Comparison of tinzaparin and acenocoumarol for the secondary prevention of venous thromboembolism: a multicentre, randomized study

Cancer-Associated Thrombosis: Not All Low-Molecular-Weight Heparins Are the Same, Focus on Tinzaparin, A Narrative Review

Cancer-associated thrombosis (CAT) is the second main cause of cancer death with high related mortality and morbidity, leading to anticancer agent delays and interruptions. The recommended therapy, low-molecular-weight heparin (LMWH), however, is burdensome for patients and costly for society, as treatment should last until cancer is no longer active, even indefinitely. Tinzaparin is a manageable, efficient, safe, and cost-effective option. Compared to the other LMWHs, advantages are single-daily dose and safety in the elderly and those with renal impairment (RI). The purpose of this review is to critically discuss recent data on its efficacy and safety in CAT.

Anticoagulation for the long-term treatment of venous thromboembolism in people with cancer

BACKGROUND

Cancer increases the risk of thromboembolic events, especially in people receiving anticoagulation treatments.

OBJECTIVES

To compare the efficacy and safety of low molecular weight heparins (LMWHs), direct oral anticoagulants (DOACs) and vitamin K antagonists (VKAs) for the long-term treatment of venous thromboembolism (VTE) in people with cancer.

SEARCH METHODS

We conducted a literature search including a major electronic search of the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 1), MEDLINE (Ovid), and Embase (Ovid); handsearching conference proceedings; checking references of included studies; use of the 'related citation' feature in PubMed and a search for ongoing studies in trial registries. As part of the living systematic review approach, we run searches continually, incorporating new evidence after it is identified. Last search date 14 May 2018.

SELECTION CRITERIA

Randomized controlled trials (RCTs) assessing the benefits and harms of long-term treatment with LMWHs, DOACs or VKAs in people with cancer and symptomatic VTE.

DATA COLLECTION AND ANALYSIS

We extracted data in duplicate on study characteristics and risk of bias. Outcomes included: all-cause mortality, recurrent VTE, major bleeding, minor bleeding, thrombocytopenia, and health-related quality of life (QoL). We assessed the certainty of the evidence at the outcome level following the GRADE approach (GRADE handbook).

MAIN RESULTS

Of 15,785 citations, including 7602 unique citations, 16 RCTs fulfilled the eligibility criteria. These trials enrolled 5167 people with cancer and VTE.Low molecular weight heparins versus vitamin K antagonistsEight studies enrolling 2327 participants compared LMWHs with VKAs. Meta-analysis of five studies probably did not rule out a beneficial or harmful effect of LMWHs compared to VKAs on mortality up to 12 months of follow-up (risk ratio (RR) 1.00, 95% confidence interval (CI) 0.88 to 1.13; risk difference (RD) 0 fewer per 1000, 95% CI 45 fewer to 48 more; moderate-certainty evidence). Meta-analysis of four studies did not rule out a beneficial or harmful effect of LMWHs compared to VKAs on major bleeding (RR 1.09, 95% CI 0.55 to 2.12; RD 4 more per 1000, 95% CI 19 fewer to 48 more, moderate-certainty evidence) or minor bleeding (RR 0.78, 95% CI 0.47 to 1.27; RD 38 fewer per 1000, 95% CI 92 fewer to 47 more; low-certainty evidence), or thrombocytopenia (RR 0.94, 95% CI 0.52 to 1.69). Meta-analysis of five studies showed that LMWHs probably reduced the recurrence of VTE compared to VKAs (RR 0.58, 95% CI 0.43 to 0.77; RD 53 fewer per 1000, 95% CI 29 fewer to 72 fewer, moderate-certainty evidence).Direct oral anticoagulants versus vitamin K antagonistsFive studies enrolling 982 participants compared DOACs with VKAs. Meta-analysis of four studies may not rule out a beneficial or harmful effect of DOACs compared to VKAs on mortality (RR 0.93, 95% CI 0.71 to 1.21; RD 12 fewer per 1000, 95% CI 51 fewer to 37 more; low-certainty evidence), recurrent VTE (RR 0.66, 95% CI 0.33 to 1.31; RD 14 fewer per 1000, 95% CI 27 fewer to 12 more; low-certainty evidence), major bleeding (RR 0.77, 95% CI 0.38 to 1.57, RD 8 fewer per 1000, 95% CI 22 fewer to 20 more; low-certainty evidence), or minor bleeding (RR 0.84, 95% CI 0.58 to 1.22; RD 21 fewer per 1000, 95% CI 54 fewer to 28 more; low-certainty evidence). One study reporting on DOAC versus VKA was published as abstract so is not included in the main analysis.Direct oral anticoagulants versus low molecular weight heparinsTwo studies enrolling 1455 participants compared DOAC with LMWH. The study by Raskob did not rule out a beneficial or harmful effect of DOACs compared to LMWH on mortality up to 12 months of follow-up (RR 1.07, 95% CI 0.92 to 1.25; RD 27 more per 1000, 95% CI 30 fewer to 95 more; low-certainty evidence). The data also showed that DOACs may have shown a likely reduction in VTE recurrence up to 12 months of follow-up compared to LMWH (RR 0.69, 95% CI 0.47 to 1.01; RD 36 fewer per 1000, 95% CI 62 fewer to 1 more; low-certainty evidence). DOAC may have increased major bleeding at 12 months of follow-up compared to LMWH (RR 1.71, 95% CI 1.01 to 2.88; RD 29 more per 1000, 95% CI 0 fewer to 78 more; low-certainty evidence) and likely increased minor bleeding up to 12 months of follow-up compared to LMWH (RR 1.31, 95% CI 0.95 to 1.80; RD 35 more per 1000, 95% CI 6 fewer to 92 more; low-certainty evidence). The second study on DOAC versus LMWH was published as an abstract and is not included in the main analysis.Idraparinux versus vitamin K antagonistsOne RCT with 284 participants compared once-weekly subcutaneous injection of idraparinux versus standard treatment (parenteral anticoagulation followed by warfarin or acenocoumarol) for three or six months. The data probably did not rule out a beneficial or harmful effect of idraparinux compared to VKAs on mortality at six months (RR 1.11, 95% CI 0.78 to 1.59; RD 31 more per 1000, 95% CI 62 fewer to 167 more; moderate-certainty evidence), VTE recurrence at six months (RR 0.46, 95% CI 0.16 to 1.32; RD 42 fewer per 1000, 95% CI 65 fewer to 25 more; low-certainty evidence) or major bleeding (RR 1.11, 95% CI 0.35 to 3.56; RD 4 more per 1000, 95% CI 25 fewer to 98 more; low-certainty evidence).

AUTHORS' CONCLUSIONS

For the long-term treatment of VTE in people with cancer, evidence shows that LMWHs compared to VKAs probably produces an important reduction in VTE and DOACs compared to LMWH, may likely reduce VTE but may increase risk of major bleeding. Decisions for a person with cancer and VTE to start long-term LMWHs versus oral anticoagulation should balance benefits and harms and integrate the person's values and preferences for the important outcomes and alternative management strategies.Editorial note: this is a living systematic review (LSR). LSRs offer new approaches to review updating in which the review is continually updated, incorporating relevant new evidence as it becomes available. Please refer to the Cochrane Database of Systematic Reviews for the current status of this review.

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.

Index clinical manifestation of venous thromboembolism predicts early recurrence type and frequency: a meta-analysis of randomized controlled trials

BACKGROUND

Observational studies suggest index clinical manifestation of venous thromboembolism (VTE) predicts recurrence type. Data regarding the association between index manifestation and recurrence rates are conflicting.

OBJECTIVES

To perform a meta-analysis of randomized controlled trials (RCTs) to determine the type and frequency of recurrent VTE (rVTE) in persons after an index deep vein thrombosis (DVT) or pulmonary embolism (PE).

PATIENTS/METHODS

We searched bibliographic databases for RCTs of acute (early) treatment of rVTE in persons with an index DVT or PE (±DVT), enrolling ≥ 50 subjects anticoagulated ≥ 3-months and reporting types of rVTE. We pooled (random-effects) the proportion of rVTEs that were DVTs, PEs, and fatal PEs, the proportion of recurrent PEs that were fatal, and absolute rVTE rates.

RESULTS

In nine RCTs (N = 13 640; 413 rVTEs) evaluating persons with an index PE; 66% (95% CI, 60-72%) of rVTEs were PE and 27% (95% CI, 22-33%) were fatal PE. Among 25 RCTs (N = 17 340; 692 rVTEs) evaluating persons with an index DVT, 36% (95% CI, 29-44%) experienced a recurrent PE and 10% (95% CI, 7-13%) a fatal PE. Recurrent PEs following an index PE had a higher fatality rate than after an index DVT (41%; 95% CI, 33-48% vs. 25%; 95% CI, 18-33%; P = 0.007). The rVTE rate was higher following an index DVT compared with a PE (2.6%; 95% CI, 1.6-3.8% vs. 4.9%; 95% CI, 4.0-6.0%; P = 0.002).

CONCLUSIONS

Our meta-analysis suggests most rVTEs will be the same type as the index event. While index DVTs are associated with a higher rVTE rate than index PEs; recurrent PEs are associated with high fatality.

Anticoagulation for the long-term treatment of venous thromboembolism in patients with cancer

BACKGROUND

Cancer increases the risk of thromboembolic events in patients including those receiving anticoagulation treatments.

OBJECTIVES

To compare the efficacy and safety of low molecular weight heparin (LMWH) and oral anticoagulants for the long-term treatment of venous thromboembolism (VTE) in patients with cancer.

SEARCH METHODS

We conducted a comprehensive search for studies of anticoagulation in cancer patients including 1. a February 2013 electronic search of: the Cochrane Central Register of Controlled Trials (CENTRAL Issue 12, 2012), MEDLINE, and EMBASE; 2. a handsearch of conference proceedings; 3. checking of references of included studies; 4. use of the 'related citation' feature in PubMed; and 5. a search of clinicaltrials.gov for ongoing studies.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) comparing long-term treatment with LMWH versus oral anticoagulants (vitamin K antagonist (VKA) or ximelagatran) in patients with cancer and symptomatic objectively confirmed VTE.

DATA COLLECTION AND ANALYSIS

Using a standardized data form, we extracted data on methodological quality, participants, interventions and outcomes of interest: survival, recurrent VTE, major bleeding, minor bleeding, thrombocytopenia, and postphlebitic syndrome. We assessed the quality of evidence at the outcome level following the GRADE approach.

MAIN RESULTS

Of 9559 identified citations, 10 RCTs (11 reports) were eligible and reported data for 1981 patients with cancer. We excluded 14 studies in which patients with cancer constituted study subgroups, but did not report outcome data for them. Meta-analysis of seven RCTs comparing LMWH with VKA found no statistically significant survival benefit (hazard ratio (HR) 0.96; 95% confidence interval (CI) 0.81 to 1.14) but a statistically significant reduction in VTE (HR 0.47; 95% CI 0.32 to 0.71). The remaining findings did not exclude a beneficial or harmful effect of LMWH compared with VKA for the outcomes of major bleeding (RR 1.07; 95% CI 0.52 to 2.19), minor bleeding (RR 0.89; 95% CI 0.51 to 1.55), or thrombocytopenia (RR 0.98; 95% CI 0.57 to 1.66). We judged the quality of evidence as low for mortality, major bleeding, and minor bleeding, and as moderate for recurrent VTE.One RCT comparing dabigatran with VKA did not exclude beneficial or harmful effects of one agent over the other. One RCT comparing six months' extension of anticoagulation with 18 months of ximelagatran 24 mg twice daily versus no extended ximelagatran did not exclude beneficial or harmful effects for the outcomes of reduction in VTE, mortality, and minor bleeding. One RCT comparing once-weekly subcutaneous injection of idraparinux for three or six months versus standard treatment (parenteral anticoagulation followed by warfarin or acenocoumarol) suggested a reduction in recurrent VTE (HR 0.39; 95% CI 0.14 to 1.11) at six months, but did not exclude beneficial or harmful effects for the outcomes of mortality (HR 0.99; 95% CI 0.66 to 1.48) and major bleeding (RR 1.04; 95% CI 0.39 to 2.83).

AUTHORS' CONCLUSIONS

For the long-term treatment of VTE in patients with cancer, LMWH compared with VKA reduces venous thromboembolic events but not mortality. The decision for a patient with cancer and VTE to start long-term LMWH versus oral anticoagulation should balance the benefits and harms and integrate the patient's values and preferences for the important outcomes and alternative management strategies.

Measures of vitamin K antagonist control reported in atrial fibrillation and venous thromboembolism studies: a systematic review

OBJECTIVE

To aid trialists, systematic reviewers and others, we evaluated the degree of standardisation of control measure reporting that has occurred in atrial fibrillation (AF) and venous thromboembolism (VTE) studies since 2000; and attempted to determine whether the prior recommendation of reporting ≥2 measures per study has been employed.

DESIGN

Systematic review.

SEARCH STRATEGY

We searched bibliographic databases (2000 to June 2013) to identify AF and VTE studies evaluating dose-adjusted vitamin K antagonists (VKAs) and reporting ≥1 control measure. The types of measures reported, proportion of studies reporting ≥2 measures and mean (±SD) number of measures per study were determined for all studies and compared between subgroups.

DATA EXTRACTION

Through the use of a standardised data extraction tool, we independently extracted all data, with disagreements resolved by a separate investigator.

RESULTS

148 studies were included, 57% of which reported ≥2 control measures (mean/study=2.13±1.36). The proportion of time spent in the target international normalised ratio range (TTR) was most commonly reported (79%), and was frequently accompanied by time above/below range (52%). AF studies more frequently reported ≥2 control measures compared with VTE studies (63% vs 37%; p=0.004), and reported a greater number of measures per study (mean=2.36 vs 1.53; p<0.001). Observational studies were more likely to provide ≥2 measures compared with randomised trials (76% vs 33%; p<0.001) and report a greater number of measures (mean=2.58 vs 1.63; p<0.001). More recent studies (2004-2013) reported ≥2 measures more often than older (2000-2003) studies (59% vs 35%; p=0.05) and reported more measures per study (mean=2.23 vs 1.48; p=0.02).

CONCLUSIONS

While TTR was often utilised, studies reported ≥2 measures of VKA control only about half of the time and lacked consistency in the types of measures reported. A trend towards studies reporting greater numbers of VKA control measures over time was observed over our review time horizon, particularly, with AF and observational studies.

Cost-effectiveness of rivaroxaban compared with enoxaparin plus a vitamin K antagonist for the treatment of venous thromboembolism

BACKGROUND

Venous thromboembolism (VTE), comprised of deep vein thrombosis (DVT) and pulmonary embolism (PE), is commonly treated with a low-molecular-weight heparin such as enoxaparin plus a vitamin K antagonist (VKA) to prevent recurrence. Administration of enoxaparin + VKA is hampered by complexities of laboratory monitoring and frequent dose adjustments. Rivaroxaban, an orally administered anticoagulant, has been compared with enoxaparin + VKA in the EINSTEIN trials. The objective was to evaluate the cost-effectiveness of rivaroxaban compared with enoxaparin + VKA as anticoagulation treatment for acute, symptomatic, objectively-confirmed DVT or PE.

METHODS

A Markov model was built to evaluate the costs, quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratios associated with rivaroxaban compared to enoxaparin + VKA in adult patients treated for acute DVT or PE. All patients entered the model in the 'on-treatment' state upon commencement of oral rivaroxaban or enoxaparin + VKA for 3, 6, or 12 months. Transition probabilities were obtained from the EINSTEIN trials during treatment and published literature after treatment. A 3-month cycle length, US payer perspective ($2012), 5-year time horizon and a 3% annual discount rate were used.

RESULTS

Treatment with rivaroxaban cost $2,448 per-patient less and was associated with 0.0058 more QALYs compared with enoxaparin + VKA, making it a dominant economic strategy. Upon one-way sensitivity analysis, the model's results were sensitive to the reduction in index VTE hospitalization length-of-stay associated with rivaroxaban compared with enoxaparin + VKA. At a willingness-to-pay threshold of $50,000/QALY, probabilistic sensitivity analysis showed rivaroxaban to be cost-effective compared with enoxaparin + VKA approximately 76% of the time.

LIMITATIONS

The model did not account for the benefits associated with an oral and minimally invasive administration of rivaroxaban. 'Real-world' applicability is limited because data from the EINSTEIN trials were used in the model. Also, resource utilization and costs were based on the US healthcare system.

CONCLUSION

Rivaroxaban is a cost-effective option for anticoagulation treatment of acute VTE patients.

Long-term treatment of deep-vein thrombosis with low-molecular-weight heparin: an update of the evidence

This article reviews updated evidence-based knowledge on long-term treatment of deep-vein thrombosis (DVT) with low-molecular-weight heparin (LMWH) or vitamin K antagonists (VKAs). Eleven trials were identified comparing the two treatments in a broad spectrum of patients with DVT and with >100 study participants. Four comparative trials were identified in patients with cancer and DVT (in whom anticoagulation treatment is more complex and bleeding complications more frequent). In the 11 trials in broad patient populations, LMWHs were as effective as VKAs in preventing recurrent venous thromboembolism (VTE), and there were no consistent differences in the incidence of bleeding complications during long-term treatment. In patients with cancer, VTE recurrence was significantly reduced with LMWH versus VKA in two studies, while major bleeding complications did not differ between groups in any of the four trials. Current evidence-based European and American guidelines recommend LMWH over VKA for the long-term treatment of DVT in patients with cancer. LMWH and VKA are recommended over the new oral anticoagulant drugs, for which there are limited data on use in long-term treatment. Post-thrombotic syndrome (PTS), a common complication of DVT, causes considerable morbidity. Long-term use of tinzaparin reduced the risk of PTS compared with VKA in one trial, and a meta-analysis of nine studies in total demonstrated a consistently favourable effect of LMWHs versus VKA on PTS-related outcomes. Given the limited treatment options available for PTS, this suggests that LMWHs provide a useful therapeutic option in any patient particularly at risk of developing PTS.

Benchmark for time in therapeutic range in venous thromboembolism: a systematic review and meta-analysis

INTRODUCTION

The percentage of time within the target INR range 2.0 to 3.0 (TTR) in patients treated with vitamin K antagonists varies considerably among efficacy-studies of novel anticoagulants. In order to properly asses the quality of anticoagulant control in upcoming cost-effectiveness studies and real life registries this systematic review reports a benchmark of TTR for different treatment durations in patients with venous thromboembolism and discusses ways to calculate TTR.

METHODS

Medline and Embase were searched for studies published between January 1990 and May 2012. Randomized controlled trials and cohort studies reporting the TTR in patients with objectively confirmed venous thromboembolism treated with vitamin K antagonists (VKA) were eligible. Duplicate reports, studies only reporting INR during initial treatment or with VKA treatment less than 3 months were excluded. Three authors assessed trials for inclusion and extracted data independently. Discrepancies were resolved by discussion between the reviewers. A meta-analysis was performed by calculating a weighted mean, based on the number of participants in each included study, for each time-period in which the TTR was measured since the confirmation of the diagnosis of VTE.

RESULTS

Forty studies were included (26064 patients). The weighted means of TTR were 54.0% in the first month since the start of treatment, 55.6% in months 1 to 3, 60.0% in months 2 to 3, 60.0% in the months 1 to 6+ and 75.2% in months 4 to 12+. Five studies reported TTR in classes. The INR in these studies was ≥ 67% of time in therapeutic range in 72.0% of the patients.

CONCLUSION

Reported quality of VKA treatment is highly dependent on the time-period since the start of treatment, with TTR ranging from approximately 56% in studies including the 1(st) month to 75% in studies excluding the first 3 months.