RD heparin compared with warfarin for prevention of venous thromboembolic disease following total hip or knee arthroplasty. RD Heparin Arthroplasty Group

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.

[Translated article] Risk of venous thromboembolism in thromboprophylaxis between aspirin and low molecular weight heparins after total hip arthroplasty or total knee arthroplasty: Systematic review and meta-analysis

INTRODUCTION

The aim of this study was to evaluate the efficacy of aspirin versus low molecular weight heparins (LMWH) for the prophylaxis of venous thromboembolism (VTE), deep vein thrombosis (DVT) and pulmonary embolism (PE) in patients undergoing total knee arthroplasty (TKA) and/or total hip arthroplasty (THA).

MATERIALS AND METHODS

Systematic review and meta-analysis. Sixteen studies were selected. The risk of VTE, DVT and PE were analysed. Mortality, risk of bleeding and surgical wound complications was also analysed.

RESULTS

248,461 patients were included. 176,406 patients with thromboprophylaxis with LMWH and 72,055 patients with aspirin thromboprophylaxis. There were no significant differences in the risk of VTE (OR=0.93; 95% CI: 0.69-1.26; p=0.64), DVT (OR=0.72; 95% CI: 0.43-1.20; p=0.21) or PE (OR=1.13; 95% CI: 0.86-1.49; p=0.38) between both groups. No significant differences were found in mortality (p=0.30), bleeding (p=0.22), or complications in the surgical wound (p=0.85) between both groups. These same findings were found in the sub-analysis of only randomised clinical trials (p>0.05).

CONCLUSIONS

No increased risk of PE, DVT, or VTE was found among patients with aspirin thromboprophylaxis versus patients with LMWH thromboprophylaxis. There was also no greater mortality, greater bleeding, or greater complications in the surgical wound found among patients with aspirin thromboprophylaxis versus patients with LMWH thromboprophylaxis.

Risk of venous thromboembolism in thromboprophylaxis between aspirin and low molecular weight heparins after total hip arthroplasty or total knee arthroplasty: Systematic review and meta-analysis

INTRODUCTION

The aim of this study was to evaluate the efficacy of aspirin versus low molecular weight heparins (LMWH) for the prophylaxis of venous thromboembolism (VTE), deep vein thrombosis (DVT) and pulmonary embolism (PE) in patients undergoing total knee arthroplasty (TKA) and/or total hip arthroplasty (THA).

MATERIALS AND METHODS

Systematic review and meta-analysis. Sixteen studies were selected. The risk of VTE, DVT and PE were analyzed. Mortality, risk of bleeding and surgical wound complications was also analyzed.

RESULTS

248,461 patients were included. 176,406 patients with thromboprophylaxis with LMWH and 72,055 patients with aspirin thromboprophylaxis. There were no significant differences in the risk of VTE (OR = 0.93; 95% CI: 0.69-1.26; P = .64), DVT (OR = 0.72; 95% CI: 0.43-1.20; P = .21) or PE (OR = 1.13; 95% CI: 0.86-1.49; P = .38) between both groups. No significant differences were found in mortality (P = .30), bleeding (P = .22), or complications in the surgical wound (P = .85) between both groups. These same findings were found in the sub-analysis of only randomized clinical trials (P>.05).

CONCLUSIONS

No increased risk of PE, DVT, or VTE was found among patients with aspirin thromboprophylaxis versus patients with LMWH thromboprophylaxis. There was also no greater mortality, greater bleeding, or greater complications in the surgical wound found among patients with aspirin thromboprophylaxis versus patients with LMWH thromboprophylaxis.

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.

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.

Thromboprophylaxis across orthopaedic surgery: Bibliometric analysis of the most cited articles

PURPOSE

One of the most common adverse events after orthopaedic surgery, with a potential for subsequent serious morbidity and mortality is venous thromboembolism (VTE). Bibliometric analysis has been performed regarding many topics and across orthopaedics. As DVT prophylaxis is a major component of both orthopaedic surgery considerations and research, a bibliometric analysis in this area would prove beneficial in not only in understanding the research done in the field thus far, but would also direct future research efforts.

METHODS

The Web of Science (WoS) database from the Institute of Scientific Information (ISI) was used to compile articles for bibliometric analysis using Boolean search: ((Orthopaedic∗ OR Orthopaedic∗) AND (thromboprophylaxis OR Thromboembolism OR Deep vein thrombosis OR thrombus OR embolism OR anticoagulation OR Embolus OR prophylaxis)).

RESULTS

The Top 100 cited articles included in the final list generated a total of 21,099 citations. The highest cited article was Prevention of venous thromboembolism by Geerts et al. published in Chest, which had a total of 2802 on WoS, and a calculated citation density of 215.54 of citations/years since publication. Comparing the overall citation against the year of publication there was a slight positive trend favoring more recent publications (R-value: 0.142; adjusted R-squared: 0.01; p = 0.16). Analysis of an articles Level of Evidence (LOE), 17 were grade with a level of I.

CONCLUSIONS

Orthopaedic thromboprophylaxis is an ever-changing field that is at the forefront of orthopaedic literature. The significant trend favoring high quality research within orthopaedic thromboprophylaxis demonstrates the importance of this topic and there was a need for a guide to best understand the evolution of DVT prophylaxis.

A Prospective Cohort Study of Symptomatic Venous Thromboembolic Events in Foot and Ankle Trauma: The Need for Stratification in Thromboprophylaxis?

The incidence of venous thromboembolic (VTE) events (deep vein thrombophlebitis [DVT] or pulmonary embolism [PE]) in foot and ankle trauma has been low, and the risk/benefit ratio associated with chemoprophylaxis is controversial. We compared the 90-day incidence of VTE events in 3 cohorts: group 1, tendo-Achillis (TA) ruptures managed with full weightbearing in a walker boot; group 2, ankle fractures immobilized non-weightbearing in a below-the-knee cast; and group 3, ankle fractures managed surgically, followed by non-weightbearing in a below-the-knee cast. Data were extracted from 2 prospectively collected trust databases for acute TA ruptures and ankle fractures. VTE risk was assessed using a U.K. national assessment tool. Chemoprophylaxis was prescribed for high-risk patients. The 90-day incidence of symptomatic VTE events was drawn from a trust-wide radiology database. In group 1 (n = 291), the incidence of VTE events was 4.8% (11 [3.8%] DVT, 3 [1.0%] PE) at a mean of 16.1 ± 6.8 days. In group 2 (n = 227), the incidence of VTE events was 2.2% (5 [2.2%] DVT) at a mean of 33.4 ± 11.3 days. In group 3 (n = 199), the incidence of VTE events was 3.0% (5 [2.5%] DVT, 1 [0.5%] PE) at a mean of 37.2 ± 14.2 days. Patients with symptomatic VTE events presented significantly earlier after acute TA rupture compared with after ankle fracture (p = .002). We found the overall incidence of VTE events in foot and ankle trauma was low, with a relatively greater incidence of symptomatic VTE events, which occurred earlier, in acute TA ruptures compared with ankle fractures.

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.

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.

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.

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.

A Current Review of Mechanical Compression and Its Role in Venous Thromboembolic Prophylaxis in Total Knee and Total Hip Arthroplasty

Interest in mechanical compression for venous thromboembolic disease prophylaxis has increased over the last several years because of concerns related to bleeding complications associated with chemoprophylaxis. However, the research evaluating compression is clearly not definitive. Therefore, this review aims to: (1) summarize methods of compression; (2) compare AAOS, ACCP, and SCIP guidelines; and (3) make recommendations regarding usage. Below-the-knee devices have demonstrated the most efficacy with multiple guidelines recommending usage. Efficacy and compliance may be improved with the use of mobile devices.

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.

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.

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.

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.

Comparison of 3,000 and 5,000 IU aXa/day certoparin in the prevention of deep-vein thrombosis after total hip replacement

Background

The aim was to investigate, whether 5,000 IUaXa/day certoparin lowers the incidence of deep vein thrombosis (DVT) in patients undergoing elective hip replacement surgery vs. 3,000 IUaXa/day. Double-blind, multicenter, randomised trial in 500 patients. Primary endpoint: incidence of symptomatic or asymptomatic DVT (bilateral ascending venography).

Results

Mean age was 71 ± 10 years with a higher prevalence of previous DVT (8vs.4%) and pulmonary embolism (PE) (4vs.1%) in the high dose group. Mean duration of surgery was 82 ± 32 and 85 ± 36 min. DVT was detected in 28 (11.1%) of the low dose and 35 (14.1%) of the high dose group (p = n.s.). Combined distal-proximal DVT was observed in 5 (2%) and 4 (1.6%) patients respectively. No difference in bleeding events was found.

Conclusion

This trial confirms prior data showing that the conventional dosage of 3,000 IU aXa is effective and safe for the prevention of venous thromboembolic events after hip replacement surgery.

Prevention of VTE in orthopedic surgery patients: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND

VTE is a serious, but decreasing complication following major orthopedic surgery. This guideline focuses on optimal prophylaxis to reduce postoperative pulmonary embolism and DVT.

METHODS

The methods of this guideline follow those described in Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines in this supplement.

RESULTS

In patients undergoing major orthopedic surgery, we recommend the use of one of the following rather than no antithrombotic prophylaxis: low-molecular-weight heparin; fondaparinux; dabigatran, apixaban, rivaroxaban (total hip arthroplasty or total knee arthroplasty but not hip fracture surgery); low-dose unfractionated heparin; adjusted-dose vitamin K antagonist; aspirin (all Grade 1B); or an intermittent pneumatic compression device (IPCD) (Grade 1C) for a minimum of 10 to 14 days. We suggest the use of low-molecular-weight heparin in preference to the other agents we have recommended as alternatives (Grade 2C/2B), and in patients receiving pharmacologic prophylaxis, we suggest adding an IPCD during the hospital stay (Grade 2C). We suggest extending thromboprophylaxis for up to 35 days (Grade 2B). In patients at increased bleeding risk, we suggest an IPCD or no prophylaxis (Grade 2C). In patients who decline injections, we recommend using apixaban or dabigatran (all Grade 1B). We suggest against using inferior vena cava filter placement for primary prevention in patients with contraindications to both pharmacologic and mechanical thromboprophylaxis (Grade 2C). We recommend against Doppler (or duplex) ultrasonography screening before hospital discharge (Grade 1B). For patients with isolated lower-extremity injuries requiring leg immobilization, we suggest no thromboprophylaxis (Grade 2B). For patients undergoing knee arthroscopy without a history of VTE, we suggest no thromboprophylaxis (Grade 2B).

CONCLUSIONS

Optimal strategies for thromboprophylaxis after major orthopedic surgery include pharmacologic and mechanical approaches.

Warfarin for Venous Thromboembolism Prophylaxis After Elective Hip or Knee Arthroplasty: Exploring the Evidence, Guidelines, and Challenges Remaining

BACKGROUND:

Guidelines for the prevention of venous thromboembolism (VTE) after elective total hip or knee arthroplasty (THA/TKA) have been developed separately by the American Academy of Orthopaedic Surgeons (AAOS) and the American College of Chest Physicians (ACCP). Differences exist in approaches to preventing postoperative VTE through prophylaxis.

OBJECTIVE:

To compare trials using vitamin K antagonists (VKAs) and differences in guidelines to determine the benefits and drawbacks of warfarin for VTE prophylaxis following THA/TKA.

DATA SOURCES:

Guidelines from the AAOS published in 2009 and revised in 2011 and from the ACCP published in 2008 were compared for recommendations on the use of VKAs. A MEDLINE search from 1960 to November 2009 was conducted to identify pertinent articles on the use of warfarin or VKAs for VTE prophylaxis following THA/TKA. Search terms included warfarin, vitamin K antagonist, total hip or total knee replacement, and total hip or total knee arthroplasty.

STUDY SELECTION AND DATA EXTRACTION:

Only clinical trials in which warfarin was the primary agent for prophylaxis compared to other anticoagulants were included.

DATA SYNTHESIS:

Data on differences between guideline recommendations for the use of VKAs and the importance of a deep vein thrombosis or asymptomatic events were extracted. Thirteen comparative trials using VKAs for VTE prophylaxis and international normalized ratio (INR) targets were assessed. Overall, the incidence of bleeding tended to be lower with the use of VKAs, but thrombosis when including asymptomatic events was numerically higher when comparing INR targets. However, INR targets varied, with no comparative trials assessing the AAOS 2009 recommended INR target of 1.5-2.0. The AAOS guidelines initially recommended a longer duration of therapy and expressed stronger support for the use of aspirin for prophylaxis; however, in 2011, its guidelines were revised, with no specific recommendations as to agent, dose, or INR target goal.

CONCLUSIONS:

Warfarin is an effective agent to prevent VTE after elective THA/TKA. The most effective approach, including extended warfarin use up to 4 weeks or longer, has not been determined.

Clinically significant thromboembolic disease in orthopedic oncology: an analysis of 986 patients treated with low-molecular-weight heparin

BACKGROUND AND OBJECTIVES

Thromboembolic risk in orthopedic oncology is high due to several factors. The aim of this study was to assess clinically significant thromboembolic disease in 986 patients operated on with a prosthetic reconstruction of the lower limbs after the resection of bone tumors and prophylactically treated with low-molecular-weight heparin (LMWH).

METHODS

Between 1983 and 2006, 986 patients had uncemented megaprostheses after a resection of the lower limbs for bone tumors. Antithromboembolic prophylaxis was always administered with LMWH from the immediate postoperative time until the time of complete weight-bearing. Phlebographies and vascular ecodoppler were not performed postoperatively on a regular basis. Patients were followed in the clinic with imaging studies for several years (lower limb CT, MRI, CT of the chest for malignant tumors). The diagnosis of symptomatic venous thromboembolism (VTE) was established or excluded on clinical evidence and MRI study.

RESULTS

Among the 986 cases treated, only 11 patients (1.1%) showed a major thromboembolic event confirmed clinically and through imaging. One of these patients died with pulmonary embolism a few days after surgery. Two cases of thromboembolism occurred in patients with a vascular bypass.

CONCLUSIONS

Despite general oncologic and orthopedic factors favoring VTE, the clinical occurrence of this event was extremely low in this series, probably due to a consistent and careful prophylaxis, prolonged until the time of complete weight-bearing.

Meta-analysis of low molecular weight heparin versus placebo in patients undergoing total hip replacement and post-operative morbidity and mortality since their introduction

OBJECTIVES

1) To establish the clinical validity for in-patient low molecular weight heparin (LMWH) following total hip replacement (THR) through a meta-analysis of peer reviewed and published randomised placebo controlled trials (RCTs). 2) To establish whether modern peri-operative practices were associated with changes in rates of clinical venous thromboembolic (VTE) and all-cause mortality after THR by review of series of patients receiving in-patient LMWH published between 1985 and 2000. DATASOURCES: Medline and Embase (from 1980 to 2005), Datastar and Proquest databases were searched and references from bibliographies traced.

REVIEW METHODS

Studies of adult patients receiving in-patient LMWH following elective primary or revision THR were sought and data abstracted. The first part of our analysis included only randomised placebo controlled trials. For the second part, randomised control trials were included and divided by their year of completion into three groups.

RESULTS

We found no difference between LMWH and placebo in the risk of fatal pulmonary embolism (PE), other deaths, all cause mortality or major bleeding. LMWH reduced non-fatal PE (OR=0.14, 95%CI 0.03 to 0.74, p=0.029) at the expense of haematoma formation (7/147 vs 0/149, p=0.015). 35 studies were included in the second part of our analysis. Point estimates of rates of fatal and non-fatal pulmonary embolism and other deaths suggest a decline over time but fell short of statistical significance.

CONCLUSION

Clinically relevant VTEs are a rare complication following THR. The lower risk of VTE narrows the risk benefit of potent pharmacological thromboprophylaxis. We do not support their use in patients undergoing THR without additional thromboembolic risk factors.

DVT prophylaxis in total joint reconstruction

Deep venous thrombosis (DVT) is the end result of a complex interaction of events including the activation of the clotting cascade in conjunction with platelet aggregation. Patients undergoing major lower extremity orthopedic surgery, especially total joint arthroplasty (TJA), are at high risk for developing a postoperative DVT or a subsequent pulmonary embolus. Venous thromboembolic (VTE) prophylaxis, most commonly pharmacologic prophylaxis, has become the standard of care for patients undergoing elective TJA. However, the controversy between the efficacy of VTE prophylaxis and the increased risk for bleeding in the postoperative period continues to exist. This review addresses the controversy underlying VTE prophylaxis by outlining 2 guidelines and demonstrating the pros and cons of different DVT prophylaxis regimens based on the available evidence-based literature.

The ACCP guidelines for thromboprophylaxis in total hip and knee arthroplasty

The 1986 National Institutes of Health consensus conference Prevention of Venous Thrombosis and Pulmonary Embolism emphasized the high rates of venous thromboembolic disease (VTE), including deep vein thrombosis (DVT) and pulmonary embolism (PE), associated with orthopedic surgery of the lower extremity when performed without thromboprophylaxis. Total joint arthroplasty patients treated with placebo or as controls have, based on studies conducted between 1908 and 2002, a total DVT prevalence of 41% to 85% and a proximal DVT prevalence of 5% to 36% when examined by venography at 7 to 14 days. Prevalence of PE is less certain, but clinical studies have reported a range of 0.9% to 28% for all PE and 0.1% to 2% for fatal PE in control or placebo patients. As the number of total joint arthroplasties in the United States has grown - nearing 1,000,000 annually and expected to increase significantly over the next 20 years as the population ages - so too has interest in appropriate thromboprophylaxis. Methods of preventing VTE are either pharmacologic or mechanical. Guidelines from the American College of Chest Physicians make evidence-based recommendations for both pharmacologic and nonpharmacologic prophylaxis in the settings of total hip and total knee arthroplasty. These recommendations and their underlying rationale are discussed herein.

Retrospective Evaluation of Delayed Administration of Fondaparinux in Providing Comparable Safety and Efficacy Outcomes in Patients Undergoing Elective-Arthroplasty Procedures

Purpose

To evaluate the selected outcome measures of venous thromboembolic (VTE) events and major bleeding in patients undergoing a major-elective arthroplasty procedure. Comparing fondaparinux initiated 18 to 24 hours after the procedure with alternative regimens recommended by the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy consensus guidelines for prophylaxis of venous thromboembolism.

Background

The Lehigh Valley Hospital, Cedar Crest campus has three large orthopedic groups providing services at this site. Each group has successfully managed post-surgical bleeding and prophylaxis of VTE occurrences using individually managed anticoagulation regimens. In house monitoring has shown equivalency. Recently, a new agent was FDA-approved that might provide a further reduction in venous embolic events, but potentially at the cost of increased major bleeding. Some data suggest that the ‘timing’ of an anticoagulant's dose may impact both bleeding and thrombotic event rates. However, the exact ‘optimum’ time and regimen to maximize these two divergent outcomes is still elusive. This paper is meant to provide some insight into these issues.

Methods

The records of all elective major orthopedic procedures involving hip or knee replacement were identified for the period of January 1 to June 30, 2004. Patients (n = 185) receiving fondaparinux 18 to 24 hours after their surgical intervention were compared with all other patients (n = 550) who received any VTE prophylaxis regimen. Electronic chart review was performed by pharmacists to collect preselected outcome data related to these procedures. Patients were evaluated for all cause 30-day readmissions related to bleeding or VTE events and any in- hospital mortality or in-hospital VTE events.

Results

Of 735 patients, 185 patients received fondaparinux post-operatively in the selected time frame. The remaining 550 patients received either warfarin or enoxaparin. The patients had similar demographic characteristics, and the ratios of procedural events were equivalent. Length of stay (LOS) data were also comparable. Outcome measures as assessed by a 30-day readmission rates for any morbidity, symptomatic venous embolic event, bleeding, or in-hospital VTE event were also statistically equivalent during the analyzed period. No major bleeds were seen in any of the evaluated patients.

Conclusions

The possibility of using fondaparinux for VTE prophylaxis and initiating therapy at the 18- to 24-hour mark post-operatively appears to provide equivalent levels of safety and efficacy compared to regimens using warfarin or enoxaparin.

Prevention of venous thromboembolism in surgical patients

Venous thromboembolism (VTE) is a common complication of surgical procedures. The risk for VTE in surgical patients is determined by the combination of individual predisposing factors and the specific type of surgery. Prophylaxis with mechanical and pharmacological methods has been shown to be effective and safe in most types of surgery and should be routinely implemented. For patients undergoing general, gynecologic, vascular, and major urologic surgery, low-dose unfractionated heparin or low-molecular-weight heparin (LMWH) are the options of choice. For low-risk urologic surgery, early postoperative mobilization of patients is the only intervention warranted. For higher-risk patients, including those undergoing elective hip or knee replacement and surgery for hip fracture, vitamin K antagonists, LMWH, or fondaparinux are recommended. For patients undergoing neurosurgery, graduated elastic stockings are effective and safe and may be combined with LMWH to further reduce the risk of VTE. The role of prophylaxis is less defined in patients undergoing elective spine surgery, as well as laparoscopic and arthroscopic surgery. A number of issues related to prophylaxis of VTE after surgery deserve further clarification, including the role of screening for asymptomatic deep vein thrombosis, the best timing for initiation of pharmacological prophylaxis, and the optimal duration of prophylaxis in high-risk patients.

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

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

Prevention of venous thromboembolism in orthopedic surgery with vitamin K antagonists: a meta-analysis

BACKGROUND

The benefit-to-risk ratio of vitamin K antagonists (VKA), relative to active comparators, especially low-molecular-weight heparins (LMWH), for preventing venous thromboembolism in patients undergoing major orthopedic surgery is debated.

OBJECTIVES

We performed a meta-analysis of all randomized trials in orthopedic surgery comparing adjusted doses of VKA to control treatments.

PATIENTS AND METHODS

An exhaustive literature search, both manual and computer-assisted, was performed. Studies were selected on the basis of randomization procedure (VKA vs. a control group). At least one of the following outcome measures was to be evaluated: deep vein thrombosis (DVT), pulmonary embolism (PE), death, major hemorrhage or wound hematoma. Four reviewers assessed each article to determine eligibility for inclusion and outcome measures.

RESULTS

VKAs were more effective than placebo or no treatment in reducing DVT [567 patients, relative risk (RR) = 0.56, 95% confidence interval (CI) 0.37, 0.84, P < 0.01] and clinical PE (651 patients, RR = 0.23, 95% CI 0.09, 0.59, P < 0.01). These results were obtained at the cost of a higher rate of wound hematoma (162 patients, RR = 2.91, 95% CI 1.09, 7.75, P = 0.03). VKAs were also more effective than intermittent pneumatic compression (534 patients, RR = 0.46, 95% CI 0.25, 0.82, P = 0.009) in preventing proximal DVT. In contrast, VKAs were less effective than LMWH in preventing total DVT and proximal DVT (9822 patients, RR = 1.51, 95% CI 1.27, 1.79, P < 0.001; and 6131 patients, RR = 1.51, 95% CI 1.04, 2.17, P = 0.028, respectively). The differences between VKA and LMWH in major hemorrhage and wound hematoma were not significant.

CONCLUSIONS

In patients undergoing major orthopedic surgery, VKAs are less effective than LMWH, without any significant difference in the bleeding risk.

Comparison of ximelagatran with warfarin for the prevention of venous thromboembolism after total knee replacement

BACKGROUND

In a previous study of the prevention of venous thromboembolism after total knee replacement, the efficacy of ximelagatran, an oral direct thrombin inhibitor that does not require monitoring of coagulation or dose adjustment, was found to be similar to that of warfarin at a dose of 24 mg of ximelagatran twice daily. The purpose of the present study was to determine whether a higher dose of ximelagatran is superior to warfarin.

METHODS

This randomized, double-blind trial compared a regimen of 7 to 12 days of oral ximelagatran, at a dose of 24 or 36 mg twice daily, starting the morning after surgery, with warfarin therapy started the evening of the day of surgery. The composite end point of venous thromboembolism and death from all causes and the incidence of bleeding were the primary outcome measures.

RESULTS

Among the 1851 patients in the efficacy analysis, oral ximelagatran at a dose of 36 mg twice daily was superior to warfarin with respect to the primary composite end point of venous thromboembolism and death from all causes (20.3 percent vs. 27.6 percent; P=0.003). There were no significant differences between these two groups with respect to major bleeding (incidence, 0.8 percent and 0.7 percent, respectively), perioperative indicators of bleeding, wound characteristics, or the composite secondary end point of proximal deep-vein thrombosis, pulmonary embolism, and death (2.7 percent vs. 4.1 percent; P=0.17).

CONCLUSIONS

The efficacy of oral ximelagatran, administered starting the morning after total knee replacement, was superior to that of warfarin for prevention of venous thromboembolism. Rates of hemorrhagic complications with the two drugs were similar.

Comparison of ximelagatran, an oral direct thrombin inhibitor, with enoxaparin for the prevention of venous thromboembolism following total hip replacement. A randomized, double-blind study

BACKGROUND

Prophylaxis is recommended following total joint replacement because of the high risk of venous thromboembolism (VTE). Postoperative low-molecular-weight heparin (LMWH) reduces the incidence of venographically detected deep vein thrombosis (DVT) to about 10-15% in total hip replacement (THR) patients. Ximelagatran is a novel, oral direct thrombin inhibitor that selectively and competitively inhibits both free and clot-bound thrombin. We compared the efficacy and safety of ximelagatran with those of enoxaparin for the prevention of VTE in patients undergoing THR.

METHODS

This was a prospective, randomized, multicenter, double-blind study conducted principally in the USA and Canada. Patients received fixed-dose oral ximelagatran 24 mg bid or subcutaneous enoxaparin 30 mg bid and matched placebo for 7-12 days; both regimens were initiated the morning after surgery. The incidence of VTE (by postoperative day 12) included thrombosis determined by mandatory venography of the leg on which surgery was performed and symptomatic, objectively proven DVT or pulmonary embolism (PE). VTE and bleeding events were interpreted by an independent central adjudication committee for primary analysis.

RESULTS

Of the 1838 patients randomized, 1557 had either adequate venography or symptomatic, proven VTE (efficacy population). Overall rate of venography acceptable for evaluation was 85.4%. Overall rates of total VTE were 7.9% (62 of 782 patients) in the ximelagatran group and 4.6% (36 of 775 patients) in the enoxaparin group, with an absolute difference of 3.3% and a 95% confidence interval for the difference of 0.9% to 5.7%. Proximal DVT and/or PE occurred in 3.6% (28 of 782 patients) in the ximelagatran group and 1.2% (nine of 774 patients) in the enoxaparin group. Major bleeding events were observed in 0.8% (seven of 906) of the ximelagatran-treated patients and in 0.9% (eight of 910) of the enoxaparin-treated patients (P > 0.95). Non-inferiority of ximelagatran 24 mg bid based on a prespecified margin of 5% was not met, resulting in superiority of the enoxaparin regimen.

CONCLUSIONS

Both ximelagatran and enoxaparin decreased the overall rate of VTE compared with that reported historically. However, in this study, enoxaparin 30 mg bid was more effective than ximelagatran 24 mg bid for prevention of VTE in THR. Oral ximelagatran was used without coagulation monitoring, was well tolerated, and had bleeding rates comparable to those of enoxaparin. Further refinement by testing a higher dose of ximelagatran in the patients undergoing THR is warranted.

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

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

Does anticoagulation do more harm than good?: A comparison of patients treated without prophylaxis and patients treated with low-dose warfarin after total knee arthroplasty

A cohort of 785 patients treated without any form of thromboprophylaxis was compared with an identical group of 957 patients treated with 6 weeks of low-dose warfarin. All complications seen within 90 days of surgery were recorded. The control group had a total complication rate of 2.2%, with a death rate from thromboembolic disease of 0.0% and a total death rate of 0.2%. The warfarin group had a total complication rate of 4.7%, with a death rate from thromboembolic disease of 0.0% and a total death rate of 0.1%. Both deaths in the control group were from cardiac disease, while the death in the warfarin group was due to a massive gastrointestinal bleeding. The warfarin group had twice the infection rate of the control group.

Managing thromboembolic risk in hip and knee arthroplasty: state of the art

Deep vein thrombosis and pulmonary embolism are major causes of morbidity and mortality after knee and hip arthroplasty in the United States. Although patients frequently receive prophylaxis for thromboembolism postarthroplasty, surgeons vary in their choice of modality and often use suboptimal strategies due to the possibility of provoking postoperative bleeding. This article discusses the rationale for the prevention of venous thromboembolism and offers an overview of clinical recommendations for prophylaxis in knee and hip replacement surgery. Supporting medical evidence for these recommendations is described. A summary of current prophylactic regimens and discussion of duration of therapy are also presented.

Measuring the outcomes and pharmacoeconomic consequences of venous thromboembolism prophylaxis in major orthopaedic surgery

Patients who have undergone orthopaedic surgery represent a high-risk group for venous thromboembolism (VTE). Despite the routine prophylactic use of antithrombotic agents, patients still experience thrombotic events that can result in mortality and acute morbidity and, in significant numbers of patients, may lead to long-term consequences such as the post-thrombotic syndrome. Increasingly, initial VTE events occur after hospital discharge since the length of stay in hospital after major orthopaedic surgery has decreased in many countries. There is a need for further improvement in the prevention of VTE. As well as undergoing extensive safety and efficacy studies for registration purposes, new prophylactic strategies need to be evaluated from a pharmacoeconomic perspective to help guide their introduction into routine clinical practice. Over the past 15 years a number of pharmacoeconomic evaluation studies of VTE prophylaxis have been carried out in orthopaedic patients, most of which evaluated short-term clinical endpoints. During the same period, improvements in our understanding of the natural history of VTE as well as the emergence of new treatments have led to changes in the management of patients with, or at risk of, VTE. The aim of this paper was to address how best to conduct pharmacoeconomic analyses of new antithrombotic agents in light of changes in practice patterns for orthopaedic patients and greater understanding of the disease process. We put forward recommendations for relevant outcome measures, timeframes, endpoints and epidemiologic data sources. We also suggest a structure for a pharmacoeconomic model. In this model, the outcomes and costs of VTE-related care during both the acute and chronic phases of the disease are incorporated. Symptomatic deep vein thrombosis and pulmonary embolism, recurrent VTE, post-thrombotic syndrome, major hemorrhage and all-cause death are included. We also recommend that the relevance of quality-adjusted survival is investigated, and that economic appraisals are presented in both cost-consequence and budget-impact approaches. These recommendations are based on extensive examination of recent advances in the management of VTE combined with a greater understanding of its natural history.

Results of an economic model to assess the cost-effectiveness of enoxaparin, a low-molecular-weight heparin, versus warfarin for the prophylaxis of deep vein thrombosis and associated long-term complications in total hip replacement surgery in the United States

BACKGROUND

Premature death due to pulmonary embolism is a short-term complication of deep vein thrombosis (DVT). The long-term clinical course after DVT can be further complicated by excess mortality, recurrent venous thromboembolism (VTE), and the post-thrombotic syndrome (PTS), which may produce sizable long-term economic burdens.

OBJECTIVE

The goal of this study was to determine the cost-effectiveness of the low-molecular-weight heparin (LMWH) enoxaparin versus warfarin for the universal prophylaxis of DVT and associated long-term complications in US patients undergoing total hip replacement surgery (THRS).

METHODS

A model was constructed to assess the long-term cost-effectiveness of the 2 treatments. Patients undergoing THRS were exposed to a short-term risk of developing a DVT. Patients surviving a DVT were exposed to increased risk of long-term complications of DVT, including PTS, recurrent VTE, and increased mortality. Published literature, augmented by expert opinion, served as input for the model's resource use and costs for DVT prophylaxis, clinical diagnosis, and treatment of DVT, VTE, and PTS.

RESULTS

When the analysis included only the short-term consequences of DVT, therapy with enoxaparin resulted in a net cost of $133 per patient and a net increase of 0.04 quality-adjusted life-years (QALYs) per patient. Thromboprophylaxis with enoxaparin versus warfarin resulted in $3733 per QALY saved. In contrast, when the long-term consequences of DVT were included, enoxaparin resulted in net lifetime savings of $89 per patient and net QALY benefits of 0.16 per patient.

CONCLUSIONS

To the best of our knowledge, this is the first US economic analysis comparing DVT prophylaxis with the LMWH enoxaparin versus warfarin that included the long-term complications of DVT. Our model suggests that use of enoxaparin in patients undergoing THRS reduces the economic burden associated with these long-term complications.

Cost/death averted with venous thromboembolism prophylaxis in patients undergoing total knee replacement or knee arthroplasty

STUDY OBJECTIVE

To compare the cost-effectiveness of warfarin or enoxaparin with no prophylaxis for prevention of venous thromboembolism in patients undergoing total knee replacement (TKR) or knee arthroplasty.

DESIGN

Literature search and retrospective database analysis.

PATIENTS

Cohort of 42,692 patients over 40 years old who underwent TKR or knee arthroplasty, with a subsequent length of stay of at least 1 day, and who did not die postoperatively.

MEASUREMENTS AND MAIN RESULTS

Both warfarin and enoxaparin were superior to no prophylaxis with regard to costs and clinical outcomes. Enoxaparin was associated with medical charges of $26,455/patient and prevented 194 deaths/10,000 patients. Warfarin was associated with medical charges of $27,360/patient and prevented 124 deaths/10,000 patients.

CONCLUSIONS

A wide range of model estimates and assumptions identify enoxaparin as the prophylaxis modality of choice for preventing venous thromboembolism and subsequent clinical complications following total knee replacement surgery.