Prevention of venous thromboembolism: consensus, controversies, and challenges

Incidence and Risk Factors of Symptomatic Venous Thromboembolism Following Foot and Ankle Surgery

BACKGROUND:

The incidence rate of venous thrombotic events (VTEs) following foot and ankle surgery is low. Currently, there is no consensus regarding postoperative prophylaxis or evidence to support risk stratification.

METHODS:

A 2-part study assessing the incidence and factors for the development of VTE was conducted: (1) a retrospective observational cohort study of 22 486 adults to calculate the overall incidence following foot and/or ankle surgery from January 2008 to May 2011 and (2) a retrospective matched case-control study to identify risk factors for development of VTE postsurgery. One control per VTE case matched on age and sex was randomly selected from the remaining patients.

RESULTS:

The overall incidence of VTE was 0.9%. Predictive risk factors in bivariate analyses included obesity, history of VTE, history of trauma, use of hormonal replacement or oral contraception therapy, anatomic location of surgery, procedure duration 60 minutes or more, general anesthesia, postoperative nonweightbearing immobilization greater than 2 weeks, and use of anticoagulation. When significant variables from bivariate analyses were placed into the multivariable regression model, 4 remained statistically significant: adjusted odds ratio (aOR) for obesity, 6.1; history of VTE, 15.7; use of hormone replacement therapy, 8.9; and postoperative nonweightbearing immobilization greater than 2 weeks, 9.0. The risk of VTE increased significantly with 3 or more risk factors ( P = .001).

CONCLUSION:

The overall low incidence of VTE following foot and ankle surgery does not support routine prophylaxis for all patients. Among patients with 3 or more risk factors, the use of chemoprophylaxis may be warranted.

LEVEL OF EVIDENCE:

Level III, retrospective case series.

Clinicians-related determinants of anticoagulation therapy and prophylaxis in Nigeria

BACKGROUND

Thromboembolic and hypercoagulable diseases are common life-threatening but treatable problems in hospital practice. Fortunately, anticoagulation is an efficacious management practice indicated for arterial, venous, and intracardiac thromboembolism. Clinicians in developing countries may have gaps in their knowledge of anticoagulation therapy/prophylaxis which could affect their clinical decision.

OBJECTIVES

The study examined the knowledge and attitude of clinicians to anticoagulation therapy/prophylaxis in some tertiary hospitals in Nigeria.

METHODOLOGY

The study was a multicenter survey. A pretested questionnaire was administered to clinicians in six tertiary hospitals in Southeast Nigeria.

RESULTS

A total of 528 questionnaires were returned by 419 (79.4%) residents and 109 (20.6%) consultants. We observed significant abysmal knowledge and lack of awareness of direct oral anticoagulants (DOACs) among most respondents irrespective of their job grades (P = 0.02, odds ratio [OR] 0.59, 95% confidence interval [CI] 0.38-0.90). Their knowledge of anti-Xa assay as laboratory monitoring tool was also significantly inadequate (P = 0.001, OR 0.23, 95% CI 0.10-0.51). On statement analysis on their attitude to anticoagulation therapy/prophylaxis, "Do you think anticoagulation therapy/prophylaxis is clinically relevant" had the highest mean of 4.60, P = 0.01, and a high degree of agreement; while "Should hospital inpatient with > 3 days admission routinely receive anticoagulation/prophylaxis?" had the lowest mean of 2.27, P = 0.02, and a low degree of agreement.

CONCLUSION

There is the need to upscale knowledge of anticoagulation agents and an attitude change to anticoagulation therapy/prophylaxis, especially on the DOACs through continuing medical education activities in emerging countries such as Nigeria.

Fondaparinux vs. enoxaparin for the prevention of venous thromboembolism after total hip replacement: A meta-analysis

The aim of the study was to compare the efficacy and safety profiles of fondaparinux and enoxaparin in preventing the venous thromboembolism (VTE) after total hip replacement. A systematic literature search in the PubMed, EMBASE and Cochrane library databases was performed to identify relevant articles published in English since inception up to November 16, 2014. The efficacy outcomes were all VTE, total deep vein thrombosis (DVT) and symptomatic VTE, while the safety outcome was major bleeding. Four eligible studies were included in the meta-analysis. The incidences of total VTEs and DVTs were significantly decreased with the use of fondaparinux when compared to enoxaparin [total VTE: risk ratio (RR)=0.59, 95% confidence interval (CI): 0.46–0.74, P<0.01; total DVT: RR=0.58, 95% CI: 0.46–0.74, P<0.01]. Significantly fewer symptomatic VTEs and major bleeding cases were observed for the enoxaparin group (symptomatic VTE: RR=2.62, 95% CI: 1.07–6.45, P=0.04; major bleeding: RR=1.75, 95% CI: 1.20–2.53, P<0.01). In conclusion, the pooled analysis revealed that, compared to enoxaparin, fondaparinux was significantly more effective in preventing VTE after total hip replacements in terms of total VTEs and DVTs, although this was accompanied with an increased risk of major bleeding. However, the pooled analysis of two small sample trials from Japan failed to demonstrate any significant advantage for fondaparinux compared to enoxaparin.

Venous thromboembolism: identifying patients at risk and establishing prophylaxis

Venous thromboembolism (VTE) is a major cause of morbidity and mortality and is associated with substantial healthcare costs. Identification of patients at risk of developing VTE enables appropriate thromboprophylaxis to be implemented. Although no predisposing risk factors can be identified in many patients in whom VTE develops, most have at least one underlying risk factor which can be categorized according to whether it confers low, moderate, or high risk. Clinical trials have demonstrated the effectiveness of thromboprophylaxis, both non-pharmacological and pharmacological, in a host of medical settings and there is sufficient evidence to support routine prophylaxis in many groups of patients. The implementation of decision making tools based on risk factor assessment improves the prescription of appropriate VTE prophylaxis. Nonetheless, thromboprophylaxis is often inadequate, with haphazard risk assessment and application of guidelines, leading to easily preventable instances of VTE. The most commonly used agents for pharmacological thromboprophylaxis of VTE are low dose unfractionated heparin; a low molecular weight heparin such as dalteparin, enoxaparin or tinzaparin; fondaparinux; warfarin; or aspirin. However, these have a number of drawbacks, principally the need for parenteral administration (with heparins) and frequent coagulation monitoring (with warfarin). The optimal anticoagulant would be orally administered, with a wide therapeutic window, rapid onset of action, predictable pharmacodynamics and pharmacokinetics, minimal interactions with food and other drugs, an ability to inhibit free and clot-bound coagulation factors, low, non-specific binding, and no requirement for routine coagulation monitoring or dose adjustment. A number of novel, single-target oral anticoagulants have been developed that appear to fulfill many of these requirements. This narrative review discusses the use of guidelines and risk assessment tools to identify patients at risk of VTE; it provides an overview of appropriate prophylaxis strategies in these patients with a summary of clinical trial results with novel oral anticoagulants.

Venous thromboembolism in the ICU: main characteristics, diagnosis and thromboprophylaxis

Venous thromboembolism (VTE), including pulmonary embolism (PE) and deep venous thrombosis (DVT), is a common and severe complication of critical illness. Although well documented in the general population, the prevalence of PE is less known in the ICU, where it is more difficult to diagnose and to treat. Critically ill patients are at high risk of VTE because they combine both general risk factors together with specific ICU risk factors of VTE, like sedation, immobilization, vasopressors or central venous catheter. Compression ultrasonography and computed tomography (CT) scan are the primary tools to diagnose DVT and PE, respectively, in the ICU. CT scan, as well as transesophageal echography, are good for evaluating the severity of PE. Thromboprophylaxis is needed in all ICU patients, mainly with low molecular weight heparin, such as fragmine, which can be used even in cases of non-severe renal failure. Mechanical thromboprophylaxis has to be used if anticoagulation is not possible. Nevertheless, VTE can occur despite well-conducted thromboprophylaxis.

Heparin and related drugs for venous thromboembolism prophylaxis: subcutaneous or intravenous continuous infusion?

In this article, the most evidenced approaches of unfractionated heparin administration for prevention of venous thromboembolism in medical and surgical hospitalized patients will be reviewed. Present data were collected by searching Scopus, PubMed, MEDLINE, Science direct, Clinical trials and Cochrane database systematic reviews. Subcutaneous low doses of unfractionated heparin (10000–15000 IU) in two or three divided doses per day are commonly administrated for venous thromboembolism prevention in different medical and surgical populations. In some populations such as obese surgical and critically ill patients, due to altered pharmacokinetics behavior of unfractionated heparin, continuous intravenous infusion of the low doses of unfractionated heparin has been proposed.

[Unilateral triangular lumbopelvic stabilization: indications and techniques]

Operative fixation has become treatment of choice for unstable sacral fractures. Osteosynthesis for these fractures results in loss of reduction in up to 15%. Vertical sacral fractures involving the S1 facet joint (Isler 2 and 3) may lead to multidirectional instability. Multidirectional instability of the posterior pelvic ring and lumbopelvic junction may be stabilized and forces balanced by a so-called lumbopelvic triangular fixation. Lumbopelvic triangular fixation combines vertical fixation between the lumbar vertebral pedicle and the ilium, with horizontal fixation, as an iliosacral screw or a transiliacal plate osteosynthesis. The iliac screw is directed from the posterior superior iliac spine (PSIS) to the anterior inferior iliac spine (AIIS). Thereby, lumbopelvic fixation decreases the load to the sacrum and SI joint and transfers axial loads from the lumbar spine directly onto the ilium. Triangular lumbopelvic fixation allows early full weight bearing and therefore reduces prolonged immobilization. The placement of iliac screws may be a complex surgical procedure. Thus, the technique requires thorough surgical preparation and operative logistics. Wound-related complications may occur. Preexisting Morell-Lavalée lesions increase the risk for infection. Prominent implants cause local irritation and pain. Hardware prominence and pain are markedly reduced with screw head recession into the PSIS.

[Thromboembolic events in malignant diseases]

There is a bidirectional connection between tumors and thrombosis. On one hand, thromboembolic events are more frequent in cases of malignancies, on the other hand, proliferation of tumor cells, progression of the malignant process and metastasis formation are facilitated by the activation of the hemostatic system. Thromboembolic events are associated with a worse prognosis in case of patients with malignant diseases. Thromboembolism is the second most frequent cause of death in patients with malignant tumors. Mortality is twice as high in patients with thromboembolism compared to those without it. The incidence of thromboembolism shows an increasing tendency. There has been a 28% increase among hospitalized cancer patients between 1995 and 2003. One reason is that the new anti-tumor agents have more pronounced prothrombotic activity than those of traditional chemotherapeutic drugs. Assessment of the thrombotic risk of cancer patients becomes more important. Several guidelines have been published concerning the prevention and treatment of thromboembolism in patients with malignancy. The risk of thrombosis is influenced not only by the type of malignancy but there are also large individual differences. Furthermore, the risk of thrombosis changes during the disease process in the same patient. Perioperative thromboprophylaxis is a very important issue considering oncologic surgery. Thromboprophylaxis of oncologic patients has a high significance in respect of morbidity and mortality. However, thromboprophylaxis may also cause serious complications thus the correct risk assessment of cancer patients is very important.

Venous thromboembolism prophylaxis in hospitalized elderly patients: Time to consider a 'MUST' strategy

Venous thromboembolism (VTE) is the commonest cause of preventable death in hospitalized patients. Elderly patients have higher risk of VTE because of the high prevalence of predisposing co-morbidities and acute illnesses. Clinical diagnosis of VTE in the elderly patient is particularly difficult and, as such, adequate VTE prophylaxis is of pivotal importance in reducing the mortality and morbidities of VTE. Omission of VTE prophylaxis is, however, very common despite continuous education. A simple way to overcome this problem is to implement universal VTE prophylaxis for all hospitalized elderly patients instead of selective prophylaxis for some patients only according to individual's risk of VTE. Although pharmacological VTE prophylaxis is effective for most patients, a high prevalence of renal impairment and drug interactions in the hospitalized elderly patients suggests that a multimodality approach may be more appropriate. Mechanical VTE prophylaxis, including calf and thigh compression devices and/or an inferior vena cava filter, are often underutilized in hospitalized elderly patients who are at high-risk of bleeding and VTE. Because pneumatic compression devices and thigh length stockings are virtually risk free, mechanical VTE prophylaxis may allow early or immediate implementation of VTE prophylaxis for all hospitalized elderly patients, regardless of their bleeding and VTE risk. Although the cost-effectiveness of this Multimodality Universal STat (‘MUST’) VTE prophylaxis approach for hospitalized elderly patients remains uncertain, this strategy appears to offer some advantages over the traditional ‘selective and single-modal’ VTE prophylaxis approach, which often becomes ‘hit or miss’ or not implemented promptly in many hospitalized elderly patients. A large clustered randomized controlled trial is, however, needed to assess whether early, multimodality, universal VTE prophylaxis can improve important clinical outcomes of hospitalized elderly patients.

Can lumbopelvic fixation salvage unstable complex sacral fractures?

BACKGROUND

Traditional screw or plate fixation options can be used to fix the majority of sacral fractures. However, these techniques are unreliable with dysmorphic upper sacral segments, U-fractures, osseous compression of neural elements, and previously failed fixation. Lumbopelvic fixation can potentially address these injuries but is a technically demanding procedure requiring spinal and pelvic fixation and it is unclear whether it reliably corrects the deformity and restores function.

QUESTIONS/PURPOSES

We therefore assessed reduction quality and loss of fixation, pain related to prominent hardware, subjective dysfunction measured by the Short Musculoskeletal Function Assessment (SMFA), and complications.

METHODS

We retrospectively reviewed 15 patients with unstable sacral fractures treated with lumbopelvic fixation between 2002 and 2010. Patients had radiographic monitoring regarding reduction quality and loss of fixation and clinical followup using the SMFA. The minimum followup was 12 months (mean, 23 months; range, 12-41 months).

RESULTS

Posterior reduction quality was 11 of 15 with less than 5 mm persistent displacement and four of 15 with 5 to 10 mm displacement. Loss of fixation was observed in one patient as a result of a technical error. Prominent hardware resulted in greater pain. Despite daily activity and bother subscores improving over time, we found long-term dysfunction in the SMFA. Eleven of the 15 patients were able to return to previous work or activities.

CONCLUSION

Complex posterior pelvic ring injuries of the sacrum not amenable to traditional fixation options can be salvaged with adherence to the technical details of lumbopelvic fixation. Hardware prominence and pain are markedly reduced with screw head recession. Long-term impairment is noted in patients with complex pelvic ring injuries requiring lumbopelvic fixation compared with normative data.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Primary prevention of venous thromboembolism

Venous thromboembolism (VTE) is the most common cause of preventable in-hospital mortality and all hospitalized patients should be VTE risk assessed. The VTE risk should be weighed up against risk of bleeding on an individualized basis to guide choice of prophylaxis. The most common method of mechanical thromboprophylaxis is graduated compression stockings, although others, such as intermittent pneumatic devices, are available. Stockings have the greatest benefit when used in combination with pharmacological prophylaxis. However, stockings are contraindicated in some patients, including those with stroke or peripheral arterial disease. Various options for pharmacological thromboprophylaxis are available. The most commonly used agents are the low-molecular-weight heparins, but newer orally active agents may play an increasing role in the future.

The Efficacy and Safety of Pharmacological Prophylaxis of Venous Thromboembolism Following Elective Knee or Hip Replacement

The present systematic review was conducted to assess the efficacy and safety of apixaban versus other anticoagulants, for the prevention of venous thromboembolism (VTE) following total hip replacement (THR) and total knee replacement (TKR) surgery. Electronic databases were interrogated to identify relevant randomized controlled trials. A series of direct/indirect comparisons and a network meta-analysis were conducted. Indirect comparisons found that the odds ratio of “all VTE and all-cause death” were significantly higher for dabigatran than for apixaban in patients with THR (odds ratio [OR], 2.51; 95% confidence interval [CI], 1.50-4.21) and TKR (OR, 1.72; 95% CI, 1.22-2.42). Rivaroxaban showed similar efficacy to apixaban in patients with THR and TKR (OR, 0.69; 95% CI, 0.38-1.25 and OR, 0.83; 95% CI, 0.57-1.19, respectively). No significant differences were observed in bleeding outcomes between treatments. The novel anticoagulants apixaban, rivaroxaban, and dabigatran demonstrated similar or improved efficacy and similar safety compared with current therapies in this indication.

Reliability of a point-based VTE risk assessment tool in the hands of medical residents

BACKGROUND

Venous thromboembolic events (VTE) are a significant cause of mortality in hospitalized medical and surgical patients. Despite recommendations and guidelines, current evidence demonstrates that VTE prophylaxis remains underutilized in at-risk patients. The process of providing VTE prophylaxis begins with assessing each patient's VTE risk. Using an individualized, point-based protocol in the assessment process is a complex task, and might contribute to variability in VTE prescribing behavior. There are no published data on how reliably residents can perform risk assessment and prophylaxis using a point-based VTE risk assessment tool.

OBJECTIVE

Our aim was to determine inter-rater reliability of a point-based risk assessment tool by residents early in the academic year.

DESIGN

The design was a cross-sectional-cohort observational study.

SETTING

The site was an academic medical center.

PATIENTS

Case-based clinical vignettes were used.

INTERVENTIONS

Verbal instructions were given to medical residents about how to apply our hospital's point-based VTE risk assessment tool.

MEASUREMENTS

Interobserver agreement was measured of: 1) risk score, 2) risk-stratification, 3) identification of contraindications, 4) VTE prophylaxis plan, and 5) resident adherence to the protocol.

RESULTS

The intra-class correlation (ICC) for the total risk score was 0.66 and the kappa coefficient for risk stratification was 0.51. The kappa scores for absolute and relative contraindications were 0.29 and 0.23, respectively. The kappa score for the VTE plan was 0.28.

CONCLUSIONS

We determined that, following brief instructions early in the academic year, a point-based VTE risk assessment tool has only fair to moderate inter-rater reliability, with suboptimal adherence to the protocol. Both might lead to underutilization of VTE prevention strategies.

[Thromboprophylaxis: medical recommendations and hospital programs]

Venous thromboembolism (VTE) is the most preventable cause of death in hospitalized patients. Hospital-related VTE is associated with more than half of the VTE burden in a community, either in-hospital or after discharge. Selective thromboprophylaxis is recommended for patients at risk. Patient selection for thromboprophylaxis requires proper VTE risk stratification. VTE stratification may be achieved by either risk assessment models (RAM) or by models based on patient's illness and associated risk factors. Whatever the model, a thromboprophylatic recommendation should be formulated for each VTE risk category. VTE thromboprophylaxis may include general measures, mechanic compression procedures, pharmacological intervention or a combined approach. After many decades of consensus statements, a large proportion of at risk patients (20% to 75%) still does not receive proper thromboprophylaxis. This study aims to alert to the relevance of thromboprophylaxis and to suggest hospital thromboprophylatic strategies in a Brazilian setting.

Prolonged and increased postoperative risk of venous thromboembolism: rationale for even more 'extended' prophylaxis?

It is well known that the risk of venous thromboembolism is increased after surgery; however, specific data on how long this risk lasts or how the risk varies by type of surgery is limited. The Million Women Study is a population-based prospective study that recruited 1.3 million women through the National Health Service breast screening program. This study used data from the Million Women Study to examine the magnitude and the duration of the risk of venous thromboembolism after different types of surgery with a mean follow-up duration of 6.2 years. The risk was found to be higher and longer lasting than previously thought, with considerable variation among different types of surgery; therefore, raising important questions regarding the optimal duration of prophylaxis.

Thrombophilia screening--at the right time, for the right patient, with a good reason

Thrombophilia can be identified in about half of all patients presenting with venous thromboembolism (VTE). Thrombophilia screening for various indications has increased tremendously, but whether the results of such tests help in the clinical management of patients is uncertain. Here, current recommendations for thrombophilia screening in selected groups of patients, and considerations whether other high-risk subjects should be tested are reviewed. The methods for determination of the most common thrombophilic defects (antithrombin, protein C, protein S deficiencies, Factor V Leiden and prothrombin G20210A) associated with strong to moderate risk of VTE are described, indicating the timing and location of thrombophilia screening. Circumstances when a positive result of thrombophilia screening helps clinicians decide if adjustments of the anticoagulant regime are needed are discussed. Finally, psychological, social and ethical dilemmas associated with thrombophilia screening are indicated.