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

Effect of tramadol and DOACs with special attention to dabigatran on concomitant use, on the risk of mayor bleeding using BIFAP database in Spain

BACKGROUND

Tramadol, a weak opioid, inhibits the reuptake of serotonin, a key feature on vascular homeostasis. A suspected interaction exists between dabigatran and tramadol, which might trigger an excess on risk of bleeding however, there is a gap in knowledge on this topic.

PURPOSE

To estimate the effects of tramadol, dabigatran and concomitant use on the risk of hospitalized major bleeds (Gastrointestinal bleeding and intra-extracranial bleeds).

METHODS

Among a validated established cohort of new users of oral anticoagulants for non-valvular atrial fibrillation (NVAF) aged 18 years or older, we identified all hospitalized bleed episodes (GIB and extra/intracranial bleeds) within 2008-2015. A nested case-control analysis was conducted using conditional logistic regression. Adjusted odds ratios (aORs) with 95% confidence intervals (CIs) were calculated for dabigatran, tramadol, and concomitant use. Several sensitivity analyses were carried out.

RESULTS

aORs (95%CIs) for current use of only dabigatran, only tramadol and concomitant users were 1.73 (1.37-2.18) and 1.38 (1.13-1.67) and 2.04 (0.74-5.67) compared with non-users of both drugs (>365 days). aORs for current continuers and non-continuer users of dabigatran were 1.36 (1.00-1.86) and 2.19 (1.61-2.98), respectively. For the latter, non-continuer users with a short duration of dabigatran cumulated the highest risk (3.36 [1.88-5.99]). There also was an increased risk with concomitant use of tramadol and rivaroxaban (2.24 [1.19-4.21]), or antagonist of vitamin K (1.30 [1.00-1.69]).

CONCLUSION

There was a trend towards and increased risk of excess bleeds when using concomitantly with dabigatran. The effect decreases with a narrower definition of current use.

Real-world evidence comparing oral anticoagulants in non-valvular atrial fibrillation: a systematic review and network meta-analysis

Aim: To compare real-world effectiveness/safety of non-vitamin K antagonist oral anticoagulants and vitamin K antagonists among patients with non-valvular atrial fibrillation. Materials & methods: A systematic review of electronic databases yielded 7661 citations published from January 2013 to January 2020. Fifty-five studies were included in Bayesian network meta-analyses of hazard ratios. Results & conclusion: In comparison with vitamin K antagonists, apixaban, dabigatran and rivaroxaban were associated with a reduced risk of stroke or systemic embolism, ischemic stroke, intracranial hemorrhage and all-cause mortality. Apixaban, dabigatran and edoxaban, but not rivaroxaban, were associated with a reduced risk of major bleeding. This study confirmed the effectiveness and safety of non-vitamin K antagonist oral anticoagulants for the treatment of non-valvular atrial fibrillation in real-world settings, consistent with clinical trial evidence.

Defining the duration of the dispensation of oral anticoagulants in administrative healthcare databases

PURPOSE

In clinical practice, warfarin therapy requires frequent dose adjustments. In pharmacy claims, the days supplied value may not reflect the true duration of warfarin dispensation. This may affect the measures of association comparing the safety of direct oral anticoagulants (DOACs) versus warfarin.

METHODS

Using Quebec healthcare administrative databases, we formed a cohort of 55 230 patients newly treated with oral anticoagulants between 2010 and 2016. The duration of dispensations was defined using two approaches: the recorded days supplied value, and the longitudinal coverage approximation (data-driven) that may account for individual variation in drug usage patterns. Propensity scores adjusted Cox proportional hazards regression models were used to estimate the hazard ratio (HR) of major bleeding with dabigatran or rivaroxaban versus warfarin.

RESULTS

Using the days supplied, the mean (and standard deviation) dispensation durations for dabigatran, rivaroxaban, and warfarin were 19 (15), 19 (14), and 13 (12) days, respectively. Using the data-driven approach, the durations were 20 (16), 19 (15), and 15 (16) days, respectively. The choice of the approach had no impact on the HR estimates.

CONCLUSIONS

In our settings, the data-driven approach closely approximated the recorded days supplied value for the standard dose therapies such as dabigatran and rivaroxaban. For warfarin, the data-driven approach captured more variability in the duration of dispensations compared to the days supplied value, which may better reflect the true drug-taking behavior of warfarin. Both approaches may provide valid estimates when comparing the safety of DOACs versus warfarin.

Burden of major gastrointestinal bleeding among oral anticoagulant-treated non-valvular atrial fibrillation patients

BACKGROUND

Gastrointestinal (GI) bleeding is the most common type of major bleeding associated with oral anticoagulant (OAC) treatment. Patients with major bleeding are at an increased risk of a stroke if an OAC is not reinitiated.

METHODS

Non-valvular atrial fibrillation (NVAF) patients initiating OACs were identified from the Centers for Medicare and Medicaid Services (CMS) Medicare data and four US commercial claims databases. Patients who had a major GI bleeding event (hospitalization with primary diagnosis of GI bleeding) while on an OAC were selected. A control cohort of patients without a major GI bleed during OAC treatment was matched to major GI bleeding patients using propensity scores. Stroke/systemic embolism (SE), major bleeding, and mortality (in the CMS population) were examined using Cox proportional hazards models with robust sandwich estimates.

RESULTS

A total of 15,888 patients with major GI bleeding and 833,052 patients without major GI bleeding were included in the study. Within 90 days of the major GI bleed, 58% of patients discontinued the initial OAC treatment. Patients with a major GI bleed had a higher risk of stroke/SE [hazard ratio (HR): 1.57, 95% confidence interval (CI): 1.42-1.74], major bleeding (HR: 2.79, 95% CI: 2.64-2.95), and all-cause mortality (HR: 1.29, 95% CI: 1.23-1.36) than patients without a major GI bleed.

CONCLUSION

Patients with a major GI bleed on OAC had a high rate of OAC discontinuation and significantly higher risk of stroke/SE, major bleeding, and mortality after hospital discharge than those without. Effective management strategies are needed for patients with risk factors for major GI bleeding.

Comparative effectiveness and safety of direct oral anticoagulants versus vitamin K antagonists in nonvalvular atrial fibrillation: a Canadian multicentre observational cohort study

BACKGROUND

Direct oral anticoagulants (DOACs) have widely replaced warfarin for stroke prevention in nonvalvular atrial fibrillation. Our objective was to compare the safety and effectiveness of DOACs (dabigatran, rivaroxaban, apixaban) versus warfarin for stroke prevention in nonvalvular atrial fibrillation in the Canadian setting.

METHODS

We conducted a population-based observational multicentre cohort study with propensity score matching and subsequent meta-analysis. We used health care databases from 7 Canadian provinces (British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, Quebec and Nova Scotia). Patients with nonvalvular atrial fibrillation who initiated anticoagulation therapy in 2009-2017 were matched to an equal number who initiated warfarin. The primary outcome was the pooled hazard ratio (HR) for ischemic stroke or systemic embolization. Secondary outcomes included pooled HRs for major bleeding; a composite outcome of stroke, systemic embolization, major bleeding and all-cause mortality; and myocardial infarction. We modelled HRs using proportional hazard Cox regression with inverse probability of censoring weights, and estimated pooled HRs with random-effect meta-analyses.

RESULTS

We included 128 273 patients who initiated anticoagulation with a DOAC (40 503 dabigatran, 49 498 rivaroxaban and 38 272 apixaban) and 128 273 patients who initiated anticoagulation with warfarin. The pooled HR for ischemic stroke or systemic embolization comparing DOACs to warfarin was 1.02 (95% confidence interval [CI] 0.87 to 1.19). Direct oral anticoagulants were associated with lower rates of major bleeding (pooled HR 0.81, 95% CI 0.69 to 0.97), the composite outcome (pooled HR 0.81, 95% CI 0.74 to 0.89) and all-cause mortality (pooled HR 0.81, 95% CI 0.78 to 0.85).

INTERPRETATION

In this real-world study, DOACs were associated with similar risks of ischemic stroke or systemic embolization, and lower risks of bleeding and total mortality compared to warfarin. These findings support the use of DOACs for anticoagulation in nonvalvular atrial fibrillation.

TRIAL REGISTRATION

ClinicalTrials.gov, no. NCT03596502.

New oral anticoagulants for nonvalvular atrial fibrillation with stable coronary artery disease: A meta-analysis

BACKGROUND

New oral anticoagulants (NOACs) are effective and safe in patients with nonvalvular atrial fibrillation (NVAF). Limited evidence is available regarding outcomes for NVAF patients with stable coronary artery disease (CAD).

METHODS

A systematic search of Medline, Embase, and the Cochrane Register was performed. Two reviewers independently performed data extraction and quality assessment using the Cochrane Collaboration risk-of-bias assessment tool. We evaluated all primary publications and secondary analyses comparing NOACs with any other OAC agent for preventing stroke in patients with both NVAF and stable CAD from phase III clinical randomized control trials. The primary outcomes were stroke, systemic embolism (SE), major bleeding, and intracranial hemorrhage (ICH), and the secondary outcomes were cardiovascular (CV) death, all-cause death, and myocardial infarction (MI).

RESULTS

Four articles with a total of 19 266 patients were included in this study. The pooled results showed a relative risk for stroke/SE with NOACs of 0.83 (95% confidence interval [CI]: 0.71-0.97), for major bleeding 0.85 (95% CI: 0.63-1.14), for ICH 0.36 (95% CI: 0.19-0.54), for MI 1.00 (95% CI: 0.82-1.20), for CV death 0.94 (95% CI: 0.83-1.06), and for all-cause death 0.95 (95% CI: 0.85-1.07).

CONCLUSION

NOACs were effective in preventing stroke/SE and reducing the risk of ICH in patients with both NVAF and CAD.

New oral anticoagulants for nonvalvular atrial fibrillation with peripheral artery disease: a meta-analysis

BACKGROUND

New oral anticoagulants (NOACs) are as effective and safe as warfarin for patients with non-valvular atrial fibrillation (NVAF). Limited evidence is available regarding outcomes for NVAF patients with peripheral artery disease (PAD).

METHODS

A systematic search of Medline, Embase, and the Cochrane Library was performed. Two reviewers independently performed data extraction and quality assessment using the Cochrane Collaboration tool for assessing risk of bias. All primary publications and secondary analyses comparing NOACs with other oral anticoagulation regimens for the prevention of stroke in patients with both NVAF and PAD from phase III clinical trials were evaluated. The primary outcomes were stroke, systemic embolism (SE), major bleeding, and intracranial hemorrhage (ICH), and the secondary outcomes were cardiovascular (CV) mortality, all-cause mortality, and myocardial infarction (MI).

RESULTS

Three articles were included in this study. The pooled results showed a relative risk for stroke/SE with NOACs of 0.86 (95% confidence interval [CI]: 0.53-1.39), for major bleeding, 1.12 (95% CI: 0.70-1.81), for ICH, 0.47 (95% CI: 0.16-1.36), for CV mortality, 0.77 (95% CI: 0.57-1.04), for all-cause mortality, 0.91 (95% CI: 0.70-1.19), and for MI, 1.10 (95% CI: 0.64-1.90).

CONCLUSION

The findings show that NOACs are effective and safe for preventing stroke/SE in patients with both NVAF and PAD.

Incidence and cost of bleeding events requiring hospitalization in patients with atrial fibrillation treated with acenocoumarol in Greece

BACKGROUND

To estimate the incidence of hemorrhagic events in patients with atrial fibrillation (AF) treated with acenocoumarol, and the management cost of those requiring hospitalization in Greece.

METHODS

A nationwide telephone survey was conducted between December 2017 and January 2018, to identify cardiologists who treat AF patients with acenocoumarol. A total of 300 cardiologists were selected and reported the number of AF acenocoumarol-treated patients during the past 12 months and the number of those who experienced a hemorrhagic event. The hospital charges to sickness fund and the cost of resource utilization of AF patients hospitalized between January 2013 and June 2017 at a tertiary hospital in Athens due to acenocoumarol-related bleedings were retrieved.

RESULTS

Out of 48,255 AF patients, 12,633 (26.2%) were treated with acenocoumarol. In all, 5.1% of patients experienced a hemorrhagic event with the incidence of bleeding requiring hospitalization being 1.7%. The most common bleeding site was the gastrointestinal system (51.5%). The mean (95% CI) management cost per bleeding event requiring hospitalization was €1,202 (€1,058-€1,420). The higher cost was that of intracranial bleeding €3,887 (€2,700-€5,046). The expected annual economic burden for the management of bleedings related to acenocoumarol and requiring hospitalization was estimated at €1,463,955.

CONCLUSIONS

The incidence of bleeding events in AF acenocoumarol-treated patients in Greece as well as the estimated annual economic burden for the management of bleeding events requiring hospitalization, emphasize the need to comply with the current guidelines and to optimize therapeutic strategies for the management of AF side effects with oral anticoagulants, particularly in patients with high bleeding risk.

Effectiveness and Safety of Oral Anticoagulants Among Nonvalvular Atrial Fibrillation Patients

Supplemental Digital Content is available in the text.

Background and Purpose—

This ARISTOPHANES study (Anticoagulants for Reduction in Stroke: Observational Pooled Analysis on Health Outcomes and Experience of Patients) used multiple data sources to compare stroke/systemic embolism (SE) and major bleeding (MB) among a large number of nonvalvular atrial fibrillation patients on non–vitamin K antagonist oral anticoagulants (NOACs) or warfarin.

Methods—

A retrospective observational study of nonvalvular atrial fibrillation patients initiating apixaban, dabigatran, rivaroxaban, or warfarin from January 1, 2013, to September 30, 2015, was conducted pooling Centers for Medicare and Medicaid Services Medicare data and 4 US commercial claims databases. After 1:1 NOAC-warfarin and NOAC-NOAC propensity score matching in each database, the resulting patient records were pooled. Cox models were used to evaluate the risk of stroke/SE and MB across matched cohorts.

Results—

A total of 285 292 patients were included in the 6 matched cohorts: 57 929 apixaban-warfarin, 26 838 dabigatran-warfarin, 83 007 rivaroxaban-warfarin, 27 096 apixaban-dabigatran, 62 619 apixaban-rivaroxaban, and 27 538 dabigatran-rivaroxaban patient pairs. Apixaban (hazard ratio [HR], 0.61; 95% CI, 0.54–0.69), dabigatran (HR, 0.80; 95% CI, 0.68–0.94), and rivaroxaban (HR, 0.75; 95% CI, 0.69–0.82) were associated with lower rates of stroke/SE compared with warfarin. Apixaban (HR, 0.58; 95% CI, 0.54–0.62) and dabigatran (HR, 0.73; 95% CI, 0.66–0.81) had lower rates of MB, and rivaroxaban (HR, 1.07; 95% CI, 1.02–1.13) had a higher rate of MB compared with warfarin. Differences exist in rates of stroke/SE and MB across NOACs.

Conclusions—

In this largest observational study to date on NOACs and warfarin, the NOACs had lower rates of stroke/SE and variable comparative rates of MB versus warfarin. The findings from this study may help inform the discussion on benefit and risk in the shared decision-making process for stroke prevention between healthcare providers and nonvalvular atrial fibrillation patients.

Clinical Trial Registration—

URL: https://www.clinicaltrials.gov/. Unique identifier: NCT03087487.

Patient characteristics and stroke and bleeding events in nonvalvular atrial fibrillation patients treated with apixaban and vitamin K antagonists: a Spanish real-world study

Aim: To compare the risk of stroke, systemic thromboembolism and bleeding, in patients initiating apixaban or acenocoumarol for the treatment of nonvalvular atrial fibrillation. Methods: An observational, retrospective study was performed using medical records of patients who initiated apixaban or acenocoumarol between 2015 and 2017. Propensity score matching was used to match patients; stroke, systemic thromboembolism, major and minor bleeding events were compared between the matched patients. Results: Patients who were prescribed apixaban had a lower rate of systemic embolism/stroke (hazard ratio [HR] = 0.54; 95% CI: 0.38–0.78; p = 0.001), minor bleeding (HR = 0.64; 95% CI: 0.52–0.79; p < 0.001) and major bleeding (HR = 0.51; 95% CI: 0.37–0.72; p < 0.001). Conclusion: Patients prescribed apixaban for the treatment of nonvalvular atrial fibrillation had lower rates of thromboembolic events and minor/major bleeding than patients on acenocoumarol.

Optimization of Pharmacotherapy with Direct Oral Anticoagulants: the Need to Choose the Right Dosage Regimen

In recent years, there has been a persistent trend towards the more frequent prescription of direct oral anticoagulants (DOACs) compared with vitamin K antagonists due to the extensive body of evidence showing their high safety and efficacy, which in some cases exceed those of warfarin, and also by reason of there is no necessity for regular monitoring of international normalized ratio. However, the question of the reasonable and rational prescription of DOACs becomes relevant, including issues of their dosing, especially as a result of increasing in the number of patients with a complex cardiovascular risk profile and multimorbidity. In these terms, apixaban stands high among the DOAC class, and its high efficacy and safety both in full dose and reasonably reduced dosage has been proved, including older patients, patients with chronic kidney disease, coronary artery disease, with history of acute coronary syndrome and individuals undergoing percutaneous coronary intervention. This DOAC has strict indications to reduce the dose, they are specified in the drug label, and in such cases a reduced dose should be prescribed, in these clinical conditions the effectiveness and safety of apixaban is also proven. The favorable apixaban pharmacokinetic properties, consisting in low renal clearance, lack of clinically relevant interaction with food and the linear smooth effect on the blood coagulation components without episodes of hypo- and hypercoagulation, are the most important components of high efficacy and safety of this DOAC. The optimal efficacy and safety coupling of apixaban is reflected in the exclusively high patients’ adherence to the treatment confirmed by evidence-based medicine data, and therefore there is no necessity for additional procedures to maintain adherence. All the aforementioned facts allow us to recommend apixaban for widespread use in patients requiring anticoagulant therapy for optimal prevention of systemic thromboembolism and minimizing the associated risk of bleeding.

Effectiveness and safety of direct oral anticoagulants compared to warfarin in treatment naïve non-valvular atrial fibrillation patients in the US Department of defense population

BACKGROUND

Clinical trials have demonstrated that direct oral anticoagulants (DOACs) are at least non-inferior to warfarin in reducing the risk of stroke/systemic embolism (SE) among patients with non-valvular atrial fibrillation (NVAF), but the comparative risk of major bleeding varies between DOACs and warfarin. Using US Department of Defense (DOD) data, this study compared the risk of stroke/SE and major bleeding for DOACs relative to warfarin.

METHODS

Adult patients with ≥1 pharmacy claim for apixaban, dabigatran, rivaroxaban, or warfarin from 01 Jan 2013-30 Sep 2015 were selected. Patients were required to have ≥1 medical claim for atrial fibrillation during the 12-month baseline period. Patients with a warfarin or DOAC claim during the 12-month baseline period were excluded. Each DOAC cohort was matched to the warfarin cohort using propensity score matching (PSM). Cox proportional hazards models were conducted to evaluate the risk of stroke/SE and major bleeding of each DOAC vs warfarin.

RESULTS

Of 41,001 identified patients, there were 3691 dabigatran-warfarin, 8226 rivaroxaban-warfarin, and 7607 apixaban-warfarin matched patient pairs. Apixaban was the only DOAC found to be associated with a significantly lower risk of stroke/SE (hazard ratio [HR]: 0.55; 95% confidence interval [CI]: 0.39, 0.77; p < 0.001) and major bleeding (HR: 0.65; 95% CI: 0.53, 0.80; p < 0.001) compared to warfarin. Dabigatran and rivaroxaban initiation were associated with similar risk of stroke/SE (dabigatran: HR: 0.68; 95% CI: 0.43, 1.07; p = 0.096; rivaroxaban: HR: 0.83; 95% CI: 0.64, 1.09; p = 0.187) and major bleeding (dabigatran: HR: 1.05; 95% CI: 0.79, 1.40; p = 0.730; rivaroxaban: HR: 1.07; 95% CI: 0.91, 1.27; p = 0.423) compared to warfarin.

CONCLUSION

Among NVAF patients in the US DOD population, apixaban was associated with significantly lower risk of stroke/SE and major bleeding compared to warfarin. Dabigatran and rivaroxaban were associated with similar risk of stroke/SE and major bleeding compared to warfarin.

Non–Vitamin K Antagonist Oral Anticoagulants in the Treatment of Atrial Fibrillation

Atrial fibrillation (AF) increases a patient's stroke risk four- to five-fold. Anticoagulation with the vitamin K antagonist (VKA) warfarin reduces the risk of stroke by 67%, but warfarin carries a significant risk of major bleeding and has unpredictable pharmacodynamics with a narrow therapeutic window, necessitating frequent monitoring of its anticoagulant effect. The non–vitamin K antagonist oral anticoagulants (NOACs) dabigatran, rivaroxaban, apixaban, and edoxaban provide more predictable anticoagulant activity than warfarin with a lower risk of major bleeding, and each is noninferior to warfarin for the prevention of stroke. All have earned regulatory approval in the past eight years. At least one of the NOACs is approved for use in all patients with AF, except those with mechanical valves and rheumatic mitral valve disease, for whom warfarin remains the only option. Recent clinical trials have shown that antithrombotic regimens including NOACs are safe and effective in patients with AF who need potent antiplatelet therapy.

A systematic review of clinicians' views and experiences of direct-acting oral anticoagulants in the management of nonvalvular atrial fibrillation

AIMS

While a plethora of systematic reviews have provided evidence of efficacy, effectiveness and safety of direct-acting oral anticoagulants (DOACs) in the management of nonvalvular atrial fibrillation, there has been little emphasis on clinicians' perspectives. This systematic review aimed to critically appraise, synthesize and present the available evidence of clinicians' views and experiences.

METHODS

Studies published in English from January 2006 to July 2017 reporting the views and/or experiences of doctors, nurses or pharmacists on any individual DOAC or as a pharmacological group were included. Studies were assessed for quality by two researchers, data extracted and findings synthesized using a narrative approach.

RESULTS

Following exclusion of duplicates, 777 titles, 394 abstracts and 196 studies were screened. Ten studies were included in the review, nine of which were quantitative (cross-sectional surveys) and one qualitative (semistructured interviews), with marked heterogeneity in outcomes reported. Studies were conducted exclusively in Europe and the USA. In those studies reporting clinician preference, DOACs were first choice over warfarin in naïve patients, based on perceptions of evidence of effectiveness equivalent or superior to warfarin and superior safety. Other advantageous factors were in those with an unstable International Normalized Ratio and likely to miss appointments. There were, however, concerns relating to management of over-anticoagulation and experiences of observed bleeding rates.

CONCLUSION

There is a limited evidence base of clinicians' perspectives of DOACs, necessitating further research, particularly given the trajectory of increased use worldwide.

Effectiveness and Safety of Anticoagulants in Adults with Non-valvular Atrial Fibrillation and Concomitant Coronary/Peripheral Artery Disease

BACKGROUND

Direct oral anticoagulants (DOAC) are at least non-inferior to warfarin in efficacy and safety among patients with nonvalvular atrial fibrillation. Limited evidence is available regarding outcomes for nonvalvular atrial fibrillation patients with coronary/peripheral artery disease.

METHODS

Non-valvular atrial fibrillation patients aged ≥65 years diagnosed with coronary/peripheral artery disease in the US Medicare population, newly initiating DOACs (apixaban, rivaroxaban, dabigatran) or warfarin were selected from January 1, 2013 to September 30, 2015. Propensity score matching was used to compare DOACs vs warfarin. Cox proportional hazards models were used to estimate the risk of stroke/systemic embolism, major bleeding, and composite of stroke/myocardial infarction/all-cause mortality.

RESULTS

There were 15,527 apixaban-warfarin, 6,962 dabigatran-warfarin, and 25,903 rivaroxaban-warfarin-matched pairs, with a mean follow-up of 5-6 months. Compared with warfarin, apixaban was associated with lower rates of stroke/systemic embolism (hazard ratio [HR] 0.48; 95% confidence interval [CI], 0.37-0.62), major bleeding (HR 0.66; 95% CI, 0.58-0.75), and stroke/myocardial infarction/all-cause mortality (HR 0.63; 95% CI, 0.58-0.69); dabigatran and rivaroxaban were associated with lower rates of stroke/myocardial infarction/all-cause mortality (HR 0.79; 95% CI, 0.70-0.90 and HR 0.87; 95% CI, 0.81-0.92, respectively). Rivaroxaban was associated with a lower rate of stroke/systemic embolism (HR 0.72; 95% CI, 0.60-0.89) and a higher rate of major bleeding (HR 1.14; 95% CI, 1.05-1.23) vs warfarin.

CONCLUSIONS

All DOACs were associated with lower stroke/myocardial infarction/all-cause mortality rates compared with warfarin; differences were observed in rates of stroke/systemic embolism and major bleeding. Findings from this observational analysis provide important insights about oral anticoagulation therapy among non-valvular atrial fibrillation patients with coronary/peripheral artery disease and may help physicians in the decision-making process when treating this high-risk group of patients.

Direct comparative effectiveness and safety between non-vitamin K antagonist oral anticoagulants for stroke prevention in nonvalvular atrial fibrillation: a systematic review and meta-analysis of observational studies

The non-vitamin K antagonist oral anticoagulants (NOACs) have been increasingly prescribed in clinical practice for stroke prevention in patients with nonvalvular atrial fibrillation (AF). Direct comparisons between NOACs in trials are lacking, leaving an important clinical decision-making gap. We aimed to perform a systematic review and meta-analysis to summarize the evidence of observational studies for direct comparative effectiveness and safety amongst NOACs in patients with AF. Conference proceedings and electronic databases including MEDLINE, CINAHL, EMBASE and PUBMED were systematically searched. We included observational studies directly comparing individual NOACs in patients with nonvalvular AF who were aged ≥ 18 years for stroke prevention. Primary outcome included effectiveness outcome (stroke or systemic embolism) and safety outcome (major bleeding). Data were extracted in duplicated by two reviewers independently. A random-effects meta-analysis was conducted to synthesize the data from included observational studies. We used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) to rate the overall quality of evidence for each outcome. Fifteen studies were included for qualitative synthesis, twelve studies for meta-analyses. It was found that rivaroxaban and dabigatran were similar with regard to risk of stroke or systemic embolism (Hazard ratio [HR] = 1.00, 95% CI 0.91-1.10; evidence quality: low), but rivaroxaban was associated with higher risk of major bleeding (HR = 1.39, 95% CI 1.28-1.50; evidence quality: moderate). Compared with apixaban, a significantly higher risk of major bleeding was observed with rivaroxaban (HR = 1.71, 95% CI 1.51-1.94; evidence quality: low). Apixaban was associated with lower risk of major bleeding, in comparison with dabigatran (HR = 0.80, 95% CI 0.68-0.95; evidence quality: low). No differences in risk of stroke or systemic embolism was observed between rivaroxaban versus apixaban, and apixaban versus dabigatran. In this study, apixaban was found to have the most favorable safety profile amongst the three NOACs. No significant difference was observed in risk of stroke or systemic embolism between the NOACs. Such findings may provide some decision-making support for physicians regarding their choices amongst NOACs in patients with AF.Registration PROSPERO (identifier: CRD42016052908).

Randomised controlled trial protocol to evaluate a fixed dose prothrombin complex concentrate against the variable dose in vitamin K antagonist related bleeding (PROPER3)

INTRODUCTION

There is currently little evidence for the optimal dosing strategy of four-factor prothrombin complex concentrates (PCC) in vitamin K antagonist (VKA)-related bleeds. The generally accepted dosing strategy is the use of a variable dose calculated using patient-specific characteristics as per manufacturer's instruction. However, evidence exists that the use of a fixed low dose of 1000 international units of factor IX (IU fIX) might also suffice. Recent studies indicate that in terms of haemostatic effectiveness, the fixed dosing strategy might be even superior to the variable dosing strategy. The PROPER3 (PROthrombin complex concentrate: Prospective Evaluation and Rationalisation, number 3) study aims to confirm the non-inferiority, and explore superiority, in haemostatic effectiveness of the fixed PCC dosing strategy compared with the variable dosing strategy in VKA-related extracranial bleeding emergencies.

METHODS AND ANALYSIS

The study is designed as a randomised controlled multicentre non-inferiority trial. Eligibility criteria are an indication for PCC due to VKA-related extracranial bleeding in subjects 18 years of age or older. The control group will receive a variable dose, determined by patient-specific bodyweight and international normalised ratio. The intervention group is dosed a fixed 1000 IU fIX PCC. Primary outcome is the haemostatic effectiveness of both treatments, as defined by the 2016 International Society on Thrombosis and Haemostasis (ISTH) criteria. The sample size is set at 155 patients per treatment arm, requiring 310 patients in total. Non-inferiority on the proportion (risk) difference of the primary outcome will be evaluated using the asymptotic Wald test for non-inferiority. The non-inferiority margin is set at 6%. The primary analysis will be based on the per-protocol population.

ETHICS AND DISSEMINATION

Study results will be published in an international journal, communicated to discipline-specific associations and presented at (inter)national meetings and congresses.

TRIAL REGISTRATION NUMBER

EUCTR2014-000392-33; Pre-results.

Comparison of major bleeding risk in patients with non-valvular atrial fibrillation receiving direct oral anticoagulants in the real-world setting: a network meta-analysis

OBJECTIVE

To conduct a systematic literature review (SLR) and network meta-analysis (NMA) of real-world studies comparing major bleeding risk among patients with non-valvular atrial fibrillation (NVAF) on direct oral anticoagulants (DOACs) or warfarin.

METHODS

Systematic searches were conducted in MEDLINE and Embase for full-text articles published between January 1, 2003 and March 18, 2017. Eligible studies compared at least two of the following in a real-world setting: warfarin, apixaban, dabigatran, rivaroxaban, or edoxaban. A Bayesian NMA was conducted to estimate hazard ratios (HRs) for major bleeding using a random-effects model.

RESULTS

Eleven studies were included in the NMA. Nine studies included DOACs vs Warfarin comparisons, and four studies included DOACs vs DOACs comparisons (two studies included both comparisons). Median follow-up duration ranged from 2.6-31.2 months. No evidence was identified for edoxaban. Apixaban was associated with a significantly lower risk of major bleeding compared to other oral anticoagulants (warfarin HR = 0.58; 95% credible interval [CrI] = 0.48-0.69; dabigatran = 0.73; 0.61-0.87; rivaroxaban = 0.55; 0.46-0.66). Dabigatran was associated with a significantly lower risk than warfarin (0.79; 0.71-0.88) and rivaroxaban (0.76; 0.67-0.85), and rivaroxaban was not statistically different from warfarin (1.05; 0.91-1.19). Sensitivity analyses with standard dose and sponsorship showed consistent results.

CONCLUSION

DOACs were associated with lower or similar risk of major bleeding compared with warfarin in NVAF patients. Apixaban was associated with a significantly lower risk of major bleeding than other DOACs. Dabigatran was associated with a significantly lower risk of major bleeding compared to rivaroxaban and warfarin.

Anticoagulation in atrial fibrillation : Current evidence and guideline recommendations

Atrial fibrillation (AF) is the most frequently encountered sustained arrhythmia with a prevalence of 0.5-10%, depending predominantly on age. The arrhythmia is associated with significant morbidity and mortality, mainly due to thromboembolic events including stroke and systemic embolisms. These complications can be effectively prevented with anticoagulation therapy either with vitamin K antagonists (VKA) or with non-vitamin K antagonists (NOAC). VKA therapy is effective in preventing strokes but these medications are difficult to use, are associated with significant bleeding risk, and have pharmacokinetic/dynamic properties that make their use cumbersome. NOACs-either factor II or factor Xa inhibitors-have been developed over the past two decades and have been tested against VKA in large randomized controlled trials. This trial evidence was complemented more recently by increasing real-world data comprising several 100,000 patients. Finally, NOACs have been examined for their use in specific clinical situations, for example, in patients undergoing cardioversion, catheter ablation, or coronary interventions. In all of these clinical scenarios, NOACs have been similarly effective or-in many instances-even superior to treatment with VKA. Recent guidelines, therefore, recommend NOAC therapy for stroke prevention in AF as first-line therapy.

Non-valvular atrial fibrillation: impact of apixaban on patient outcomes

Atrial fibrillation is the most common arrhythmia worldwide, and carries a significantly increased risk of thromboembolic stroke. Initially, vitamin K antagonists were used as stroke prophylaxis; but more recently, a group of drugs known as novel oral anticoagulants have been developed. Apixaban belongs to this group of drugs, and is a factor Xa inhibitor that has emerged as a popular pharmacological agent worldwide. In this review, we will provide an overview of the pivotal trials in the development of apixaban, while also critically evaluating the new emerging real-world data, and discussing the effectiveness, safety, economic viability and future prospects of apixaban and how it impacts on patient outcomes in those with non-valvular atrial fibrillation.