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

A Comparison of Dabigatran With Warfarin for Stroke Prevention in Atrial Fibrillation in an Asian Population

BACKGROUND

The Asian population with atrial fibrillation (AF) have a higher risk of stroke than the caucasian population and a higher risk of intracranial bleeding when anticoagulated with warfarin. There are few real-world studies comparing the efficacy of non-vitamin K antagonist oral anticoagulants (NOACs) and warfarin among Asian patients to assess its outcomes of ischemic stroke and hemorrhagic stroke.

METHODS

A retrospective cohort study of 1000 patients on dabigatran and warfarin from 2009 to 2013.

RESULTS

Data were available for 500 patients on dabigatran and 500 patients on warfarin. The average follow-up duration was 315 ± 280 days in the dabigatran group and 355 ± 232 in the warfarin group. The time in therapeutic range (TTR) was 53.2% in the warfarin-treated group, with 32.8% of patients in the subtherapeutic international normalized ratio range of <2. None of the patients in the dabigatran group had ischemic cerebrovascular accident (CVA) compared to 4 (0.8%) patients in the warfarin group, hazard ratio (HR) 0.13, P = .3. There was 1 (0.2%) patient in both dabigatran and warfarin groups with hemorrhagic CVA (HR 1.16, P = .92). There were 3 (0.6%) patients with major bleeding in the dabigatran group compared to 2 (0.4%) patients in the warfarin group (HR 1.57, P = .59).

CONCLUSION

There were similar rates of efficacy for outcomes of ischemic CVA, hemorrhagic CVA, and bleeding when comparing dabigatran with warfarin. Our study shows that despite similar efficacy, suboptimal TTR rates and inconveniences with warfarin demonstrate that NOACs are preferred for stroke prevention in AF.

The current landscape of treatment options for venous thromboembolism: a focus on novel oral anticoagulants

BACKGROUND

Venous thromboembolism (VTE), comprising deep vein thrombosis (DVT) and pulmonary embolism (PE), is a major cause of morbidity, mortality, and healthcare expenditure. Anticoagulant therapy is recommended for at least 3 months in patients with acute VTE to prevent recurrence. Conventional anticoagulants are associated with inherent limitations including route of administration, required monitoring and dose adjustments, potential for food-drug and drug-drug interactions, unpredictable pharmacokinetics and pharmacodynamics, and possible severe adverse events.

SCOPE

This manuscript reviews the pharmacology of the novel oral anticoagulants (NOACs), and analyzes the differences in phase 3 clinical trial designs, outcomes, and specific patient populations investigated for the treatment of acute and prevention of secondary VTE.

METHODS

A literature search was performed in PubMed using the key words dabigatran, apixaban, rivaroxaban, edoxaban, and venous thromboembolism in PubMed. The search included all years, English language, and peer-reviewed articles relating to phase 3 clinical trials, subanalyses, and meta-analyses of these NOACs for the treatment of acute VTE and secondary prevention.

FINDINGS

NOACs have demonstrated comparable efficacy and comparable or superior safety in large, randomized clinical trials in the treatment and prevention of VTE compared with conventional therapy. New oral anticoagulants, including the direct thrombin (dabigatran etexilate) and direct factor Xa inhibitors (rivaroxaban, apixaban, and edoxaban), have advantages over conventional agents such as oral administration at fixed doses, predictable pharmacokinetics and pharmacodynamics, minimal potential for food-drug and drug-drug interactions, and lack of required monitoring.

CONCLUSIONS

NOACs offer additional oral anticoagulation treatment options for patients with VTE.

Long-term quality of VKA treatment and clinical outcome after extreme overanticoagulation in 14,777 AF and VTE patients

Vitamin K antagonists (VKA) are widely used in atrial fibrillation and venous thromboembolism (VTE). Their efficacy and safety depend on individual time in the therapeutic range (iTTR). Due to the variable dose-response relationship within patients, also patients with initially stable VKA treatment may develop extreme overanticoagulation (EO). EO is associated with an immediate bleeding risk, but it is unknown whether VKA treatment will subsequently restabilise. We evaluated long-term quality of VKA treatment and clinical outcome after EO. EO was defined as international normalized ratio (INR) ≥ 8.0 and/or unscheduled vitamin K supplementation. We included a consecutive cohort of initially stable atrial fibrillation and venous thromboembolism patients. In EO patients, the 90 days pre- and post-period were compared. In addition, patients with EO were compared with patients without EO using a matched 1:2 cohort. Of 14,777 initially stable patients, 800 patients developed EO. The pre-period was characterised by frequent overanticoagulation, and half of EO patients had an inadequate iTTR (< 65 %). After EO, underanticoagulation became more prevalent. Although the mean time between INR-measurements decreased from 18.6 to 13.2 days, after EO inadequate iTTR became more frequent (62 %), p-value < 0.001. A 2.3 times (95 % confidence interval [CI] 2.0-2.5) higher risk for iTTR< 65 % after EO, was accompanied by increased risk of bleeding (hazard ratio [HR] 2.1;CI 1.4-3.2), VKA-related death 17.0 (HR 17.0;CI 2.1-138) and thrombosis (HR 5.7;CI 1.5-22.2), compared to the 1600 controls. In conclusion, patients continuing VKA after EO have long-lasting inferior quality of VKA treatment despite intensified INR-monitoring, and an increased risk of bleeding, thrombosis and VKA-related death.

Defining time in therapeutic range for busy clinicians: frequency of dose changes is a good surrogate marker to identify patients with suboptimal anticoagulation with warfarin

INTRODUCTION

Patients on warfarin with sub-optimal time-in-therapeutic-range (TTR) are more likely to have adverse events. Target-specific oral anticoagulants (TSOACs) are approved and can be used as an alternative to warfarin for a number of indications. Further, the efficacy and safety profiles of the TSOACs compared to warfarin are more favourable when the TTR is ≤65% for certain indications.

OBJECTIVE

We aimed to determine simple, sensitive and specific diagnostic tools to identify TTR ≤ 65% during the initial three months of warfarin therapy.

METHODS

A cross-sectional study including patients newly initiated on warfarin without any interruption for three months was conducted. TTR was calculated using the Rosendaal method. Patients were stratified by TTR (≤ 65% or >65%). Number of INR measurements, dose changes and INR measurements of ≤ 1.7 or ≥ 4.0 were evaluated as potential diagnostic tools to identify TTR ≤ 65%.

RESULTS

670 patients were included. The most common indication for anticoagulation was venous thromboembolism. The mean TTR in the first three months was 68 ± 21% (Range: 10 to 100%). Three or more dose changes identified TTR ≤ 65% and demonstrated a sensitivity and specificity of 90% (95%CI 86 to 93%) and 56% (95%CI 51 to 61%), respectively. Three or more INR measurements of ≤ 1.7 during the initial three months of anticoagulation showed a sensitivity and specificity of 37% (95%CI 32 to 43%) and 98% (95%CI 96 to 99%), respectively.

CONCLUSION

Three or more dose changes and three or more INR measurements of ≤ 1.7 could identify patients with a TTR ≤ 65% in the first three months of warfarin therapy.

Direct oral anticoagulants in the treatment of acute venous thromboembolism: a systematic review and meta-analysis

INTRODUCTION

Acute venous thromboembolism (VTE) is a common disease associated to significant morbidity and mortality.

MATERIALS AND METHODS

We systematically reviewed and meta-analysed clinical outcomes with direct oral anticoagulants (DOAC: dabigatran, rivaroxaban, apixaban or edoxaban) for treatment of acute VTE. We used MEDLINE and CENTRAL, clinical trials registers, conference proceedings, and websites of regulatory agencies to identify randomised clinical trials of DOAC compared with conventional treatment [parenteral anticoagulant followed by a vitamin K antagonist (VKA)] for acute VTE. Two investigators independently extracted data. Relative risk of recurrent VTE, bleeding events, deaths and a net clinical endpoint (composite of recurrent VTE, major bleeding, and death) were estimated using a random effect meta-analysis (RevMan software).

RESULTS

Six trials including 27,127 patients were selected. The risk of recurrent VTE was similar with the DOAC and standard treatment (relative risk 0.91, 95% confidence interval 0.79 to 1.06). The DOAC reduced the risk of major bleeding in comparison with standard treatment (0.62, 0.45 to 0.85) (absolute risk difference, -0.6%; 95% confidence interval -1.0% to -0.3%), but there was heterogeneity across trials in the relative risk of bleeding. No between treatment differences were found in the relative risk of all-cause mortality (0.98, 0.84 to 1.14). The DOAC and conventional treatment differed on the net clinical endpoint (0.85, 0.75 to 0.97). Subgroup analyses in relevant subgroups (index pulmonary embolism, heparin lead-in, age, gender, renal function, presence of cancer), as well as sensitivity analyses, were consistent with the main analysis.

CONCLUSIONS

The DOAC seem as effective as, and probably safer than standard treatment of acute VTE. The relative efficacy and safety of the DOAC was consistent across a wide range of patients.

The clinical impact of different coagulometers on patient outcomes

Introduction

Long-term anticoagulation therapy using vitamin K antagonists (VKA) is used in millions of patients worldwide to reduce the risk of thrombotic or thromboembolic events. Control and monitoring of VKA therapy is improved by the regular self-measurement of international normalized ratio (INR) using a home monitoring device. This retrospective analysis of a large cohort of patients in the Netherlands seeks to determine whether the choice of INR monitor could have a clinical impact on patient outcomes.

Methods

The National Thrombosis Service provides medical supervision, training and support to anticoagulant patients eligible for home-monitoring of INR in the Netherlands. Two INR monitors (CoaguChek XS and INRatio2) have been distributed at random to patients since June 2011, and patient self-testing data (INR measurements and other clinical parameters) have been recorded to measure and improve treatment outcomes. The data have been retrospectively analyzed to determine any effect of the choice of monitor. Univariate and multivariate statistical tests are used to assess any differences between groups in terms of efficacy and safety parameters.

Results

Data from 4,326 patients were collated, and 156,507 INR values were included in the analysis. Over half the patients (54.3%) were being treated for atrial fibrillation, and 77.6% were prescribed acenocoumarol. There were few differences between the patient populations using the two different monitors. Anticoagulant control overall was good, with high percentage of time (87.9%) in the appropriate INR range and low incidence of excessively high or low INR values (0.085/month). Minor clinical events related to safety were low (0.78 per patient-year) and showed few differences between monitors. Mortality rates were similar [hazard ratio (HR) 1.05, 95% confidence interval (CI) 0.65–1.70].

Conclusion

Self-testing data from a large cohort of patients in the Netherlands suggest that there is no clinically relevant effect of the choice of coagulation monitor (CoaguChek XS or INRatio2) on the time in therapeutic range (TTR), minor or fatal outcomes of long-term anticoagulation management.

Electronic supplementary material

The online version of this article (doi:10.1007/s12325-014-0124-x) contains supplementary material, which is available to authorized users.

Phase III trials of new oral anticoagulants in the acute treatment and secondary prevention of VTE: comparison and critique of study methodology and results

The traditional treatment of venous thromboembolism (VTE) has been use of heparin and vitamin K antagonists (VKA), and although shown to be effective, they have numerous limitations. New oral anticoagulants (NOACs) including direct thrombin (factor IIa) inhibitors (dabigatran) and selective factor Xa inhibitors (rivaroxaban, apixaban and edoxaban) have emerged as promising alternatives with the potential to overcome the limitations of traditional treatments. Clinical trials have been performed with a view to making significant changes to the acute, long-term and extended treatment of VTE. Data are now available on the efficacy and safety, including bleeding rates, of the NOACs in comparison with VKA in the acute treatment and secondary prevention of VTE as well as in comparison with placebo extended VTE treatment. This review compares and contrasts the design and results of the Phase III trials of NOACs in VTE and discusses the implications of the NOACs in terms of treatment strategies in VTE patients.

Direct oral anticoagulants and antiplatelet agents. Clinical relevance and options for laboratory testing

Oral anticoagulants and platelet receptor blockers are widely used in clinical practice with the aim of reducing the risk of thrombotic complications in patients with cardiovascular diseases. Their regular intake and adequate antithrombotic action is vital and this is way numerous assays have been developed for laboratory testing and monitoring of these agents. Available assays can be stratified into pharmacokinetic and pharmacodynamic assays. Such assays are increasingly used in clinical routine and their daily use is triggered by the advent of the novel direct oral anticoagulants (DOACs) as an alternative for vitamin K antagonist (VKA) treatment, which are dabigatran, rivaroxaban and apixaban, and by the advent of prasugrel or ticagrelor as an alternative for clopidogrel with regard to platelet P2Y12 receptor inhibition. In this review the most important and most commonly used laboratory assays are summarized as well as their clinical implications with the focus on DOACs as an alternative for VKAs and the different P2Y12 receptor blockers for antiplatelet treatment.

Oral rivaroxaban versus standard therapy for the treatment of symptomatic venous thromboembolism: a pooled analysis of the EINSTEIN-DVT and PE randomized studies

BACKGROUND

Standard treatment for venous thromboembolism (VTE) consists of a heparin combined with vitamin K antagonists. Direct oral anticoagulants have been investigated for acute and extended treatment of symptomatic VTE; their use could avoid parenteral treatment and/or laboratory monitoring of anticoagulant effects.

METHODS

A prespecified pooled analysis of the EINSTEIN-DVT and EINSTEIN-PE studies compared the efficacy and safety of rivaroxaban (15 mg twice-daily for 21 days, followed by 20 mg once-daily) with standard-therapy (enoxaparin 1.0 mg/kg twice-daily and warfarin or acenocoumarol). Patients were treated for 3, 6, or 12 months and followed for suspected recurrent VTE and bleeding. The prespecified noninferiority margin was 1.75.

RESULTS

A total of 8282 patients were enrolled; 4151 received rivaroxaban and 4131 received standard-therapy. The primary efficacy outcome occurred in 86 (2.1%) rivaroxaban-treated patients compared with 95 (2.3%) standard-therapy-treated patients (hazard ratio, 0.89; 95% confidence interval [CI], 0.66-1.19; pnoninferiority < 0.001). Major bleeding was observed in 40 (1.0%) and 72 (1.7%) patients in the rivaroxaban and standard-therapy groups, respectively (hazard ratio, 0.54; 95% CI, 0.37-0.79; p = 0.002). In key subgroups, including fragile patients, cancer patients, patients presenting with large clots, and those with a history of recurrent VTE, the efficacy and safety of rivaroxaban were similar compared with standard-therapy.

CONCLUSION

The single-drug approach with rivaroxaban resulted in similar efficacy to standard-therapy and was associated with a significantly lower rate of major bleeding. Efficacy and safety results were consistent among key patient subgroups.

TRIAL REGISTRATION EINSTEIN-PE

ClinicalTrials.gov, NCT00439777; EINSTEIN-DVT: ClinicalTrials.gov, NCT00440193.

Timing of recurrent venous thromboembolism early after the index event: a meta-analysis of randomized controlled trials

INTRODUCTION

Studies suggest a decreasing risk of recurrent venous thromboembolism (rVTE) in relation to time since the index event. We sought to conduct a meta-analysis examining the time course of rVTE over the first 3-months of anticoagulation.

MATERIALS AND METHODS

A literature search of MEDLINE, EMBASE and CENTRAL (through 4/2013) was conducted to identify randomized trials of acute pharmacologic treatment and prevention of rVTE, enrolling ≥200 subjects/treatment arm, requiring anticoagulation for ≥3-months and reporting time-to-objectively-confirmed rVTE. Trials assessing extended-duration treatment, randomizing only cancer patients or not in English were excluded. Treatment arms were divided into monthly and weekly time periods for comparison (months 1-3 and weeks 1-12 after the index event). Treatment arm rVTE rates (per person-year) were pooled using a random-effects approach.

RESULTS

Fifteen trials (31 treatment arms; n=27,237) were included. Higher rVTE rates were observed during the first month after the index event (0.19, 95% CI=0.16-0.23) compared to the second (0.05, 95% CI 0.04-0.06; p<0.001 vs. first month) and third months (0.02, 95% CI=0.02-0.03; p<0.001 vs. first month). While the highest rate of rVTE was in week 1 (0.29, 95% CI=0.21-0.37; p<0.01 vs. week 2), rates remained high through the fourth week (between 0.15 and 0.10 events/person-year) before decreasing and stabilizing at week 5 (≤0.05 events/person-year; p<0.01 vs. week 4).

CONCLUSIONS

Our findings demonstrate a significant interaction between rVTE rates and time after the index event. High rVTE rates during the 3-4 weeks following the index event emphasize the importance of frequent surveillance during this time and the early optimization of pharmacologic therapy.

Do novel oral anticoagulants do better than standard therapy in the treatment of deep vein thrombosis?

The focus of DVT treatment is the prevention of recurrence and thrombus migration by treatment with anticoagulants. The aim is to improve outcomes by reducing clot burden and by preventing thrombus propagation, in order to prevent PE and the development of long-term complication. Actually, initial therapy is parenteral anticoagulation, mainly with low molecular weight heparin followed by a vitamin K antagonist (VKA) for triggered and idiopathic DVT. The long term treatment suggestion with a VKA is for sure the most challenging therapeutic scenario, showing all the disadvantages of VKA especially in the onset phase when therapeutic levels of VKA are difficult to achieve. The difference between VKAs and NOACs is the fact, that NOACs target a specific factor in the coagulation cascade. At time now two pathways have been chosen for treatment options, the direct inhibition of active sites of thrombin and factor Xa. Routine monitoring is not required and the drugs can be administered in fixed doses, which should increase patient adherence to long term treatment. At time now, four novel anticoagulants are called to be options for DVT treatment. Rivaroxaban, apixaban and edoxaban are direct FXa inhibitors, whereas dabigtran etexilate is a direct thrombin inhibitor.