Deep vein thrombosis prophylaxis: a survey of current practice in Australia and New Zealand

Efficacy and safety of commonly used thromboprophylaxis agents following hip and knee arthroplasty

Aims

We investigated the efficacy and safety profile of commonly used venous thromboembolism (VTE) prophylaxis agents following hip and knee arthroplasty.

Methods

A systematic search of PubMed, Embase, Cochrane Library, Web of Science, and OrthoSearch was performed. Prophylaxis agents investigated were aspirin (< 325 mg and ≥ 325 mg daily), enoxaparin, dalteparin, fondaparinux, unfractionated heparin, warfarin, rivaroxaban, apixaban, and dabigatran. The primary efficacy outcome of interest was the risk of VTE, whereas the primary safety outcomes of interest were the risk of major bleeding events (MBE) and wound complications (WC). VTE was defined as the confirmed diagnosis of any deep vein thrombosis and/or pulmonary embolism. Network meta-analysis combining direct and indirect evidence was performed. Cluster rank analysis using the surface under cumulative ranking (SUCRA) was applied to compare each intervention group, weighing safety and efficacy outcomes.

Results

Of 86 studies eligible studies, cluster rank analysis showed that aspirin < 325 mg daily (SUCRA-VTE 89.3%; SUCRA-MBE 75.3%; SUCRA-WC 71.1%), enoxaparin (SUCRA-VTE 55.7%; SUCRA-MBE 49.8%; SUCRA-WC 45.2%), and dabigatran (SUCRA-VTE 44.9%; SUCRA-MBE 52.0%; SUCRA-WC 41.9%) have an overall satisfactory efficacy and safety profile.

Conclusion

We recommend the use of either aspirin < 325 mg daily, enoxaparin, or dabigatran for VTE prophylaxis following hip and knee arthroplasty.

Randomized clinical trial of low molecular weight heparin with thigh-length or knee-length antiembolism stockings for patients undergoing surgery

Background

This was a randomized clinical trial to determine the efficacy and safety of a ‘blanket’ protocol of low molecular weight heparin (LMWH) and the best length of antiembolism stocking, for every patient requiring surgery under general anaesthesia.

Methods

Of 426 patients interviewed, 376 agreed to be randomized to receive one of three types of stocking: thigh-length Medi thrombexin® climax™ (Medi UK, Hereford, UK), knee-length thrombexin® climax™ and thigh-length Kendall T.E.D.™ (Tyco Healthcare UK, Redruth, UK). All patients received LMWH thromboprophylaxis. Duplex ultrasonography was used to assess the incidence of postoperative deep vein thrombosis (DVT).

Results

No postoperative DVT occurred in 85 patients at low or moderate risk. Nineteen DVTs occurred, all in the 291 high-risk patients: two with the Medi thigh-length stockings, 11 with the Medi knee-length stockings (odds ratio 0·18 (95 per cent confidence interval 0·04 to 0·82); P = 0·026) and six with the Kendall T.E.D.™ thigh-length stockings. No patient developed a pulmonary embolism. Stocking groups were similar for age, sex, thromboembolic risk, type of operation and compliance. One significant bleeding complication occurred.

Conclusion

A single protocol comprising LMWH and thigh-length stockings abolished DVT in low- and moderate-risk patients, and reduced the rate of DVT to 2 per cent in high-risk patients.

Thromboprophylaxis practice patterns in hip fracture surgery patients: experience in Perth, Western Australia

BACKGROUND

International guidelines recommend that all patients undergoing hip fracture surgery receive specific thromboprophylaxis. The purpose of the present study was to examine current thromboprophylaxis practice patterns in patients undergoing hip fracture surgery at Royal Perth Hospital.

METHODS

A total of 129 consecutive patients admitted to Royal Perth Hospital between 4 February and 21 July 2002 for surgical repair of a fractured neck of femur, was studied. The primary outcome was the frequency, type, and duration of thromboprophylaxis use during hospitalization.

RESULTS

Mean patient age was 79.4 +/- 13.4 years and 69.8% (90/129) were female. Seventy-four patients (57.8%; 95% confidence interval (CI): 48.8-66.8%) received specific thromboprophylaxis during hospitalization, including 50 patients (39.1%; 95%CI: 30.6-48.1%) who received pharmacological prophylaxis only, three (2.3%; 95%CI: 0.5-6.7%) who received mechanical prophylaxis only, and 21 (16.4%; 95%CI: 10.5-24.0%) who received both mechanical and pharmacological prophylaxis. Of those receiving pharmacological prophylaxis, 35 (49.3%; 95%CI: 37.2-61.4%) received low-molecular-weight heparin, 26 (36.6%; 95%CI: 25.5-48.9%) received low-dose unfractionated heparin, eight (11.3%; 95%CI: 5.0-21.0%) received warfarin, 35 (49.3%; 95%CI: 37.2-61.8%) received aspirin or clopidogrel, and 27 (38.0%; 95% CI: 26.8-50.3%) received combined anticoagulant and antiplatelet prophylaxis. The median duration of mechanical prophylaxis was 8 days (range: 6-12 days) and that of pharmacological prophylaxis was 12 days (range: 6-26 days). When the 32 patients already taking aspirin or warfarin at the time of admission were excluded, only 45 (46.9%; 95%CI: 36.6-57.3%) of the remaining 96 patients received specific thromboprophylaxis.

CONCLUSION

Specific thromboprophylaxis remains under-utilized in patients undergoing surgery for hip fracture at Royal Perth Hospital. These data should prompt the implementation of effective strategies to improve thromboprophylaxis practice patterns in high-risk orthopaedic patients.

Venous Thromboembolism Prophylaxis in a South Australian Teaching Hospital

BACKGROUND

Venous thromboembolism (VTE) is relatively common among hospitalized patients, is often clinically silent, and is associated with substantial morbidity and mortality. Risk stratification and routine use of thromboprophylaxis for patients at moderate to high risk for VTE are key strategies that can be used to prevent VTE.

OBJECTIVE

To assess the appropriateness of the selection and implementation of thromboprophylactic measures for prevention of VTE within a South Australian teaching hospital.

METHODS

Guidelines for risk stratification and prophylaxis were compiled from a range of studies, consensus statements, and tertiary references. Using prospective, observational methodology, data collection was performed through case note audit for 130 inpatient admissions over a 4-week period.

RESULTS

The decisions regarding the usage of thromboprophylaxis were considered inappropriate in 32% of cases in the study cohort. Suboptimal practices were also observed with respect to factors including the choice between mechanical and pharmacologic methods and the timing of initiation and cessation of thromboprophylaxis.

CONCLUSIONS

These findings provide evidence suggesting that the selection and implementation of thromboprophylaxis require improvement and that appropriate means to facilitate this improvement need to be developed and evaluated through future research.

Prevention of venous thromboembolism in Wales: results of a survey among general surgeons

OBJECTIVE

To examine the current attitudes towards the prevention of venous thromboembolism among a cohort of surgeons.

DESIGN

A postal survey, comprising a questionnaire covering various aspects of venous thromboembolism prophylaxis was sent to all (n=84) consultant general surgeons in Wales.

RESULTS

Replies were received from 57 surgeons (68%), all of whom routinely used prophylaxis, the most frequent modalities used being heparin (100%) and graded compression stockings (79%). A combination of physical and pharmacological methods was used by over 89% of surgeons, with 60% starting prophylaxis more than two hours before operation. All surgeons continued prophylaxis after surgery, 53% until patients were mobile, 45% until they were discharged, and one surgeon continued prophylaxis for seven days after discharge. The thrombosis risk factors considered most important by surgeons when deciding about prophylaxis were (i) a previous history of venous thromboembolism, (ii) hypercoagulability, and (iii) malignancy.

CONCLUSIONS

This study confirms that Welsh surgeons conform to standard methods, but also highlights some uncertainties that are present in current surgical practice. Those who responded all routinely used prophylaxis, the timing of which was variable. The main risk factors identified when considering prophylaxis were previous history of deep vein thrombosis/pulmonary embolism, hypercoagulability, and the presence of malignancy. Suggestions for future practice are made.

Effective risk stratification of surgical and nonsurgical patients for venous thromboembolic disease

Effective and safe methods of preventing venous thromboembolism (VTE) are now widely available, but a significant proportion of patients develop VTE either because thromboprophylaxis has not been used or because the intensity of thromboprophylaxis is not matched to the level of risk. Thromboembolic risk varies widely according to the clinical setting and presence of underlying risk factors, but VTE may not be suspected even in high-risk patients. Clinical risk factors for VTE include recent surgery, cancer, stroke, previous VTE, immobilization, and advanced age. Recent attention has focused on the role of inherited and acquired molecular factors in determining overall thromboembolic risk. These factors include the classic thrombophilias-deficiencies of antithrombin III, protein C, and protein S-and several newly described molecular risk factors: factor V Leiden, the prothrombin 20210A gene mutation, and hyperhomocysteinemia. Based on emerging knowledge of risk factors, several risk assessment models (RAMs) have been devised that stratify patients according to overall VTE risk, allowing thromboprophylaxis to be tailored appropriately. Compared with older risk assessment formulas, current RAMs are simpler and include specific recommendations for thromboprophylaxis based on the available scientific evidence. Consensus documents on VTE prevention classify patients into low-, moderate-, and high-risk categories. More recently, a new risk group, very high risk, has been described. Very-high-risk patients are especially prone to thromboembolic complications and need intensive and in some cases prolonged thromboprophylaxis.

Developing a novel antithrombotic in the academic environment

In recent years, academic research institutions have increasingly sought to commercialize their discoveries, providing the opportunity to raise venture capital and benefit financially from their developments. In the last 6 years, Hamilton Civic Hospitals Research Center, affiliated with McMaster University, Ontario, Canada, has set up two companies, Vascular Therapeutics and Osteokine, to commercialize its discoveries in thrombosis and osteoporosis. Epidemiological evidence shows a continuing socioeconomic burden of both of these disorders, thereby offering opportunities for new drug development. Key areas in the field of thrombosis include novel parenteral anticoagulants to replace heparin as adjunctive therapy in acute coronary syndromes, safer and more practical oral anticoagulants that do not require monitoring to replace coumarins, and oral antiplatelet drugs for use in combination with aspirin. Since their creation, Vascular Therapeutics and Osteokine have attracted major funding and developed several patentable compounds that show clinical and commercial promise.

Graduated compression stockings in the prevention of venous thromboembolism

BACKGROUND

Surveys still show a wide variation in routine use of deep vein thrombosis (DVT) prophylaxis despite its established place in current patient management. This article reviews the mechanism of action, efficacy and complications of stockings in preventing DVT.

METHODS

Relevant publications indexed in Medline (1966-1998) and the Cochrane database were identified. Appropriate articles identified from the reference lists of the above searches were also selected and reviewed.

RESULTS AND CONCLUSION

Graduated compression stockings reduce the overall cross-sectional area of the limb, increase the linear velocity of venous flow, reduce venous wall distension and improve valvular function. Fifteen randomized controlled trials of graduated compression stockings alone were reviewed. Stockings reduced the relative risk of DVT by 64 per cent in general surgical patients and 57 per cent following total hip replacement. The effect of stockings was enhanced by combination with pharmacological agents such as heparin; the combination is recommended in patients at moderate or high risk of DVT. Knee-length stockings are as effective and should replace above-knee stockings. Complications are rare and avoidable.

Deep venous thrombosis and pulmonary embolism in bilateral lower-extremity amputee patients

OBJECTIVE

To determine the incidence of deep venous thrombosis and pulmonary emboli and the value of an inferior vena cava filter in patients with bilateral lower-extremity amputations, and to determine the incidence of pulmonary emboli after filter placement.

DESIGN

Retrospective study with a follow-up of 3 to 64 months.

SETTING

Inner-city university hospital.

PATIENTS

Twenty-seven consecutive patients with bilateral lower-limb amputation.

RESULTS

Age, sex, and race were assessed, and had no impact on the incidence of pulmonary embolus in these patients with lower-extremity amputation.

CONCLUSION

No clinical objective evidence of pulmonary emboli occurred after placement of an inferior vena caval filter.

Incidence of fatal pulmonary embolism after 1,390 knee arthroplasties without routine prophylactic anticoagulation, except in high-risk cases

A consecutive series of 1,390 primary total knee arthroplasty (TKA) procedures (1,201 patients, 1,600 arthroplasties) performed between January 1980 and July 1994 were reviewed to establish the incidence of death from pulmonary embolism (PE). Nine hundred twenty-three bi- or tricompartment TKAs and 467 unicompartment TKAs were performed as one-stage procedures. Chemical thromboprophylaxis was used only in high-risk cases in which there was a history of previous thromboembolism or obesity. There were no deaths from PE after unicompartment arthroplasty procedures. Autopsy confirmed PE as the cause of death in 2 patients following bi- and tricompartment TKAs (0.22%; 95% confidence interval [CI], 0.03-0.8%). The incidence was higher for one-stage bilateral TKA as 1 of the autopsy-confirmed deaths occurred in this group 0.7% (95% CI, 0.02-3.78%). Two other deaths were certified without postmortem examination (pneumonia and myocardial infarction in each case). As PE could not be ruled out as the cause of death in the latter 2 cases, these were considered as possible PE deaths to provide the maximum possible death rate that could result. Thus, the maximum possible incidence of fatal PE after TKA without routine use of chemical anticoagulation was 0.4% (95% CI 0.1-1.1%). It is concluded that the risk of fatal PE after unilateral TKA and unicompartment knee arthroplasty is low. The risk of clinical, nonfatal thromboembolic events, which might themselves warrant prophylaxis, was not quantified in this article.

Prevention of venous thromboembolism in North America: results of a survey among general surgeons

PURPOSE

The purpose of this study was to analyze current attitudes toward the prevention of postoperative venous thromboembolism among North American general surgeons.

METHODS

A survey regarding awareness of the problem of venous thromboembolism and preferred modalities of prophylaxis was sent to 3500 randomly selected Fellows of the American College of Surgeons.

RESULTS

A total of 1018 (29.1%) surveys was returned. Most of the responding surgeons consider venous thromboembolism a serious health problem. Ninety percent of the surgeons use prophylaxis against venous thromboembolism routinely. The most frequently used modalities are intermittent pneumatic compression, low-dose heparin, and elastic stocking. A combination of physical and pharmacologic methods is used by one fourth of respondents, and only 50% start pharmacologic prophylaxis before the surgical procedure. The thrombosis risk factors that are most frequently considered by surgeons when deciding about using prophylaxis are history of venous thromboembolism, immobility, and length of operation.

CONCLUSIONS

North American surgeons who responded to this survey are well aware of the problem of venous thromboembolism and their approach to prevention has been significantly modified in the last 10 years. Compared with similar European surveys this survey reveals a higher implementations of physical methods such as intermittent pneumatic compression and elastic stockings. Because of the limited response rate and possibility of sampling bias, these findings should be interpreted with caution.

Pharmacological thromboprophylaxis in hip and knee surgery: a survey of New Zealand orthopaedic surgeons

A survey was conducted of the attitudes and practices of New Zealand orthopaedic surgeons on the use of pharmacological thromboprophylaxis (PT) for patients undergoing major hip or knee surgery. A questionnaire was sent to all 106 consultant surgeons known to perform hip or knee surgery and a response rate of 89% was obtained. The results suggested that while almost all surgeons used PT at some time, only about one-third of elective surgery patients and just a few per cent of patients with neck of femur fracture (NOFF) receive PT. For about three-quarters of surgeons, heparin (usually low molecular weight) was the most frequently used PT. About half of the surgeons began prophylaxis pre-operatively and about half stopped it when the patients were mobile postoperatively. Previous venous thromboembolism was felt by almost all surgeons to be a very important indication for PT; gross obesity, prolonged pre-operative immobility and active malignancy were thought to be very important factors by approximately one-half of the surgeons. The presence of a major bleeding diathesis or active peptic ulcer was cited as a contraindication to PT by more than two-thirds of all surgeons. Fear of bleeding complications and the rarity of thromboembolic complications were cited as reasons for limited use of PT by about one-third of surgeons. The results suggest that most surgeons usually rely on non-pharmacological methods of thromboprophylaxis, particularly for NOFF patients.(ABSTRACT TRUNCATED AT 250 WORDS)