Risk of stroke/systemic embolism,major bleeding and associated costs in non-valvular atrial fibrillation patients who initiated apixaban,dabigatran or rivaroxaban compared with warfarin in the United States Medicare population

Objective: To compare the risk and cost of stroke/systemic embolism (SE) and major bleeding between each direct oral anticoagulant (DOAC) and warfarin among non-valvular atrial fibrillation (NVAF) patients.

Methods: Patients (≥65 years) initiating warfarin or DOACs (apixaban, rivaroxaban, and dabigatran) were selected from the Medicare database from 1 January 2013 to 31 December 2014. Patients initiating each DOAC were matched 1:1 to warfarin patients using propensity score matching to balance demographics and clinical characteristics. Cox proportional hazards models were used to estimate the risks of stroke/SE and major bleeding of each DOAC vs. warfarin. Two-part models were used to compare the stroke/SE- and major-bleeding-related medical costs between matched cohorts.

Results: Of the 186,132 eligible patients, 20,803 apixaban–warfarin pairs, 52,476 rivaroxaban–warfarin pairs, and 16,731 dabigatran–warfarin pairs were matched. Apixaban (hazard ratio [HR]?=?0.40; 95% confidence interval [CI] 0.31, 0.53) and rivaroxaban (HR?=?0.72; 95% CI 0.63, 0.83) were significantly associated with lower risk of stroke/SE compared to warfarin. Apixaban (HR?=?0.51; 95% CI 0.44, 0.58) and dabigatran (HR?=?0.79; 95% CI 0.69, 0.91) were significantly associated with lower risk of major bleeding; rivaroxaban (HR?=?1.17; 95% CI 1.10, 1.26) was significantly associated with higher risk of major bleeding compared to warfarin. Compared to warfarin, apixaban ($63 vs. $131) and rivaroxaban ($93 vs. $139) had significantly lower stroke/SE-related medical costs; apixaban ($292 vs. $529) and dabigatran ($369 vs. $450) had significantly lower major bleeding-related medical costs.

Conclusions: Among the DOACs in the study, only apixaban is associated with a significantly lower risk of stroke/SE and major bleeding and lower related medical costs compared to warfarin.     

Comparison of effectiveness and safety of treatment with apixaban vs. other oral anticoagulants among elderly nonvalvular atrial fibrillation patients

Objective: To compare the risk of stroke/systemic embolism (S/SE) and major bleeding (MB) of elderly (≥65 years of age) nonvalvular atrial fibrillation (NVAF) patients initiating apixaban vs. rivaroxaban, dabigatran, or warfarin.

Methods: NVAF patients with Medicare Advantage coverage in the US initiating oral anticoagulants (OACs, index event) were identified from the Humana database (1 January 2013–30 September 2015) and grouped into cohorts depending on OAC initiated. Propensity score matching (PSM), 1:1, was conducted among patients treated with apixaban vs. each other OAC, separately. Rates of S/SE and MB were evaluated in the follow-up. Cox regressions were used to compare the risk of S/SE and MB between apixaban and each of the other OACs during the follow-up.

Results: The matched pairs of apixaban vs. rivaroxaban (n?=?13,620), apixaban vs. dabigatran (n?=?4654), and apixaban vs. warfarin (n?=?14,214) were well balanced for key patient characteristics. Adjusted risks for S/SE (hazard ratio [HR] vs. rivaroxaban: 0.72, p?=?.003; vs. warfarin: 0.65, p?p?p?p?=?.27) and MB (HR: 0.82, p?=?.23) of NVAF patients treated with apixaban vs. dabigatran trended to be lower, but did not reach statistical significance.

Conclusions: In the real-world setting after controlling for differences in patient characteristics, apixaban is associated with significantly lower risk of S/SE and MB than rivaroxaban and warfarin, and a trend towards better outcomes vs. dabigatran among elderly NVAF patients in the US.     

An early evaluation of bleeding-related hospital readmissions among hospitalized patients with nonvalvular atrial fibrillation treated with direct oral anticoagulants

Objective:

Clinical trials have demonstrated that direct oral anticoagulants (DOACs) are efficacious in reducing stroke risk among patients with nonvalvular atrial fibrillation (NVAF) with differences in the reduction of bleeding risks vs. warfarin. The objective of this study was to assess bleeding-related hospital readmissions among hospitalized NVAF patients treated with dabigatran, rivaroxaban, and apixaban in the US.

Research design and methods:

Patients (≥18 years) with a discharge diagnosis of NVAF who received apixaban, dabigatran, or rivaroxaban during hospitalization were identified from the Premier Hospital database (1 January 2012–31 March 2014) and the Cerner Health Facts hospital database (1 January 2012–31 August 2014). Patients identified from each database were analyzed separately and grouped into three cohorts depending on which DOAC was received. Patient characteristics, hospital resource use and costs, and frequency of readmissions within 1 month were evaluated.

Results:

Among study populations identified from the Premier database (N?=?74,730) and the Cerner database (N?=?14,201), patients who received apixaban were older, had greater comorbidity, and had higher stroke and bleeding risks. After controlling for patient characteristics, including comorbidity and stroke and bleeding risks, compared with patients who received apixaban during their index hospitalizations, the odds of bleeding-related hospital readmissions were significantly greater by 1.4-fold (p?<?0.01) for patients who received rivaroxaban and 1.2-fold (p?=?0.16) numerically greater for patients who received dabigatran among patients identified from the Premier Hospital database. Among patients in the Cerner Health Facts hospital database, bleeding-related hospital readmissions were significantly greater by 1.6-fold (p?=?0.04) for patients who received rivaroxaban and 1.3-fold (p?=?0.30) numerically greater for patients who received dabigatran compared to patients who received apixaban.

Limitations:

No causal relationship between treatment and outcomes can be concluded.

Conclusions:

NVAF patients using different DOACs had different characteristics, including stroke and bleeding risks. Use of rivaroxaban, compared to apixaban was associated with significantly greater risk of bleeding-related readmissions across two database claims analyses.     

Impact of methodological choices on a meta-analysis of real-world evidence comparing non-vitamin-K antagonist oral anticoagulants with vitamin K antagonists for the treatment of patients with non-valvular atrial fibrillation

Objective: The aim of this study was to investigate the impact of methodological choices in a meta-analysis of real-world evidence (RWE) comparing three non-vitamin-K antagonist oral anticoagulants with vitamin K antagonists (VKAs) for the treatment of patients with non-valvular atrial fibrillation (NVAF).

Methods: The meta-analysis was based on a systematic review of RWE studies enrolling incident and prevalent patients aged ≥18 years with NVAF and receiving either rivaroxaban, dabigatran, apixaban or a VKA. Five different scenarios were considered to explore the impact of the initial meta-analysis assumptions: (1) using studies that involved only incident patients; (2) excluding studies that only reported crude values and did not consider any adjustment; (3) including all studies independently of possible database overlap; (4) using studies with data on different dosages for rivaroxaban and dabigatran; and (5) assigning quality weights to studies to assess quality of reporting. These scenarios were run on three outcomes: ischemic stroke (IS), myocardial infarction (MI) and intracranial hemorrhage (ICH).

Results: Across all scenarios, rivaroxaban was associated with significantly lower risks of IS and ICH than VKAs. In most scenarios, dabigatran was associated with significantly lower risks of IS and ICH. In all scenarios, apixaban was associated with a significantly lower risk of ICH.

Conclusions: Sensitivity analyses showed the impact of similar assumptions was different depending on the outcome and the drug considered. The development of recommendations and guidelines for the inclusion of RWE in meta-analyses could prove useful in evaluating the effectiveness of health care interventions.     

Effectiveness and safety of rivaroxaban in nonvalvular atrial fibrillation: data from a contemporary Spanish registry

Objective: To ascertain the clinical profile, management and rates of thromboembolic and bleeding complications in a contemporary cohort of patients with nonvalvular atrial fibrillation (NVAF) on rivaroxaban treatment, with a particular focus on some subgroups of patients.

Methods: Retrospective study that included all NVAF patients who started treatment with rivaroxaban for the prevention of stroke or systemic embolism between December 2012 and December 2015. Rates of outcomes (stroke, nonfatal myocardial infarction, major bleeding, intracranial bleeding and death) during follow-up were calculated.

Results: A total of 732 patients (mean age 76.4?±?9.2?years; 54.5% women) were included. Comorbidities were common (hypertension 87.5%; diabetes 26.5%; renal insufficiency 24.6%; prior stroke/transient ischemic attack 16.8%). Mean CHA₂DS₂-VASc was 3.9?±?1.5 and HAS-BLED 2.3?±?0.9; 61.9% of patients were rivaroxaban naïve users. After a mean treatment period of 22.7?±?7.4?months, rates of stroke, nonfatal myocardial infarction, major bleeding, intracranial bleeding and death were 1.8, 1.0, 3.2, 0.4 and 5.5 events per 100 patient-years, respectively. Rates of stroke and death were higher in patients >75?years (vs. ≤75?years) and in patients with prior stroke/transient ischemic attack or renal insufficiency. Rates of major bleeding were higher among patients >75?years and in patients with prior stroke/transient ischemic attack.

Conclusions: In this contemporary Spanish cohort of NVAF patients on rivaroxaban, patients had many comorbidities, a high thromboembolic risk and a moderate bleeding risk. Overall, rates of stroke and bleeding complications were low and similar to other previous studies. These data suggest that rivaroxaban is effective and safe in routine practice.     

Safety and efficacy of non-vitamin K oral anticoagulants in non-valvular atrial fibrillation: a Bayesian meta-analysis approach

Introduction: Choosing between different non-vitamin K antagonist oral anticoagulants (NOACs) in non-valvular atrial fibrillation (NVAF) is difficult due to the absence of head to head comparative studies. We performed a Bayesian meta-analysis to explore similarities and differences between different NOACs and to rank treatments overall for safety and efficacy outcomes.

Areas covered: Through a systematic literature search we identified randomized controlled Phase III trials of dabigatran, rivaroxaban, apixaban, and edoxaban versus adjusted-dose warfarin in patients with NVAF.

Expert opinion: Warfarin ranked worst for all-cause mortality and intracranial bleedings and had a nil probability of ranking first for any outcome. The risk of major bleeding versus warfarin was lower with apixaban, dabigatran 110 mg, and both doses of edoxaban. All agents reduced the risk of intracranial bleeding versus warfarin. Edoxaban 30 mg was the best among the treatments being compared for major and gastrointestinal bleeding. Dabigatran 150 mg was the best for stroke and systemic embolism. This study suggests that NOACs are generally preferable to warfarin in patients with NVAF. However, safety and efficacy differences do exist among NOACs, which might drive their use in specific subsets of AF patients, allowing prescribers to tailor treatment to distinct patient profiles.     

Long-term outcome in patients with non-valvular atrial fibrillation on dabigatran: a prospective cohort study

ABSTRACT

Introduction: Most studies on thromboembolic and bleeding risk in patients with non-valvular atrial fibrillation (NVAF) exposed to non-vitamin K oral anticoagulants stem from interrogation of insurance databases.

Areas covered: We studied 742 consecutive patients with NVAF who started treatment with dabigatran in three hospitals in Italy. Average follow-up was 1.80 years.

Mean age was 76.2 years. CHA₂DS₂VASc score was 0–1 in 37 (5%), 2 in 97 (13%) and ≥ 3 in 604 (82%) patients. NVAF was permanent in 349 (48%). Overall, 76% of patients remained on treatment over the entire follow-up period. Among 180 patients who discontinued permanently, the most frequent reasons were dyspepsia (33.9%), bleeding (17.8%), and renal worsening (12.1%). About 48% and 74% of permanent discontinuations occurred during the first 6 and 12 months of treatment, respectively. Rates of major events (per 100 patient-years) were 0.75 for stroke, 0.31 for myocardial infarction, 1.50 for all-cause death, and 1.80 for major bleedings. The rate of intracranial bleedings was 0.45 and that of major gastrointestinal bleedings was 0.75.

Expert opinion: This prospective cohort study confirms the low incidence of stroke, major bleeding and intracranial bleeding, and a 76% persistence with treatment, in patients with NVAF treated with dabigatran over about 2 years.     

Impact of renal function on ischemic stroke and major bleeding rates in nonvalvular atrial fibrillation patients treated with warfarin or rivaroxaban: a retrospective cohort study using real-world evidence

Objectives: Renal dysfunction is associated with increased risk of cardiovascular disease and is an independent predictor of stroke and systemic embolism. Nonvalvular atrial fibrillation (NVAF) patients with renal dysfunction may face a particularly high risk of thromboembolism and bleeding. The current retrospective cohort study was designed to assess the impact of renal function on ischemic stroke and major bleeding rates in NVAF patients in the real-world setting (outside a clinical trial).

Methods: Medical claims and Electronic Health Records were retrieved retrospectively from Optum’s Integrated Claims–Clinical de-identified dataset from May 2011 to August 2014. Patients with NVAF treated with warfarin (2468) or rivaroxaban (1290) were selected. Each treatment cohort was stratified by baseline estimated creatinine clearance (eCrCl) levels. Confounding adjustments were made using inverse probability of treatment weights (IPTWs). Incidence rates and hazard ratios of ischemic stroke and major bleeding events were calculated for both cohorts.

Results: Overall, patients treated with rivaroxaban had an ischemic stroke incidence rate of 1.9 per 100 person-years (PY) while patients treated with warfarin had a rate of 4.2 per 100 PY (HR?=?0.41 [0.21–0.80], p?=?.009). Rivaroxaban patients with an eCrCl below 50?mL/min (N?=?229) had an ischemic stroke rate of 0.8 per 100 PY, while the rate for the warfarin cohort (N?=?647) was 6.0 per 100 PY (HR?=?0.09 [0.01–0.72], p?=?.02). For the other renal function levels (i.e. eCrCl 50–80 and ≥80?mL/min) HRs indicated no statistically significant differences in ischemic stroke risks. Bleeding events did not differ significantly between cohorts stratified by renal function.

Conclusions: Ischemic stroke rates were significantly lower in the overall NVAF population for rivaroxaban vs. warfarin users, including patients with eCrCl below 50?mL/min. For all renal function groups, major bleeding risks were not statistically different between treatment groups.     

Comparative Real-Life Effectiveness and Safety of Dabigatran or Rivaroxaban vs. Vitamin K Antagonists: A High-Dimensional Propensity Score Matched New Users Cohort Study in the French National Healthcare Data System SNDS

Clinical trials have indicated that the direct-acting oral anticoagulants dabigatran and rivaroxaban have better risk/benefit profiles than do vitamin K antagonists (VKAs) for stroke prevention in non-valvular atrial fibrillation (NVAF). Our objective was to compare the 1-year real-life risk of major clinical events with dabigatran or rivaroxaban versus VKAs for NVAF. This was a high-dimensional propensity score (hdPS)-matched cohort study of new users of dabigatran, rivaroxaban or VKAs for NVAF in the French national healthcare systems database in 2013 followed-up for 1 year [22]. Hazard ratios (HRs) with 95% confidence intervals (CIs) for clinical events and death were determined during exposure. In 2013, a total of 103,101 new anticoagulant users had definite NVAF: 44,653 VKA, 27,060 dabigatran, and 31,388 rivaroxaban. In matched populations, HRs were as follows for dabigatran versus VKAs (20,489 per group): stroke and systemic embolism (SSE) 0.75 (95% CI 0.63–0.88), clinically relevant bleeding (CRB) 0.58 (95% CI 0.51–0.66), hemorrhagic stroke (HS) 0.22 (95% CI 0.14–0.36), gastrointestinal bleeding (GIB) 0.98 (95% CI 0.80–1.19), acute coronary syndrome (ACS) 0.79 (95% CI 0.65–0.95), death 0.74 (95% CI 0.67–0.82), composite (any of the above) 0.71 (95% CI 0.66–0.76). For matched rivaroxaban versus VKA (23,053 per group) HRs were as follows: SSE 0.98 (95% CI 0.85–1.14), CRB 0.83 (95% CI 0.75–0.92), HS 0.65 (95% CI 0.49–0.87), GIB 1.08 (95% CI 0.90–1.30), ACS 0.84 (95% CI 0.71–1.00), death 0.77 (95% CI 0.71–0.84), composite 0.84 (95% CI 0.79–0.89). Numbers needed to treat to observe one fewer death were 49 ± 0.05 with dabigatran or rivaroxaban versus VKAs. Consistent with results from clinical trials and other observational studies, dabigatran and rivaroxaban were at least as effective and safer than VKAs for the prevention of thromboembolic events in NVAF over 1 year in the French population. European Medicines Agency EUPAS 13017 (www.encepp.eu) Clinicaltrials.gov id NCT02785354.     

Risk of major bleeding in patients with non-valvular atrial fibrillation treated with oral anticoagulants: a systematic review of real-world observational studies

Objective: To conduct a systematic review of real-world (RWD) studies comparing the risk of major bleeding (MB) among patients with non-valvular atrial fibrillation (NVAF) on direct oral anticoagulants (DOACs) or warfarin.

Methods: MEDLINE, Embase, NHS-EED, and EconLit were searched for RWD studies published between January 2003 and November 2016 comparing MB risk among DOACs and warfarin. Proceedings of clinical conferences from 2012 to 2016 were reviewed.

Results: A total of 4218 citations were identified, 26 of which met eligibility criteria. Most studies were retrospective analyses of administrative claims databases and patient registries (n?=?23 of 26); about half were based in the United States (n?=?15). Apixaban showed a significantly lower risk of MB versus warfarin in all eight included studies. MB risk was either significantly lower (n?=?9 of 16) or not significantly different (n?=?7 of 16) between dabigatran and warfarin; there was no significant difference between rivaroxaban and warfarin in all seven included studies. The risk was significantly lower with apixaban versus rivaroxaban (n?=?7 of 7) but not significantly different from dabigatran (n?=?6 of 7). MB risk was significantly lower (n?=?3 of 4) or not significantly different (n?=?1 of 4) with dabigatran versus rivaroxaban. No evidence was identified for edoxaban.

Conclusion: DOACs were associated with similar or lower risks of MB versus warfarin. A lower MB risk was consistently observed for apixaban, but less consistently for dabigatran; MB risk was similar between rivaroxaban and warfarin. Among DOACs, the risk of MB with apixaban was consistently lower than with rivaroxaban, but similar to dabigatran.     

A rapid evidence assessment of bleed-related healthcare resource utilization in publications reporting the use of direct oral anticoagulants for non-valvular atrial fibrillation

Objective: Non-valvular atrial fibrillation (NVAF), a common cardiac arrhythmia, is associated with high morbidity and carries a substantial economic burden. Historically, vitamin K antagonists (VKAs; e.g. warfarin) have been used for therapy of NVAF, but recently several direct oral anticoagulants (DOACs) have been approved for prevention of stroke in patients with NVAF. This review summarizes the real-world evidence (RWE) for healthcare resource utilization (HRU) in patients receiving oral anticoagulants (VKAs and/or DOACs) for therapy of NVAF.

Methods: A PRISMA-compliant literature search assessed Medline^® and Embase^® databases from 1 January 2011 to 4 May 2017, and the National Health Service Economic Evaluation Database from 1 January 2011 to 31 December 2015. Publications were included if they reported observational data from real-world use of one or more anticoagulant therapies. Outcomes of interest included hospitalizations, length of stay (LOS), mortality and costs.

Results: Twenty-eight publications were included. Apixaban and dabigatran were associated with fewer bleed-related hospitalizations than warfarin. Bleed-related LOS were generally longer for warfarin than for DOACs. Bleed-related treatment costs were lower for patients receiving apixaban or receiving dabigatran than patients receiving rivaroxaban or receiving warfarin. Bleed-related mortality in patients receiving oral anticoagulation for treatment of NVAF were low across all DOACs and warfarin.

Conclusions: The limited available evidence for HRU burden among patients receiving oral anticoagulation for NVAF suggests that DOACs (particularly apixaban and dabigatran) offer some degree of benefit in terms of HRU outcomes, compared with warfarin. Further work is required to understand HRU outcomes in patients receiving DOACs.     

Novel oral anticoagulants: clinical pharmacology, indications and practical considerations

Background

Novel oral anticoagulants are approved in several indications: rivaroxaban, apixaban, and dabigatran for the prevention of venous thromboembolism after elective hip or knee replacement surgery, and edoxaban for hip or knee replacement surgery and hip fracture surgery (in Japan only); rivaroxaban for the treatment of deep vein thrombosis (DVT) and pulmonary embolism (PE), and prevention of recurrent DVT and PE; and rivaroxaban, apixaban, and dabigatran for the prevention of stroke and systemic embolism in patients with non-valvular atrial fibrillation. These agents overcome some limitations of traditional anticoagulants, are suggested to have no requirement for routine coagulation monitoring, and are administered orally. Rivaroxaban, apixaban, and dabigatran have different pharmacological characteristics, and guidance is needed on optimum doses and dosing intervals and the effects of renal or hepatic impairment, age, food, and other drugs. Dabigatran has stricter prescribing advice than rivaroxaban or apixaban for patients with moderate-to-severe renal impairment. All three drugs have restrictions on use in patients with hepatic impairment. Apixaban requires twice-daily dosing in all indications, whereas rivaroxaban and dabigatran are dosed once- or twice-daily depending on indication. Although head-to-head comparisons are lacking, the novel oral anticoagulants may show favorable cost–benefit relations compared with traditional vitamin K antagonists or no therapy.

Aim

This review summarizes the pharmacology of rivaroxaban, apixaban, edoxaban, and dabigatran, and the indications for which they are approved. Issues regarding the optimization of the use of these anticoagulants for the management of thromboembolic disorders will also be discussed.     

Modeling the impact of real-world adherence to once-daily (QD) versus twice-daily (BID) non-vitamin K antagonist oral anticoagulants on stroke and major bleeding events among non-valvular atrial fibrillation patients

Objectives: To estimate the real-world (RW) impact of adherence to once-daily (QD: rivaroxaban and edoxaban) and twice-daily (BID: apixaban and dabigatran) non-vitamin K antagonist (NOACs) on the risk of stroke and major bleeding (MB) among non-valvular atrial fibrillation (NVAF) patients.

Methods: First, claims from the Optum Clinformatics Data Mart database (July 2012–December 2016) were analyzed. Adult NVAF patients with ≥2 NOAC dispensings (index date) were included. The relationship between NOAC adherence (proportion of days covered ≥80%) and stroke/MB 1-year post-index was evaluated using adjusted Cox proportional hazards models. Second, the natural logarithm of hazard ratios (HRs) was multiplied to a literature-derived mean adherence difference between QD and BID NOACs yielding stroke and MB rates. Third, these rates were multiplied by 1-year Kaplan-Meier rates of stroke and MB which yielded the number of strokes prevented and MBs caused. Annual cost savings were evaluated using literature-based stroke ($81,414/patient) and MB ($63,905/patient) cost estimates.

Results: In total, 54,280 patients were included. HRs for adherent vs non-adherent patients were 0.67 (p?<?.001) for stroke and 1.09 (p?=?.179) for MB. The claims-derived 1-year Kaplan-Meier rates were 3.0% and 3.4% for strokes and MBs, respectively. For 100,000?AF patients, 64 strokes were prevented (p?<?.001), and a non-significant number of MBs (n?=?15, p?<?.191) were caused by QD vs BID NOACs annually, which leads to cost savings estimated at $58 million for QD NOACs.

Conclusion: QD NOACs prevented a significant number of strokes and caused no significant increase in MBs compared to BID NOACs, which leads to significant net cost savings for NVAF patients in the US.     

新型抗凝药与华法林用于非瓣膜性房颤患者卒中防治的成本效果分析

目的:评估中国非瓣膜性房颤患者使用新型抗凝药预防卒中的成本效果,为中国房颤患者抗凝治疗药物的合理选用提供理论依据。方法:基于全球性临床试验ARISTOTLE、RE-LY及ROCKET-AF的研究数据及我国目前医疗成本,建立一年期决策树及长期外推Markov模型的方法,通过分别计算3种新型口服抗凝药物阿哌沙班(5 mg bid)、达比加群(150 mg bid、110 mg bid)、利伐沙班(20 mg qd)和华法林的调整质量生命年(QLAYs)及治疗成本,对新型抗凝药物用于中国房颤患者卒中预防的成本效果进行了分析和研究。结果:NOACs治疗的总成本为163586~582710元,使用NOACs患者可获得的质量调整生命年为6.812~7.010。以华法林为参考的增效成本效果分析显示,成本效果比(ICER)为177271~739480元/QLAY,ICER_利伐沙班> ICER_阿哌沙班> ICER_{达比加群150 mg}> ICER_{达比加群110 mg}。3种抗凝药物与华法林比较的ICER均大于我国人均国民生产总值(GDP)的3倍,但小于部分城市人均GDP的3倍。一维敏感度分析显示该成本效果分析结果稳定可靠。结论:目前在我国,与华法林相比,使用新型抗凝药物预防非瓣膜性房颤患者卒中不具备成本效果优势。目前仅在我国经济发达的某些城市,可推荐阿哌沙班或达比加群用于房颤卒中的治疗。     

New evidences for old concerns with oral anticoagulation in atrial fibrillation: focus on dabigatran

Introduction: Nonvalvular atrial fibrillation (NVAF) is associated with a fivefold excess risk of stroke. Antithrombotic therapy is crucial to reduce the risk of stroke. During past decades, vitamin K antagonists (warfarin or acenocoumarol) have been widely used for this purpose. However, they have several disadvantages that limit their daily use in clinical practice.

Areas covered: In patients with NVAF at risk of stroke, the randomized evaluation of long-term anticoagulation therapy (RE-LY) trial demonstrated that, compared with warfarin, dabigatran 150 mg b.i.d. was associated with lower rates of stroke and systemic embolism but similar rates of major hemorrhage, whereas dabigatran 110 mg b.i.d. exhibited similar rates of stroke and systemic embolism, but lower rates of major hemorrhage. Fortunately, data about dabigatran are not limited to RE-LY trial. In fact, many substudies have been drawn, providing new and important evidences about the benefits of dabigatran.

Expert opinion: The most recent evidences about efficacy and safety of dabigatran in patients with NVAF, focusing on different substudies of RE-LY trial, are reviewed. In summary, dabigatran is beneficial not only in general population with NVAF but also in different subgroups of patients or different clinical settings (i.e., CHADS2 score, INR control, type of AF, elderly, previous transient ischemic attack or stroke, cardioversion and so on).     

The evolving role of dabigatran etexilate in clinical practice

Introduction: Stroke and venous thromboembolism (VTE) affect millions of patients. The vitamin K antagonist, warfarin, has been the main oral anticoagulant used to treat these conditions despite many limitations associated with its use. Recently, multiple novel oral anticoagulants have been approved and are reshaping how patients with atrial fibrillation (AF) at risk of stroke and patients with VTE are treated. The direct thrombin inhibitor, dabigatran etexilate, is among these novel agents that have been developed to overcome limitations with warfarin.

Areas covered: In this article, authors describe the pharmacokinetic and pharmacodynamic properties of dabigatran etexilate and summarize the clinical evidence and controversy surrounding its use in the US, Canada and Europe.

Expert opinion: Dabigatran has demonstrated similar efficacy and safety to enoxaparin for VTE prevention in patients undergoing hip and knee arthroplasty, and to warfarin for the treatment of VTE. Dabigatran (110 mg) is noninferior and dabigatran (150 mg) is superior to warfarin for stroke prevention in patients with nonvalvular AF, with a lower rate of intracranial hemorrhage reported at both doses. Apixaban, rivaroxaban and edoxaban provide alternate anticoagulant options to dabigatran. While there are many similarities, there are also significant differences to consider in agent selection based on patient-specific characteristics.     

An update on the pharmaceutical management of thrombosis

Introduction: Anticoagulants such as heparins and vitamin K antagonists (VKA) are effective for thrombosis prevention and treatment, but are associated with the risk of bleeding and other limitations, spurring the search for improved drugs.

Areas covered: to evaluate the newer anticoagulants, focusing on those tested in phase III clinical trials such as direct oral anticoagulants (DOACs), antisense oligonucleotides (ASO) and warfarin analogues. DOACs such as dabigatran, rivaroxaban, apixaban and edoxaban are licensed for stroke prevention in atrial fibrillation and treatment of venous thromboembolism, dabigatran, rivaroxaban and apixaban for postoperative thromboprophylaxis in patients undergoing elective hip or knee arthroplasty and rivaroxaban for secondary prevention of acute coronary syndromes. ASO interfering with Factor XI hepatic synthesis were effective and safe for thromboprophylaxis in elective knee arthroplasty.

Expert opinion: DOACs have overcome some limitations of anticoagulants such as VKA, but are still associated with a risk of bleeding and they lack both standardized and widely available tests measuring their anticoagulant effect and a reversal agent, except for idarucizumab, specific for dabigatran, in case of major or life threatening bleeding or emergency surgery. Agents targeting Factor XI and possibly Factor XII may be ideal anticoagulants, as they can prevent thrombosis with low bleeding risk.     

Dabigatran etexilate: a pharmacoeconomic review of its use in the prevention of stroke and systemic embolism in patients with atrial fibrillation

This article provides an overview of the clinical profile of oral dabigatran etexilate (Pradaxa?, Pradax?) [hereafter referred to as dabigatran] when used for the prevention of stroke and systemic embolism in patients with nonvalvular atrial fibrillation (AF), followed by a review of cost-utility analyses of dabigatran in this patient population. Dabigatran (110 or 150?mg twice daily) demonstrated noninferiority versus adjusted-dose warfarin with regard to the prevention of stroke and systemic embolism (primary endpoint) in patients with AF in the RE-LY trial, and the 150?mg twice-daily dosage was significantly more effective than warfarin for this endpoint, as well as most other efficacy endpoints. The incidence of major bleeding was generally similar in patients receiving dabigatran 150?mg twice daily or warfarin, but was lower in patients receiving dabigatran 110?mg twice daily. With regard to other bleeding endpoints, dabigatran was generally associated with lower rates than warfarin, except for gastrointestinal major bleeding. Dabigatran (both dosages) was associated with a higher incidence of dyspepsia than warfarin. Results of modelled cost-utility analyses from several countries from the perspective of a healthcare payer over a lifetime (or 20-year) time horizon and primarily based on data from the RE-LY trial were generally consistent. All but one analysis demonstrated that twice-daily dabigatran 150?mg (or age-adjusted, sequential dosing) was cost effective with regard to the incremental cost per QALY gained relative to adjusted-dose warfarin in the prevention of stroke and systemic embolism in AF patients, as the results were below generally accepted cost-effectiveness thresholds. In contrast, the incremental cost per QALY gained for dabigatran 110?mg twice daily versus warfarin exceeded cost-effectiveness thresholds in all studies except one. Sensitivity analyses suggested that the cost utility of dabigatran versus warfarin was generally robust to variations in the majority of parameters. However, the incremental cost per QALY gained for dabigatran versus warfarin improved when levels of international normalized ratio control in warfarin recipients decreased and when the baseline level of risk of stroke increased.