Meta-Analysis of Reversal Agents for Severe Bleeding Associated With Direct Oral Anticoagulants.

BACKGROUND: Direct oral anticoagulants (DOACs) have shown a positive benefit-risk balance in both clinical trials and real-world data, but approximately 2% to 3.5% of patients experience major bleeding annually. Many of these patients require hospitalization, and the administration of reversal agents may be required to control bleeding. OBJECTIVES: The aim of this study was to investigate clinical outcomes associated with the use of 4-factor prothrombin complex concentrates, idarucizumab, or andexanet for reversal of severe DOAC-associated bleeding. METHODS: The investigators systematically searched for studies of reversal agents for the treatment of severe bleeding associated with DOAC. Mortality rates, thromboembolic events, and hemostatic efficacy were meta-analyzed using a random effects model. RESULTS: The investigators evaluated 60 studies in 4,735 patients with severe DOAC-related bleeding who were treated with 4-factor prothrombin complex concentrates (n = 2,688), idarucizumab (n = 1,111), or andexanet (n = 936). The mortality rate was 17.7% (95% confidence interval [CI]: 15.1% to 20.4%), and it was higher in patients with intracranial bleedings (20.2%) than in patients with extracranial hemorrhages (15.4%). The thromboembolism rate was 4.6% (95% CI: 3.3% to 6.0%), being particularly high with andexanet (10.7%; 95% CI: 6.5% to 15.7%). The effective hemostasis rate was 78.5% (95% CI: 75.1% to 81.8%) and was similar regardless of the reversal agent considered. The rebleeding rate was 13.2% (95% CI: 5.5% to 23.1%) and 78% of rebleeds occurred after resumption of anticoagulation. The risk of death was markedly and significantly associated with failure to achieve effective hemostasis (relative risk: 3.63; 95% CI: 2.56 to 5.16). The results were robust regardless of the type of study or the hemostatic scale used. CONCLUSIONS: The risk of death after severe DOAC-related bleeding remains significant despite a high rate of effective hemostasis with reversal agents. Failure to achieve effective hemostasis strongly correlated with a fatal outcome. Thromboembolism rates are particularly high with andexanet. Comparative clinical trials are needed.

Causes of Death in Patients with Venous Thromboembolism Anticoagulated with Direct Oral Anticoagulants: A Systematic Review and Meta-Analysis.

Death is more frequent than nonfatal recurrent venous thromboembolism (VTE) and major bleeding after acute VTE. The analysis of the causes of death is fundamental to explore new strategies to reduce mortality rates in these patients. The authors performed a meta-analysis to analyze mortality and independently adjudicated causes of death in anticoagulated patients due to VTE, and to evaluate potential differences between different anticoagulant schemes. They searched MEDLINE and CENTRAL, from January 1, 2000, to January 31, 2017, and performed additional searches in Web sites of regulatory agencies, clinical trial registers, and conference proceedings. Two investigators independently selected studies and extracted the data. Study quality was assessed with the Cochrane Collaboration's tool for assessing the risk of bias in randomized studies. Seven prospective randomized trials in 29,844 patients (22,025 patient-year follow-up) were included, comparing dabigatran, rivaroxaban, apixaban, and edoxaban with the standard anticoagulant treatment of VTE. A total of 718 patients died during the follow-up (3.4% per year; 95% confidence interval [CI]: 2.3-4.8). The most frequent causes of death were cancer (42%), followed by VTE (20%), infections (13%), hemorrhage (6%), heart disease (4%), and stroke (2%). There were no differences in the overall survival and causes of death according to the anticoagulant type. Concomitant active cancer during the study was significantly associated with death (odds ratio: 15.2; 95% CI: 9.2-25.1). Cancer is the leading cause of death in contemporary VTE trials. Interventions beyond anticoagulation, particularly in patients with active cancer, are needed.

Causes of Death in Anticoagulated Patients With Atrial Fibrillation.

BACKGROUND: Oral anticoagulation reduces the risk of mortality in atrial fibrillation (AF), but examination of the causes of death is essential to design new strategies to further reduce the high mortality rates observed in this population. OBJECTIVES: The authors sought to analyze and compare causes of death in patients receiving direct oral anticoagulants (DOAC) or warfarin for prevention of stroke and systemic embolism (SE) in AF. METHODS: The authors systematically searched for randomized trials of DOAC versus warfarin for prevention of stroke/SE in AF. The main outcome was mortality and independently adjudicated specific causes of death. The authors used the random effects model of meta-analysis to combine the studies. RESULTS: 71,683 patients from 4 trials were included (134,046 patient-years of follow-up). A total of 6,206 patients (9%) died during follow-up. Adjusted mortality rate was 4.72%/year (95% confidence interval [CI]: 4.19 to 5.28). Cardiac deaths accounted for 46% of all deaths, whereas nonhemorrhagic stroke/SE and hemorrhage-related deaths represented 5.7% and 5.6% of the total mortality, respectively. Compared with patients who were alive, those who died had more frequent history of heart failure (odds ratio [OR]: 1.75; 95% CI: 1.25 to 2.44), permanent/persistent AF (OR: 1.38; 95% CI: 1.25 to 1.52) and diabetes (OR: 1.37; 95% CI: 1.11 to 1.68); were more frequently male (OR: 1.24; 95% CI: 1.13 to 1.37) and older (mean difference 3.2 years; 95% CI: 1.6 to 4.8); and had a lower creatinine clearance (-9.9 ml/min; 95% CI: -11.3 to -8.4). There was a small, but significant, reduction in all-cause mortality with the DOAC versus warfarin (difference -0.42%/year; 95% CI: -0.66 to -0.18), mainly driven by a reduction in fatal bleedings. CONCLUSIONS: In contemporary AF trials, most deaths were cardiac-related, whereas stroke and bleeding represented only a small subset of deaths. Interventions beyond anticoagulation are needed to further reduce mortality in AF.

Direct oral anticoagulants for stroke prevention in patients with atrial fibrillation: meta-analysis by geographic region with a focus on European patients.

AIMS: To analyse clinical outcomes with direct oral anticoagulants in patients with atrial fibrillation according to geographic region. METHODS: We systematically searched MEDLINE, CENTRAL, websites of regulatory agencies, clinical trials registers and conference proceedings for randomized controlled trials of direct oral anticoagulants (DOAC: dabigatran, rivaroxaban, apixaban or edoxaban) against warfarin for prophylaxis of stroke and systemic embolic events (SEE) in patients with atrial fibrillation (AF). Two investigators independently extracted data. Relative risks of stroke and SEE as well as major bleeding depending on geographic region were estimated using a random effect meta-analysis. RESULTS: Five trials in 72 963 patients were analysed; 32 089 (44%) patients were recruited in Europe (Western Europe: 13 676; Eastern Europe: 18 413). We found significant subgroup differences for stroke/SEE depending on the geographic region (interaction P = 0.003; I(2) 88.5%), with a neutral effect of the DOAC vs. warfarin in Europe [relative risk (RR) 0.97, 95% confidence interval (CI) 0.85-1.11, I(2) 0%] and a significant reduction of stroke/SEE in other regions including North America, Latin America and Asia-Pacific/other (RR 0.72, 95% CI 0.63-0.83, I(2) 33%). There was a similar reduction in risk of major bleeding in Europe (RR 0.82, 95% CI 0.73-0.92, I(2) 0%) and in other regions (RR 0.86, 95% CI 0.72-1.02, I(2) 78%). CONCLUSION: The DOAC did not provide additional benefit in reducing the risk of stroke/SEE compared with warfarin in European patients with AF, but were generally associated with a lower bleeding tendency than warfarin regardless of geographic region.

Direct-acting oral anticoagulants: pharmacology, indications, management, and future perspectives.

In recent years, several direct-acting oral anticoagulants (DOAC) have become available for use in Europe and other regions in indications related to prophylaxis and treatment of venous and arterial thromboembolism. They include the oral direct thrombin inhibitor dabigatran etexilate (Pradaxa, Boehringer Ingelheim) and the oral direct FXa inhibitors rivaroxaban (Xarelto, Bayer HealthCare), apixaban (Eliquis, Bristol-Myers Squibb), and edoxaban (Lixiana/Savaysa, Daiichi-Sankyo). The new compounds have a predictable dose response and few drug-drug interactions (unlike vitamin k antagonists), and they do not require parenteral administration (unlike heparins). However, they accumulate in patients with renal impairment, lack widely available monitoring tests for measuring its anticoagulant activity, and no specific antidotes for neutralization in case of overdose and/or severe bleeding are currently available. In this review, we describe the pharmacology of the DOAC, the efficacy, and safety data from pivotal studies that support their currently approved indications and discuss the postmarketing experience available. We also summarize practical recommendations to ensure an appropriate use of the DOAC according to existing data. Finally, we discuss relevant ongoing studies and future perspectives.

Case Fatality Rates of Recurrent Thromboembolism and Bleeding in Patients Receiving Direct Oral Anticoagulants for the Initial and Extended Treatment of Venous Thromboembolism: A Systematic Review.

BACKGROUND: In patients with venous thromboembolism (VTE), the study of the case fatality rate (CFR) of VTE recurrences and bleeding complications may be of help to balance the risks and benefits of anticoagulant therapy. OBJECTIVE: To investigate the CFR with the direct oral anticoagulants (DOACs; dabigatran, rivaroxaban, apixaban, and edoxaban) in patients with VTE. METHODS: We conducted a systematic review and meta-analysis of randomized clinical trials testing the DOACs versus standard initial treatment of VTE (parenteral anticoagulant for ≥5 days plus vitamin K antagonists [VKAs] for ≥3 months) and DOACs versus placebo or VKA for extended treatment. Two investigators independently extracted the data. A random effects meta-analysis was conducted using StatsDirect software. RESULTS: Overall, 10 trials in 35 029 patients were included. During initial treatment, the rate of recurrent VTE per 100 patient-years (%/yr) and CFR (%) was similar in patients receiving DOACs or standard therapy (4.1%/yr vs 4.4%/yr; P = .21 and 16% vs 13%; P = .61, respectively). However, major bleeding (1.8%/yr vs 3.1%/yr; P = .003), fatal bleeding (0.1%/yr vs 0.3%/yr; P = .02), and CFR (6% vs 10%; P = .18) were lower with DOACs than with standard therapy. During extended treatment, both all-cause mortality and recurrent VTE per 100 patient-years were lower with DOACs than with placebo (0.6%/yr vs 1.1%/yr; P = .01 and 1.9%/yr vs 10.9%/yr; P < .0001, respectively), but there were no statistical differences between treatments on CFR of VTE recurrences (P = .17). No fatal bleeding events were reported during extended treatment. CONCLUSION: The use of DOACs was associated with fewer major and fatal bleedings and corresponding CFR than standard initial treatment of VTE, and fewer recurrent VTEs and mortality than placebo during extended therapy, although the CFR of recurrent VTE was not reduced.

Direct oral anticoagulants in the treatment of venous thromboembolism, with a focus on patients with pulmonary embolism: an evidence-based review.

Pulmonary embolism (PE) is a relatively common cardiovascular emergency. PE and deep vein thrombosis (DVT) are considered expressions of the same disease, termed as venous thromboembolism (VTE). In the present review, we describe and meta-analyze the efficacy and safety data available with the direct oral anticoagulants (DOAC; dabigatran, rivaroxaban, apixaban, edoxaban) in clinical trials testing these new compounds in the acute/long-term and extended therapy of VTE, providing subgroup analyses in patients with index PE. We analyzed ten studies in 35,019 randomized patients. A total of 14,364 patients (41%) had index PE. In the acute/long-term treatment of VTE, the DOAC showed comparable efficacy in preventing recurrent VTE to standard treatment in patients with index PE (risk ratio [RR]: 0.88; 95% confidence interval [CI]: 0.70-1.11) and index DVT (RR: 0.93; 95% CI: 0.75-1.16) (P for subgroup differences =0.76). VTE recurrence depending on PE anatomical extension and presence/absence of right ventricular dysfunction was only reported in two trials, with results being consistent with those obtained in the overall study populations. In the single trial comparing extended therapy of VTE with DOAC versus warfarin, the point estimate for recurrent VTE tended to disfavor the DOAC in patients with index PE (RR: 2.05; 95% CI: 0.83-5.03) and in patients with index DVT (RR: 1.11; 95% CI: 0.49-2.50) (P for subgroup differences =0.32). In trials that compared DOAC versus placebo for extended therapy, the reduction in recurrent VTE was consistent in patients with PE (RR: 0.15; 95% CI: 0.01-1.82) and in patients with DVT (RR: 0.25; 95% CI: 0.10-0.61) (P for subgroup differences =0.71). The DOAC were associated with a consistently lower risk of clinically relevant bleeding (CRB) than standard treatment of acute VTE and higher risk of CRB than placebo for extended therapy of VTE regardless of index event. In summary, the DOAC were as effective as, and safer than, standard treatment of (hemodynamically stable) PE. Their efficacy in preventing recurrent VTE seemed consistent regardless of anatomical extension of PE (extensive, intermediate, or limit) or presence/absence of right ventricular dysfunction although the data are limited. For extended therapy, the DOAC were more effective than placebo in preventing recurrent VTE but were associated with an increase in CRB regardless of index event.

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.

Pharmacoeconomic evaluation of dabigatran, rivaroxaban and apixaban versus enoxaparin for the prevention of venous thromboembolism after total hip or knee replacement in Spain.

BACKGROUND: Patients undergoing total hip replacement (THR) or total knee replacement (TKR) surgery are at high risk of developing venous thromboembolism (VTE). Thromboprophylaxis with low-molecular-weight heparin, such as enoxaparin, is standard of care in these patients. Recently, three direct oral anticoagulants (DOACs; dabigatran, rivaroxaban and apixaban), have been approved for this indication, but their cost effectiveness is still unclear as it has usually been extrapolated from surrogate venographic outcomes in clinical trials. OBJECTIVE: To conduct a pharmacoeconomic evaluation of the DOACs versus subcutaneous (SC) enoxaparin for the prevention of VTE after THR or TKR surgery. METHODS: A decision-tree model was developed using TreeAge Pro 2011 to compare the cost utility and cost effectiveness of the DOACs with SC enoxaparin, with separate models for THR and TKR over a 3-month postoperative time horizon from the perspective of the Spanish National Health System. The probabilities of events (symptomatic VTE, clinically relevant bleedings, heparin-induced thrombocytopenia and deaths) were derived from a systematic review and meta-analysis. We used local cost estimates (€2013) and utility values were obtained from the literature. We reported costs, quality-adjusted life-years (QALYs) and symptomatic VTE events. We conducted sensitivity analyses to evaluate parameter uncertainty. RESULTS: The average costs per 1,000 patients treated with enoxaparin were higher than costs incurred by dabigatran, rivaroxaban and apixaban in THR (€435,208 vs. €283,574, €257,900 and €212,472, respectively) and TKR (€336,550 vs. €219,856, €251,734 and €201,946, respectively), with cost savings ranging from €151,634 to €222,766 in THR, and from €84,816 to €134,604 in TKR. Cost differences were largely driven by differences in costs associated with drug administration. The average QALYs per 1,000 patients treated were very similar for enoxaparin, dabigatran, rivaroxaban and apixaban in THR (199.34, 198.83, 199.08 and 199.68, respectively) and TKR (198.95, 199.41, 198.75 and 199.97, respectively). Rivaroxaban (in TKR and THR) and apixaban (in THR) avoided additional symptomatic VTE events compared with enoxaparin. Sensitivity analyses generally supported the robustness of the analysis to changes in model parameters. CONCLUSIONS: Our model suggests, based on its underlying assumptions and data, that the DOACs are cost-saving alternatives to SC enoxaparin for the prevention of VTE after THR or TKR, in the Spanish healthcare setting.

Potential role of new anticoagulants for prevention and treatment of venous thromboembolism in cancer patients.

Venous thromboembolism (VTE), encompassing deep vein thrombosis and pulmonary embolism, represents a major cause of morbidity and mortality in patients with cancer. Low molecular weight heparins are the preferred option for anticoagulation in cancer patients according to current clinical practice guidelines. Fondaparinux may also have a place in prevention of VTE in hospitalized cancer patients with additional risk factors and for initial treatment of VTE. Although low molecular weight heparins and fondaparinux are effective and safe, they require daily subcutaneous administration, which may be problematic for many patients, particularly if long-term treatment is needed. Studying anticoagulant therapy in oncology patients is challenging because this patient group has an increased risk of VTE and bleeding during anticoagulant therapy compared with the population without cancer. Risk factors for increased VTE and bleeding risk in these patients include concomitant treatments (surgery, chemotherapy, placement of central venous catheters, radiotherapy, hormonal therapy, angiogenesis inhibitors, antiplatelet drugs), supportive therapies (ie, steroids, blood transfusion, white blood cell growth factors, and erythropoiesis-stimulating agents), and tumor-related factors (local vessel damage and invasion, abnormalities in platelet function, and number). New anticoagulants in development for prophylaxis and treatment of VTE include parenteral compounds for once-daily administration (ie, semuloparin) or once-weekly dosing (ie, idraparinux and idrabiotaparinux), as well as orally active compounds (ie, dabigatran, rivaroxaban, apixaban, edoxaban, betrixaban). In the present review, we discuss the pharmacology of the new anticoagulants, the results of clinical trials testing these new compounds in VTE, with special emphasis on studies that included cancer patients, and their potential advantages and drawbacks compared with existing therapies.

Dabigatran, Rivaroxaban, or Apixaban versus Warfarin in Patients with Nonvalvular Atrial Fibrillation: A Systematic Review and Meta-Analysis of Subgroups.

Background. New oral anticoagulants (NOAC; rivaroxaban, dabigatran, apixaban) have become available as an alternative to warfarin anticoagulation in non-valvular atrial fibrillation (NVAF). Methods. MEDLINE and CENTRAL, regulatory agencies websites, clinical trials registers and conference proceedings were searched to identify randomised controlled trials of NOAC versus warfarin in NVAF. Two investigators reviewed all studies and extracted data on patient and study characteristics along with cardiovascular outcomes. Relative risks (RR) and 95% confidence intervals (CI) were estimated using a random effect meta-analysis. Results. Three clinical trials in 50,578 patients were included. The risk of non-hemorrhagic stroke and systemic embolic events (SEE) was similar with the NOAC and warfarin (RR = 0.93; 95% CI = 0.83-1.04), while the risk of intracranial bleeding (ICB) with the NOAC was lower than with warfarin (RR = 0.46; 95% CI = 0.33-0.65). We found differences in the effect size on all strokes and SEE depending on geographic region as well as on non-hemorrhagic stroke, SEE, bleeding and mortality depending on time in therapeutic range. Conclusion. The NOAC seem no more effective than warfarin for prevention of nonhemorrhagic stroke and SEE in the overall NVAF population, but are generally associated with a lower risk of ICB than warfarin.

Dabigatran, rivaroxaban, or apixaban versus enoxaparin for thromboprophylaxis after total hip or knee replacement: systematic review, meta-analysis, and indirect treatment comparisons.

OBJECTIVE: To analyse clinical outcomes with new oral anticoagulants for prophylaxis against venous thromboembolism after total hip or knee replacement. DESIGN: Systematic review, meta-analysis, and indirect treatment comparisons. DATA SOURCES: Medline and CENTRAL (up to April 2011), clinical trials registers, conference proceedings, and websites of regulatory agencies. STUDY SELECTION: Randomised controlled trials of rivaroxaban, dabigatran, or apixaban compared with enoxaparin for prophylaxis against venous thromboembolism after total hip or knee replacement. Two investigators independently extracted data. Relative risks of symptomatic venous thromboembolism, clinically relevant bleeding, deaths, and a net clinical endpoint (composite of symptomatic venous thromboembolism, major bleeding, and death) were estimated using a random effect meta-analysis. RevMan and ITC software were used for direct and indirect comparisons, respectively. RESULTS: 16 trials in 38,747 patients were included. Compared with enoxaparin, the risk of symptomatic venous thromboembolism was lower with rivaroxaban (relative risk 0.48, 95% confidence interval 0.31 to 0.75) and similar with dabigatran (0.71, 0.23 to 2.12) and apixaban (0.82, 0.41 to 1.64). Compared with enoxaparin, the relative risk of clinically relevant bleeding was higher with rivaroxaban (1.25, 1.05 to 1.49), similar with dabigatran (1.12, 0.94 to 1.35), and lower with apixaban (0.82, 0.69 to 0.98). The treatments did not differ on the net clinical endpoint in direct or indirect comparisons. CONCLUSIONS: A higher efficacy of new anticoagulants was generally associated with a higher bleeding tendency. The new anticoagulants did not differ significantly for efficacy and safety.

Discovery of anticoagulant drugs: a historical perspective.

The history of the traditional anticoagulants is marked by both perseverance and serendipity. The anticoagulant effect of heparin was discovered by McLean in 1915, while he was searching for a procoagulant in dog liver. Link identified dicumarol from spoiled sweet clover hay in 1939 as the causal agent of the sweet clover disease, a hemorrhagic disorder in cattle. Hirudin extracts from the medicinal leech were first used for parenteral anticoagulation in the clinic in 1909, but their use was limited due to adverse effects and difficulties in achieving highly purified extracts. Heparins and coumarins (i.e.: warfarin, phenprocoumon, acenocoumarol) have been the mainstay of anticoagulant therapy for more than 60 years. Over the past decades, the drug discovery paradigm has shifted toward rational design following a target-based approach, in which specific proteins, or "targets", are chosen on current understandings of pathophysiology, small molecules that inhibit the target's activity may be identified by high-throughput screening and, in selected cases, these new molecules can be developed further as drugs. Despite the application of rational design, serendipity has still played a significant role in some of the new discoveries. This review will focus on the discovery of the main anticoagulant drugs in current clinical use, like unfractionated heparin, low-molecular-weight heparins, fondaparinux, coumarins (i.e.: warfarin, acenocoumarol, phenprocoumon), parenteral direct thrombin inhibitors (DTIs) (i.e.: argatroban, recombinant hirudins, bivalirudin), oral DTIs (i.e.: dabigatran) and oral direct factor Xa inhibitors (i.e.: rivaroxaban, apixaban).