Is Recurrent Venous Thromboembolism After Therapy Reduced by Low-Molecular-Weight Heparin Compared With Oral Anticoagulants?

The treatment of venous thromboembolism with low-molecular-weight heparins

The currently recommended method of venous thromboembolism (VTE) treatment is the application of vitamin K antagonists (VKA) in most patients, and low-molecular-weight heparins (LMWH) in selected groups. The VKA dose adjustment is difficult which might well render the treatment ineffective. The study aimed to compare LMWH with VKA in treating VTE in terms of efficacy and safety. A systematic review of literature and the meta-analysis of the treatment results were performed. The main differences between LMWH and VKA in terms of their respective effectiveness in treating VTE consist in appreciably more advantageous effects of LMWH in preventing deep venous thrombosis (DVT). The key difference in terms of respective safety is the greater effectiveness of LMWH in preventing minor bleedings. The advantage of LMWH in cancer patients consists predominantly in a significantly better protection against DVT episodes, whereas the advantage of LMWH in non-cancer patients is mainly owed to better protection against minor bleedings. In none of the analysed outcomes of VTE treatment, the application of VKA proved to hold any advantage over LMWH. Although, arguably, there might well be sufficient medical grounds to propose more widespread use of LMWH, it still remains a debatable issue whether the currently used therapeutic standard should also be modified accordingly. Apart from the actual findings of the present meta-analysis, pertinent economic considerations must also be addressed.

Vitamin K antagonists versus low-molecular-weight heparin for the long term treatment of symptomatic venous thromboembolism

BACKGROUND

People with venous thromboembolism (VTE) generally are treated for five days with intravenous unfractionated heparin or subcutaneous low-molecular-weight heparin (LMWH), followed by three months of vitamin K antagonists (VKAs). Treatment with VKAs requires regular laboratory measurements and carries risk of bleeding; some patients have contraindications to such treatment. Treatment with LMWH has been proposed to minimise the risk of bleeding complications. This is the second update of a review first published in 2001.

OBJECTIVES

The purpose of this review was to evaluate the efficacy and safety of long term treatment (three months) with LMWH versus long term treatment (three months) with VKAs for symptomatic VTE.

SEARCH METHODS

For this update, the Cochrane Vascular Information Specialist searched the Specialised Register (last searched November 2016) and the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 10), The Cochrane Vascular Information Specialistalso searched clinical trials registries for ongoing studies.

SELECTION CRITERIA

Randomised controlled trials comparing LMWH versus VKA for long treatment (three months) of symptomatic VTE. Two review authors independently evaluated trials for inclusion and methodological quality.

DATA COLLECTION AND ANALYSIS

Review authors independently extracted data and assessed risk of bias. We resolved disagreements by discussion and performed meta-analysis using fixed-effect models with Peto odds ratios (Peto ORs) and 95% confidence intervals (CIs). Outcomes of interest were recurrent VTE, major bleeding, and mortality. We used GRADE to assess the overall quality of evidence supporting these outcomes.

MAIN RESULTS

Sixteen trials, with a combined total of 3299 participants fulfilled our inclusion criteria. According to GRADE, the quality of evidence was moderate for recurrent VTE, low for major bleeding, and moderate for mortality. We downgraded the quality of the evidence for imprecision (recurrent VTE, mortality) and for risk of bias and inconsistency (major bleeding).We found no clear differences in recurrent VTE between LMWH and VKA (Peto OR 0.83, 95% confidence interval (CI) 0.60 to 1.15; P = 0.27; 3299 participants; 16 studies; moderate-quality evidence). We found less bleeding with LMWH than with VKA (Peto OR 0.51, 95% CI 0.32 to 0.80; P = 0.004; 3299 participants; 16 studies; low-quality evidence). However, when comparing only high-quality studies for bleeding, we observed no clear differences between LMWH and VKA (Peto OR 0.62, 95% CI 0.36 to 1.07; P = 0.08; 1872 participants; seven studies). We found no clear differences between LMWH and VKA in terms of mortality (Peto OR 1.08, 95% CI 0.75 to 1.56; P = 0.68; 3299 participants; 16 studies; moderate-quality evidence).

AUTHORS' CONCLUSIONS

Moderate-quality evidence shows no clear differences between LMWH and VKA in preventing symptomatic VTE and death after an episode of symptomatic DVT. Low-quality evidence suggests fewer cases of major bleeding with LMWH than with VKA. However, comparison of only high-quality studies for bleeding shows no clear differences between LMWH and VKA. LMWH may represent an alternative for some patients, for example, those residing in geographically inaccessible areas, those who are unable or reluctant to visit the thrombosis service regularly, and those with contraindications to VKA.

Venous thromboembolism in cancer patients: an underestimated major health problem

Venous thromboembolism (VTE) is a major health problem among patients with cancer, its incidence in this particular population is widely increasing. Although VTE is associated with high rates of mortality and morbidity in cancer patients, its severity is still underestimated by many oncologists. Thromboprophylaxis of VTE now considered as a standard of care is still not prescribed in many institutions; the appropriate treatment of an established VTE is not yet well known by many physicians and nurses in the cancer field. Patients are also not well informed about VTE and its consequences. Many studies and meta-analyses have addressed this question so have many guidelines that dedicated a whole chapter to clarify and expose different treatment strategies adapted to this particular population. There is a general belief that the prevention and treatment of VTE cannot be optimized without a complete awareness by oncologists and patients. The aim of this article is to make VTE a more clear and understood subject.

CATCH: a randomised clinical trial comparing long-term tinzaparin versus warfarin for treatment of acute venous thromboembolism in cancer patients

BACKGROUND

Low-molecular-weight heparin (LMWH) is recommended and commonly used for extended treatment of cancer-associated thrombosis (CAT), but its superiority over warfarin has been demonstrated in only one randomised study. We report here the rationale, design and a priori analysis plans of Comparison of Acute Treatments in Cancer Haemostasis (CATCH; NCT01130025), a multinational, Phase III, open-label, randomised controlled trial comparing tinzaparin with warfarin for extended treatment of CAT.

METHODS/DESIGN

The primary objective is to assess the efficacy of tinzaparin in preventing recurrent venous thromboembolism (VTE) in patients with active cancer and acute, symptomatic proximal deep vein thrombosis and/or pulmonary embolism. The secondary objectives are to determine: safety of tinzaparin given over 6 months; clinical and laboratory markers for recurrent VTE and/or major bleeding; 6-month overall mortality; incidence and severity of post-thrombotic syndrome; patient-reported quality of life; and healthcare resource utilisation. Nine hundred patients are randomised to receive tinzaparin 175 IU/kg once daily for 6 months or initial tinzaparin 175 IU/kg once daily for 5-10 days and dose-adjusted warfarin (target INR 2.0-3.0) for 6 months. The primary composite outcome is time to recurrent VTE, including incidental VTE and fatal pulmonary embolism. All patients are followed up to 6 months or death, whichever comes sooner. Blinded adjudication will be performed for all reported VTE, bleeding events and causes of death. Efficacy will be analysed using centrally adjudicated results of all patients according to intention-to-treat analysis. An independent Data Safety Monitoring Board is reviewing data at regular intervals and an interim analysis is planned after 450 patients have completed the study.

DISCUSSION

The results will add significantly to the knowledge of the efficacy, safety and cost effectiveness of tinzaparin in the prevention of recurrent VTE in patients with cancer and thrombosis. Prospective data will emerge on the clinical significance of incidental VTE and risk stratification in patients with CAT. Results on post-thrombotic syndrome, quality of life and healthcare resource utilisation will inform decision makers on how to secure better patient care. If tinzaparin is shown to be more effective than warfarin, CATCH will provide valuable confirmatory data to support the use of the LMWH tinzaparin for extended treatment of CAT.

Thrombosis in women: what are the knowledge gaps in 2013?

Several aspects of the diagnostic and therapeutic management of women with venous thrombosis are uncertain. In this overview, I will discuss three major areas. First, the contribution of hormone use to venous thromboembolism (VTE) will be discussed as prudent prescribing of safe preparations can further reduce the risk of hormone-related VTE. Uncertainties remain regarding certain low-dose progestagens and transdermal routing of hormones and their associated risk of VTE. Second, I will review the diagnosis, treatment, and prevention of pregnancy-related VTE. As direct evidence is largely absent for these individuals, these areas are subject to extrapolation from the non-pregnant population. There is therefore an urgent need for the evaluation of diagnostic strategies that safely exclude the diagnosis of acute pulmonary embolism in pregnant women without the need for diagnostic imaging, which is currently the gold standard, as no studies have confidently demonstrated the safety of ruling out VTE by clinical probability assessment combined with the use of D-dimer levels. Although identification of women at increased risk of pregnancy-related VTE is relatively well established, controversy remains for asymptomatic women from thrombophilic families. The optimal duration and intensity of anticoagulant treatment for, and prophylaxis of, pregnancy-related VTE with low molecular weight heparin is unknown. Third, anticoagulant therapy to prevent recurrence in women with unexplained recurrent miscarriage has shown to have no benefit and should not be prescribed. However, whether antithrombotic therapy prevents recurrent miscarriage in thrombophilic women, or in women with severe pregnancy complications, remains unknown and urgently requires future research.

International clinical practice guidelines for the treatment and prophylaxis of venous thromboembolism in patients with cancer

BACKGROUND

 Guidelines addressing the management of venous thromboembolism (VTE) in cancer patients are heterogeneous and their implementation has been suboptimal worldwide.

OBJECTIVES

To establish a common international consensus addressing practical, clinically relevant questions in this setting.

METHODS

An international consensus working group of experts was set up to develop guidelines according to an evidence-based medicine approach, using the GRADE system.

RESULTS

For the initial treatment of established VTE: low-molecular-weight heparin (LMWH) is recommended [1B]; fondaparinux and unfractionated heparin (UFH) can be also used [2D]; thrombolysis may only be considered on a case-by-case basis [Best clinical practice (Guidance)]; vena cava filters (VCF) may be considered if contraindication to anticoagulation or pulmonary embolism recurrence under optimal anticoagulation; periodic reassessment of contraindications to anticoagulation is recommended and anticoagulation should be resumed when safe; VCF are not recommended for primary VTE prophylaxis in cancer patients [Guidance]. For the early maintenance (10 days to 3 months) and long-term (beyond 3 months) treatment of established VTE, LMWH for a minimum of 3 months is preferred over vitamin K antagonists (VKA) [1A]; idraparinux is not recommended [2C]; after 3-6 months, LMWH or VKA continuation should be based on individual evaluation of the benefit-risk ratio, tolerability, patient preference and cancer activity [Guidance]. For the treatment of VTE recurrence in cancer patients under anticoagulation, three options can be considered: (i) switch from VKA to LMWH when treated with VKA; (ii) increase in LMWH dose when treated with LMWH, and (iii) VCF insertion [Guidance]. For the prophylaxis of postoperative VTE in surgical cancer patients, use of LMWH o.d. or low dose of UFH t.i.d. is recommended; pharmacological prophylaxis should be started 12-2 h preoperatively and continued for at least 7-10 days; there are no data allowing conclusion that one type of LMWH is superior to another [1A]; there is no evidence to support fondaparinux as an alternative to LMWH [2C]; use of the highest prophylactic dose of LMWH is recommended [1A]; extended prophylaxis (4 weeks) after major laparotomy may be indicated in cancer patients with a high risk of VTE and low risk of bleeding [2B]; the use of LMWH for VTE prevention in cancer patients undergoing laparoscopic surgery may be recommended as for laparotomy [Guidance]; mechanical methods are not recommended as monotherapy except when pharmacological methods are contraindicated [2C]. For the prophylaxis of VTE in hospitalized medical patients with cancer and reduced mobility, we recommend prophylaxis with LMWH, UFH or fondaparinux [1B]; for children and adults with acute lymphocytic leukemia treated with l-asparaginase, depending on local policy and patient characteristics, prophylaxis may be considered in some patients [Guidance]; in patients receiving chemotherapy, prophylaxis is not recommended routinely [1B]; primary pharmacological prophylaxis of VTE may be indicated in patients with locally advanced or metastatic pancreatic [1B] or lung [2B] cancer treated with chemotherapy and having a low risk of bleeding; in patients treated with thalidomide or lenalidomide combined with steroids and/or chemotherapy, VTE prophylaxis is recommended; in this setting, VKA at low or therapeutic doses, LMWH at prophylactic doses and low-dose aspirin have shown similar effects; however, the efficacy of these regimens remains unclear [2C]. Special situations include brain tumors, severe renal failure (CrCl<30 mL min(-1) ), thrombocytopenia and pregnancy. Guidances are provided in these contexts.

CONCLUSIONS

Dissemination and implementation of good clinical practice for the management of VTE, the second cause of death in cancer patients, is a major public health priority.

Vitamin K antagonists or low-molecular-weight heparin for the long term treatment of symptomatic venous thromboembolism

BACKGROUND

People with venous thromboembolism (VTE) are generally treated for five days with intravenous unfractionated heparin or subcutaneous low-molecular-weight heparin (LMWH) followed by three months of vitamin K antagonist treatment. Treatment with vitamin K antagonists requires regular laboratory measurements and some patients have contraindications to treatment. This is an update of a review first published in 2000 and updated in 2002.

OBJECTIVES

To evaluate the efficacy and safety of long term treatment of VTE with LMWH compared to vitamin K antagonists.

SEARCH METHODS

For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched their Specialised Register (last searched February 2012) and CENTRAL (2012, Issue 1).

SELECTION CRITERIA

Two authors evaluated trials independently for methodological quality.

DATA COLLECTION AND ANALYSIS

The review authors extracted data independently. Primary analysis included all trial participants randomised to the allocated treatment groups. Separate analyses were performed according to the quality of the trials and for subgroups such as trials initially using similar treatments in both trial arms and those that did not, trials concerning deep vein thrombosis (DVT) and pulmonary embolism (PE) and the different periods of follow-up.

MAIN RESULTS

All 15 trials, with a combined total of 3197 patients, fulfilling our criteria were combined in a meta-analysis. We found a non-statistically significant reduction in the risk of recurrent VTE between the two treatments (odds ratio (OR) 0.82, 95% CI 0.59 to 1.13). Analysis of pooled data for category I trials (those with a high methodological quality) showed a non-significant reduction in the odds of recurrent VTE favouring LMWH treatment (OR 0.80, 95% CI 0.54 to 1.18).For all trials combined, the difference in bleeding significantly favoured treatment with LMWH (OR 0.50, 95% CI 0.31 to 0.79). Considering only category I trials, a non-significant trend favouring LMWH remained (OR 0.62, 95% CI 0.36 to 1.07). No difference was observed in mortality (OR 1.06, 95% CI 0.74 to 1.54).

AUTHORS' CONCLUSIONS

LMWHs are possibly as effective as vitamin K antagonists in preventing symptomatic VTE after an episode of symptomatic deep venous thrombosis, but are much more expensive. Treatment with LMWH is significantly safer than treatment with vitamin K antagonists. LMWH may result in fewer episodes of bleeding and is possibly a safe alternative in some patients, especially those in geographically inaccessible areas, are reluctant to visit the thrombosis service regularly, or with contraindications to vitamin K antagonists. However, treatment with vitamin K antagonists remains the treatment of choice for the majority of patients.

How I treat pregnancy-related venous thromboembolism

Venous thromboembolism (VTE) complicates ∼ 1 to 2 of 1000 pregnancies, with pulmonary embolism being a leading cause of maternal mortality and deep vein thrombosis an important cause of maternal morbidity, also on the long term. However, a strong evidence base for the management of pregnancy-related VTE is missing. Management is not standardized between physicians, centers, and countries. The management of pregnancy-related VTE is based on extrapolation from the nonpregnant population, and clinical trial data for the optimal treatment are not available. Low-molecular-weight heparin (LMWH) in therapeutic doses is the treatment of choice during pregnancy, and anticoagulation (LMWH or vitamin K antagonists postpartum) should be continued until 6 weeks after delivery with a minimum total duration of 3 months. Use of LMWH or vitamin K antagonists does not preclude breastfeeding. Whether dosing should be based on weight or anti-Xa levels is unknown, and practices differ between centers. Management of delivery, including the type of anesthesia if deemed necessary, requires a multidisciplinary approach, and several options are possible, depending on local preferences and patient-specific conditions.

Long-term low-molecular-weight heparin and the post-thrombotic syndrome: a systematic review

OBJECTIVE

Post-thrombotic syndrome causes considerable morbidity. The Home-LITE study showed a lower incidence of post-thrombotic syndrome and venous ulcers after 3 months of treating deep vein thrombosis with the low-molecular-weight heparin tinzaparin versus oral anticoagulation. This systematic review examined whether long-term treatment of deep vein thrombosis using low-molecular-weight heparin, rather than oral anticoagulation, reduces development of post-thrombotic syndrome.

METHODS

We identified 9 articles comparing treatment of deep vein thrombosis using long-term low-molecular-weight heparin with any comparator, which reported outcomes relevant to the post-thrombotic syndrome assessed ≥ 3 months post-deep vein thrombosis.

RESULTS

Pooled analysis of 2 studies yielded an 87% risk reduction with low-molecular-weight heparin in the incidence of venous ulcers at ≥ 3 months (P = .019). One study showed an overall odds ratio of 0.77 (P = .001) favoring low-molecular-weight heparin for the presence of 8 patient-reported post-thrombotic syndrome signs and symptoms. Pooled analysis of 5 studies showed a risk ratio for low-molecular-weight heparin versus oral anticoagulation of 0.66 (P < .0001) for complete recanalization of thrombosed veins.

CONCLUSION

These results support the lower incidence of post-thrombotic syndrome and venous ulcers observed in Home-LITE. Long-term treatment with low-molecular-weight heparin rather than oral anticoagulation after a deep vein thrombosis may reduce or prevent development of signs and symptoms associated with post-thrombotic syndrome. Post-thrombotic syndrome and associated acute ulcers may develop more rapidly after deep vein thrombosis than previously recognized.

How to improve the implementation of guidelines on cancer-related thrombosis

Venous thromboembolism (VTE; defined by deep-vein thrombosis, central venous catheter-related thrombosis or pulmonary embolism) is a major therapeutic issue in cancer patients. VTE is reported in 15-20% of patients with cancer and is an independent prognostic factor and a leading cause of death. In this population, low-molecular-weight heparins have been shown to be superior to vitamin K antagonists. The Italian Association of Medical Oncology, the National Comprehensive Cancer Network, the American Society of Clinical Oncology, the French 'Institut National du Cancer', the European Society of Medical Oncology and the American College of Chest Physicians have all published specific guidelines, but their implementation is still low in clinical practice. Methodological assessment of these guidelines was performed using the Appraisal of Guidelines Research & Evaluation Instrument. None of the guidelines on thrombosis and cancer have sought for patients' preferences, nor were they tested among target users. VTE in cancer patients requires a multidisciplinary approach but downstream of the guidelines publication, the potential organisational barriers in applying the recommendations have not been discussed. Tolerance and cost-effectiveness of long-term use of low-molecular-weight heparin may account for the large heterogeneity seen in daily clinical practice. Homogenization of guidelines in international consensus working groups followed by educational and active implementation strategies would be very valuable in order to improve the care of VTE in cancer patients.

Lessons from French National Guidelines on the treatment of venous thrombosis and central venous catheter thrombosis in cancer patients

Increased prevalence of Venous thromboembolism (VTE), as defined by deep-vein thrombosis (DVT), central venous catheter (CVC) related thrombosis or pulmonary embolism (PE) in cancer patients has become a major therapeutic issue. Considering the epidemiology and each national recommendations on the treatment of VTE in cancer patients, we analysed guidelines implementation in clinical practice. Thrombosis is the second-leading cause of death in cancer patients and cancer is a major risk factor of VTE, due to activation of coagulation, use of long-term CVC, the thrombogenic effects of chemotherapy and anti-angiogenic drugs. Three pivotal trials (CANTHANOX, LITE and CLOT) and several meta-analysis led to recommend the long term (3 to 6 months) use of LMWH during for treating VTE in cancer patients with a high level of evidence. The Italian Association of Medical Oncology (AIOM), the National Comprehensive Cancer Network (NCCN), the American Society of Clinical Oncology (ASCO), the French "Institut National du Cancer" (INCa), the European Society of Medical Oncology (ESMO) and the American College of Chest Physicians (ACCCP) have published specific guidelines for health care providers regarding the prevention and treatment of cancer-associated VTE. Critical appraisal of these guidelines, difficulties in implementation of prophylaxis regimen, tolerance and cost effectiveness of long term use of LMWH may account for large heterogenity in daily clinical practice. Homogenization of these guidelines in international consensus using an adapted independent methodological approach followed by educational and active implementation strategies at each national level would be very valuable to improve the care of VTE in cancer patients.

Anticoagulation therapy for prevention and treatment of venous thromboembolic events in cancer patients: a review of current guidelines

Cancer patients in general have a high risk of venous thromboembolic events (VTE) driven not only by patient-related risk factors, but also risk factors related to the disease and anti-cancer therapies. Cancer patients with documented VTE have a notably worse outcome than non-cancer VTE patients. Since VTE is a highly preventable condition, it is striking that large surveys have shown significant underuse of VTE prophylaxis in surgical cancer patients and in medical cancer patients in particular. Recently, guidelines have been issued from European and American medical oncology societies and organizations for identification of cancer patients at risk, and the guidelines give recommendations for treatment of individual groups of cancer patients. This review summarizes the recommendations for VTE prophylaxis and treatment from the recent guidelines and reviews some outstanding issues in VTE prophylaxis and treatment of cancer patients.

Oral Warfarin Remains An Effective Treatment Option in the Extended Prophylaxis of VTE for Patients with Cancer: The Effectiveness of the CancerCare Manitoba (CCMB) Anticoagulation Clinic (ACC)

Venothromboembolism (VTE) in patients with active malignancy is associated with adverse outcomes and effective anticoagulation for extended duration with either oral vitamin K antagonist (VKA) or low molecular weight heparin (LMWH) is indicated for as long as the cancer is active. Although current literature suggests that LMWH is more efficacious in reducing VTE recurrence in patients with cancer when compared with oral VKA1, the need for daily injection and high drug cost are major drawbacks to the upfront use of LMWH in this setting. At our institution in Manitoba (Canada), we treat all patients with first line VKA, managed by a specialized pharmacist-run anticoagulation clinic (CCMB ACC), switching to LMWH if thrombosis recurs despite VKA. The aim of this retrospective review is to access the efficacy and safety of this approach, comparing outcomes between patients with cancer to a convenience cohort (controls) on VKA managed by the same ACC and to that of the literature. We hypothesize that appropriate anticoagulation with an oral VKA can be achieved through ACC and its use as first line therapy for extended VTE prophylaxis in cancer patients is not associated with significant increase in VTE recurrence or major bleeding episodes.

Methods: We analyzed retrospectively all patients receiving oral VKA who were monitored by the CCMB ACC from July 23, 2002 to August 9, 2007, using the ACC database and CCMB electronic charts. Primary outcome is the time spent within the target INR range (%TSTR) which is defined as the proportion of patient-days for which the INR was between 2 and 3, and imputing daily values between INR tests by linear interpolation2. We limit this analysis to include only patients with at least 30 days of follow up to ensure adequate time for stabilization of INR. Secondary outcomes include rate of VTE recurrence, rate of major bleeding and rate of switching to LMWH for any reason. Multinomial logistic regression was performed to identify predictors for poor anticoagulation as well as cox regression to identify predictors of recurrence VTE or bleeding complications.

Results: Although the quality of anticoagulation with oral VKA is inferior in patients with VTE and active cancer when compared to control patients (%TSTR 54% versus 64%, p&lt;0.001), the rate of VTE recurrence and bleeding is similar. The TSTR in this cohort compared favourably with those obtained from the literature (%TSTR 54% vs 46% in the CLOT trial3) and the risk of VTE recurrence and bleeding is not excessive (10% and 5.3% respectively). However, patients with cancer are more likely to experience VKA failure (OR 7.22; 95% CI 1.47–35.5) and risk of death (OR 4.48; 95% CI 2.72–7.34) compared to control. No significant predictors were identified for recurrent VTE but those with poor INR control were more likely to suffer from bleeding complications.

Conclusions: Oral VKA remains an effective option for anticoagulation for most patients and LMWH can be reserved for patients with additional risks for VKA failure and those with poor INR control due to increased risk of bleeding.