is an important finding as DVT occurs predominantly in the soleal sinuses. NMES is silent and portable and thus does not suffer many of the issues associated with IPC. This work supports the potential widespread application of NMES in hospital and home settings where the risk of DVT formation is high.

Venous Thromboembolism (VTE) Prophylaxis for Hip and Knee Arthroplasty: Changing Trends

Venous thromboembolism (VTE) has been identified as an immediate threat to patients undergoing major orthopedic procedures such as total hip arthroplasty (THA) and total knee arthroplasty (TKA). Given the known dangers of VTE, arthroplasty surgeons are sensitive to the need for VTE thromboprophylaxis. However, the modalities of thromboprophylaxis used to minimize the risks to patients have been variable. Clinical practice guidelines have been published by several professional organizations, while some hospitals have established their own protocols. The 2 most popular guidelines are those published by the Academy of Orthopaedic Surgeons (AAOS) and American College of Chest Physicians (ACCP), both from North America. Prior to 2012, these recommendations varied depending on underlying definitions, methodology, and goals of the 2 groups. For the first time, both groups have similar recommendations that focus on minimizing symptomatic VTE and bleeding complications. The key to determining the appropriate chemoprophylaxis for patients is to balance efficacy of a prophylactic agent, while being safe in regards to bleeding complications. However, a multimodal approach that focuses on early postoperative mobilization and the use of mechanical prophylaxis, in addition to chemoprophylaxis, is essential.

Administration of enoxaparin 24 h after total knee arthroplasty: safer for bleeding and equally effective for deep venous thrombosis prevention

BACKGROUND

The purpose of this study was to determine the safety and effectiveness, as assessed by risk of bleeding and incidence of deep venous thrombosis (DVT), of administering delayed low-molecular-weight heparin (LMWH) after total knee arthroplasty.

METHODS

A prospective study of 210 consecutive patients undergoing primary unilateral total knee arthroplasty was undertaken. The patients were randomized into two groups: one of which was managed according to a standard LMWH program (LMWH-s group) and the other with delayed LMWH (LMWH-p). LMWH was initiated 12 h after wound closure in the LMWH-s group, and 24 h after wound closure in the LMWH-p group.

RESULTS

The total blood loss in the first three postoperative days was calculated and all complications were recorded. The mean total blood loss was 435 and 387 mL in the LMWH-s group and LMWH-p group, respectively (p < 0.01). No significant difference in the incidence of symptomatic DVT was observed. The mean length of hospital stay was 7.29 days in the LMWH-s group and 6.56 days in the LMWH-p group (p < 0.05).

CONCLUSIONS

After total knee arthroplasty, LMWH-p is safer for bleeding than LMWH-s and equally effective concerning prevention of DVT.

Utility of noninvasive endothelial function test for prediction of deep vein thrombosis after total hip or knee arthroplasty

BACKGROUND

Venous thromboembolism (VTE) is a common and sometimes lethal postoperative complication of arthroplasty. Endothelial dysfunction is important in the pathogenesis of thrombus formation. Reactive hyperemia-peripheral arterial tonometry (RH-PAT) can noninvasively evaluate endothelial function. This study investigated the predictive value of RH-PAT for deep vein thrombosis (DVT) after lower limb arthroplasty.

METHODS AND RESULTS

A prospective observational study of 126 osteoarthritic patients who underwent total knee arthroplasty (TKA) or hip arthroplasty (THA) was conducted. The RH-PAT index (RHI) was measured on the day before surgery, and presence of DVT was checked by ultrasonography or phlebography before and after surgery. Following arthroplasty, DVT was diagnosed in 51 patients (40.5%). RHI in the DVT group (0.58±0.25) was significantly lower than in the non-DVT group (0.71±0.25, P=0.004). RHI was a significant and independent predictor of postoperative DVT in multivariate logistic regression analyses and improved a net reclassification index (23.8%, P=0.022). Subgroup analyses according to operation site with adjustment for Qthrombosis score demonstrated that RHI significantly predicted postoperative DVT in the THA group (odds ratio per 0.1, 0.77; 95% confidence interval 0.60-0.98; P=0.03), but did not reach statistical significance in the TKA group.

CONCLUSIONS

Low RHI was significantly associated with DVT after lower limb arthroplasty. Endothelial dysfunction, as assessed by RH-PAT, is potentially useful for identifying patients at high risk for VTE especially after THA.

Surgical site infections and other postoperative complications following prophylactic anticoagulation in total joint arthroplasty

Background

Anticoagulants reduce the risk of venous thromboembolism (VTE) after total joint replacement. However, concern remains that pharmacologic VTE prophylaxis can lead to bleeding, which may impact on postoperative complications such as infections and reoperations.

Methods and Findings

From the Global Orthopedic Registry (GLORY), we reviewed 3,755 patients in US who elected for primary total hip or knee arthroplasty, received either warfarin or low molecular weight heparin (LMWH) as VTE prophylactics, and had up-to-90-day follow-up after discharge. We compared incidence rates of VTE, infections and other complications between LMWH and warfarin groups, and used multivariate analyses with propensity score weighting to generate the odds ratio (OR). Patients receiving LMWH tended to be older and higher in the American Society of Anesthesiologists grade scores. In contrast, warfarin was used more frequently for hip arthroplasty with longer duration among patients with more pre-existing comorbidity (all P<0.02). A weight variable was created with propensity score to account for differences in covariate distributions. Propensity score-weighted analyses showed no differences in VTE complications. However, compared to warfarin, LMWH was associated with significantly higher rates of bleeding (6.2% vs. 2.1%; OR = 3.82, 95% confidence interval [CI], 2.64 to 5.52), blood transfusion (29.4% vs. 22.0%; OR = 1.75, 95% CI, 1.51 to 2.04), reoperations (2.4% vs. 1.3%; OR = 1.77, 95% CI, 1.07 to 2.93) and infections (1.6% vs. 0.6%; OR = 2.79, 95% CI, 1.42 to 5.45). Similar results were obtained from compliant uses of warfarin (26%) and LMWH (62%) according to clinical guidelines. While surgical site infections were mostly superficial, current study was underpowered to compare incidence rates of deep infections (<1.0%).

Conclusions

Surgical site infections and reoperations in 3 months following primary total joint arthroplasty may be associated with anticoagulant use that exhibited higher bleeding risk. Long-term complications and deep wound infections remain to be studied.

The rate of symptomatic venous thromboembolism in patients undergoing elective Ilizarov surgery and the cost of chemical prophylaxis

Recent recommendations by the National Institute for Health and Care Excellence (NICE) suggest that all patients undergoing elective orthopaedic surgery should be assessed for the risk of venous thromboembolism (VTE).

Little is known about the incidence of symptomatic VTE after elective external fixation. We studied a consecutive series of adult patients who had undergone elective Ilizarov surgery without routine pharmacological prophylaxis to establish the incidence of symptomatic VTE.

A review of a prospectively maintained database of consecutive patients who were treated between October 1998 and February 2011 identified 457 frames in 442 adults whose mean age was 42.6 years (16.0 to 84.6). There were 425 lower limb and 32 upper limb frames. The mean duration of treatment was 25.7 weeks (1.6 to 85.3).

According to NICE guidelines all the patients had at least one risk factor for VTE, 246 had two, 172 had three and 31 had four or more.

One patient (0.23%) developed a pulmonary embolus after surgery and was later found to have an inherited thrombophilia. There were 27 deaths, all unrelated to VTE.

The cost of providing VTE prophylaxis according to NICE guidelines in this group of patients would be £89 493.40 (£195.80 per patient) even if the cheapest recommended medication was used.

The rate of symptomatic VTE after Ilizarov surgery was low despite using no pharmacological prophylaxis. This study leads us to question whether NICE guidelines are applicable to these patients.

Cite this article: Bone Joint J 2014;96-B:426–30.

Quantitative index for deciding whether to administer preventive anticoagulant therapy in osteoarthritis patients undergoing total knee arthroplasty

BACKGROUND

The 2008 American Academy of Orthopedic Surgeons recommended that surgeons assess the relative risks of venous thromboembolism and bleeding in patients undergoing total knee arthroplasty (TKA). In this situation, a quantitative index is required for deciding whether to administer preventive anticoagulant therapy for deep venous thrombosis (DVT). In this study, we investigated the risk factors for DVT after TKA.

METHODS

We included 102 patients (122 knees) who underwent primary TKA for osteoarthritis of the knee between October 2007 and March 2010. DVT was evaluated using lower limb venous ultrasonography. Cutoff values for individual risk factors were determined using a receiver-operating characteristic analysis, and the patients were grouped according to the cutoff values; the odds ratios (95% CI) were also investigated. The Wilcoxon signed-rank test and χ² test were also used.

RESULTS

DVT was positive in 25 knees (20.5%). Three risk factors for DVT after TKA were identified: age 76 years or older, preoperative maximum soleus vein (MAX-SV) diameter of 6.0 mm or greater, and preoperative D-dimer value of 1.1 μg/dl or higher. The incidence of DVT was significantly higher in the group with two or more risk factors than in the group with one or no risk factors (p = 0.0001).

CONCLUSIONS

Development of postoperative DVT correlated significantly with the presence of the following risk factors: age 76 years or older, preoperative MAX-SV diameter of 6.0 mm or greater, and a preoperative D-dimer value of 1.1 μg/dl or higher. Considering the risk-benefit ratio, avoiding preventive anticoagulant therapy following TKA can be an option for patients with osteoarthritis with one or no risk factors.

Antithrombotic prophylaxis in major orthopaedic surgery: an historical overview and update of current recommendations

The risk of venous thromboembolism following major orthopaedic procedures, such as joint arthroplasty and hip fracture surgery, are well recognised and represent one of the major challenges in orthopaedic practice, having in mind the increasing number of arthroplasties of the hip and knee done worldwide per year and their successful outcome. This potentially fatal complication remains a challenge in orthopaedic practice. The percentage of patients in whom antithrombotic prophylaxis has not been administrated or has been inadequate may reach 50%. Until recently, anticoagulant prophylaxis with low molecular weight heparins (LMWHs) has been a "gold standard". LMWHs are indirect inhibitors of the clotting factors Xa and thrombin and are administered by daily subcutaneous injection. Their efficacy has been proven in numerous clinical trials and the rate of complications with their use is relatively low. However these compounds are associated with a failure rate and are inconvenient to administer, requiring subcutaneous injection, leading to inadequate compliance. For these reasons postoperative thrombembolism continues to occur in up to 10% of this patient population. Recently, novel oral anticoagulants have been introduced into practice for thromboprophylaxis after joint arthroplasy and hip fracture surgery. These drugs are direct thrombin inhibitors (dabigatran) or direct factor Xa inhibitors (rivaroxaban, apixaban and edoxaban). These oral drugs have the same efficacy as the LMWHs with the same or slightly more clinically significant haemorrhage as their main side effect. Their ease of administration and favourable clinical profile makes them an important addition to the therapeutic armamentarium available for venous thromboprophylaxis. In this paper we review the aetiology and pathogenesis of venous thromboembolism and present the various alternatives for its prevention after major orthopaedic surgical procedures with emphasis on the new oral drugs.

Prevention of venous thromboembolic disease after total hip and knee arthroplasty

The selection of a regimen for venous thromboembolic prophylaxis after total joint arthroplasty is a balance between efficacy and safety. Bleeding may have a negative impact on clinical outcomes. Recently, both the American Academy of Orthopaedic Surgeons (AAOS) and the American College of Chest Physicians (ACCP) developed new evidence-based guidelines for venous thromboembolic prophylaxis after total joint arthroplasty. On the basis of a review of the available literature, the AAOS guideline panel was unable to make a recommendation with respect to the selection of a specific prophylaxis regimen or duration of prophylaxis following routine total joint arthroplasty. The ACCP panel recommended one of the following modalities as prophylaxis (rather than no prophylaxis at all) for a minimum of fourteen days: warfarin, low-molecular-weight heparin, fondaparinux, aspirin, rivaroxaban, dabigatran, apixaban, or portable mechanical compression. Both the AAOS and the ACCP guidelines recommended against screening with postoperative duplex ultrasonography at the time of discharge after routine total joint arthroplasty. There is renewed interest in the use of mechanical compression as prophylaxis with the advent of portable compression devices, which allow continuation of this type of prophylaxis after hospital discharge. Although the early data are promising, appropriately powered randomized trials are needed to determine the efficacy of the devices compared with other prophylaxis regimens.

Deep Vein Thrombosis After Total Hip Arthroplasty and Total Knee Arthroplasty in Patients With Previous Ischemic Stroke

The present study evaluated the prevalence and therapy of deep vein thrombosis (DVT) after total hip arthroplasty (THA) and total knee arthroplasty (TKA) in 57 patients with previous ischemic stroke. Postoperative anticoagulants were used for DVT prophylaxis, and batroxobin and prolonged anticoagulants were used for thrombolysis in DVT subjects. The incidence of DVT after THA and TKA in patients with previous ischemic stroke was 16.2% and 20%, respectively. No bleeding complications were observed and no new ischemic stroke occurred during the following 3 months. The prevalence DVT after THA and TKA in patients with previous ischemic stroke was not specific, and the treatment of DVT with batroxobin and anticoagulants was effective and safe.

Comparative safety and efficacy of antithrombotics in the management of venous thromboembolism after knee or hip replacement surgery: focus on rivaroxaban

Routine thromboprophylaxis represents the current standard of care in the management of patients following total hip or knee replacement. Legacy agents used to address the issue of risk of venous thromboembolism present barriers to use, either by the need for monitoring and dose adjustment (warfarin) or the need for injection (low molecular weight heparins and fondaparinux), or pose a risk of upper gastrointestinal bleeding (acetylsalicylic acid and all antithrombotic agents). The introduction of new pharmacologic agents in recent years has sought to address the issues of not only efficacy, but also safety, ease of use, and patient compliance. New orally administered agents, ie, apixaban, dabigatran, and rivaroxaban, have demonstrated various degrees of efficacy over enoxaparin while preserving safety. Indirect comparisons of the relative efficacies of apixaban, dabigatran, and rivaroxaban have shown rivaroxaban to be more efficacious than dabigatran and apixaban in reducing symptomatic and total venous thromboembolism following total hip or knee replacement surgery. A pooled analysis of the four RECORD (Regulation of Coagulation in Orthopedic Surgery to Prevent deep vein thrombosis and pulmonary embolism) trials (two in total hip replacement and two in total knee replacement) demonstrated rivaroxaban to be the first and only antithrombotic agent ever to demonstrate superiority in reducing symptomatic venous thromboembolism and all-cause mortality compared with another antithrombotic agent (enoxaparin). New oral antithrombotic agents have demonstrated efficacy in prophylaxis against venous thromboembolism following total hip or knee replacement surgery while preserving safety, with increased ease of administration of thromboprophylaxis for both the patient and the physician, which may contribute to improved compliance.

A Prospective Study of Venous Thromboembolic Prophylaxis using Foot Pumps following Total Knee Replacement in a Chinese Population

Purpose

The purpose of this study was to evaluate foot pumps as mechanical prophylaxis for deep vein thrombosis (DVT) following total knee replacement (TKR) in a Chinese population.

Methods

All consecutive patients following TKR during 2002–2006 received routine duplex ultrasound surveillance for DVT 9 days postoperatively. The demographic data and risk factors were recorded. No medication was given for DVT prophylaxis in all patients.

Results

We evaluated 91 consecutive TKRs in 85 patients. Although 44 knee replacements (Group 1) done before December 2004 were not given foot pumps, 47 knee replacements (Group 2) done afterwards were given foot pumps. All patients were followed up for more than 6 months. DVT was detected in three cases (6.8%) in Group 1 compared with four knees (8.5%) in Group 2. Proximal thrombosis was observed in two knees (4.5%) in Group 1 compared with two knees (4.3%) in Group 2. No patient had pulmonary embolism. Six out of 59 (10.2%) patients who underwent the operations under general anaesthesia suffered from DVT, whereas one in 28 (3.6%) patients operated under spinal anaesthesia had DVT. All had no statistical significance.

Conclusion

The rate of proximal DVT after TKR was low (4.5%) without pharmacological prophylaxis. We advise against the use of pharmacological prophylaxis in Chinese population for TKRs because of the low risk of proximal DVT and its possible bleeding complications. Foot pump did not lower the rate of DVTfurther, and its use for DVT prophylaxis in TKR is not necessary.