Clinical and Pharmacological Effects of Apixaban Dose Adjustment in the ARISTOTLE Trial

Plasma apixaban concentrations and thrombin generation assay parameters in response to dose reduction for atrial fibrillation

AIMS

To investigate plasma apixaban concentrations and thrombin generation assay (TGA) parameters across different apixaban doses in atrial fibrillation patients who had dose-reduction criteria for apixaban.

METHODS

This observational study included 374 patients (mean age 75.6 ± 7.7 years, 54.8% female) with dose-reduction criteria for apixaban. The patients were divided into 3 groups: (i) on-label standard dose (5 mg twice daily, n = 166); (ii) on-label reduced dose (2.5 mg twice daily, n = 55); and (iii) off-label underdose (2.5 mg twice daily, n = 153). Apixaban concentrations determined via the anti-Xa assay and TGA parameters were compared at trough levels.

RESULTS

The off-label underdose group exhibited significantly lower apixaban trough concentrations than the on-label reduced-dose and standard-dose groups (56.7 ± 42.9 vs. 83.7 ± 70.4 vs. 129.9 ± 101.8 ng/mL, all P < .001). Less than 70% of all patients fell within the expected range of apixaban concentrations. Proportions exceeding the upper limit of the expected range were significantly lower in the off-label underdose group (1.3%) than in the on-label reduced-dose (9.1%, P = .005) and standard-dose (12.7%, P < .001) groups. The TGA parameters showed the on-label standard-dose group displaying the lowest thrombogenic profiles. Lower creatinine clearance was the most significant predictor of higher apixaban concentrations.

CONCLUSION

Off-label underdosed apixaban resulted in lower apixaban concentrations than both on-label standard and reduced-dose regimens. A considerable proportion of the patients exhibited apixaban concentrations outside the expected range, suggesting the potential benefits of plasma concentration monitoring. Further studies are needed to compare dosages directly, investigate the impact of plasma apixaban concentration monitoring and validate the current dose-reduction criteria.

Perils of reduced dose apixaban in atrial fibrillation/flutter - A case report with a brief literature review

Patients with atrial fibrillation/atrial flutter (AF) are notoriously predisposed to thromboembolic events secondary to the development of thrombi within the left atrium of the heart. AF accompanied by a fairly decent CHA2DS2-VASc score is a known indication for full anticoagulation, frequently with direct oral anticoagulants (DOACs), such as apixaban. Following extensive studies weighing the benefits of anticoagulation versus risks of major bleeding, patients meeting two or more of the dose-reduction criteria (age ≥80 years, weight ≤60 kg, and/or creatinine ≥ 1.5 mg/dL) require appropriate step-down to a reduced dose of apixaban. However, with rising concern for bleeding complications, many physicians are found to have been reducing the dose of apixaban despite the patient not completely meeting the defined criteria. Our study particularly emphasizes the risk of significantly increased thromboembolic complications in the setting of sub-therapeutic anticoagulation, in patients with both appropriately and inappropriately reduced doses of apixaban.

Thrombotic events associated with low baseline direct oral anticoagulant levels in atrial fibrillation: the MAS study

ABSTRACT

Although effective and safe, treatment with direct oral anticoagulants (DOAC) in atrial fibrillation (AF) is still associated with thrombotic complications. Whether the measurement of DOAC levels may improve treatment efficacy is an open issue. We carried out the observational, prospective, multicenter Measure and See (MAS) study. Blood was collected 15 to 30 days after starting DOAC treatment in patients with AF who were followed-up for 1 year. Plasma samples were centralized for DOAC level measurement. Patients' DOAC levels were converted into drug/dosage standardized values to allow a pooled analysis in a time-dependent, competitive-risk model. The measured values were transformed into standardized values (representing the distance of each value from the overall mean) by subtracting the DOAC-specific mean value from the original values and dividing by the standard deviation. Trough and peak DOAC levels were assessed in 1657 and 1303 patients, respectively. In total, 21 thrombotic complications were recorded during 1606 years of follow-up (incidence of 1.31% of patients per year). Of 21 thrombotic events, 17 occurred in patients whose standardized activity levels were below the mean of each DOAC (0); the incidence was the highest (4.82% of patients per year) in patients whose standardized values were in the lowest class (-1.00 or less). Early measurement of DOAC levels in patients with AF allowed us to identify most of the patients who, having low baseline DOAC levels, subsequently developed thrombotic complications. Further studies are warranted to assess whether thrombotic complications may be reduced by measuring baseline DOAC levels and modifying treatment when indicated. This trial was registered at www.ClinicalTrials.gov as #NCT03803579.

Gene polymorphism as a cause of hemorrhagic complications in patients with non-valvular atrial fibrillation treated with oral vitamin K-independent anticoagulants

Atrial fibrillation (AF) accounts for 40% of all cardiac arrhythmias and is associated with a high risk of stroke and systemic thromboembolic complications. Dabigatran, rivaroxaban, apixaban, and edoxaban are direct oral anticoagulants (DOACs) that have been proven to prevent stroke in patients with non-valvular AF. This review summarizes the pharmacokinetics, pharmacodynamics, and drug interactions of DOACs, as well as new data from pharmacogenetic studies of these drugs. This review is aimed at analyzing the scientific literature on the gene polymorphisms involved in the metabolism of DOACs. We searched PubMed, Cochrane, Google Scholar, and CyberLeninka (Russian version) databases with keywords: 'dabigatran', 'apixaban', 'rivaroxaban', 'edoxaban', 'gene polymorphism', 'pharmacogenetics', 'ABCB1', 'CES1', 'SULT1A', 'ABCG2', and 'CYP3A4'. The articles referred for this review include (1) full-text articles; (2) study design with meta-analysis, an observational study in patients taking DOAC; and (3) data on the single-nucleotide polymorphisms and kinetic parameters of DOACs (plasma concentration), or a particular clinical outcome, published in English and Russian languages during the last 10 years. The ages of the patients ranged from 18 to 75 years. Out of 114 reviewed works, 24 were found eligible. As per the available pharmacogenomic data, polymorphisms affecting DOACs are different. This may aid in developing individual approaches to optimize DOAC pharmacotherapy to reduce the risk of hemorrhagic complications. However, large-scale population studies are required to determine the dosage of the new oral anticoagulants based on genotyping. Information on the genetic effects is limited owing to the lack of large-scale studies. Uncovering the mechanisms of the genetic basis of sensitivity to DOACs helps in developing personalized therapy based on patient-specific genetic variants and improves the efficacy and safety of DOACs in the general population.

Antioxidant Properties of Oral Antithrombotic Therapies in Atherosclerotic Disease and Atrial Fibrillation

The thrombosis-related diseases are one of the leading causes of illness and death in the general population, and despite significant improvements in long-term survival due to remarkable advances in pharmacologic therapy, they continue to pose a tremendous burden on healthcare systems. The oxidative stress plays a role of pivotal importance in thrombosis pathophysiology. The anticoagulant and antiplatelet drugs commonly used in the management of thrombosis-related diseases show several pleiotropic effects, beyond the antithrombotic effects. The present review aims to describe the current evidence about the antioxidant effects of the oral antithrombotic therapies in patients with atherosclerotic disease and atrial fibrillation.

Single-Dose Pharmacokinetics of Milvexian in Participants with Normal Renal Function and Participants with Moderate or Severe Renal Impairment

OBJECTIVE

The aim of this study was to assess the effect of moderate or severe renal impairment on the pharmacokinetic (PK) properties of milvexian.

METHODS

This open-label, parallel-group study assessed the PK, safety, and tolerability of a single oral 60 mg dose of milvexian in participants with normal renal function (n = 8; estimated glomerular filtration rate [eGFR] ≥ 90 mL/min/1.73 m2) and participants with moderate (n = 8; eGFR ≥ 30 to ≤ 59 mL/min/1.73 m2) or severe (n = 8; eGFR < 30 mL/min/1.73 m2) renal impairment. Regression analysis was performed using linear regression of log-transformed PK parameters versus eGFR.

RESULTS

Milvexian was well tolerated, with no deaths, serious adverse events, or serious bleeding reported. The maximum milvexian concentration (Cmax) was similar for all groups. Based on a regression analysis of milvexian concentration versus eGFR, participants with eGFR values of 30 and 15 mL/min/1.73 m2, respectively, had area under the curve (AUC) values that were 41% and 54% greater than in participants with normal renal function. Median time to maximum concentration (Tmax) was similar for the three groups (4.5-5.0 h). The half-life increased for participants with moderate (18.0 h) or severe (17.7 h) renal impairment compared with those with normal renal function (13.8 h).

CONCLUSION

A single dose of milvexian 60 mg was safe and well tolerated in participants with normal renal function and moderate or severe renal impairment. There was a similar increase in milvexian exposure between the moderate and severe renal groups.

CLINICAL TRIALS REGISTRATION

This study was registered with ClinicalTrials.gov (NCT03196206, first posted 22 June 2017).

Nine-Year Trends in Prevention of Thromboembolic Complications in Elderly Patients with Atrial Fibrillation Treated with NOACs

BACKGROUND

Atrial fibrillation (AF) is the most common disease in elderly patients and thromboembolic complication prophylaxis significantly improves the prognosis in these patients. The study assessed the frequency of individual non-vitamin K antagonist oral anticoagulant (NOAC) use among patients ≥75 years and attempted to identify factors predisposing to their prescription.

METHODS

The data of patients with non-valvular AF hospitalized in the reference cardiology center between 2011 and 2019 were analyzed.

RESULTS

Out of 1443 analyzed patients, 329 (22.8%) received apixaban, 618 (42.8%) dabigatran, and 496 (34.4%) rivaroxaban. The entire population mean age was 82.3 ± 5 years, and 57.9% were females. Independent predictors of apixaban use were age, and bleeding history. Hospitalization for the implantation/reimplantation of a cardiac implantable electronic device (CIED) reduced the chance of apixaban use. Hypertension was a predictor of dabigatran prescription. The chance of using dabigatran decreased with age. Hypertension and bleeding history decreased the chance of rivaroxaban application.

CONCLUSIONS

In hospitalized AF patients ≥75 years, dabigatran was the most frequently used NOAC. Age, comorbidities and bleeding risk determined the selection of individual NOACs.

A ten-year review of the impact of the transition from warfarin to direct oral anticoagulant - Has venous thromboembolism treatment become safer?

BACKGROUND

The introduction of direct oral anticoagulants (DOAC) has resulted in a paradigm shift in the management of venous thromboembolism (VTE). We evaluate the impact of the transition to DOAC, over the last decade, on overall VTE clinical outcomes including in first unprovoked major VTEs.

METHOD

A retrospective analysis of all VTE admissions in non-cancer patients from January 2011 to December 2020 at Northern Health, Victoria, Australia. "Warfarin era" included events that occurred between January 2011 and December 2014 and "DOAC era" from January 2016.

RESULTS

There were 2687 cases involving 2508 patients (45.9 % males; median age 63 years). 98 % were symptomatic and 1261 events (47 %) were unprovoked. 1003 events occurred during the warfarin era (79 % warfarin, 6 % DOAC) and 1479 during the DOAC era (18 % warfarin, 70 % DOAC). While recurrent thrombosis during the acute phase of treatment was comparable, there were fewer recurrences during the long-term preventative phase of treatment in the DOAC era compared to warfarin era (HR 0.602, 95 % CI: 0.393-0.924, p0.020). Clinically significant bleeding events were lower in the DOAC era (HR 0.623, 95 % CI: 0.395-0.985, p = 0.043). A subanalysis of first unprovoked major VTE events (n = 602) demonstrated a significant reduction in recurrent VTE during the long-term preventative phase of treatment in the DOAC era (HR 0.296, 95 % CI: 0.097-0.901, p = 0.032) with no difference in clinically significantly bleeding rates (HR 0.529, 95 % CI 0.219-1.280, p = 0.158) between the eras.

CONCLUSION

Treatment outcomes for VTE appear to have improved over time with reduced rate of thrombotic and clinically significant bleeding complications in the DOAC era.

Do Apixaban Plasma Levels Relate to Bleeding? The Clinical Outcomes and Predictive Factors for Bleeding in Patients with Non-Valvular Atrial Fibrillation

Apixaban can significantly prevent stroke events in patients with non-valvular atrial fibrillation (NVAF), as can be observed from the large, randomized, controlled trial conducted in the present study. However, the real-world evidence of bleeding events related to the apixaban plasma levels in Asian populations is limited. This study aimed to investigate the apixaban plasma levels and clinical outcomes among NVAF patients receiving apixaban, including determining the risk factors associated with bleeding during routine care. Seventy-one patients were included in the study. The median values were 112.79 (5–95th percentiles: 68.69–207.8) μg/L and 185.62 (5–95th percentiles: 124.06–384.34) μg/L for the apixaban trough (C_trough) and apixaban peak plasma levels (C_peak), respectively. Stroke and bleeding were found in 8 (11.27%) and 14 patients (19.72%), respectively. There was no statistical significance for C_trough and C_peak in the stroke and non-stroke groups, respectively. The median of C_trough (139.15 μg/L) in patients with bleeding was higher than that in the non-bleeding group (108.14 μg/L), but there was no statistical significance. However, multivariate analyses showed that bleeding history (odds ratio (OR): 17.62; 95% confidence interval (CI): 3.54–176.64; and p-value = 0.002) and C_trough (OR: 1.01; 95%: CI 1.00–1.03; and p-value = 0.038) were related to bleeding events. Almost all of the patients presented apixaban plasma levels within the expected range. Interestingly, bleeding events were associated with the troughs of the apixaban plasma levels and bleeding history.

Preadmission Oral Anticoagulation for Atrial Fibrillation/Flutter and Death or Thrombotic Events During COVID-19 Admission

Atrial fibrillation/flutter (AF) and COVID-19 are associated with an elevated risk of arterial and venous thrombosis. Whether preadmission oral anticoagulation (OAC) for AF reduces the incidence of in-hospital death or thrombotic events among patients with COVID-19 is unknown. We identified 630 patients with pre-existing AF and a hospitalization diagnosis of COVID-19 and stratified them according to preadmission OAC use. Multivariable logistic regression was employed to relate preadmission OAC to composite in-hospital mortality or thrombotic events. Unadjusted composite in-hospital mortality or thrombotic complications occurred less often in those on than not on preadmission OAC (27.1% vs 46.8%, p <0.001). After adjustment, the incidence of composite in-hospital all-cause mortality or thrombotic complications remained lower with preadmission OAC (odds ratio 0.37, confidence interval 0.25 to 0.53, p <0.0001). Secondary outcomes including all-cause mortality (16.3% vs 24.9%, p = 0.007), intensive care unit admission (14.7% vs 29.0%, p <0.001), intubation (6.4% vs 18.6%, p <0.001), and noninvasive ventilation (18.6% vs 27.5%, p = 0.007) occurred less frequently, and length of stay was shorter (6 vs 7 days, p <0.001) in patients on than those not on preadmission OAC. A higher CHA₂DS₂-VASc score was associated with an increased risk of thrombotic events. In conclusion, among patients with baseline AF who were hospitalized with COVID-19, those on preadmission OAC had lower rates of death, arterial and venous thrombotic events, and less severe COVID-19.

Clinical features and outcomes of patients in different age groups with non-valvular atrial fibrillation receiving oral anticoagulants

Background

Patients with non-valvular atrial fibrillation (NVAF) need prophylactically antithrombotic therapies to reduce the risk of stroke. We hypothesized that the prognostic benefits of prophylactic antithrombotic therapies outweighed the bleeding risk among very elderly (≥85 years old) patients.

Methods

We analyzed clinical characteristics and outcomes of patients with NVAF in different age groups who had received different prophylactic antithrombotic therapies. We enrolled 3895 consecutive NVAF patients in the Macau Special Administrative Region (Macau SAR) of China from January 1, 2010, to December 31, 2018. Among 3524 patients [including 1252 (35.53%) very elderly patients] who completed the entire study, 2897 (82.21%) patients had a CHA₂DS₂-VASc score ≥ 2, 2274 (64.53%) had HAS-BLED score < 3, and 1659 (47.08%) had both of the above. The follow-up time was 3.80 (median, interquartile range 1.89–6.56) years. The primary outcome was the first occurrence of ischemic stroke, major bleeding, clinically relevant non-major gastrointestinal bleeding (CRNM-GIB), and all-cause mortality.

Results

A total of 2012 patients (57.09%) received no antithrombotic (NAT), 665 (18.87%) received antiplatelet (AP) agents, 371 (10.53%) received vitamin K antagonist (VKA), and 476 (13.51%) received non-vitamin K antagonist oral anticoagulants (NOACs). Eventually, 610 (17.31%) patients experienced thromboembolic events, with 167 (4.74%) strokes and 483 (13.71%) transient ischemia attack (TIA)/strokes. Bleeding events occurred in 614 (17.42%) patients, with 131 (3.72%) major bleeding, 381 (10.81%) CRNM-GIB and 102 (2.89%) minor bleeding events. All-cause deaths occurred in 483 (13.71%) patients. Compared with patients receiving NAT, patients receiving NOACs and VKA had fewer strokes (hazard ratio [HR]: 0.038; 95 %CI 0.004–0.401; p = 0.006 and HR: 0.544; 95 %CI 0.307–0.965; p = 0.037, respectively), and lower all-cause mortality (HR: 0.270; 95 %CI 0.170–0.429; p < 0.001 and HR: 0.531; 95 %CI 0.373–0.756; p < 0.001, respectively). Of note, very elderly patients with NVAF receiving NOACs had fewer strokes (adjust hazard ratio [_adjHR]: 0.042; 95 %CI 0.002–1.003; p = 0.050) and lower all-cause mortality (_adjHR: 0.308; 95 %CI 0.158–0.601; p = 0.001). Meanwhile, despite higher CRNM-GIB events (_adjHR: 1.736; 95 %CI 1.042–2.892; p = 0.034), major bleeding events (_adjHR: 1.045; 95 %CI 0.366–2.979; p = 0.935) did not significantly increase. VKA neither reduced strokes (_adjHR: 1.015; 95 %CI 0.529–1.948; p = 0.963), nor improved all-cause mortality (_adjHR: 0.995; 95 %CI 0.641–1.542; p = 0.981) in very elderly patients with NVAF.

Conclusions

Antithrombotic treatment (VKA and NOACs) reduces stroke and improves prognosis in patients in different age groups with NVAF. The prognostic benefits of NOACs outweigh their bleeding risks in very elderly patients with NVAF.

Increased Prevalence of Elevated D-Dimer Levels in Patients on Direct Oral Anticoagulants: Results of a Large Retrospective Study

Elevated D-dimer levels during anticoagulant therapy with vitamin K antagonists (VKA) are associated with an increased risk of thrombosis. It has been hypothesized that elevated D-dimer levels in patients receiving direct oral anticoagulants (DOACs) also indicate an increased risk of thrombosis recurrence, but data on the distribution of D-dimer levels in patients with VTE on DOACs are sparse. In the present study we retrospectively analyzed D-dimer levels in patients taking DOACs after first or recurrent venous thrombosis (n = 1,716, 1,126 thereof rivaroxaban, 481 apixaban, 62 edoxaban, and 47 dabigatran). Patients on VKA (n = 402) served as control group. Thrombotic events in the study population were categorized into distal deep venous thrombosis (DVT, n = 552 patients), distal DVT with pulmonary embolism (PE, n = 166), proximal DVT (n = 685), proximal DVT with PE (n = 462), PE without DVT (n = 522), DVT of the upper extremity (n = 78), cerebral venous sinus thrombosis (CVST, n = 48), and other venous thrombosis (n = 74). In VKA users a median D-dimer level of 0.20 mg/l was observed. In patients on DOACs D-dimer levels were significantly higher, with 0.26 mg/l for rivaroxaban, 0.31 mg/l for apixaban (P &lt; 10−16 each), 0.24 mg/l for edoxaban (P = 2 × 10−5), and 0.25 mg/l for dabigatran (P = 4 × 10−4). These differences in comparison to patients on VKA treatment could not be explained by the patients' age, sex, body mass index, and type of thrombosis as these characteristics did not differ significantly between cohorts. Moreover, the prevalence of D-dimer levels above age-adjusted cut-offs [≥0.50 mg/l in ≤50-year-old patients, ≥(age × 0.01) mg/l in &gt;50-year-old patients] was higher in patients on rivaroxaban (13.9%, RR 1.74, 95% CI 1.21–2.50), apixaban (17.0%, RR 2.14, 95% CI 1.45–3.15) and dabigatran (23.4%, RR 2.94, 95% CI 1.59–5.44) than in patients on VKA (8.0%). In patients on edoxaban D-dimer levels above the reference range were observed in 14.5%, but no statistical significance was reached in comparison to the VKA cohort. In conclusion, the obtained data suggest, that the type of oral anticoagulant should be considered in the clinical assessment of D-dimer levels in thrombosis patients. Further studies are warranted to evaluate a potential association between elevated D-dimer levels and thrombosis risk in patients on DOACs.

Net clinical benefit of a reduced dose of DOACs in non-valvular atrial fibrillation: A meta-analysis of randomized trials

BACKGROUND

In standard dosing, direct Oral Anticoagulants (DOACs) are used as an alternative to warfarin to prevent ischemic stroke and systemic embolism in non-valvular Atrial Fibrillation (AF). However, randomized comprehensive evidence considering the efficacy and safety of the low-dose DOACs in the same setting is still lacking. Toward this end, we conducted a meta-analysis of randomized trials to estimate the risk/benefit ratio, in terms of net clinical benefit, by comparing a reduced dose of DOACs and warfarin.

METHODS

We searched three electronic databases, covering the period until end-February 2021. All-cause death, non-fatal stroke/systemic embolism, and major bleeding events, with or without the inclusion of myocardial infarction, were used to define two different net clinical benefit outcomes. In addition, we evaluated different component outcomes of net clinical benefit as secondary outcomes. Finally, risk ratios and 95% Confidence Intervals (CI) of each outcome were calculated (random-effects model).

RESULTS

In the four randomized trials included (n = 29,779 patients), the net clinical benefit - with or without the inclusion of myocardial infarction - of low-dose DOACs, compared to warfarin, was a 12% (95% CI, 7%-16%) or a 10% (95% CI, 5%-13%) reduction of events, respectively. Compared to warfarin, the reduced dose of DOACs decreased death outcomes, major bleeding events, and hemorrhagic stroke, whereas all thrombotic outcomes were not different among the groups.

CONCLUSIONS

DOACs at low dosing present a more favorable net clinical benefit profile compared to warfarin.

Direct Oral Anticoagulants in Patients with Obesity and Atrial Fibrillation: Position Paper of Italian National Association of Hospital Cardiologists (ANMCO)

The use of the direct oral anticoagulants dabigatran, rivaroxaban, apixaban and edoxaban (DOACs) offers some major advantages over warfarin and other vitamin K antagonists (VKAs). One advantage is the possibility to use a fixed dose in normal-weight patients, overweight patients and patients with obesity. However, the "one size fits all" strategy raised a concern regarding the possibility to undertreat patients with a high body mass index. No randomized controlled trials (RCTs) have ever compared VKAs and DOACs in this population. We analyzed data from the literature on DOAC pharmacokinetics and pharmacodynamics, results from the four pivotal phase III trials on non-valvular atrial fibrillation, retrospective observational studies and metanalyses. While we are aware of the limitation imposed by the absence of specific RCTs, we propose the position of the Italian Association of Hospital Cardiologists (ANMCO) on the use of DOACs in patients with obesity based on the existing evidence.

Validity of different dose reduction criteria for apixaban

Reduced-dose apixaban is recommended in patients fulfilling 2 of 3 criteria: age ≥80 years, body weight ≤60 kg, and serum creatinine ≥1.5 mg/dL. However, patient weight is often not available in electronic health data. We examined the validity of alternative definitions based on age and renal function alone using an observational dataset of patients with atrial fibrillation and chronic kidney disease which included weight measurements.

Severe Inflammation, Acute Kidney Injury, and Drug-Drug Interaction: Triple Penalty for Prolonged Elimination of Apixaban in Patients With Coronavirus Disease 2019: A Grand Round

ABSTRACT

In this article, we present a case of apixaban elimination prolonged by 450% in a patient with coronavirus disease 2019 because of multiple conditions, including drug-drug interaction, severe inflammation, and acute kidney injury. Therapeutic drug monitoring was used to explain unusual routine coagulation assays. This grand round highlights the importance of dialog between the clinician and a therapeutic drug monitoring consultant for optimal patient care.

Critical Analysis of Apixaban Dose Adjustment Criteria

Apixaban is indicated for the prevention of ischemic stroke in non-valvular atrial fibrillation (NVAF), as well as for the prevention and treatment of venous thromboembolism (VTE). Dose adjustment is based on age, weight, and serum creatinine in NVAF, while there are no recommended adjustment criteria for VTE. Such adjustment is unconventional compared to other commonly used medications. The objective of this manuscript is to critically analyze each apixaban dosing adjustment criterion and its associated outcomes. PubMed articles from March 2013 to March 2020 were selected with search terms “apixaban,” and “dose adjustment,” “adjustment,” or “adjustment criteria.” Pharmacokinetic studies demonstrated increased apixaban exposure in patients >65 years of age, those with extreme body weights, and those with advanced renal impairment, though post-hemodialysis dosing may off-set the elevated apixaban exposure. However, clinical data show that among patients >75 years, <60 kg, and with estimated glomerular filtration rate <50 mL/min, including those on dialysis, there is no reduction in apixaban safety or efficacy. Published literature describes variable dosing strategies utilized in clinical practice. Overall, apixaban dose adjustment criteria may need to be re-evaluated.

Differences in Preferences Between Clinicians and Patients for the Use and Dosing of Direct Oral Anticoagulants for Atrial Fibrillation

Background Direct oral anticoagulants (DOACs) are effective in reducing the stroke risk for patients with nonvalvular atrial fibrillation if prescribed at the labeled dose, yet underdosing is frequent. Little is known about clinician knowledge and patient or clinician preferences for DOAC dosing. Methods and Results From April 2019 to March 2020, 240 clinicians and 343 patients with atrial fibrillation completed an assessment of anticoagulation knowledge/preferences. Clinician knowledge of DOAC dosing was tested with 4 hypothetical patient scenarios. Patients and clinicians were asked to grade the importance of 25 factors in anticoagulation decision making. Among clinicians, the median age was 55 years, and 23% were primary care clinicians. In scenarios of a patient indicated for full-dose DOAC, 41.2% of clinicians underdosed apixaban and 17.6% underdosed rivaroxaban. In scenarios of a patient indicated for reduced-dose DOAC, 64.6% and 71.7% of clinicians chose to use reduced-dose apixaban and rivaroxaban, respectively. Only 35.0% of clinicians correctly answered all 4 scenarios with the label-indicated dose; this knowledge gap was similar between clinicians who did and did not underdose. Among patients with atrial fibrillation, the median age was 65 years, and 89% were currently anticoagulated. Patients and clinicians ranked stroke prevention and avoiding severe bleeding as very important to anticoagulation decision making. Patients were more likely than clinicians to rank the ability to reduce anticoagulation dose if needed as very important (70.5% versus 43.6%; P<0.001). Conclusions There are considerable knowledge gaps regarding DOAC dosing in clinicians treating patients with atrial fibrillation, as well as significant differences in treatment dosing preferences between clinicians and patients.

Inappropriate Dosing of Direct Oral Anticoagulants in Patients with Atrial Fibrillation

Direct Oral Anticoagulants (DOACs) require dose adjustment based on specific patient characteristics, making them prone to incorrect dosing. The current study aimed to evaluate the prevalence of inappropriate DOAC dosing, its predictors, and corresponding outcomes in a single-center cohort of atrial fibrillation (AF) patients. We reviewed all patients with AF treated at Mayo Clinic with a DOAC (Apixaban, Rivaroxaban, or Dabigatran) between 2010 and 2017. Outcomes examined were ischemic stroke /transient ischemic attack (TIA)/embolism and bleeding. 8,576 patients (mean age 69.5 ± 11.9 years, 35.1 % female, CHA₂DS₂-VASc 3.0±1.8) received a DOAC (38.6% apixaban, 35.8% rivaroxaban, 25.6% dabigatran). DOAC dosing was inappropriate in 1,273 (14.8%) with 1071 (12.4%) receiving an inappropriately low dose, and 202(2.4%) an inappropriately high dose. Patients prescribed inappropriate doses were older (72.4 ± 11.7 vs 69.0 ± 11.8, p <0.0001), more likely to be female (43.1% vs 33.7%, p <0.0001), had a higher CHA₂DS₂-VASc score (3.4 ± 1.8 vs 2.9 ± 1.8, p <0.0001) and a greater Charlson co-morbidity index (3.5 ± 3.3 vs 2.9 ± 3.2, p<0.0001). Over 1.2 ±1.6 years (median 0.5 years) follow up; there was no significant difference in the incidence of stroke and/or TIA and/or embolism and bleeding between patients who were inappropriately dosed versus appropriately dosed. In conclusion, DOAC dosing was not in compliance with current recommendations in 15% of AF patients. Patients at higher risk of stroke and/or TIA based on older age, female gender, and higher CHA₂DS₂-VASc score were more likely to be underdosed, but there was no significant difference in outcomes including stroke/TIA/embolism and bleeding.

Direct Oral Anticoagulants in Patients with Atrial Fibrillation and Renal Dysfunction

Atrial fibrillation and renal dysfunction often coexist, each disorder may predispose to the other and contribute to worsening prognosis. Both atrial fibrillation and chronic kidney disease are associated with increased risk of stroke and thromboembolic complications. Oral anticoagulation for stroke prevention is therefore recommended in patients with atrial fibrillation and decreased renal function. Each direct oral anticoagulant has unique pharmacologic properties of which clinician should be aware to optimally manage patients. The doses of direct oral anticoagulants require adjustment for renal function. There is debate regarding which equation, the Chronic Kidney Disease Epidemiology (CKD-EPI) equation vs. the Cockcroft-Gault equation, should be used to estimate glomerular filtration rate in patients with atrial fibrillation treated with direct oral anticoagulants. Our review tries to find arguments for benefit of direct oral anticoagulants in patients with renal dysfunction.

Anticoagulation Management In Hemodialysis Patients With Atrial Fibrillation: Evidence And Opinion

In the absence of robust evidence to guide clinical decision making, the optimal approach to prevent stroke and systemic embolism in hemodialysis patients with atrial fibrillation (AF) remains moot. In this position paper, studies on oral anticoagulation in hemodialysis patients with AF are highlighted, followed by an evidence-based conclusion, a critical analysis to identify sources of bias, and practical opinion-based suggestions on how to manage anticoagulation in this specific population. It remains unclear whether AF is a true risk factor for embolic stroke in hemodialysis. The currently employed cutoff values for the CHA2DS2-VASc score do not adequately discriminate dialysis patients deriving a net benefit from those suffering a net harm from oral anticoagulation. Anticoagulation initiation should probably be more restrictive than currently advocated by official guidelines. Recent evidence reveals that the superior benefit-risk profile of direct oral anticoagulants (DOAC) versus vitamin K antagonists (VKA) observed in the general population and in moderate chronic kidney disease can be extended to the hemodialysis population. VKA may be especially harmful in dialysis patients and should therefore be avoided, in particular in patients with a high bleeding risk and labile international normalized ratio. Dose-finding studies of DOAC suggest that rivaroxaban 10 mg daily and apixaban 2.5 mg twice daily are appropriate choices in dialysis patients. Combined treatment of oral anticoagulants and antiplatelet agents should be reserved for strong indications and limited in time. Left atrial appendage occlusion is a potential attractive solution to reduce the risk of stroke without increasing bleeding propensity, but has not been properly studied in dialysis patients.

Clinical outcomes according to dose reduction criteria of apixaban in Japanese elderly patients with atrial fibrillation: J-ELD AF Registry subanalysis

Dose reduction of apixaban is applied in atrial fibrillation (AF) patients fulfilling ≥ 2 of the following criteria: (1) age ≥ 80 years, (2) body weight ≤ 60 kg and (3) serum creatinine ≥ 1.5 mg/dL. However, the clinical significance of each criterion remains unclear. The J-ELD AF Registry is a prospective observational study of elderly (≥ 75 years) Japanese AF patients receiving on-label dose of apixaban. In patients receiving the standard dose (5 mg bid, n = 1243), the incidence rates (% per patient-year) of stroke or systemic embolism in those fulfilling none [n = 516] or one of the above criteria (1) [n = 328], (2) [n = 378] and (3) [n = 21] were 1.24, 2.32, 1.41 and 4.93 (log-rank P = 0.422), respectively, and those of bleeding requiring hospitalization were 1.03, 0.99, 1.98 and 4.93 (P = 0.318), respectively. In patients receiving a reduced dose (2.5 mg bid, n = 1,515), the incidences of stroke or systemic embolism in those fulfilling (1)/(2) [n = 1,331], (1)/(3) [n = 65], (2)/(3) [n = 23] and all three criteria [n = 96] were 1.38, 1.64, 4.67 and 3.51 (P = 0.295), respectively, and those of bleeding requiring hospitalization were 2.04, 1.64, 0.00 and 4.71 (P = 0.318), respectively. Univariate analysis demonstrated that the types or combinations of each criterion was not significantly associated with the incidence of thromboembolic or bleeding events. The types or combinations of the three apixaban dose reduction criteria did not have significant impact on effectiveness and safety in Japanese elderly AF patients receiving on-label dose of apixaban, although the impact of the creatinine criterion remains uncertain due to the few number of the patients.

Off-label underdosed apixaban use in Asian patients with non-valvular atrial fibrillation

AIMS

To compare the effectiveness and safety of off-label underdosed apixaban with on-label standard dose apixaban in Asian patients with atrial fibrillation (AF).

METHODS AND RESULTS

Using the Korean nationwide claims database, we identified patients who were prescribed apixaban and did not fulfil the dose reduction criteria for apixaban between January 2015 and December 2017. A multivariable Cox hazard regression model was performed, and hazard ratios (HRs) for ischemic stroke, major bleeding (MB), all-cause death, and composite outcome were analysed. Compared to patients prescribed on-label standard dose apixaban (n = 4,194), patients prescribed off-label underdosed apixaban (n = 2,890) showed a higher risk of ischemic stroke (adjusted HR [aHR], 1.38; 95% confidence interval [CI], 1.06-1.81), all-cause death (aHR, 1.19; 95% CI, 1.01-1.39), and the composite outcome (aHR, 1.17; 95% CI, 1.03-1.34), but with no significant differences in MB between the two groups. Among the patients who did not meet any dose reduction criteria, off-label underdosed apixaban use was associated with a significantly higher risk of ischemic stroke than on-label standard dose apixaban use (aHR, 1.85; 95% CI, 1.25-2.73). Among the patients who met a single dose reduction criterion, off-label underdosed apixaban use was associated with a higher risk of all-cause death than on-label standard dose apixaban (aHR, 1.32; 95% CI, 1.07-1.64).

CONCLUSION

The off-label underdosed apixaban group showed higher risks of ischemic stroke, all-cause death, and composite clinical outcomes than the on-label standard dose apixaban group, but both showed comparable risks of MB. Label-adherence to apixaban dosing should be emphasised to achieve the best clinical outcomes for Asian patients with AF.

Non-vitamin K antagonist oral anticoagulants for stroke prevention in atrial fibrillation: safety issues in the elderly

INTRODUCTION

Non-vitamin K antagonist oral anticoagulants (NOACs) are increasingly used for stroke prevention in patients with atrial fibrillation (AF). Since NOACs are predominantly used in the elderly with AF at high risk for stroke and bleeding and with comorbidities requiring polypharmacy, it is important to assess their safety and efficacy in this population.

AREAS COVERED

We review changes in pharmacokinetics and pharmacodynamics observed with senescence and the effect on NOACs and drug and food interactions. We also provide an update on challenges related to NOAC use in situations that increases the risk for bleeding or require temporary discontinuation and address practical issues in the elderly AF patients managed on NOACs. Clinical studies and trials with cardiovascular outcomes reported from January 1990 to August 2020 were identified through the Medline database using PubMed, Cochrane Library, and EMBASE database.

EXPERT OPINION

NOACs are highly effective in preventing stroke in AF patients with non-inferior or superior efficacy to warfarin, with reduced risk of major bleeding. However, in the older-elderly, evidence comes mainly from observational studies or extrapolation from studies in populations with minimal functional limitations or comorbidities. The high upfront cost and out-of-pocket expense for copayment or deductibles also limit the use of this effective therapy in a substantial number of patients. The cost reduction may further improve long-term use for NOACs in stroke prevention in elderly patients with AF.

Off-label use of reduced dose direct oral factor Xa inhibitors in subjects with atrial fibrillation: a review of clinical evidence

In real-world clinical practice, underdosing, i.e. off-label use of reduced doses (RDs), of oral factor Xa inhibitors (oFXaIs) is quite common in stroke prevention in non-valvular atrial fibrillation, possibly reflecting the hope to increase safety without reducing efficacy in selected patients. To assess whether this strategy is associated with some clinical benefit, we used a physician-centred approach to evaluate whether current evidence supports the hypothesis that a substantial proportion of underdosing may be voluntary rather than casual, whether and to what extent oFXaIs' dose rather than patients' characteristics are associated with bleeding events, and which are the safety and efficacy clinical implications of oFXaIs' underdosing. Our review found consistent evidence that underdosing is often an intentional strategy; however, available studies do not demonstrate a sizeable net clinical benefit of using off-label RD oFXaIs.