Low-Dose Rivaroxaban and Risks of Adverse Events in Patients With Atrial Fibrillation

Comparative Effectiveness and Safety of Off-Label Underdosed Direct Oral Anticoagulants in Asian Patients with Atrial Fibrillation: A Systematic Review and Meta-analysis

INTRODUCTION

Off-label underdosed direct oral anticoagulants (DOACs) are commonly utilised in Asian patients with atrial fibrillation (AF) since they are prone to bleeding with OACs. However, the efficacy and safety of off-label underdosing DOACs are controversial. This study aimed to compare the effectiveness and safety of off-label underdosed DOACs in Asian patients with AF.

METHODS

PubMed, Embase, Cochrane library, and ClinicalTrials.gov were searched from 2010 to July 5, 2024, for randomised controlled trials or observational studies that compared off-label DOACs and on-label/warfarin in Asian patients with AF. The primary outcomes included ischaemic stroke or systemic embolism (ISSE) and major bleeding (MB), while secondary outcomes included all-cause death, gastrointestinal bleeding (GIB), intracranial haemorrhage (ICH), and myocardial infarction (MI). Hazard ratios (HRs) with 95% confidence intervals (CIs) were pooled using random-effects models.

RESULTS

Twenty observational studies were included. Seventeen studies compared off-label underdosed DOACs versus on-label DOACs, whereas five studies compared off-label underdosed DOACs versus warfarin. Off-label underdosed DOACs were associated with higher risk of ISSE (pooled HR [pHR] = 1.17; 95% CI: 1.00-1.38, p = 0.048) and ICH (pHR = 1.27; 95% CI: 1.06-1.52, p = 0.010) versus on-label. Subgroup analysis demonstrated increased ISSE risk with off-label underdosed rivaroxaban compared to on-label (pHR = 1.49; 95% CI: 1.07-2.08). Compared to warfarin, off-label underdosed DOACs were associated with decreased risk of MB (pHR = 0.46; 95% CI: 0.32-0.65, p < 0.001), GIB (pHR = 0.52; 95% CI: 0.29-0.93, p = 0.028), ICH (pHR = 0.60; 95% CI: 0.42-0.86, p = 0.005), and all-cause death (pHR = 0.70; 95% CI: 0.56-0.87, p = 0.001), while illustrating similar ISSE risk.

CONCLUSIONS

Off-label underdosed DOACs, particularly rivaroxaban, was associated with increased ISSE risk but did not decrease bleeding compared to on-label. Adherence to appropriate DOAC doses should be emphasised to achieve the best clinical outcomes for Asian patients with AF.

Mortality after major bleeding in Asian atrial fibrillation patients receiving different direct oral anticoagulants: a nationwide, propensity score study

In this research, we assessed mortality after major bleeding events in atrial fibrillation (AF) patients taking four direct oral anticoagulants (DOACs). Drawing data from the Taiwan National Health Insurance Research Database between 2016 and 2019, we focused on AF patients on DOACs who had major bleeding episodes. Using propensity score stabilized weighting, we established four comparable pseudo-DOAC groups. Among 2770 patients (460 dabigatran, 1322 rivaroxaban, 548 apixaban, 440 edoxaban), 85.3% were prescribed low-dose regimens. The 7-day mortality rate was 9.0%, surging to 16.0% by the 30th day. Compared with dabigatran, there was a distinct divergence in 7-day mortality of factor Xa inhibitors (p = 0.012), with hazard ratios of 1.83 (95% CI 1.11-3.00, p = 0.017) for rivaroxaban, 2.13 (95% CI 1.23-3.66, p = 0.007) for apixaban, and 2.41 (95% CI 1.39-4.19, p = 0.002) for edoxaban. This pattern remained consistent when analyzing the subgroup that received lower dosages of DOACs. In conclusion, factor Xa inhibitors were associated with a significantly higher risk of 7-day mortality following major bleeding events than dabigatran among AF patients.

A cross-sectional study of appropriateness evaluation of anticoagulation therapy for inpatients with nonvalvular atrial fibrillation

Background: Oral anticoagulants (OACs) are essential for stroke prevention in patients with nonvalvular atrial fibrillation (NVAF). However, the appropriateness of anticoagulation treatment in locally practice remains unclear. This study evaluated compliance with anticoagulation therapy concerning the guidelines and drug labels in patients with NVAF. Methods: Hospitalized patients diagnosed with NVAF between 1 November 2020, and 31 December 2021, were retrospectively enrolled. The appropriateness of anticoagulation regimens at discharge was evaluated based on a flowchart designed according to atrial fibrillation (AF) guidelines and medication labels. Furthermore, we explored factors potentially influencing the "no-use of OACs" using binary logistic regression and verified anticoagulation-related issues through a physician questionnaire. Results: A total of 536 patients were enrolled in this study, including 254 patients (47.4%) with inappropriate anticoagulation regimens. 112 patients (20.9%) were categorized as "underdosing-use of OACs," 134 (25%) who needed anticoagulation therapy were "no-use of OACs" and eight (1.5%) were "over-use of OACs." The results of a binary logistic regression analysis showed that paroxysmal AF (odds ratio [OR], 7.74; 95% confidence interval [CI], 4.57-13.10), increased blood creatinine levels (OR, 1.88; 95% CI, 1.11-3.16), hospitalized pacemaker implantation (OR, 6.76; 95% CI, 2.67-17.11), percutaneous coronary intervention (OR, 3.35; 95% CI, 1.44-7.80), and an increased HAS-BLED score (OR, 1.62; 95% CI, 1.11-2.35) were associated with "no-use of OACs" in patients with NVAF who had indications for anticoagulation therapy. Conclusion: For patients with NVAF with severe renal dysfunction and paroxysmal AF, anticoagulation therapy was inadequate. The underdosing-use of OACs in patients with NVAF was frequently observed. We recommend an anticoagulation management team to tailor anticoagulation regimens to suit each patient's needs.

Left atrial appendage occlusion using the LAmbre device in atrial fibrillation patients with a history of ischemic stroke: 1-Year outcomes from a multicenter study in China

BACKGROUND

Patients with non-valvular atrial fibrillation (NVAF) and previous stroke have a significantly higher risk of stroke recurrence. This study aimed to examine the safety and efficacy of the LAmbre left atrial appendage occlusion device in NVAF patients with a history of stroke.

METHODS

We examined 103 consecutive NVAF patients in 11 Chinese medical centers who had a history of stroke or transient ischemic attacks (TIA) and underwent placement of the LAmbre device. Follow-up was conducted 1, 3, 6, and 12 months after the procedure. The primary endpoints were the incidence of new ischemic or hemorrhagic stroke, TIA, systemic embolism, or cardiac death. Secondary endpoints were serious perioperative or device-related complications and cerebral, gastrointestinal, or other bleeding events requiring transfusion of at least 2 units of packed red blood cells.

RESULTS

Mean patient age was 67.63 ± 7.14 years; mean CHA2DS2-VASc score was 4.72 ± 1.18 and mean HAS-BLED score was 1.90 ± 1.00. LAmbre device placement was successful in 101 patients (98.05%). Mean follow-up was 12.2 months. Five patients (4.95%) developed a new pericardial effusion after the procedure; none required treatment. Eighty-six patients (85.15%) exhibited no peri-device leak (PDL). However, 13 (12.8%) had a small (0-3 mm) PDL and two (2.3%) had a moderate PDL (3-5 mm). One recurrent stroke occurred during follow-up (1.1%). No other complications occurred.

CONCLUSIONS

This multicenter study shows the safety and efficacy of LAmbre left atrial appendage occlusion for NVAF patients with a history of stroke or TIA.

Effectiveness and safety of reduced-dose rivaroxaban for elderly patients with non-valvular atrial fibrillation: A subanalysis of the EXPAND study

BACKGROUND

Establishing the appropriate rivaroxaban dose in older patients with non-valvular atrial fibrillation (NVAF) is important because of the high risk of adverse events. In this EXPAND study subanalysis, we examined the safety and efficacy of standard-dose (15 mg/day) and non-recommended reduced-dose (10 mg/day) rivaroxaban in patients aged ≥65 years with NVAF and preserved renal function.

METHODS

The entire analysis population (ALL cohort [n = 3982]; ≥65 years) was divided into early elderly (ELD) (65-74 years [n = 1444]) and late ELD (≥75 years [n = 2386]) sub-cohorts. Each sub-cohort was divided into reduced-dose and standard-dose groups. Kaplan-Meier survival curves with adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs) were used to assess efficacy (thromboembolic events) and safety (hemorrhagic events) outcomes.

RESULTS

The aHR for major bleeding did not differ between the dosages in any of the cohorts (aHRs: 0.86-0.93). There were no significant differences in the occurrence of stroke + systemic embolism (SE) or stroke + SE + myocardial infarction (MI) + cardiovascular (CV) death among the cohorts. The aHR for MI/unstable angina + interventional/CV surgery + CV death was higher with 10-mg/day rivaroxaban than 15-mg/day rivaroxaban in the ALL cohort (aHR: 1.56 [95% CI 1.02-2.37], p = 0.039) and the late ELD sub-cohort (aHR: 1.86 [95% CI 1.01-3.42], p = 0.045).

CONCLUSIONS

Reduced-dose rivaroxaban may increase the risk of coronary artery events. The use of rivaroxaban 15 mg/day in patients with NVAF aged ≥75 years with preserved renal function was supported.

Comparisons of effectiveness and safety between on-label dosing, off-label underdosing, and off-label overdosing in Asian and non-Asian atrial fibrillation patients treated with rivaroxaban: a systematic review and meta-analysis of observational studies

AIMS

Limited real-world data show that rivaroxaban following dosage criteria from either ROCKET AF [20 mg/day or 15 mg/day if creatinine clearance (CrCl) < 50 mL/min] or J-ROCKET AF (15 mg/day or 10 mg/day if CrCl < 50 mL/min) is associated with comparable risks of thromboembolism and bleeding with each other in patients with non-valvular atrial fibrillation (NVAF). We are aimed to study whether these observations differ between Asian and non-Asian subjects.

METHODS AND RESULTS

A systematic review and meta-analysis with random effects was conducted to estimate the aggregate hazard ratio (HR) and 95% confidence interval (CI) using PubMed and MEDLINE databases from 8 September 2011 to 31 December 2022 searched for adjusted observational studies that reported relevant clinical outcomes of NVAF patients receiving rivaroxaban 10 mg/day if CrCl > 50 mL/min, on-label dose rivaroxaban eligible for ROCKET AF or J-ROCKET AF, and rivaroxaban 20 mg/day if CrCl < 50 mL/min. Effectiveness and safety endpoints were compared between ROCKET AF and J-ROCKET AF dosing regimen in Asian and non-Asian subjects, separately. Also, risks of events of rivaroxaban 10 mg/day despite of CrCl > 50 mL/min and rivaroxaban 20 mg/day despite of CrCl < 50 mL/min were compared to that of 'ROCKET AF/J-ROCKET AF dosing'. Sensitivity analyses were performed by sequential elimination of each study from the pool. The meta-regression analysis was performed to explore the influence of potential factors on the effectiveness and safety outcomes. Eighteen studies involving 67 571 Asian and 54 882 non-Asian patients were included. Rivaroxaban following J-ROCKET AF criteria was associated with comparable risks of thromboembolism in the Asian subgroup, whereas rivaroxaban following J-ROCKET AF criteria was associated with higher risks of all-cause mortality (HR:1.30; 95% CI:1.05-1.60) compared with that of ROCKET AF criteria in the non-Asian population. There were no differences in risks of major bleeding between rivaroxaban following J-ROCKET AF vs. ROCKET AF criteria either in the Asian or non-Asian population. The use of rivaroxaban 10 mg despite of CrCl > 50 mL/min was associated with a higher risk of thromboembolism (HR:1.64; 95% CI:1.28-2.11) but lower risk of major bleeding (HR:0.72; 95% CI:0.57-0.90) compared with eligible dosage criteria. The use of rivaroxaban 20 mg despite of CrCl < 50 mL/min was associated with worse clinical outcomes in the risks of thromboembolism (HR:1.32; 95% CI:1.09-1.59), mortality (HR:1.33; 95% CI:1.10-1.59), and major bleeding (HR:1.26; 95% CI:1.03-1.53) compared with eligible dosage criteria. The pooled results were generally in line with the primary effectiveness and safety outcomes by removing a single study at one time. Meta-regression analyses failed to detect the bias in most potential patient characteristics associated with the clinical outcomes.

CONCLUSION

Rivaroxaban dosing regimen following J-ROCKET criteria may serve as an alternative to ROCKET AF criteria for the Asian population with NVAF, whereas the dosing regimen following ROCKET AF criteria was more favourable for the non-Asian population. The use of rivaroxaban 10 mg despite of CrCl > 50 mL/min was associated with a higher risk of thromboembolism but a lower risk of major bleeding, while use of rivaroxaban 20 mg despite of CrCl < 50 mL/min was associated with worse outcome in most clinical events.

Patterns of oral anticoagulant use and outcomes in Asian patients with atrial fibrillation: a post-hoc analysis from the GLORIA-AF Registry

Background

Previous studies suggested potential ethnic differences in the management and outcomes of atrial fibrillation (AF). We aim to analyse oral anticoagulant (OAC) prescription, discontinuation, and risk of adverse outcomes in Asian patients with AF, using data from a global prospective cohort study.

Methods

From the GLORIA-AF Registry Phase II-III (November 2011-December 2014 for Phase II, and January 2014-December 2016 for Phase III), we analysed patients according to their self-reported ethnicity (Asian vs. non-Asian), as well as according to Asian subgroups (Chinese, Japanese, Korean and other Asian). Logistic regression was used to analyse OAC prescription, while the risk of OAC discontinuation and adverse outcomes were analysed through Cox-regression model. Our primary outcome was the composite of all-cause death and major adverse cardiovascular events (MACE). The original studies were registered with ClinicalTrials.gov, NCT01468701, NCT01671007, and NCT01937377.

Findings

34,421 patients were included (70.0 ± 10.5 years, 45.1% females, 6900 (20.0%) Asian: 3829 (55.5%) Chinese, 814 (11.8%) Japanese, 1964 (28.5%) Korean and 293 (4.2%) other Asian). Most of the Asian patients were recruited in Asia (n = 6701, 97.1%), while non-Asian patients were mainly recruited in Europe (n = 15,449, 56.1%) and North America (n = 8378, 30.4%). Compared to non-Asian individuals, prescription of OAC and non-vitamin K antagonist oral anticoagulant (NOAC) was lower in Asian patients (Odds Ratio [OR] and 95% Confidence Intervals (CI): 0.23 [0.22-0.25] and 0.66 [0.61-0.71], respectively), but higher in the Japanese subgroup. Asian ethnicity was also associated with higher risk of OAC discontinuation (Hazard Ratio [HR] and [95% CI]: 1.79 [1.67-1.92]), and lower risk of the primary composite outcome (HR [95% CI]: 0.86 [0.76-0.96]). Among the exploratory secondary outcomes, Asian ethnicity was associated with higher risks of thromboembolism and intracranial haemorrhage, and lower risk of major bleeding.

Interpretation

Our results showed that Asian patients with AF showed suboptimal thromboembolic risk management and a specific risk profile of adverse outcomes; these differences may also reflect differences in country-specific factors. Ensuring integrated and appropriate treatment of these patients is crucial to improve their prognosis.

Funding

The GLORIA-AF Registry was funded by Boehringer Ingelheim GmbH.

Safety and Efficacy Re-Evaluation of Edoxaban and Rivaroxaban Dosing With Plasma Concentration Monitoring in Non-Valvular Atrial Fibrillation: With Observations of On-Label and Off-Label Dosing

Background: Off-label dosing of direct oral anticoagulants (DOAC) as a treatment for non-valvular atrial fibrillation (NVAF) is problematic. Here, we investigated the status of rivaroxaban and edoxaban dosing by monitoring plasma concentrations (PCs). Methods and Results: We monitored drug PCs in 391 and 333 outpatients receiving rivaroxaban and edoxaban, respectively, for NVAF. Drug doses were adjusted if the PC was above the cut-off value (rivaroxaban: 404 ng/mL; edoxaban: 402 ng/mL), determined from receiver operating characteristic curves for predicting bleeding events. On-label standard dosing was reduced to off-label underdosing due to high PCs above the cut-off more often for rivaroxaban (28.1%) than edoxaban (12.6%; P<0.001). Over a median follow-up of 13 months for rivaroxaban and 10 months for edoxaban, the annual incidence of bleeding events was higher with rivaroxaban than with edoxaban (4.88 vs. 3.73 patient-years; P<0.05), although no thromboembolic events occurred in either group. Furthermore, for patients with creatinine clearance >50 mL/min and body weight ≤60 kg, there was a greater incidence of bleeding events with rivaroxaban on-label 15 mg dosing than with edoxaban on-label 30 mg dosing (22.2% vs 2.9%; P<0.01). Conclusions: Monitoring the PCs of rivaroxaban and edoxaban in NVAF patients enables dose adjustments to reduce bleeding risk. The incidence of bleeding under drug PC monitoring was less in the edoxaban than rivaroxaban group.

Reduced dose direct oral anticoagulants compared with warfarin with high time in therapeutic range in nonvalvular atrial fibrillation

Direct oral anticoagulants (DOACs) used in nonvalvular atrial fibrillation (NVAF) are dose-reduced in elderly and patients with impaired renal function. Only reduced dose dabigatran is concluded as having similar stroke risk reduction and lower risk of major bleeding than warfarin in the pivotal studies. In clinical practice, reduced dose is prescribed more often than expected making this an important issue. The objective of this study was to compare effectiveness and safety between reduced dose DOACs and high TTR warfarin treatment (TTR ≥ 70%) in NVAF. A Swedish anticoagulation registry was used in identifying eligible patients from July 2011 to December 2017. The study cohort consisted of 40,564 patients with newly initiated DOAC (apixaban, dabigatran, or rivaroxaban) (11,083 patients) or warfarin treatment (29,481 patients) after exclusion of 374,135 patients due to not being warfarin or DOAC naïve, not being prescribed reduced dose, having previous mechanical heart valve (MHV), or being under 18 years old. The median durations of follow up were 365, 419, 432 and 473 days for apixaban, dabigatran, rivaroxaban and warfarin, respectively. Warfarin TTR identified from Auricula was 70.0%. Endpoints (stroke and major bleeding) and baseline characteristics were collected from hospital administrative registers using ICD-10 codes. Cohorts were compared using weighted adjusted Cox regression after full optimal matching based on propensity scores. DOACs are associated with lower risk of major bleeding (HR with 95% CI) 0.85 (0.78-0.93), intracranial bleeding HR 0.64 (0.51-0.80), hemorrhagic stroke HR 0.68 (0.50-0.92), gastrointestinal bleeding HR 0.81 (0.69-0.96) and all-cause stroke HR 0.87 (0.76-0.99), than warfarin. Apixaban and dabigatran are associated with lower risk of major bleeding, HR 0.70 (0.63-0.78) and HR 0.80 (0.69-0.94), and rivaroxaban is associated with lower risk of ischemic stroke, HR 0.73 (0.59-0.96), with higher major bleeding risk, HR 1.31 (1.15-1.48), compared to warfarin. Apixaban is associated with higher all-cause mortality compared to warfarin, HR 1.12 (1.03-1.21). DOACs are associated with lower risk of major bleeding and all-cause stroke, than high quality warfarin treatment, with exception of rivaroxaban that carried higher risk of major bleeding and lower risk of stroke or systemic embolism. In this large observational registry-based NVAF cohort, DOACs are preferred treatment in patients with indication for DOAC dose reduction, even in a high TTR setting.

Trough Concentration Deficiency of Rivaroxaban in Patients With Nonvalvular Atrial Fibrillation Leading to Thromboembolism Events

ABSTRACT

This retrospective study investigated factors influencing the steady-state trough concentrations (C trough ) of rivaroxaban in patients with nonvalvular atrial fibrillation (NVAF). We retrieved data from patients with NAVF who first started rivaroxaban anticoagulation at the Fujian Provincial Hospital from October 2017 to October 2020 through the electronic medical record system. Patients were followed for 1 year after the first dose of rivaroxaban, and the primary efficacy and safety end points were recorded. All follow-up visits were completed by October 2021. A C trough of <12 ng/mL was defined as C trough deficiency. Factors that influenced rivaroxaban C trough deficiency were investigated using multivariate binary logistic regression analysis. Kaplan-Meier survival curve analysis was used to determine differences between C trough deficiency and event-free survival. A total of 167 patients with NVAF were enrolled in the study, including 113 men and 54 women, with an average (± SD) age of 70.40 ± 12.46 years. High albumin levels were an independent protective factor against C trough deficiency (odds ratio, 0.932; P = 0.031). C trough deficiency was associated with the probability of freedom from thrombotic events ( P = 0.004); however, there were no significant differences in the probability of freedom from bleeding events ( P > 0.05). In conclusion, among the variables studied, a low albumin level was the main contributor to C trough deficiency. Rivaroxaban C trough deficiency also increased thrombotic events, but this was not associated with hemorrhagic events in Chinese patients with NVAF.

Population Pharmacokinetics and Dose Optimization Based on Renal Function of Rivaroxaban in Thai Patients with Non-Valvular Atrial Fibrillation

Low-dose rivaroxaban has been used in Asian patients with direct oral anticoagulants (DOACs) eligible for atrial fibrillation (AF). However, there are few pharmacokinetic (PK) data in Thai patients to support precise dosing. This study aimed to develop a population PK model and determine the optimal rivaroxaban doses in Thai patients. A total of 240 Anti-Xa levels of rivaroxaban from 60 Thai patients were analyzed. A population PK model was established using the nonlinear mixed-effect modeling approach. Monte Carlo simulations were used to predict drug exposures at a steady state for various dosages. Proportions of patients having rivaroxaban exposure within typical exposure ranges were determined. A one-compartment model with first-order absorption best described the data. Creatinine clearance (CrCl) and body weight significantly affected CL/F and V/F, respectively. Regardless of body weight, a higher proportion of patients with CrCl < 50 mL/min receiving the 10-mg once-daily dose had rivaroxaban exposures within the typical exposure ranges. In contrast, a higher proportion of patients with CrCl ≥ 50 mL/min receiving the 15-mg once-daily dose had rivaroxaban exposures within the typical exposure ranges. The study’s findings suggested that low-dose rivaroxaban would be better suited for Thai patients and suggested adjusting the medication’s dose in accordance with renal function.

Stroke Prevention in Atrial Fibrillation: A Scientific Statement of JACC: Asia (Part 1)

Atrial fibrillation is the most common sustained cardiac arrhythmia and is associated with substantial increases in the risk of stroke and systemic thromboembolism. With the successful introduction of the first non-vitamin K antagonist direct oral anticoagulant (NOAC) in 2009, the role of vitamin K antagonists has been replaced in most clinical settings except in a few conditions when NOACs are contraindicated. Data for the use of NOACs in different clinical scenarios have been accumulating in the recent decade, and a more sophisticated strategy for atrial fibrillation patients is now warranted. JACC: Asia recently appointed a working group to summarize the most updated information regarding stroke prevention in AF. This statement aimed to provide possible treatment option in daily practice. Local availability, cost, and patient comorbidities should also be considered. Final decisions may still need to be individualized and based on clinicians' discretion. This is the part 1 of the whole statement.

Rationale and design of a prospective study evaluating population pharmacokinetics and pharmacodynamics of rivaroxaban in Chinese patients with non-valvular atrial fibrillation

INTRODUCTION

Rivaroxaban is one of the most commonly used non-vitamin K antagonists for stroke prevention in patients with non-valvular atrial fibrillation (NVAF). Different individual exposures exist for Asian and non-Asian populations, and dose selection is different for Japanese and non-Japanese subjects. Few studies have investigated the pharmacokinetics (PK) and pharmacodynamics (PD) of rivaroxaban in Chinese patients and provided a solid reference for dose selection and individualised therapy.

METHODS AND ANALYSIS

This is a single-centre prospective study. Rivaroxaban-treated Chinese NVAF patients will be recruited according to predetermined inclusion criteria. Blood samples will be collected from both outpatients and inpatients with different sampling strategies at steady state. Rivaroxaban plasma concentration, factor Xa activity, prothrombin time and single-nucleotide polymorphisms of candidate genes will be evaluated. Follow-up will be conducted following 3 and 6 months after enrolment to collect information about the safety and efficacy outcomes. A nonlinear mixed-effects modelling strategy will be used to develop a population PK-PD model of rivaroxaban.

ETHICS AND DISSEMINATION

The study has been approved by the Ethics Committee of Huashan Hospital, Fudan University (KY2020-016). The study findings will be submitted to peer-reviewed journals and shared with public health authorities.

TRIAL REGISTRATION NUMBER

ChiCTR2100046685.

Safety and effectiveness of appropriately and inappropriately dosed rivaroxaban or apixaban versus warfarin in patients with atrial fibrillation: a cohort study with nested case-control analyses from UK primary care

OBJECTIVES

To investigate effects of appropriately and inappropriately dosed apixaban/rivaroxaban versus warfarin on effectiveness and safety outcomes in patients with non-valvular atrial fibrillation (NVAF).

DESIGN

Cohort study with nested case-control analyses using primary care electronic health records (IQVIA Medical Research Data UK database).

SETTING

UK primary care.

PARTICIPANTS

Patients aged ≥18 years with NVAF newly prescribed apixaban (N=14 701), rivaroxaban (N=14 288) or warfarin (N=16 175) between 1 January 2012 and 30 June 2018, and followed up to 31 December 2018.

PRIMARY AND SECONDARY OUTCOME MEASURES

Incident cases of ischaemic stroke/systemic embolism (IS/SE) and intracranial bleeding (ICB). Cases were matched to controls on age, sex and OAC naïve status. Using logistic regression, adjusted ORs with 95% CIs were calculated for the outcomes comparing apixaban/rivaroxaban use (appropriate or inappropriate dosing based on the product label criteria) and warfarin.

RESULTS

For IS/SE, ORs (95% CIs) for apixaban versus warfarin were 1.19 (0.92-1.52) for appropriate dose and 1.01 (0.67-1.51) for inappropriate dose; for rivaroxaban versus warfarin, estimates were 1.07 (0.83-1.37) for appropriate dose and 1.21 (0.78-1.88) for inappropriate dose. For ICB, ORs (95% CIs) for apixaban versus warfarin were 0.67 (0.44-1.00) for appropriate dose and 0.45 (0.21-0.95) for inappropriate dose; for rivaroxaban versus warfarin, estimates were 0.81 (0.55-1.20) for appropriate dose and 1.14 (0.56-2.31) for inappropriate dose.

CONCLUSIONS

Dosing appropriateness in NVAF was not associated with a significant difference in IS/SE risk or increase in ICB risk versus warfarin. These findings may reflect residual confounding and biases that were difficult to control, as also seen in other observational studies. They should, therefore, be interpreted with caution, and prescribers should adhere to the dosing instructions in the respective Summary of Product Characteristics. Further studies on this topic from real-world populations are needed.

Clinical effects of off-label reduced doses of Direct Oral Anticoagulants: A systematic review and meta-analysis

BACKGOUND

Atrial Fibrillation (AF) is the most prevalent cardiac arrhythmia among older patients, associated with thromboembolic events. Direct Oral Anticoagulants (DOAC) are the treatment of choice for most patients, but its use may have risks on standard dose. However, it is still unclear the effects related with the use of a lower dose off labelled DOAC.

OBJECTIVES

We conducted a systematic review and meta-analysis to assess the effects of off-label underdose use of DOAC in patients with AF.

METHODS

MEDLINE, Cochrane Central Register of Controlled Trials, PsycINFO databases and EMBASE were searched for observational longitudinal studies evaluating the outcomes on off label underdosed patients compared with standard dosed patients with AF. We performed a random-effects meta-analysis to estimate the pooled Hazard Ratios (HR) with 95%Cis.

RESULTS

Eighteen cohort studies evaluating 237,533 patients with AF were included. Off-label underdose DOAC use is associated with higher risk of all-cause mortality [HR = 1.27 (95%CI 1.09-1.48)] and cardiovascular composite outcomes [HR = 1.32 (95%CI 1.08-1.62)], when compared with standard dose DOAC use. The effects in thromboembolic events [HR = 1.14 (95%CI 1.00-1.31)], major bleeding [HR = 1.02 (95%CI 0.91-1.15)], and composite of ischemic and bleeding events [HR = 1.22 (95%CI 0.79-1.88)] were not statistically significant. The certainty in the evidence was low or very low.

CONCLUSIONS

Off label underdose DOAC use is associated with higher risk of all-cause mortality and cardiovascular composite outcomes, compared with standard dose.

Off-Label Use and Inappropriate Dosing of Direct Oral Anticoagulants in Cardiopulmonary Disease

Direct oral anticoagulants (DOACs) are increasingly used in clinical practice and have become essential in the management of atrial fibrillation and VTE. The enthusiasm for DOACs has fueled the off-label application of these agents in cardiopulmonary disease, and their use has often outpaced the evidence supporting their application. This article reviews the evidence and current off-label use of DOACs in various cardiopulmonary disease states.

Effectiveness and Safety of Reduced and Standard Daily Doses of Direct Oral Anticoagulants in Patients with Nonvalvular Atrial Fibrillation: A Cohort Study Using National Database Representing the Japanese Population

Purpose

To compare the effectiveness and safety of reduced or standard daily doses of direct oral anticoagulants (DOACs) with warfarin in Japanese patients with nonvalvular atrial fibrillation (NVAF). We used post-hoc analyses to identify patient groups that could benefit from reduced-dose DOACs.

Patients and Methods

Using the National Database of Health Insurance Claims and Specific Health Checkups of Japan, we identified 944,776 patients with NVAF who had started an oral anticoagulant after at least one year of non-use between April 2011 and March 2016. We matched patients taking any, reduced, or standard doses of DOACs 1:1 with those taking warfarin. We measured treatment effectiveness based on admission due to stroke or systemic embolism (S/SE) and safety based on admission due to any bleeding (defined as major bleeding, MB). We compared both outcomes between DOACs and warfarin using the Cox proportional hazards model. We used post-hoc analysis to match patients receiving reduced-dose DOACs to those receiving standard-dose DOACs and compared treatment effectiveness and safety.

Results

More than half of patients receiving DOACs used a reduced dose. The occurrences of S/SE and MB in patients receiving any, reduced, or standard doses of DOACs were equal to or lower than those receiving warfarin. In the post-hoc analysis, the risk of S/SE and MB was similar between reduced and standard doses of DOACs except for those with a history of cerebral infarction and CHA2DS2-VASc score ≥3, where the risk of S/SE was lower for reduced doses of any and individual DOACs.

Conclusion

Findings from the current study are consistent with recent Asian and global studies but different from most studies conducted in North America and Europe, where patients receiving a reduced dose of DOACs had an increased risk of S/SE. Future studies should test the reproducibility of results from the current study.

Efficacy and Safety of Clinically Driven Low-Dose Treatment with Direct Oral Anticoagulants in Asians with Atrial Fibrillation: a Systematic Review and Meta-analysis

PURPOSE

Although clinically driven low-dose (CDLD) treatment with direct oral anticoagulants (DOACs) is frequently administered to Asian patients with atrial fibrillation, clinical evidence confirming its efficacy remains insufficient. We evaluated the clinical efficacy and safety of CDLD treatment with DOACs compared to on-label dose treatment in Asian patients with atrial fibrillation and assessed the differences in the baseline characteristics between patients receiving these treatments.

METHODS

We searched the MEDLINE, CENTRAL, EMBASE, Web of Science, and Scopus databases for articles from inception through July 2020.

RESULTS

Thirteen studies were included in this meta-analysis. The baseline characteristics of the CDLD group were significantly different from those of the standard dose (STD) and standard low-dose (SLD) groups. The incidences of thromboembolic events (risk ratio [RR] 0.46, 95% confidence interval [CI] 0.29-0.73, p < 0.001) and major bleeding (RR 0.55, 95% CI 0.35-0.87, p = 0.01) in the CDLD group were lower than those in the SLD group; however, they were comparable with those in the STD group. The incidence of a composite endpoint in the CDLD group was not significantly different from that in the STD group but was significantly lower than that in the SLD group (RR 0.50, 95% CI 0.38-0.65, p < 0.001).

CONCLUSION

The clinical outcomes of CDLD treatment showed no difference compared to those of the STD treatment despite the vulnerable baseline characteristics of the CDLD group for thromboembolic and major bleeding events.

Different Renal Function Equations and Dosing of Direct Oral Anticoagulants in Atrial Fibrillation

Background

Randomized trials of direct oral anticoagulants (DOACs) adopted the Cockcroft-Gault (CG) formula to calculate estimated glomerular filtration rate (eGFR) to determine the dosages of DOACs.

Objectives

The authors aimed to investigate the agreements/disagreements of eGFRs calculated using different equations (CG, Modified Diet in Renal Disease [MDRD], and Chronic Kidney Disease Epidemiology Collaboration [CKD-EPI] formulas), and their impacts on the dosages of DOACs and clinical outcomes.

Methods

Medical data from a multicenter health care provider in Taiwan including 39,239 patients with atrial fibrillation were used. Among these patients, there were 11,185 and 2,323 patients treated with DOACs and warfarin, respectively.

Results

At the cutoff values of eGFR of <15, 15-50, and >50 mL/min, the agreements were 78% between MDRD and CG and 81% between CKD-EPI and CG. The disagreements among the different equations were largely due to overestimations, especially for patients aged >75 years and with a body weight of <50 kg (58.8% for MDRD and 50.9% for CKD-EPI). Among patients receiving DOACs whose dosages were defined as “on label” based on MDRD or CKD-EPI, only those whose dosages were “truly on label” based on CG were associated with a lower risk of major bleeding (adjusted HR: 0.34; 95% CI: 0.26-0.45) compared to warfarin.

Conclusions

The adoptions of MDRD or CKD-EPI rather than CG would result in inappropriate dosing of DOACs (mainly overdosing), which would attenuate the advantages of DOACs compared to warfarin. The CG equation should be used as the gold standard to calculate eGFRs and guide the DOAC dosages.

2021 Focused Update Consensus Guidelines of the Asia Pacific Heart Rhythm Society on Stroke Prevention in Atrial Fibrillation: Executive Summary

The consensus of the Asia Pacific Heart Rhythm Society (APHRS) on stroke prevention in atrial fibrillation (AF) has been published in 2017 which provided useful clinical guidance for cardiologists, neurologists, geriatricians, and general practitioners in the Asia-Pacific region. In these years, many important new data regarding stroke prevention in AF were reported. The practice guidelines subcommittee members comprehensively reviewed updated information on stroke prevention in AF, and summarized them in this 2021 focused update of the 2017 consensus guidelines of the APHRS on stroke prevention in AF. We highlighted and focused on several issues, including the importance of the AF Better Care pathway, the advantages of non-vitamin K antagonist oral anticoagulants (NOACs) for Asians, the considerations of use of NOACs for Asian AF patients with single one stroke risk factor beyond gender, the role of lifestyle factors on stroke risk, the use of oral anticoagulants during the "coronavirus disease 2019" pandemic, etc. We fully realize that there are gaps, unaddressed questions, and many areas of uncertainty and debate in the current knowledge of AF, and the physician's decision remains the most important factor in the management of AF.

Off-Label Under- and Overdosing of Direct Oral Anticoagulants in Patients With Atrial Fibrillation: A Meta-Analysis

BACKGROUND

Prescriptions of off-label under- and overdosing of direct oral anticoagulants (DOACs) are common for patients with atrial fibrillation, but their efficacy and safety remain unknown.

METHODS

Databases were searched for randomized controlled trial or adjusted observational study that compared an off-label versus on-label dosing of DOACs through June 15, 2021. The primary efficacy outcome was ischemic stroke/system embolism (IS/SE), and primary safety outcome was major bleeding. Net clinical outcome was generally defined as the composite of IS/SE, major bleeding, and all-cause death. Hazard ratios (HRs) with 95% CIs were pooled with random-effects models with Hartung-Knapp-Sidik-Jonkman method for adjustment.

RESULTS

Sixteen studies with 130 609 patients were included. Compared with on-labeling dosing, off-label underdosing of DOACs was associated with a higher risk of IS/SE (HR, 1.22 [95% CI, 1.05-1.42], P=0.01). The incidence of major bleeding was similar (HR, 0.95 [95% CI, 0.82-1.11], P=0.48). Off-label underdosing was associated with a higher risk of net clinical outcome (HR, 1.19 [95% CI, 1.04-1.40], P=0.04) and all-cause death (HR, 1.24 [95% CI, 1.04-1.48], P=0.02). Stratified analysis of off-label underdosing of DOACs for IS/SE showed subgroup differences among different DOAC types and study regions. Limited data showed that off-label overdosing was associated with a higher risk of IS/SE (HR, 1.26 [95% CI, 1.11-1.43], P=0.003) and major bleeding (HR, 1.30 [95% CI, 1.04-1.62], P=0.025).

CONCLUSIONS

Compared with on-label dosing, off-label underdosing of DOACs increased the risk of thromboembolic events but did not decrease the risk of bleeding. Limited data for off-label overdosing showed higher risks of thromboembolic and bleeding. Further studies are warranted to confirm the results of off-label overdosing DOACs and subgroup results of underdosing DOACs.

2021 Focused update of the 2017 consensus guidelines of the Asia Pacific Heart Rhythm Society (APHRS) on stroke prevention in atrial fibrillation

The consensus of the Asia Pacific Heart Rhythm Society (APHRS) on stroke prevention in atrial fibrillation (AF) has been published in 2017 which provided useful clinical guidance for cardiologists, neurologists, geriatricians, and general practitioners in Asia-Pacific region. In these years, many important new data regarding stroke prevention in AF were reported. The Practice Guidelines subcommittee members comprehensively reviewed updated information on stroke prevention in AF, and summarized them in this 2021 focused update of the 2017 consensus guidelines of the APHRS on stroke prevention in AF. We highlighted and focused on several issues, including the importance of AF Better Care (ABC) pathway, the advantages of non-vitamin K antagonist oral anticoagulants (NOACs) for Asians, the considerations of use of NOACs for Asian patients with AF with single 1 stroke risk factor beyond gender, the role of lifestyle factors on stroke risk, the use of oral anticoagulants during the "coronavirus disease 2019" (COVID-19) pandemic, etc. We fully realize that there are gaps, unaddressed questions, and many areas of uncertainty and debate in the current knowledge of AF, and the physician's decision remains the most important factor in the management of AF.

A retrospective study on the evaluation of the appropriateness of oral anticoagulant therapy for patients with atrial fibrillation

BACKGROUND

The incidence of atrial fibrillation (AF) is increasing, and effective anticoagulation therapy can prevent adverse events. Selecting the appropriate OAC based on patient characteristics has become a challenge. Interventions are going to be a potential area of focus.

OBJECTIVES

To explore the discrepancies between clinician prescriptions and recommended guidelines of oral anticoagulants (OACs) for patients with atrial fibrillation (AF), and to provide direction for improving anticoagulation strategies for treating patients with AF.

MATERIALS AND METHODS

Data were collected from the electronic medical record system of Fuwai Yunnan Cardiovascular Hospital between July 2019 and January 2020. The suitability of prescribed OACs for patients with AF was assessed according to the Rules for Avoiding Prescription Inappropriateness, the prescribed medicine label, and any relevant antithrombotic guidelines for treating patients with AF.

RESULTS

A total of 460 patients met the inclusion criteria. Of these, 53.7% received an appropriate prescription and 46.3% received an inappropriate prescription. Of the patients who received inappropriate prescriptions, 15.4% were prescribed without the presenting appropriate indicators, 1.3% were prescribed inappropriate drug selection, and 29.6% were prescribed inappropriate drug doses. For patients prescribed without providing appropriate indicators, 2.2% had no indication for medication and 13.3% had an indication for medication, but not a specific OAC. For patients with inappropriate drug selection, 1, 5 patients were on rivaroxaban, dabigatran respectively. The distribution of NOAC doses was as follows: dabigatran standard dose (45.2%), the low dose (54.8%). Rivaroxaban standard dose (58.9%), low dose (36.8%), high dose (4.3%). A total of 44 patients (9.6%) experienced bleeding events, 12 patients (2.6%) experienced embolic events, and 7 patients experienced other adverse events after dosing.

CONCLUSIONS

In clinical practice, it is common for patients with AF to receive inappropriate prescriptions of OACs. Therefore there is a need to enhance anticoagulation management in patients with AF to improve the appropriate use of OACs.

Meta-analysis comparing inappropriately low dose versus standard dose of direct oral anticoagulants in patients with atrial fibrillation

BACKGROUND

The appropriateness of direct oral anticoagulant (DOAC) dosing has been the issue in the real-world setting, and inappropriately lower DOAC dose may not be as effective or safe as the standard dose in patients with atrial fibrillation (AF). Multiple real-world studies compared the inappropriately lower DOAC dose versus the standard dose, but their main findings were contradictory.

METHODS

A meta-analysis was performed to compare the efficacy and safety of the inappropriately lower DOAC dose with the standard DOAC dose in patients with AF. Database searches through May 30, 2021, were performed using Medline and Google Scholar. The primary efficacy outcome was stroke or systemic embolism, and the primary safety outcome was major bleeding. The secondary outcome was all-cause mortality.

RESULTS

A total of 16 studies were included in this meta-analysis. It revealed that the inappropriately lower DOAC dose was significantly associated with a higher event rate of stroke or systemic embolism compared with the DOAC standard dose (odds ratio 1.21 [95% CI 1.02-1.43], P = 0.03, I² = 66%). There was no significant difference in the major bleeding event rate between these groups (1.03, [0.92-1.15], P = 0.62; I² = 27%).

CONCLUSION

The inappropriately lower DOAC dose should be avoided to optimize DOAC effectiveness in patients with AF.

Are low doses of non-vitamin K antagonists effective in Chinese patients with atrial fibrillation? A report from the Optimal Thromboprophylaxis in Elderly Chinese Patients with Atrial Fibrillation (ChiOTEAF) registry

BACKGROUND

Suboptimal low dosages of non-vitamin K antagonist oral anticoagulants (NOACs) are often inappropriately used due to a fear of bleeding, particularly among elderly patients. Such practice is common in Asia, and we aimed to evaluate the use of low-dose NOACs and their impact on clinical outcomes among Chinese patients with atrial fibrillation.

METHODS

The Optimal Thromboprophylaxis in Elderly Chinese Patients with Atrial Fibrillation (ChiOTEAF) registry was a prospective, multicenter study conducted in China from October 2014 to December 2018. For this report, we included NOAC-treated patients with available data on NOAC dosage and one-year follow-up. Logistic regression analysis assessed the association (adjusted for age, sex, prior ischemic stroke, prior major bleeding, heart failure, coronary artery disease, hypertension, diabetes mellitus, chronic kidney disease, liver disease, current anemia) between the low doses and study outcomes among NOAC-treated patients, as well as comparisons with non-anticoagulated patients.

RESULTS

The eligible cohort included 1310 NOAC-treated patients (mean age of 72.1 ± 10.9; 38.9% female), of whom 341 (26.0%) received a low "off-label" dose. The use of low-dose NOACs was independently associated with higher odds of the composite outcome (OR: 2.51; 95% CI: 1.11-5.71) and thromboembolism (OR: 4.73; 95% CI: 1.11-20.01). Compared with non-anticoagulated patients, lower rates of the composite outcome (7.3% vs. 11.3%; p = 0.025) and all-cause death (5.3% vs. 9.7%; p = 0.007) were seen in the low-dose group (ORs 0.50; 95% CI: 0.32-0.78, and 0.42; 95% CI: 0.26-0.70, respectively).

CONCLUSIONS

Low doses of NOACs should not be recommended as a part of standard therapy among Chinese patients with atrial fibrillation as their use was associated with a higher odds ratio of the composite outcome and thromboembolic events compared with standard dose NOAC regimens. Compared to non-treatment, the use of low-dose NOAC may result in a survival benefit (but not thromboembolic reduction) among high-risk patients.

Off-Label Underdosing or Overdosing of Non-vitamin K Antagonist Oral Anticoagulants in Patients With Atrial Fibrillation: A Meta-Analysis

Background: Several studies have investigated the role of off-label non-vitamin K antagonist oral anticoagulants (NOACs) in patients with atrial fibrillation (AF). We aimed to compare the effectiveness and safety outcomes between off-label underdose or overdose vs. on-label dose of NOACs in AF patients.

Methods: The PubMed database was systematically searched until August 2021. Observational cohorts were included if they compared the outcomes of off-label underdose or overdose with on-label dose of NOACs in AF patients. The risk ratios (RRs) and 95% confidence intervals (CIs) were pooled using a fixed-effects model (I² ≤ 50%) or a random-effects model (I² > 50%).

Results: A total of 15 observational studies were included. Compared with on-label dose of NOACs, off-label underdose of NOACs was associated with increased risks of stroke or systemic embolism (RR = 1.09, 95% CI 1.02–1.16), and all-cause death (RR = 1.29, 95% CI 1.10–1.52) but not ischemic stroke (RR = 1.34, 95% CI 0.76–2.36), myocardial infarction (RR = 1.08, 95% CI 0.92–1.28), major bleeding (RR = 0.97, 95% CI 0.89–1.05), intracranial hemorrhage (RR = 1.12, 95% CI 0.90–1.40), and gastrointestinal bleeding (RR = 0.96, 95% CI 0.85–1.07), whereas off-label overdose of NOACs was associated with increased risks of SSE (RR = 1.20, 95% CI 1.05–1.36), all-cause death (RR = 1.22, 95% CI 1.06–1.39), and major bleeding (RR = 1.33, 95% CI 1.16–1.52) but not gastrointestinal bleeding (RR = 1.18, 95% CI 0.99–1.42) and myocardial infarction (RR = 0.98, 95% CI 0.75–1.30).

Conclusion: Compared with on-label dose of NOACs, off-label underdose was associated with increased risks of stroke or systemic embolism and all-cause death, whereas off-label overdose of NOACs was associated with increased risks of stroke or systemic embolism, all-cause death, and major bleeding.

Real-world comparisons of reduced-dose non-vitamin K antagonist oral anticoagulants versus warfarin in atrial fibrillation: a systematic review and meta-analysis

We performed this meta-analysis to compare the efficacy and safety of reduced-dose non-vitamin K antagonist oral anticoagulants (NOACs) versus warfarin in patients with atrial fibrillation (AF). The PubMed and Embase databases were systematically searched until July 2019 for eligible studies that comparing the effect between any reduced-dose NOAC and warfarin in patients with AF. Risk ratios (RRs) and 95% confidence intervals (CIs) were pooled by using a random-effects model. A total of 14 observational cohorts were included. Compared with warfarin use, the use of reduced-dose NOACs was associated with decreased risks of stroke or systemic embolism (RR, 0.83; 95% CI 0.74-0.93), ischemic stroke (RR, 0.87; 95% CI 0.77-0.98), major bleeding (RR, 0.71; 95% CI 0.60-0.84), intracranial hemorrhage (RR, 0.51; 95% CI 0.44-0.60), and gastrointestinal bleeding (RR, 0.72; 95% CI 0.54-0.94), but not all cause death (RR, 0.84; 95% CI 0.67-1.06). In the subgroup analyses, all NOAC users had lower or similar rates of thromboembolic and bleeding events; and the reductions in stroke or systemic embolism, all-cause death, major bleeding, and gastrointestinal bleeding were more prominent in Asians than non-Asians. In conclusion, current published data suggest that the use of reduced-dose NOACs is non-inferior to warfarin in patients with AF (in particular Asians).

Optimal Management of Anticoagulation Therapy in Asian Patients With Atrial Fibrillation

Stroke prevention is the cornerstone of management of atrial fibrillation (AF), and non-vitamin K antagonist oral anticoagulants (NOACs) are commonly prescribed. Because routine monitoring of anticoagulant effects of NOACs is not necessary, appropriate dosing following the criteria of each NOACs defined in pivotal randomized trials is important. Real-world data demonstrate that underdosing NOACs is associated with a higher risk of ischemic stroke without a lower risk of major bleeding. Furthermore, renal function of AF patients should be assessed using the Cockcroft-Gault formula to prevent overestimation that could result in overdosing of NOACs. The assessment of bleeding risk is important, and the HAS-BLED score should be used to help identify patients at high risk of bleeding (HAS-BLED score ≥3). Moreover, the HAS-BLED score should be reassessed at periodic intervals to address potentially modifiable bleeding risk factors because bleeding risks of AF patients are not static. When managing NOAC-related bleeding episodes, the possibility of occult malignancies (e.g., grastrointestinal [GI] tract cancers for patients experiencing GI bleeding and bladder cancer for patients with hematuria) should be kept in mind. Addressing all of these issues is crucial to achieving better clinical outcomes for anticoagulated AF patients. More efforts are necessary to incorporate clear and easy-to-follow recommendations about optimal management of anticoagulation into the guidelines to improve AF patient care.

Real-World Prevalence of Direct Oral Anticoagulant Off-Label Doses in Atrial Fibrillation: An Epidemiological Meta-Analysis

Background: The use of direct oral anticoagulant (DOAC) off-label doses in atrial fibrillation (AF) patients may result in poor clinical outcomes. However, the true prevalence remains scarce. This study aims at estimating the prevalence of DOAC off-label doses in AF patients.

Methods: Databases of MEDLINE, EMBASE, and COCHRANE were searched from inception through February 2020 for real-world studies that reported the off-label definition and prevalence data of AF patients using DOACs. The primacy outcomes were the overall prevalence of DOAC off-label doses and the corresponding underdose and overdose. The random-effects model was used for data synthesis. Variations on individual DOAC and different regions were examined by subgroup analyses.

Results: A total of 23 studies involving 162,474 AF patients were finally included. The overall prevalence of DOAC off-label doses was 24% (95% CI, 19–28%), with 18% for dabigatran, 27% for rivaroxaban, 24% for apixaban, and 26% for edoxaban. The prevalence of underdosed DOACs was 20% (95% CI, 16–24%) with significant difference among individual anticoagulants (13% for dabigatran, 22% for rivaroxaban, 22% for apixaban, and 18% for edoxaban; P_interaction=0.02). The prevalence of overdosed DOACs was 5% (95% CI, 3–7%), with the lowest prevalence observed in apixaban (2%). Subgroup analyses by regions demonstrated that the prevalence of DOAC off-label doses was higher in Asia (32%) than in North America (14%) and in Europe (22%), with underdose being predominant. Regardless of different regions, the prevalence of overdose was relatively low (4–6%).

Conclusion: This study provides an estimation of DOAC off-label doses in the real-world setting. The prevalence rate of DOAC off-label doses in AF patients was relatively high, with underdose being predominant. Clinicians in Asia preferred to prescribe underdose of DOACs to AF patients. More evidence about the appropriateness of DOAC off-label doses in AF patients is urgently needed. Education programs concerning the appropriate prescription of DOACs within the drug labels and accepted guidelines are necessary to DOAC prescribers to ensure the safety and effectiveness of anticoagulation therapy for patients with AF.

Rationale and design of a prospective, multicenter, cross-sectional study of appropriateness evaluation of the prescription of non-vitamin K antagonist oral anticoagulants for Chinese atrial fibrillation patients (Chi-NOACs-AF trial)

BACKGROUND

Non-vitamin K antagonist oral anticoagulants (NOACs) are alternative to vitamin K antagonists (VKAs) for stroke prevention in patients with atrial fibrillation (AF). Along with their widespread clinical use in China, the off-label use of NOACs is commonly seen in real-world practice, which could result in adverse drug events and poor clinical outcomes. However, guideline adherence and label adherence for NOAC prescriptions have not been well evaluated in a real-world setting in China.

METHODS

Between January 2021 and June 2021, a total of 1,750 outpatients or inpatients with AF will be consecutively enrolled at 26 canters in China. Data on patient demographics, clinical characteristics, treatment strategies, and prescribing information related to anticoagulation therapy for patients with AF will be collected. Clinical pharmacists will evaluate the rationality of the anticoagulation regimens and NOAC prescriptions based on the guideline recommendations and drug labels that are approved by the National Medical Products Administration. The primary outcomes will be the prevalence of irrational anticoagulation strategies and the inappropriate NOAC prescriptions, as well as potential risk factors associated with inappropriate prescriptions in patients with AF.

DISCUSSION

This study will be the first national, multicenter, prospective study performed by pharmacists to explore real-world data on the appropriateness of NOAC prescription in Chinese patients with AF.

TRIAL REGISTRATION

The Chi-NOACs-AF trial (Trial number: ChiCTR2000035908).

Effectiveness and Safety of Under or Over-dosing of Direct Oral Anticoagulants in Atrial Fibrillation: A Systematic Review and Meta-analysis of 148909 Patients From 10 Real-World Studies

Background: In routine clinical practice, non-standard doses of direct oral anticoagulants (DOACs) are commonly used in patients with atrial fibrillation (AF). However, data on the clinical outcomes of non-standard doses of DOACs are limited.

Methods: The MEDLINE, Embase, and Cochrane Library databases were systematically searched from their inception until 30 June 2020 for studies that reported the effectiveness or safety outcomes of non-standard doses of DOACs compared with on-label doses of DOACs in patients with atrial fibrillation. Non-standard doses of DOACs were defined as under or over-dose of DOACs based on the recommended standard doses in drug labels. A random-effects meta-analysis was performed to calculate the pooled hazard ratio and associated 95% confidence interval (95% confidence interval). Subgroup analyses were conducted according to individual DOACs and different geographic regions.

Results: Ten articles involving 148,909 patients with AF were included. There were no significant differences between under-dosing and on-label dosing with respect to stroke/systematic embolism (HR: 1.01, 95% CI: 0.93–1.09), major bleeding (HR: 0.98, 95% CI: 0.77–1.19), intracranial haemorrhage (HR: 1.07, 95% CI: 0.74–1.40), gastrointestinal bleeding (HR: 1.10, 95% CI: 0.82–1.39), and myocardial infarction (HR: 1.07, 95% CI: 0.89–1.25), except for an increased risk of death (HR: 1.37, 95% CI: 1.01–1.73). We observed a significant association between over-dosing of DOACs and increased risk of stroke/systematic embolism (HR: 1.18, 95% CI: 1.04–1.32), major bleeding (HR: 1.16, 95% CI: 1.03–1.29), and death (HR: 1.21, 95% CI: 1.03–1.38) compared with on-label dosing. Furthermore, over-dosing of DOACs increased the risk of stroke/systematic embolism (HR: 1.16; 95% CI: 1.00–1.33) and major bleeding events (HR: 1.18; 95% CI: 1.00–1.37) in Asian patients.

Conclusion: A reduced dose of DOACs might be safely and effectively used in clinical practice, especially in Asian patients, whereas high-dose DOACs might not be well tolerated by Asian patients.

Effect of non-recommended doses versus recommended doses of direct oral anticoagulants in atrial fibrillation patients: A meta-analysis

Background

Several observational studies have shown that the inappropriate dosing use of direct oral anticoagulants (DOACs) in atrial fibrillation (AF) that does not conform to recommendations is becoming a widespread phenomenon. Therefore, we performed a meta‐analysis and systematic review to assess the effect of non‐recommended doses versus recommended doses of DOACs on the effectiveness and safety outcomes among AF patients.

Methods

The PubMed and Ovid databases were systematically searched to identify the relevant studies until December 2020. The effect estimates were hazard ratios (HRs) and 95% confidence intervals (CIs), which were pooled using a fixed‐effects model (I² ≤ 50%) or a random‐effects model (I² > 50%).

Results

A total of 11 studies were included in this meta‐analysis. Compared with recommended dosing of DOACs, non‐recommended low dosing of DOACs was associated with increased risks of stroke or systemic embolism (SSE, HR = 1.29, 95% CI 1.12–1.49) and all‐cause death (HR = 1.37, 95% CI 1.15–1.62), but not the ischemic stroke, myocardial infarction, gastrointestinal bleeding, intracranial bleeding, and major bleeding. Compared with recommended dosing of DOACs, non‐recommended high dosing of DOACs was associated with increased risks of SSE (HR = 1.44, 95% CI 1.01–2.04), major bleeding (HR = 1.99, 95% CI 1.48–2.68), and all‐cause death(HR = 1.38, 95% CI 1.02–1.87).

Conclusion

Compared with recommended dosing of DOACs, non‐recommended low dosing of DOACs was associated with increased risks of SSE and all‐cause death. Further study should confirm the findings of non‐recommended high dosing versus recommended dosing of DOACs.

Stroke prevention strategies in high-risk patients with atrial fibrillation

Effective stroke prevention with oral anticoagulation (OAC) is the cornerstone of the management of patients with atrial fibrillation. The use of OAC reduces the risk of stroke and death. For most patients with atrial fibrillation without moderate or severe mitral valve stenosis or prosthetic mechanical heart valves, treatment options include vitamin K antagonists, such as warfarin, and non-vitamin K antagonist oral anticoagulants (NOACs). Although most guidelines generally recommend NOACs as the first-line OAC, caution is required in some groups of patients with atrial fibrillation at high risk of stroke and bleeding who have been under-represented or not studied in the randomized clinical trials on NOACs for stroke prevention. In addition to OAC, non-pharmacological, percutaneous therapies, including left atrial appendage occlusion, for stroke prevention have emerged, sometimes used in combination with catheter ablation for the treatment of the atrial fibrillation. High-risk groups of patients with atrial fibrillation include patients with end-stage renal failure (including those receiving dialysis), extremely old patients (such as those aged >80 years with multiple risk factors for bleeding), patients with dementia or those living in a long-term care home, patients with previous intracranial bleeding or recent acute bleeding (such as gastrointestinal bleeding), patients with acute ischaemic stroke and patients with an intracardiac thrombus. This Review provides an overview of stroke prevention strategies, including left atrial appendage occlusion, in patients with atrial fibrillation at high risk of stroke and bleeding.

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.

Anti-Factor Xa Activity of Standard and Japan-Specific Doses of Rivaroxaban in Thai Patients With Non-Valvular Atrial Fibrillation

BACKGROUND

Recommended rivaroxaban doses for stroke prevention in atrial fibrillation (SPAF) are 20 and 15 mg/day in patients with normal and reduced renal function, respectively, but lower doses (15 and 10 mg) have been tested and approved in Japan. It is not known whether 15 and 10 mg rivaroxaban are appropriate in other Asian populations. This study compared the anti-Factor Xa (FXa) activity of 20 and 15 mg rivaroxaban in Thai patients with normal renal function and 15 and 10 mg rivaroxaban in patients with reduced renal function.

METHODS AND RESULTS

Sixty non-valvular atrial fibrillation patients receiving rivaroxaban (mean [±SD] age 69.3±9.1 years, mean creatinine clearance 59.2±22.7 mL/min) were enrolled. The anti-FXa activity of standard rivaroxaban and Japan-specific doses was measured at peak and trough concentrations. Median anti-FXa activity at peak concentrations was significantly higher for the standard than Japan-specific dose. Median anti-FXa activity measured at the trough was significantly higher for the standard dose only in those with impaired renal function. A higher proportion of patients receiving the Japan-specific rather than standard dose had anti-FXa activity at peak concentrations within the expected range (87.7% vs. 64.4%; P=0.001). One-third of those receiving the standard dose had anti-FXa activity higher than the expected range.

CONCLUSIONS

A significantly higher proportion of Thai patients receiving the Japan-specific dose of rivaroxaban had anti-FXa activity at peak concentrations within the expected range.

Off-Label Medicines Use: Complex Problem of Modern Clinical Practice

World experience in off-label medicines use is presented in the article. Data on the history of changes in tactics and approaches to solve the problem of medicines off-label use in the USA and some European countries, as well as in the European Union as a whole, are presented. The reasons, why doctors should use medicines off-label, are discussed. The expert opinion on the conditions ensuring the maximum safety in off-label medicines use is presented. In particular, the validity of obtaining patient informed consent is discussed. The article does not apply to the Russian regulation regarding “off-label” therapy but describes the foreign practice related to off-label medicines use. In addition, the results of some recently completed randomized clinical trials evaluating the effects of direct oral anticoagulants are presented in order to demonstrate the need to clarify the effectiveness and safety of medicines used in certain clinical situations. The results of such studies clarify the indications for the drug use, which are subsequently entered into the summary of product characteristics.