INTRODUCTION: Direct oral anticoagulants (DOACs) effectively prevent recurrent venous thromboembolism (VTE). However, it is unknown which agents should be used to prevent recurrent VTE and which patients with unprovoked VTE should receive extended anticoagulation. We therefore sought to compare the efficacy and safety among DOACs for secondary prevention of VTE. We also determined a risk-adapted threshold for initiating extended anticoagulation based on the likelihood of VTE recurrence (without treatment) and bleeding (with treatment) in patients with unprovoked VTE.
METHODS: Our systematic review of randomized controlled trials compares extended anticoagulation with DOACs to another DOAC, aspirin, or placebo for the prevention of recurrent VTE. We searched PubMed, EMBASE, and Cochrane Registry of Controlled Trials (CENTRAL) in October 2018. Our outcomes of interest were VTE recurrence, major bleeding, and all clinically relevant bleeding. We used network meta-analysis to make indirect comparisons among DOACs. We populated the threshold decision-analytic model with data from our meta-analysis to determine the risk of VTE recurrence above which the benefits of extended anticoagulation outweigh the harms compared with no treatment.
RESULTS: We included four, high-quality, randomized trials comprising 8386 participants. Low-dose apixaban, full-dose apixaban, low-dose rivaroxaban, full-dose rivaroxaban, and dabigatran reduce VTE recurrence compared with placebo (RR = 0.19, 95% CI, 0.12-0.31; RR = 0.20, 95% CI, 0.12-0.32; RR = 0.08, 95% CI, 0.03-0.27; RR = 0.14, 95% CI, 0.06-0.35; RR = 0.19, 95% CI, 0.09-0.40, respectively). No DOACs increased major bleeding risk compared with placebo. A VTE recurrence risk above 0.3% to 0.4% at approximately 1 year is the threshold to treat a patient with unprovoked VTE with extended anticoagulation (with any DOAC).
CONCLUSIONS: All DOACs exhibit comparable efficacy for the prevention of recurrent VTE. Given that the risk of VTE recurrence is much higher than the calculated threshold for treatment, extended thromboprophylaxis should be considered in all patients with unprovoked VTE who do not have increased bleeding risk.
OBJECTIVE: To evaluate efficacy and safety of oral anticoagulant regimens and aspirin for extended venous thromboembolism (VTE) treatment.
METHODS: We searched MEDLINE, Embase, CENTRAL and conference proceedings for randomised controlled trials studying vitamin K antagonists (VKAs), direct oral anticoagulants (DOACs) or aspirin for secondary prevention of VTE beyond 3 months. ORs (95% credible intervals) between treatments were estimated using random-effects Bayesian network meta-analysis.
RESULTS: Sixteen studies, totaling more than 22 000 patients, were included. Compared with placebo or observation and with aspirin, respectively, the risk of recurrent VTE was lower with standard-intensity VKAs (0.15 (0.08 to 0.24) and 0.23 (0.09 to 0.54)), low-dose factor Xa inhibitors (0.16 (0.06 to 0.38) and 0.25 (0.09 to 0.66)), standard-dose factor Xa inhibitors (0.17 (0.08 to 0.33) and 0.27 (0.11 to 0.65)) and the direct thrombin inhibitor (0.15 (0.04 to 0.37) and 0.23 (0.06 to 0.74)) although the risk of major bleeding was higher with standard-intensity VKAs (4.42 (1.99 to 12.24) and 4.14 (1.17 to 18.86)). Effect estimates were consistent in male patients and those with index pulmonary embolism or with unprovoked VTE and in sensitivity analyses. In addition, compared with placebo or observation, the risk of all-cause mortality was reduced with standard-intensity VKAs (0.44 (0.20 to 0.87)) and low-dose factor Xa inhibitors (0.38 (0.12 to 0.995)).
CONCLUSIONS: Standard-intensity VKAs and DOACs are more efficacious than aspirin for extended VTE treatment. Despite a higher risk of major bleeding, standard-intensity VKAs was associated with a lower risk of all-cause mortality. Since overall efficacy and safety of standard-intensity VKAs and DOACs are in equipoise, patient factors, costs and patient preferences should be considered when recommending extending anticoagulation treatment.
BACKGROUND: The efficacy and safety of direct oral anticoagulants (DOACs) and vitamin K antagonists (VKAs) during extended anticoagulation for a VTE remains largely unknown, especially in terms of potential survival benefit. The goal of this study was to assess the effects of VKAs and DOACs on overall mortality and VTE-related mortality, as well as VTE recurrence and safety.
METHODS: PubMed, EMBASE, and the Cochrane Library were searched from January 1990 through September 2018 for randomized controlled trials evaluating the effect of extended anticoagulants as secondary prevention for VTE compared with placebo. The primary outcome was the specific effects of standard-intensity VKAs and DOACs on overall mortality.
RESULTS: Sixteen studies (12,458 patients) were included. DOACs were associated with a reduction in overall (risk ratio [RR], 0.48; 95% CI, 0.27-0.86; P = .01) and VTE-related (RR, 0.36; 95% CI, 0.15-0.89; P = .03) mortality, whereas VKAs were not (P > .50). Although VKAs and DOACs similarly prevented recurrent VTE, only VKAs were associated with an increased risk of major bleeding (RR, 2.67; 95% CI, 1.28-5.60; P < .01), resulting in an improved net clinical benefit for DOACs (RR, 0.25 [95% CI, 0.16-0.39; P < .01] vs 0.46 [95% CI, 0.30-0.72; P < .01]; Pinteraction = .05).
CONCLUSIONS: DOACs for extended anticoagulation were associated with a significant reduction in overall mortality compared with observation alone.
TRIAL REGISTRY: PROSPERO; No.: CRD42018088739; URL: https://www.crd.york.ac.uk/prospero/.
Data on all-cause mortality in patients with venous thromboembolism (VTE) and prolonged anticoagulation are inconclusive. The aim of this study was to compare the incidence of all-cause mortality in patients with VTE at intermediate risk of recurrence, i.e. without transient risk factors or cancer, exposed to shorter (at least three months) or longer anticoagulation. We did a systematic revue and meta-analysis of randomized clinical trials searching MEDLINE and COCHRANE bibliographic databases. A random-effects model was used to pool study results. I2 testing was used to test for heterogeneity. Six studies (5920 patients) entered in the final analysis. Mean course of anticoagulation was 7.5months in the shorter and 18.6months in the longer treatment arm. Prolonged anticoagulation was associated with a statistically significant reduction in all-cause mortality (RR 0.47, 95% CI 0.29 to 0.75; 0.8% vs 1.8%). Pulmonary embolism-related death was also lowered in the longer anticoagulation arm (RR 0.32, 95% CI 0.12 to 0.83; 0.2% vs 0.6%). Longer compared with shorter anticoagulation significantly reduced all-cause mortality in patients with VTE at intermediate risk of recurrence.
BACKGROUND: Historically, warfarin or aspirin have been the recommended therapeutic options for the extended treatment (>3 months) of VTE. Data from Phase III randomised controlled trials (RCTs) are now available for non-VKA oral anticoagulants (NOACs) in this indication. The current systematic review and network meta-analysis (NMA) were conducted to compare the efficacy and safety of anticoagulants for the extended treatment of VTE.
METHODS: Electronic databases (accessed July 2014 and updated April 2016) were systematically searched to identify RCTs evaluating apixaban, aspirin, dabigatran, edoxaban, rivaroxaban, and warfarin for the extended treatment of VTE. Eligible studies included adults with an objectively confirmed deep vein thrombosis, pulmonary embolism or both. A fixed-effect Bayesian NMA was conducted, and results were presented as relative risks (RRs). Sensitivity analyses examining (i) the dataset employed according to the time frame for outcome assessment (ii) the model used for the NMA were conducted.
RESULTS: Eleven Phase III RCTs (examining apixaban, aspirin, dabigatran, rivaroxaban, warfarin and placebo) were included. The risk of the composite efficacy outcome (VTE and VTE-related death) was statistically significantly lower with the NOACs and warfarin INR 2.0-3.0 compared with aspirin, with no significant differences between the NOACs. Treatment with apixaban (RR 0.23, 95% CrI 0.10, 0.55) or dabigatran (RR 0.55, 95% Crl 0.43, 0.71) was associated with a statistically significantly reduced risk of 'major or clinically relevant non-major bleed' compared with warfarin INR 2.0-3.0. Apixaban also showed a significantly reduced risk compared with dabigatran (RR 0.42, 95% Crl 0.18, 0.97) and rivaroxaban (RR 0.23, 95% Crl 0.09, 0.59). Sensitivity analyses indicate that results were dependent on the dataset, but not on the type of NMA model employed.
CONCLUSIONS: Results from the NMA indicate that NOACs are an effective treatment for prevention of VTE or VTE-related death) in the extended treatment setting. However, bleeding risk differs between potential treatments, with apixaban reporting the most favourable profile compared with other NOACs, warfarin INR 2.0-3.0, and aspirin.
Background A meta-analysis was performed to evaluate the risk of major bleeding with the use of New Oral Anticoagulants (NOACs). Methods Randomized controlled trials (RCTs) comparing NOACs (rivaroxaban, dabigatran, apixaban, edoxaban and darexaban) with comparators were selected. Results Fifty trials included 155,537 patients. Pooled analysis of all NOACs for all indications together demonstrated no significant difference between NOACs and comparators for risk of major bleeding (odds ratio [OR] 0.93, 95% CI 0.79-1.09). Pooled analysis also showed that NOACs caused significantly less major bleeding compared to vitamin K antagonists (VKA) (0.77, 0.64-0.91). The analysis for individual NOACs showed risk of major bleeding were not different with rivaroxaban, apixaban or dabigatran compared to pharmacologically active comparators or VKA. Indication specific analysis showed that NOACs were associated with significantly higher major bleeding after hip surgery (1.43, 1.02-1.99), in patients with acute coronary syndrome (ACS), (compared against placebo) (2.89, 2.01-4.14), and for medically ill patients (2.79, 1.69-4.60). For the treatment of acute venous thromboembolism (VTE) or pulmonary embolism (PE), NOACs were associated with significantly less bleeding (0.63, 0.44-0.90). No significant difference was found between NOACs and comparators in treatment of atrial fibrillation and for extended treatment of VTE. Conclusions Risk of major bleeding with new oral anticoagulants varies with their indication for use. New agents may be associated with comparatively less major bleeding compared to VKA. NOAC may increase the risk of major bleeding after hip surgery, ACS and acute medically ill patients; but may be associated with less bleeding in treatment of acute VTE/PE.
INTRODUCTION: The duration of anticoagulation after venous thromboembolic events (VTE) is based on the balance between the risk of recurrent VTE and bleeding. The purpose of this study was to estimate the frequency and case-fatality rate of major bleeding and recurrent VTE during secondary prevention of VTE.
MATERIALS AND METHODS: MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials databases were searched through September 2014. Two reviewers independently screened citations to identify trials that enrolled patients for secondary prevention of VTE with direct oral anticoagulants (DOACs), vitamin K antagonists (VKAs), aspirin or placebo. Two reviewers independently extracted data onto standardized forms.
RESULTS: Twelve RCTs that enrolled 10,542 patients were included. The rate of major bleeding was 1.6 per 100 patient-years (95% CI, 1.2-2.1), and 0.58 per 100 patient-years (95% CI, 0.24-1.1) on VKAs and DOACs, respectively, with an incidence rate ratio of 0.35 (95% CI, 0.17-0.68, p=0.0023). The case-fatality rates for DOACs and VKAs were not significantly different at 0% (95% CI, 0.0-15.4) and 6.8% (95% CI, 1.4-18.6), respectively. The rate of recurrent VTE was not different between DOACs and VKA, IRR 0.88 (95% CI, 0.15-4.8, p=0.88). Case-fatality rates for recurrent VTE for DOAC and VKAs were 10.8% (95% CI, 4.4-20.9) and 5.6% (95% CI, 1.2-15.4), respectively. Only DOACs showed a significant reduction in the composite outcome of fatal recurrent VTE and fatal bleeding when compared to placebo, IRR 0.40 (95% CI, 0.14-1.0, p=0.03).
CONCLUSION: Case-fatality rates for major bleeding and recurrent VTE for DOACs appear to be similar to those for VKA and the composite of fatal events is lower for DOACs than placebo. Overall, given the favorable safety profile and comparable efficacy of DOAC therapy, the threshold to continue anticoagulation with DOACs after unprovoked VTE should be low if the baseline risk of anticoagulation-related bleeding is not high.
Introduction Limited information exists on gender-related differences in the safety and efficacy of non-vitamin K antagonist oral anticoagulants (NOACs). Aim of the Study To assess the safety and efficacy of direct oral anticoagulants (DOACs)/NOACs in men and women pooling data from randomized controlled trials on the prevention of stroke and systemic embolism in patients with nonvalvular atrial fibrillation (AF) and on the acute and extended treatment of venous thromboembolism (VTE). Methods MEDLINE and EMBASE databases were searched up to June 2014. The efficacy outcome was defined as the prevention of stroke and systemic embolism (AF studies), or as the prevention of recurrent VTE or VTE-related death (VTE studies). The safety outcome was defined as the occurrence of major and/or clinically relevant nonmajor bleeding. Differences in the efficacy and safety outcomes were expressed as risk ratio (RR) with pertinent 95% confidence intervals (95% CI). Results A total of 13 studies (> 100,000 patients) were included. DOACs appeared to have a similar efficacy and safety compared with vitamin K antagonists in female and male patients treated for nonvalvular AF and acute VTE. In the extended treatment of VTE NOACs had a RR of bleeding of 4.97 (95% CI 1.06, 23.41) in males and 1.33 (95% CI 0.63, 2.83) in females compared with placebo (subgroup difference chi-square test: 2.25, p = 0.13). Conclusions No gender-related difference in the efficacy and safety of NOACs in patients with AF or acute VTE was found. A trend toward an increased risk of bleeding in male patients as compared with female patients was detected in the extended treatment of VTE.
Apixaban is a novel oral anticoagulant which is approved for the management of atrial fibrillation and venous thromboembolism prophylaxis. There have been concerns regarding bleeding risks with apixaban in patients with renal impairment. We performed a systematic review and meta-analysis to evaluate the risk of bleeding with apixaban in these patients. Relevant studies were identified through electronic literature searches of MEDLINE, EMBASE, Cochrane library, and clinicaltrials.gov (from inception to February 24, 2014). Phase III randomized controlled trials that compared apixaban with conventional agents (vitamin K antagonist and/or warfarin, low molecular weight heparin, aspirin, and placebo) were included. We defined mild renal impairment as creatinine clearance of 50 to 80 ml/min and moderate to severe renal impairment as creatinine clearance <50 ml/min. Study-specific risk ratios were calculated, and between-study heterogeneity was assessed using the I(2) statistics. In 6 trials involving 40,145 patients, the risk of bleeding with apixaban in patients with mild renal impairment was significantly less (risk ratio 0.80, 95% confidence interval 0.66 to 0.96, I(2) = 13%) compared with conventional anticoagulants. In patients with moderate to severe renal impairment, the risk of bleeding with was found to be similar (risk ratio 1.01, 95% confidence interval 0.49 to 2.10, I(2) = 72%). In conclusion, compared with the conventional agents, bleeding risk with apixaban in patients with mild and moderate to severe renal insufficiency is lower and similar, respectively.
OBJECTIVE: To systematically review the literature and to quantitatively evaluate the efficacy and safety of extended pharmacologic treatment of venous thromboembolism (VTE) through network meta-analysis (NMA).
METHODS: A systematic literature search (MEDLINE, Embase, Cochrane CENTRAL, through September 2014) and searching of reference lists of included studies and relevant reviews was conducted to identify randomized controlled trials of patients who completed initial anticoagulant treatment for VTE and then randomized for the extension study; compared extension of anticoagulant treatment to placebo or active control; and reported at least one outcome of interest (VTE or a composite of major bleeding or clinically relevant non-major bleeding). A random-effects Frequentist approach to NMA was used to calculate relative risks with 95% confidence intervals.
RESULTS: Ten trials (n=11,079) were included. Risk of bias (assessed with the Cochrane tool) was low in most domains assessed across the included trials. Apixaban (2.5mg and 5mg), dabigatran, rivaroxaban, idraparinux and vitamin K antagonists (VKA) each significantly reduced the risk of VTE recurrence compared to placebo, ranging from a 73% reduction with idraparinux to 86% with VKAs. With exception of idraparinux, all active therapies significantly reduced VTE recurrence risk versus aspirin, ranging from a 73% reduction with either apixaban 2.5mg or rivaroxaban to 80% with VKAs. Apixaban and aspirin were the only therapies that did not increase composite bleeding risk significantly compared to placebo. All active therapies except aspirin increased risk of composite bleeding by 2 to 4-fold compared to apixaban 2.5mg, with no difference found between the two apixaban doses.
CONCLUSION: Extended treatment of VTE is a reasonable approach to provide continued protection from VTE recurrence although bleeding risk is variable across therapeutic options. Our results indicate that apixaban, dabigatran, rivaroxaban, idraparinux and VKAs all reduced VTE recurrence when compared to placebo. Apixaban appears to have a more favorable safety profile compared to other therapies.
Direct oral anticoagulants (DOACs) effectively prevent recurrent venous thromboembolism (VTE). However, it is unknown which agents should be used to prevent recurrent VTE and which patients with unprovoked VTE should receive extended anticoagulation. We therefore sought to compare the efficacy and safety among DOACs for secondary prevention of VTE. We also determined a risk-adapted threshold for initiating extended anticoagulation based on the likelihood of VTE recurrence (without treatment) and bleeding (with treatment) in patients with unprovoked VTE.
METHODS:
Our systematic review of randomized controlled trials compares extended anticoagulation with DOACs to another DOAC, aspirin, or placebo for the prevention of recurrent VTE. We searched PubMed, EMBASE, and Cochrane Registry of Controlled Trials (CENTRAL) in October 2018. Our outcomes of interest were VTE recurrence, major bleeding, and all clinically relevant bleeding. We used network meta-analysis to make indirect comparisons among DOACs. We populated the threshold decision-analytic model with data from our meta-analysis to determine the risk of VTE recurrence above which the benefits of extended anticoagulation outweigh the harms compared with no treatment.
RESULTS:
We included four, high-quality, randomized trials comprising 8386 participants. Low-dose apixaban, full-dose apixaban, low-dose rivaroxaban, full-dose rivaroxaban, and dabigatran reduce VTE recurrence compared with placebo (RR = 0.19, 95% CI, 0.12-0.31; RR = 0.20, 95% CI, 0.12-0.32; RR = 0.08, 95% CI, 0.03-0.27; RR = 0.14, 95% CI, 0.06-0.35; RR = 0.19, 95% CI, 0.09-0.40, respectively). No DOACs increased major bleeding risk compared with placebo. A VTE recurrence risk above 0.3% to 0.4% at approximately 1 year is the threshold to treat a patient with unprovoked VTE with extended anticoagulation (with any DOAC).
CONCLUSIONS:
All DOACs exhibit comparable efficacy for the prevention of recurrent VTE. Given that the risk of VTE recurrence is much higher than the calculated threshold for treatment, extended thromboprophylaxis should be considered in all patients with unprovoked VTE who do not have increased bleeding risk.
