Long-term treatment of deep venous thrombosis with a low molecular weight heparin (tinzaparin): a prospective randomized trial

Current challenges in the prevention and management of post-thrombotic syndrome-towards improved prevention

Post-thrombotic syndrome (PTS) is a common and potentially debilitating complication of deep vein thrombosis (DVT), affecting up to 50% of DVT patients. The consequence of this chronic condition includes reduced quality of life, increased use of the healthcare system and decreased productivity. The societal impact of this condition is projected to increase, given our ageing population and increased burden of thrombotic diseases. Despite significant recent advances in our understanding of PTS, many unanswered questions remain. Currently, there are few effective and proven options for established PTS; hence, the emphasis should be on instituting effective prevention to reduce the progression to PTS. Effective anticoagulation lowers the risk of PTS, with direct oral anticoagulants appearing to outperform vitamin-K antagonists. However, the evidence for elastic compression stockings and endovascular thrombolysis or thrombectomy techniques remains unclear. Accurate identification of individuals at high risk of developing PTS may also improve the targeting of preventative interventions. This review will examine the current body of evidence regarding PTS, with a focus on preventative strategies as well as novel biomarkers.

Tinzaparin—a review of its molecular profile, pharmacology, special properties, and clinical uses

Purpose

Low molecular weight heparins (LMWHs) are a group of heterogenous moieties, long used in the prevention and treatment of thrombosis. They derive from heparin and since they are prepared by different methods of depolymerization, they differ in pharmacokinetic properties and anticoagulant profiles, and thus are not clinically interchangeable.

Methods

In this review we provide an overview of tinzaparin's main characteristics and uses.

Results

Tinzaparin which is produced by the enzymatic depolymerization of unfractionated heparin (UFH) can be used for the treatment and prevention of deep venous thrombosis (DVT) and pulmonary embolism (PE); it has been also used in special populations such as elders, obese, pregnant women, and patients with renal impairment and/or cancer with favorable outcomes in both safety and efficacy, with a once daily dose regimen. Furthermore, LMWHs are extensively used in clinical practice for both thromboprophylaxis and thrombosis treatment of COVID-19 patients.

Conclusion

Tinzaparin features support the hypothesis for having a role in immunothrombosis treatment (i.e. in the context of cancer ,COVID-19), interfering not only with coagulation cascade but also exhibiting anti-inflammatory potency.

Therapeutically dosed low molecular weight heparins in renal impairment: a nationwide survey

PURPOSE

International guidelines vary in their recommendations whether or not to reduce the therapeutic dose of low molecular weight heparins (LMWHs) in renal impairment. The use of anti-Xa monitoring as a basis of dose adjustments is also a matter of debate. As this may lead to variations in treatment policies, we aimed to study the treatment policies of therapeutically dosed LMWHs in renal impairment in Dutch hospitals.

METHODS

An 11-item survey was distributed between June 2020 and March 2021 to hospital pharmacists, representing Dutch hospital organisations. Primary outcomes were the dosing regimens of therapeutically dosed LMWHs in renally impaired patients. Secondary outcomes were the proportion of hospitals that used anti-Xa monitoring and the anti-Xa target range used.

RESULTS

There was a response from 56 of 69 (81%) Dutch hospital organisations where in each case a hospital pharmacist completed the survey. In these hospitals, 77 LMWH regimens were in use. In 76 of 77 (99%) regimens, a regular dose reduction was used at the start of treatment. Fifty-five of these hospitals used a dose reduction if estimated glomerular filtration rate (eGFR) < 50 ml/min and 17 used a dose reduction if eGFR < 30 ml/min. Anti-Xa levels were not routinely monitored in 40% of regimens, while 22% monitored anti-Xa if eGFR < 50 ml/min, 27% if eGFR < 30 ml/min and 10% in other eGFR cutoff values. Target ranges of 1.0-2.0 IU/ml (once daily) and 0.5/0.6-1.0 IU/ml (twice daily) were used in 69% of regimens that included monitoring of anti-Xa.

CONCLUSION

Treatment policies show substantial diversity in therapeutically dosed LMWHs in renally impaired patients. The most commonly used treatment regimen was a regular dose reduction if eGFR is < 50 ml/min, without anti-Xa monitoring.

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.

Safety and Efficacy of Low Molecular Weight Heparin for Thromboprophylaxis in the Elderly: A Network Meta-Analysis of Randomized Clinical Trials

Background: Given their changing pathophysiology, elderly patients carry a high risk of embolism and bleeding events; hence, use of appropriate anticoagulants is very important. Low molecular weight heparin (LMWH) is one of the most widely used anticoagulants although LMWHs differ in their anti-Xa, antithrombin, and anticoagulant activities. To date, no study has directly compared the safety and efficacy of different LMWHs in the elderly. We aimed to compare such differences by conducting a network meta-analysis.

Methods: We searched the Pubmed, Embase, and Cochrane databases for randomized controlled trials (RCTs) of LMWHs that included patients ≥60 years old up to July 22, 2020. Safety outcomes included venous thromboembolism (VTE) or VTE-related death, deep thrombus embolism, and pulmonary embolism. Safety outcomes were clinically relevant bleeding, major bleeding, minor bleeding, and all-cause death. We calculated relative ratios (RR) and 95% confidence intervals (CI) for all outcomes. The cumulative ranking probabilities (SUCRA) were conducted to rank the comparative effects and safety of all LMWHs.

Results: We included 27 RCTs (30,441 elderly), comprising five LMWHs. LMWH was more effective than placebo in preventing VTE or VTE-related death (RR 0.36, 95% CI 0.25–0.53) but less effective than a novel oral anticoagulant (RR 1.59, 95% CI 1.33–1.91) and safer than acenocoumarol regarding risk of clinically relevant bleeding (RR 0.67, 95% CI 0.49–0.90). However, indirect comparison of efficacy and safety of the five LMWHs showed no significant difference in our network analysis, and the subgroup analyses (such as in patients with deep venous thrombosis, cardiac disease, or age >65 years old) supported the results. The SUCRA showed that tinzaparin performed best in preventing VTE or VTE-related death (SUCRA 68.8%, cumulative probability 42.3%) and all-cause death (SUCRA 84.2%, cumulative probability 40.7%), whereas nadroparin was predominant in decreasing the risk of clinically relevant bleeding (SUCRA 84.8%, cumulative probability 77.0%).

Conclusions: On present evidence, there are no significant differences in the efficacy and safety of different LMWHs for the elderly. According to the rank probability analysis, nadroparin seems to be safer for the elderly with a high risk of bleeding, whereas tinzaparin is more effective for those with low bleeding risk.

Pharmacomechanical catheter-directed thrombolysis for acute iliofemoral deep vein thrombosis in a large study population

BACKGROUND

We have analyzed our single-center immediate and follow-up results in the management of acute iliofemoral deep vein thrombosis (IFDVT) using pharmacomechanical catheter-directed thrombolysis (PMCDT) to determine the safety, accuracy, and effects on quality of life and whether this treatment strategy prevents post-thrombotic syndrome (PTS).

METHODS

The cases of 230 patients who had undergone PMCDT to treat IFDVT from January 2017 to December 2018 were retrospectively reviewed. The preoperative, operative, and postoperative variables, Marder scores, outcomes, and follow-up assessments with the Villalta score and venous clinical severity score were investigated.

RESULTS

Anatomic success was achieved for 95.2% of the 230 patients. The mean Marder score had decreased from 12.65 ± 2.1 to 2.4 ± 1.3 postoperatively (P < .01). Early recurrent thrombosis had developed in 13 patients (5.65%). The primary patency at the 1-, 6-, and 12-month follow-up visits was 94.0%, 87.2%, and 81.7%, respectively. From 1 to 6 months, the Villalta score had decreased from 8.32 ± 4.14 to 3.43 ± 0.61 and the venous clinical severity score had decreased from 4.0 ± 1.8 to 1.82 ± 0.36 (P < .05). No statistically significant difference was found in the PTS severity scores at 12 months of follow-up compared with at 6 months. The mean change in the venous disease-specific quality of life from baseline to 12 months was 29.41 ± 1.99 (P = .029). The total recurrence rate was 19.63% at 1 year.

CONCLUSIONS

For a select group of patients with acute IFDVT, the use of PMCDT and postoperative anticoagulation therapy offered significant reductions in clot burden, leg pain, and swelling, achieving a significant reduction in PTS severity scores at 6 months.

Prevention of the post thrombotic syndrome with anticoagulation: a narrative review

The post thrombotic syndrome (PTS) is chronic venous insufficiency secondary to a prior deep vein thrombosis (DVT). It is the most common complication of VTE and, while not fatal, it can lead to chronic, unremitting symptoms as well as societal and economic consequences. The cornerstone of PTS treatment lies in its prevention after DVT. Specific PTS preventative measures include the use of elastic compression stockings (ECS) and pharmacomechanical catheter directed thrombolysis (PCDT). However, the efficacy of these treatments has been questioned by large RCTs. So far, anticoagulation, primarily prescribed to prevent DVT extension and recurrence, appears to be the only unquestionably effective treatment for the prevention of PTS. In this literature review we present pathophysiological, biological, radiological and clinical data supporting the efficacy of anticoagulants to prevent PTS and the possible differential efficacy among available classes of anticoagulants (vitamin K antagonists (VKA), low molecular weight heparins (LMWHs) and direct oral anticoagulants (DOACs)). Data suggest that LMWHs and DOACs are superior to VKAs, but no head-to-head comparison is available between DOACs and LMWHs. Owing to their potentially greater anti-inflammatory properties, LMWHs could be superior to DOACs. This finding may be of interest particularly in patients with extensive DVT at high risk of moderate to severe PTS, but needs to be confirmed by a dedicated RCT.

Site of Deep Venous Thrombosis and Age in the Selection of Patients in the Emergency Department for Hospitalization Versus Home Treatment

Despite apparent advantages of home treatment of deep venous thrombosis (DVT) based upon results of randomized controlled trials, physicians maintain a conservative approach, and a large proportion of patients with DVT are hospitalized. In the present investigation we assess whether selection of patients for hospitalization for acute DVT was related to the site of the DVT or to age. This was a retrospective cohort study based on administrative data from the Nationwide Emergency Department Sample, 2016. Patients were identified by International Classification of Diseases-10-Clinical Modification codes. Most, 87,436 of 133,414 (66%), had proximal DVT. A minority of patients with isolated distal DVT were hospitalized, 10,621 of 37,592 (28%). However, hospitalization was selected for 47,459 of 87,436 (54%) with proximal DVT; 4,867 of 7,599 (64%) with pelvic vein DVT; and 611 of 788 (78%) with DVT involving the inferior vena cava. Hospitalization for patients with distal DVT, proximal DVT, and pelvic vein DVT was age-dependent. In conclusion, both the site of acute DVT and age were factors affecting the clinical decision of emergency department physicians to select patients for hospital treatment.

American Society of Hematology 2020 guidelines for management of venous thromboembolism: treatment of deep vein thrombosis and pulmonary embolism

BACKGROUND

Venous thromboembolism (VTE), which includes deep vein thrombosis (DVT) and pulmonary embolism (PE), occurs in ∼1 to 2 individuals per 1000 each year, corresponding to ∼300 000 to 600 000 events in the United States annually.

OBJECTIVE

These evidence-based guidelines from the American Society of Hematology (ASH) intend to support patients, clinicians, and others in decisions about treatment of VTE.

METHODS

ASH formed a multidisciplinary guideline panel balanced to minimize potential bias from conflicts of interest. The McMaster University GRADE Centre supported the guideline development process, including updating or performing systematic evidence reviews. The panel prioritized clinical questions and outcomes according to their importance for clinicians and adult patients. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used to assess evidence and make recommendations, which were subject to public comment.

RESULTS

The panel agreed on 28 recommendations for the initial management of VTE, primary treatment, secondary prevention, and treatment of recurrent VTE events.

CONCLUSIONS

Strong recommendations include the use of thrombolytic therapy for patients with PE and hemodynamic compromise, use of an international normalized ratio (INR) range of 2.0 to 3.0 over a lower INR range for patients with VTE who use a vitamin K antagonist (VKA) for secondary prevention, and use of indefinite anticoagulation for patients with recurrent unprovoked VTE. Conditional recommendations include the preference for home treatment over hospital-based treatment for uncomplicated DVT and PE at low risk for complications and a preference for direct oral anticoagulants over VKA for primary treatment of VTE.

Network meta-analysis of anticoagulation strategies for venous thromboembolism in patients with cancer

Cancer-associated thrombosis (CAT) is a common complication in patients with malignancy. Although direct oral anticoagulants (DOACs) have emerged as a treatment option for CAT, there have not been head-to-head comparisons of these agents. We searched MEDLINE and EMBASE from inception to April 2020 for studies comparing the effect of different long-term anticoagulation strategies for venous thromboembolism (VTE) in patients with cancer. We performed a network meta-analysis comparing the antithrombotic strategies in the selected studies using random-effects model. We identified a total of 20 studies [9 randomized control trials (RCTs) and 11 subgroup analyses from other unique RCTs] with total of 6699 patients for inclusion in our analysis. There was no significant difference in recurrent VTE, all-cause death, major bleeding and clinically relevant non-major bleeding among DOACs. When DOACs were combined, recurrent VTE was significantly decreased in DOACs compared to low-molecular weight heparin (LMWH) and Vitamin K antagonist (VKA) [RR (95% CI) 0.75 (0.59-0.94); RR (95% CI) 0.51 (0.39-0.66), respectively] without significant increase in major bleeding or clinically relevant non-major bleeding. In patients with CAT, there was no significant difference in recurrent thrombotic event among different DOACs. Bleeding risk was comparable among all anticoagulation strategies. When DOACs were combined, DOACs were associated with a significant decrease in recurrent VTE with comparable bleeding risk to LMWH and VKA.

Home vs hospital treatment of low-risk venous thromboembolism: a systematic review and meta-analysis

Increasing evidence supports the safety and effectiveness of managing low-risk deep vein thrombosis (DVT) or pulmonary embolism (PE) in outpatient settings. We performed a systematic review to assess safety and effectiveness of managing patients with DVT or PE at home compared with the hospital. Medline, Embase, and Cochrane databases were searched up to July 2019 for relevant randomized clinical trials (RCTs), and prospective cohort studies. Two investigators independently screened titles and abstracts of identified citations and extracted data from relevant full-text papers. Risk ratios (RRs) were calculated, and certainty of evidence was assessed using Grading of Recommendations Assessment, Development and Evaluation (GRADE). Seven RCTs (1922 patients) were included in meta-analyses on managing patients with DVT. Pooled estimates indicated decreased risk of PE (RR = 0.64; 95% confidence interval [CI], 0.44-0.93) and recurrent DVT (RR = 0.61; 95% CI, 0.42-0.90) for home management, both with moderate certainty of the evidence. Reductions in mortality and major bleeding were not significant, both with low certainty of the evidence. Two RCTs (445 patients) were included in meta-analyses on home management of low-risk patients with PE. Pooled estimates indicated no significant difference in all-cause mortality, recurrent PE, and major bleeding, all with low certainty of the evidence. Results of pooled estimates from 3 prospective cohort studies (234 patients) on home management of PE showed similar results. Our findings indicate that low-risk DVT patients had similar or lower risk of patient-important outcomes with home treatment compared with hospital treatment. In patients with low-risk PE, there was important uncertainty about a difference between home and hospital treatment.

Comparison of Treatment Result Between Anticoagulation Alone and Catheter-Directed Thrombolysis Plus Anticoagulation in Acute Lower Extremity Deep Vein Thrombosis

Purpose

Deep vein thrombosis (DVT) is the third most common cause of cardiovascular morbidity and mortality. Anticoagulation has been the primary treatment modality for acute DVT. However, catheter-directed thrombolysis (CDT) has recently become widely accepted as an additional therapy to anticoagulation. We assessed comparative outcomes in patients with acute DVT who underwent anticoagulation therapy alone (ACA) group and those treated with CDT group.

Materials and Methods

We retrospectively reviewed medical records of 149 patients with DVT from January 2011 to December 2015. We compared patients who received ACA group (n=120) and those who received CDT plus anticoagulation (CDT group, n=29). We analyzed the prevalence of lesions, thrombus removal rate in each lesion, and recurrence-free rate between the two groups.

Results

We found thrombus involvement in a total of 281 lesions in the ACA group and 85 lesions in the CDT group. For the distribution of lesions in each group, those in the femoral vein accounted for 34.2% of all lesions and those in the popliteal vein accounted for 31.7%. During follow-up, the overall thrombus removal rate was 91.1% in the ACA group and 87.0% in the CDT group (P=0.273). The recurrence-free rate was higher in the CDT group in a log-rank test; however, there was no statistically significant difference between the two groups (P=0.594).

Conclusion

According to our results, there was no significant difference in thrombus removal and recurrence-free rates between the CDT and ACA groups. ACA still has an important role in the treatment of DVT.

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.

Home versus in-patient treatment for deep vein thrombosis

BACKGROUND

Deep vein thrombosis (DVT) occurs when a blood clot blocks blood flow through a vein, which can occur after surgery, after trauma, or when a person has been immobile for a long time. Clots can dislodge and block blood flow to the lungs (pulmonary embolism (PE)), causing death. DVT and PE are known by the term venous thromboembolism (VTE). Heparin (in the form of unfractionated heparin (UFH)) is a blood-thinning drug used during the first three to five days of DVT treatment. Low molecular weight heparins (LMWHs) allow people with DVT to receive their initial treatment at home instead of in hospital. This is an update of a review first published in 2001 and updated in 2007.

OBJECTIVES

To compare the incidence and complications of venous thromboembolism (VTE) in patients treated at home versus patients treated with standard in-patient hospital regimens. Secondary objectives included assessment of patient satisfaction and cost-effectiveness of treatment.

SEARCH METHODS

For this update, the Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register (last searched 16 March 2017), the Cochrane Central Register of Controlled Trials (CENTRAL; 2017, Issue 2), and trials registries. We also checked the reference lists of relevant publications.

SELECTION CRITERIA

Randomised controlled trials (RCTs) examining home versus hospital treatment for DVT, in which DVT was clinically confirmed and was treated with LMWHs or UFH.

DATA COLLECTION AND ANALYSIS

One review author selected material for inclusion, and another reviewed the selection of trials. Two review authors independently extracted data and assessed included studies for risk of bias. Primary outcomes included combined VTE events (PE and recurrent DVT), gangrene, heparin complications, and death. Secondary outcomes were patient satisfaction and cost implications. We performed meta-analysis using fixed-effect models with risk ratios (RRs) and 95% confidence intervals (CIs) for dichotomous data.

MAIN RESULTS

We included in this review seven RCTs involving 1839 randomised participants with comparable treatment arms. All seven had fundamental problems including high exclusion rates, partial hospital treatment of many in the home treatment arms, and comparison of UFH in hospital versus LMWH at home. These trials showed that patients treated at home with LMWH were less likely to have recurrence of VTE events than those given hospital treatment with UFH or LMWH (fixed-effect risk ratio (RR) 0.58, 95% confidence interval (CI) 0.39 to 0.86; 6 studies; 1708 participants; P = 0.007; low-quality evidence). No clear difference was seen between groups for major bleeding (RR 0.67, 95% CI 0.33 to 1.36; 6 studies; 1708 participants; P = 0.27; low-quality evidence), minor bleeding (RR 1.29, 95% CI 0.94 to 1.78; 6 studies; 1708 participants; P = 0.11; low-quality evidence), or mortality (RR 0.69, 95% CI 0.44 to 1.09; 6 studies; 1708 participants; P = 0.11; low-quality evidence). The included studies reported no cases of venous gangrene. We could not combine patient satisfaction and quality of life outcomes in meta-analysis owing to heterogeneity of reporting, but two of three studies found evidence that home treatment led to greater improvement in quality of life compared with in-patient treatment at some point during follow-up, and the third study reported that a large number of participants chose to switch from in-patient care to home-based care for social and personal reasons, suggesting it is the patient's preferred option (very low-quality evidence). None of the studies included in this review carried out a full cost-effectiveness analysis. However, a small randomised economic evaluation of the two alternative treatment settings involving 131 participants found that direct costs were higher for those in the in-patient group. These findings were supported by three other studies that reported on their costs (very low-quality evidence).Quality of evidence for data from meta-analyses was low to very low. This was due to risk of bias, as many of the included studies used unclear randomisation techniques, and blinding was a concern for many. Also, indirectness was a concern, as most studies included a large number of participants randomised to the home (LMWH) treatment group who were treated in hospital for some or all of the treatment period. A further issue for some outcomes was heterogeneity that was evident in measurement and reporting of outcomes.

AUTHORS' CONCLUSIONS

Low-quality evidence suggests that patients treated at home with LMWH are less likely to have recurrence of VTE than those treated in hospital. However, data show no clear differences in major or minor bleeding, nor in mortality (low-quality evidence), indicating that home treatment is no worse than in-patient treatment for these outcomes. Because most healthcare systems are moving towards more LMWH usage in the home setting it is unlikely that additional large trials will be undertaken to compare these treatments. Therefore, home treatment is likely to become the norm, and further research will be directed towards resolving practical issues by devising local guidelines that include clinical prediction rules, developing biomarkers and imaging that can be used to tailor therapy to disease severity, and providing training for community healthcare workers who administer treatment and monitor treatment progress.

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.

The Role of Tinzaparin in Oncology

Current guidelines recommend low-molecular-weight heparin treatment in patients with cancer with established venous thromboembolism (VTE). The aim of this article was to study the pharmacological properties and effectiveness of tinzaparin in patients with cancer as well as its potential anticancer properties. A search of PubMed and ScienceDirect databases up to March 2016 was carried out to identify published studies that detect the properties and use of tinzaparin in oncology. Protamine sulfate partially (60% to 65%) neutralized tinzaparin’s anti-Xa activity. No dose adjustment of tinzaparin is needed even in patients with severe renal impairment and Creatinine Clearance ≥20 mL/min. Tinzaparin demonstrated a statistically significant decline in VTE recurrence at 1 year post the index thromboembolic event. A statistically significant reduction in minor bleeding rates was also described, whereas major bleeding events did not decrease in patients with cancer treated with tinzaparin versus those who received vitamin K antagonists. Tinzaparin treatment in patients suffering from deep vein thrombosis reduced the incidence of postthrombotic syndrome and venous ulcers. Tinzaparin’s ability to prevent both metastatic dissemination of cancer cells and tumor angiogenesis has been delineated in preclinical research. Current data show that tinzaparin is safe and efficacious either for short-term or for long-term treatment of VTE in patients with cancer. Clinical trials are needed in order to examine the utility of tinzaparin in primary prevention of VTE and validate its potential anticancer advantages exhibited in preclinical research.

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.

Unfractionated heparin versus low molecular weight heparins for avoiding heparin-induced thrombocytopenia in postoperative patients

BACKGROUND

Heparin-induced thrombocytopenia (HIT) is an adverse drug reaction presenting as a prothrombotic disorder related to antibody-mediated platelet activation. It is a paradoxical immune reaction resulting in thrombin generation in vivo, which leads to a hypercoagulable state and the potential to initiate venous or arterial thrombosis. A number of factors are thought to influence the incidence of HIT including the type and preparation of heparin (unfractionated heparin (UFH) or low molecular weight heparin (LMWH)) and the heparin-exposed patient population, with the postoperative patient population at higher risk.Although LMWH has largely replaced UFH as a front-line therapy, there is evidence supporting a lack of superiority of LMWH compared with UFH regarding prevention of deep vein thrombosis and pulmonary embolism following surgery, and similar frequencies of bleeding have been described with LMWH and UFH. The decision as to which of these two preparations of heparin to use may thus be influenced by harmful effects such as HIT. We therefore sought to determine the relative impact of UFH and LMWH on HIT in postoperative patients receiving thromboembolism prophylaxis. This is an update of a review first published in 2012.

OBJECTIVES

The objective of this review was to compare the incidence of heparin-induced thrombocytopenia (HIT) and HIT complicated by venous thromboembolism in postoperative patients exposed to unfractionated heparin (UFH) versus low molecular weight heparin (LMWH).

SEARCH METHODS

For this update, the Cochrane Vascular Information Specialist searched the Specialised Register (May 2016), CENTRAL (2016, Issue 4) and trials registries. The authors searched Lilacs (June 2016) and additional trials were sought from reference lists of relevant publications.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) in which participants were postoperative patients allocated to receive prophylaxis with UFH or LMWH, in a blinded or unblinded fashion. Studies were excluded if they did not use the accepted definition of HIT. This was defined as a relative reduction in the platelet count of 50% or greater from the postoperative peak (even if the platelet count at its lowest remained greater than 150 x 10⁹/L) occurring within five to 14 days after the surgery, with or without a thrombotic event occurring in this timeframe. Additionally, we required circulating antibodies associated with the syndrome to have been investigated through laboratory assays.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed the risk of bias. Disagreements were resolved by consensus with participation of a third author.

MAIN RESULTS

In this update, we included three trials involving 1398 postoperative participants. Participants were submitted to general surgical procedures, minor and major, and the minimum mean age was 49 years. Pooled analysis showed a significant reduction in the risk of HIT with LMWH compared with UFH (risk ratio (RR) 0.23, 95% confidence interval (CI) 0.07 to 0.73); low-quality evidence. The number needed to treat for an additional beneficial outcome (NNTB) was 59. The risk of HIT was consistently reduced comparing participants undergoing major surgical procedures exposed to LMWH or UFH (RR 0.22, 95% CI 0.06 to 0.75); low-quality evidence. The occurrence of HIT complicated by venous thromboembolism was significantly lower in participants receiving LMWH compared with UFH (RR 0.22, 95% CI 0.06 to 0.84); low-quality evidence. The NNTB was 75. Arterial thrombosis occurred in only one participant who received UFH. There were no amputations or deaths documented. Although limited evidence is available, it appears that HIT induced by both types of heparins is common in people undergoing major surgical procedures (incidence greater than 1% and less than 10%).

AUTHORS' CONCLUSIONS

This updated review demonstrated low-quality evidence of a lower incidence of HIT, and HIT complicated by venous thromboembolism, in postoperative patients undergoing thromboprophylaxis with LMWH compared with UFH. Similarily, the risk of HIT in people undergoing major surgical procedures was lower when treated with LMWH compared to UFH (low-quality evidence). The quality of the evidence was downgraded due to concerns about the risk of bias in the included studies and imprecision of the study results. These findings may support current clinical use of LMWH over UFH as front-line heparin therapy. However, our conclusions are limited and there was an unexpected paucity of RCTs including HIT as an outcome. To address the scarcity of clinically-relevant information on HIT, HIT must be included as a core harmful outcome in future RCTs of heparin.

The Saudi Clinical Practice Guideline for the treatment of venous thromboembolism. Outpatient versus inpatient management

Venous thromboembolism (VTE) including deep vein thrombosis (DVT) and pulmonary embolism (PE) is commonly encountered in daily clinical practice. After diagnosis, its management frequently carries significant challenges to the clinical practitioner. Treatment of VTE with the inappropriate modality and/or in the inappropriate setting may lead to serious complications and have life-threatening consequences. As a result of an initiative of the Ministry of Health of the Kingdom of Saudi Arabia, an expert panel led by the Saudi Association for Venous Thrombo-Embolism (a subsidiary of the Saudi Thoracic Society) and the Saudi Scientific Hematology Society with the methodological support of the McMaster University Guideline working group, this clinical practice guideline was produced to assist health care providers in VTE management. Two questions were identified and were related to the inpatient versus outpatient treatment of acute DVT, and the early versus standard discharge from hospital for patients with acute PE. The corresponding recommendations were made following the GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) approach.

Admission rates for emergency department patients with venous thromboembolism and estimation of the proportion of low risk pulmonary embolism patients: a US perspective

Objective

Introduction of target specific anticoagulants and recent guidelines encourage outpatient management of low risk patients with venous thromboembolism. We describe hospital admission rates over time for patients presenting to US emergency departments (EDs) with deep vein thrombosis (DVT) and pulmonary embolism (PE) and estimate the proportion of low-risk PE patients who could potentially be managed as outpatients.

Methods

We performed a structured analysis of the National Hospital Ambulatory Medical Care Survey (a nationally representative weighted sampling of US ED visits) database for the years 2006–2010 including all adult patients with a primary diagnosis of DVT or PE. Simplified pulmonary embolus scoring index (sPESI) scores were determined in patients with PE to identify low risk patients.

Results

There were an estimated 652,000 and 394,000 ED visits for DVT and PE over the 5-year period (0.17%). Mean (SE) age was 59 (1.3), 50% were female, and 40% were > 65 years. Admission rates for DVT and PE were 52% and 90% respectively with no significant changes over time. In patients with DVT, predictors for admission were age (odds ratio, 1.03 per year of age [95% confidence interval, 1.01 to 1.05]) and race (odds ratio, 4.1 [95% confidence interval, 0.9 to 19.8] for Hispanics and 2.9 [1.2 to 7.4] for Blacks). Of all ED patients with PE, 51% were low risk based on sPESI scores.

Conclusion

Admission rates for DVT and PE have remained high and unchanged, especially with PE, minorities, and in older patients. Based on sPESI scores, up to half of PE patients might be eligible for early discharge or outpatient therapy.

Home Treatment of Deep Venous Thrombosis According to Comorbid Conditions

BACKGROUND

Cautious exploration of the safety of home treatment of deep venous thrombosis has been recommended by many. Our goal was to identify categories of patients with deep venous thrombosis who typically are hospitalized, and categories frequently treated at home.

METHODS

The Nationwide Emergency Department Sample and the Nationwide Inpatient Sample, 2007-2012, were used to determine the number of patients seen in emergency departments throughout the US with deep venous thrombosis and no diagnosis of pulmonary embolism, the proportion of such patients hospitalized according to comorbid conditions and age, the proportion discharged early (≤2 days), and charges for hospitalization and emergency department visits.

RESULTS

From 2007-2012, home treatment was selected for 905,152 of 2,671,452 (33.9%) patients with deep venous thrombosis. Home treatment was more frequent in those with no comorbid conditions than with comorbid conditions, 58.0% compared with 15.5% (P <.0001). Early discharge (≤2 days) was in 23.9% with no comorbid conditions, compared with 12.8% with comorbid conditions. Among patients aged 18-50 years, home treatment was selected in 62.9% with no comorbid conditions, compared with 24.2% with comorbid conditions (P <.0001). Among hospitalized patients with no comorbid conditions, 40.7% were aged 18-50 years. Their charges for hospitalization in 2012 were $494 million.

CONCLUSION

Patients aged 50 years or younger with deep venous thrombosis and no comorbid conditions appear to be a group that can be targeted for more frequent home treatment, which would save millions of dollars.

Venous Thromboembolism in Patients Diagnosed With Lung Cancer

PURPOSE

Considering the high prevalence of lung cancer, our purpose was to summarize the existing literature to identify the several factors that contribute to the increased risk of venous thromboembolism (VTE) in patients with lung cancer and to analyze the current recommendations for thromboprophylaxis and treatment of VTE in those patients.

METHODS

We searched the Medline and EMBASE databases from February 1985 to February 2014 to identify retrospective and prospective randomized controlled studies that investigate one or more risk factors for VTEs in patients with lung cancer.

RESULTS

A VTE is a major complication for patients diagnosed with lung cancer. The risk factors for VTE events in patients with lung cancer consist of cancer-related (histological type and stage of cancer), treatment-related (surgery, chemotherapy, angiogenic agents, and supportive care agents), and patient-related factors (comorbidities, immobility, performance status, and prior thrombosis). Low-molecular-weight heparins are recommended for long-term treatment of cancer-associated thrombosis. Duration of anticoagulant therapy beyond 6 months should be based on individual clinical evaluation. Thromboprophylaxis for patients with lung cancer during hospitalization and immediate postoperative period is well established.

CONCLUSIONS

Efforts to assess thrombotic risk in patients with lung cancer may improve therapeutic and preventive strategies in the future, with final goal to minimize the burden and consequences of thrombotic events in patients with lung cancer.

Home treatment of deep venous thrombosis in the era of new oral anticoagulants

This is a retrospective cohort study of adults with a primary diagnosis of deep venous thrombosis (DVT) unaccompanied by pulmonary embolism (PE), seen in 4 emergency departments in 2013 and part of 2014. The purpose was to assess the prevalence of home treatment of DVT in the present era of new oral anticoagulants. Among 96 patients with DVT and no PE, 85 (88.5%) were hospitalized and 11 (11.5%) were discharged to home. Most of the patients discharged to home received low-molecular-weight heparin, 9 (81.8%) of 11. None were prescribed new oral anticoagulants. Early discharge in ≤2 days occurred 28 (32.9%) of 85 patients. Most (64.3%) received enoxaparin and/or warfarin at early discharge. Rivaroxaban was prescribed in 7 (25.0%) of those discharged in ≤2 days. We conclude that in some emergency departments, patients with DVT are uncommonly discharged to home even though new oral anticoagulants are available.

Treatment of deep vein thrombosis in patients with pulmonary embolism: subgroup analysis on the efficacy and safety of certoparin vs. unfractionated heparin

The objective of this subgroup analysis of the pivotal studies NMH-TH-3 and NMH-TH-4 was to investigate the incidence of recurrent events of venous thromboembolism in patients with acute deep vein thrombosis (DVT) with and without pulmonary embolism treated with subcutaneous fixed-dose low-molecular-weight heparin certoparin or intravenous unfractionated heparin (UFH). To assess whether the efficacy of the two treatments is modified by the presence or absence of pulmonary embolism, a P value for subgroup by treatment interaction was calculated using logistic regression. The rate of recurrent venous thromboembolic events, defined as DVT, pulmonary embolism and death due to pulmonary embolism, was observed over 6 months. After 6 months of follow-up, 6.58% of patients with pulmonary embolism at baseline treated with certoparin (5/76) compared with 11.5% of patients with pulmonary embolism at baseline treated with UFH (7/61) had a venous thromboembolic event [relative risk (RR) = 0.57, confidence interval (CI) = 0.19-1.72]. In the group of patients without pulmonary embolism at baseline, 2.82% of patients treated with certoparin (23/816) and 4.63% of patients treated with UFH (37/800) had a venous thromboembolic event (RR = 0.61, CI = 0.37-1.02). The test for interaction between the groups of patients with and without pulmonary embolism was not significant (P = 0.886). The same was true for the safety results with regard to major bleedings and death. These data suggest that the recommendation for the use of certoparin in the treatment of isolated DVT can safely be extended to treatment of DVT in patients concomitantly suffering from pulmonary embolism.

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.

Influence of sex on risk of bleeding in anticoagulated patients: a systematic review and meta-analysis

BACKGROUND

The risk of bleeding on anticoagulation varies between patients. It is uncertain whether sex influences this risk.

OBJECTIVES

To determine if the risk of major bleeding differs between men and women receiving anticoagulation for atrial fibrillation or venous thromboembolism(VTE).

METHODS

We searched MEDLINE, EMBASE, and Cochrane databases, and relevant conference proceedings, until February 2013. We included randomized controlled trials and prospective cohort studies of patients on therapeutic anticoagulation for atrial fibrillation or VTE. Two reviewers independently extracted data. The relative risk of bleeding in men compared to women was pooled using a random-effects model.

RESULTS

Forty-two studies including 94 293 patients were eligible; 78 044 patients (83%) had atrial fibrillation; 16 156 patients (17%) had VTE; 37 250 patients were women (40%); and there were 4147 major bleeds. The relative risk of major bleeding for men vs. women was 1.02(95% CI 0.95–1.10; P = 0.27 for heterogeniety). The relative risk was 1.02 (95% CI 0.95–1.09) in patients with atrial fibrillation and 0.80 (95% CI 0.65–0.98) in patients with VTE (P = 0.03 for subgroup effect). Type of anticoagulant,intensity of anticoagulation, and whether patients began or were already established on anticoagulants at enrollment did not influence the relative risk of major bleeding in men compared to women.

CONCLUSIONS

The risk of major bleeding on anticoagulation appears to be the same in men and women, particularly if patients have atrial fibrillation. This finding is less certain for patients with VTE, in whom the risk of bleeding may be marginally lower in men compared to in women.

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.

Cost-effectiveness of pharmacogenetics in anticoagulation: international differences in healthcare systems and costs

Genotyping patients for CYP2C9 and VKORC1 polymorphisms can improve the accuracy of dosing during the initiation of anticoagulation with vitamin K antagonists (coumarin derivatives). The anticipated degree of improvement in the safety of anticoagulation with coumarins through genotyping may vary depending on the quality of patient care, which varies both with and among countries. The management and the cost of anticoagulant care can therefore influence the cost-effectiveness of genotyping within any given country. In this article, we provide an overview of the cost-effectiveness of pharmacogenetics-guided dosing of coumarin derivatives. We describe the organization of anticoagulant care in the UK, Sweden, The Netherlands, Greece, Germany and Austria, where a genotype-guided dosing algorithm is currently being investigated as part of the EU-PACT trial. We also explore the costs of anticoagulant care for the treatment of atrial fibrillation in these countries.

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.

Effect of long-term LMWH on post-thrombotic syndrome in patients with iliac/noniliac venous thrombosis: a subanalysis from the home-LITE study

Patients with iliac deep vein thrombosis (DVT) have a poor prognosis and high incidence of postthrombotic syndrome (PTS). We evaluated the effect of low-molecular-weight heparin (LMWH; tinzaparin) versus usual care (tinzaparin plus warfarin for ≥12 weeks at home) in the development of PTS according to DVT location (iliac/noniliac) by retrospective analysis of the Home-LITE cohort (480 patients with proximal DVT). Patients with iliac DVT had an overall odds ratio of 0.53 (95% confidence interval [CI] 0.33, 0.83; P = .0079) for PTS (including ulcer data) in favor of tinzaparin. Patients with noniliac DVT had a similar odds ratio (0.79 [95% CI 0.67, 0.93], P = .0046) to that reported in the overall Home-LITE population (0.76 [95% CI 0.66, 0.89], P = .0004; including ulcer data), both in favor of tinzaparin. Long-term LMWH may be a suitable alternative for the prevention of PTS in patients with iliac DVT who are unlikely to undergo invasive thrombolysis.

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.

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.

Unfractionated heparin versus low molecular weight heparin for avoiding heparin-induced thrombocytopenia in postoperative patients

BACKGROUND

Heparin-induced thrombocytopenia (HIT) is an adverse drug reaction presenting as a prothrombotic disorder related to antibody-mediated platelet activation. It is a poorly understood paradoxical immune reaction resulting in thrombin generation in vivo, which leads to a hypercoagulable state and the potential to initiate venous or arterial thrombosis. A number of factors are thought to influence the incidence of HIT including the type and preparation of heparin (unfractionated heparin (UFH) or low molecular weight heparin (LMWH)) and the heparin-exposed patient population, with the postoperative patient population presenting a higher risk.Although LMWH has largely replaced UFH as a front-line therapy, there is evidence supporting a lack of superiority of LMWH compared with UFH regarding prevention of deep vein thrombosis and pulmonary embolism following surgery, and similar frequencies of bleeding have been described with LMWH and UFH. The decision as to which of these two preparations of heparin to use may thus be influenced by adverse reactions such as HIT. We therefore sought to determine the relative impact of UFH and LMWH specifically on HIT in postoperative patients receiving thromboembolism prophylaxis.

OBJECTIVES

The objective of this review was to compare the incidence of HIT and HIT complicated by thrombosis in patients exposed to UFH versus LMWH in randomised controlled trials (RCTs) of postoperative heparin therapy.

SEARCH METHODS

The Cochrane Peripheral Vascular Diseases Group searched their Specialised Register (March 2012) and CENTRAL (2012, Issue 2). In addition, the authors searched LILACS (March 2012) and additional trials were sought from reference lists of relevant publications.

SELECTION CRITERIA

We were interested in comparing the incidence of HIT occurring during exposure to UFH or LMWH after any surgical intervention. Therefore, we studied RCTs in which participants were postoperative patients allocated to receive UFH or LMWH, in a blinded or unblinded fashion. Eligible studies were required to have as an outcome clinically diagnosed HIT, defined as a relative reduction in the platelet count of 50% or greater from the postoperative peak (even if the platelet count at its lowest remained > 150 x 10(9)/L) occurring within five to 14 days after the surgery, with or without a thrombotic event occurring in this timeframe. Additionally, circulating antibodies associated with the syndrome were required to have been investigated through laboratory assays.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed the risk of bias. Disagreements were resolved by consensus with participation of a third author.

MAIN RESULTS

In total two studies involving 923 participants met all the inclusion criteria and were included in the review. Pooled analysis showed a statistically significant reduction in the risk of HIT with LMWH compared with UFH (risk ratio (RR) 0.24, 95% confidence interval (CI) 0.07 to 0.82; P = 0.02). This result suggests that patients treated with LMWH would have a relative risk reduction (RRR) of 76% in the probability of developing HIT compared with patients treated with UFH.Venous thromboembolism (VTE) complicating HIT occurred in 12 of 17 patients who developed HIT. Pooled analysis showed a statistically significant reduction in HIT complicated by VTE with LMWH compared with UFH (RR 0.20, 95% CI 0.04 to 0.90; P = 0.04). This result indicates that patients using LMWH would have a RRR of 80% for developing HIT complicated by VTE compared with patients using UFH. Arterial thrombosis occurred in only one patient who received UFH and there were no amputations or deaths documented.

AUTHORS' CONCLUSIONS

There was a lower incidence of HIT and HIT complicated by VTE in postoperative patients undergoing thromboprophylaxis with LMWH compared with UFH. This is consistent with the current clinical use of LMWH over UFH as front-line heparin therapy. However, conclusions are limited by a scarcity of high quality evidence. We did not expect the paucity of RCTs including HIT as an outcome as heparin is one of the most commonly used drugs worldwide and HIT is a life-threatening adverse drug reaction. To address the scarcity of clinically-relevant information on the topic of HIT as a whole, HIT should be included as an outcome in future RCTs of heparin, and HIT as an adverse drug reaction should be considered in clinical recommendations regarding monitoring of the platelet count for HIT.

Cancer-related venous thromboembolic disease: current management and areas of uncertainty

The relationship between cancer and venothromboembolic events is a complex, multifactorial process which is still not fully understood and therefore the use of current generic guidelines may be inadequate. Current management of cancer-related VTE may be suboptimal because of the lack of cancer-specific studies into the role of primary prophylaxis in both ambulant and non-ambulant cancer patients. Further research into developing cancer-specific risk assessment tools and the choice, dose and duration of prophylaxis is required. The management of confirmed symptomatic VTE in cancer patients is outlined but certain controversies remain. Areas for further research include the management of asymptomatic unsuspected VTE events, recurrent VTE events on treatment and the role of IVC filters and other treatment options are required. This paper attempts to cover some of the recent developments and areas of uncertainty surrounding the management of cancer-related VTE.

Antithrombotic therapy for VTE disease: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND

This article addresses the treatment of VTE disease.

METHODS

We generated strong (Grade 1) and weak (Grade 2) recommendations based on high-quality (Grade A), moderate-quality (Grade B), and low-quality (Grade C) evidence.

RESULTS

For acute DVT or pulmonary embolism (PE), we recommend initial parenteral anticoagulant therapy (Grade 1B) or anticoagulation with rivaroxaban. We suggest low-molecular-weight heparin (LMWH) or fondaparinux over IV unfractionated heparin (Grade 2C) or subcutaneous unfractionated heparin (Grade 2B). We suggest thrombolytic therapy for PE with hypotension (Grade 2C). For proximal DVT or PE, we recommend treatment of 3 months over shorter periods (Grade 1B). For a first proximal DVT or PE that is provoked by surgery or by a nonsurgical transient risk factor, we recommend 3 months of therapy (Grade 1B; Grade 2B if provoked by a nonsurgical risk factor and low or moderate bleeding risk); that is unprovoked, we suggest extended therapy if bleeding risk is low or moderate (Grade 2B) and recommend 3 months of therapy if bleeding risk is high (Grade 1B); and that is associated with active cancer, we recommend extended therapy (Grade 1B; Grade 2B if high bleeding risk) and suggest LMWH over vitamin K antagonists (Grade 2B). We suggest vitamin K antagonists or LMWH over dabigatran or rivaroxaban (Grade 2B). We suggest compression stockings to prevent the postthrombotic syndrome (Grade 2B). For extensive superficial vein thrombosis, we suggest prophylactic-dose fondaparinux or LMWH over no anticoagulation (Grade 2B), and suggest fondaparinux over LMWH (Grade 2C).

CONCLUSION

Strong recommendations apply to most patients, whereas weak recommendations are sensitive to differences among patients, including their preferences.

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.

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

BACKGROUND

Cancer increases the risk of thromboembolic events even while on anticoagulation.

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 STRATEGY

A comprehensive search for studies of anticoagulation in cancer patients including a February 2010 electronic search of: the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and ISI Web of Science.

SELECTION CRITERIA

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 8187 identified citations, nine RCTs were eligible and reported data for 1908 patients with cancer. Meta-analysis of seven RCTs showed that LMWH, compared to VKA provided 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). Other results did not exclude a beneficial or harmful effect of LMWH compared to VKA for the outcomes of major bleeding (RR 1.05; 95% CI 0.53 to 2.10) or thrombocytopenia (RR 1.02; 95% CI 0.60 to 1.74). The quality of evidence was low for mortality, major bleeding and minor bleeding and moderate for recurrent VTE. One RCT comparing six months extension of anticoagulation with 18 months ximelagatran 24 mg twice daily versus placebo found a reduction in VTE (HR 0.16; 95% CI 0.09 to 0.30) but did not exclude beneficial or harmful effects for the outcomes of mortality and bleeding. One RCT, comparing dabigatran to VKA, did not exclude beneficial or harmful effect of one agent over the other.

AUTHORS' CONCLUSIONS

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