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

Direct-Acting Oral Anticoagulants and Potential Inconsistencies with FDA-Approved Dosing for Non-Valvular Atrial Fibrillation: A Retrospective Real-World Analysis Across Nine US Healthcare Systems

BACKGROUND

Direct-acting oral anticoagulants (DOACs) are recommended to reduce risk of stroke and systemic embolism in patients with non-valvular atrial fibrillation (NVAF). However, DOAC dosing inconsistent with FDA-approved product labels is common and associated with poor clinical outcomes.

OBJECTIVES

Identify DOAC dosing inconsistent with FDA-approved product labels in ambulatory care patients with NVAF; identify variables associated with dosing lower and higher than label.

DESIGN

Retrospective analysis using electronic health records from nine US healthcare systems.

PATIENTS

Adults with NVAF receiving DOAC therapy in 2022.

MAIN MEASURES

Rates of label-inconsistent dosing; multivariable regression analysis to identify demographic and clinical variables associated with dosing lower and higher than label.

KEY RESULTS

Among 51,128 NVAF patients (56.1% male, 94.3% White, mean [SD] age 73.5 [10.5] years), 5008 (9.8%) were prescribed label-inconsistent doses of DOACs (6.8% lower and 3.0% higher than label). Age ≥ 75 years, renal impairment, and hypertension were significantly associated with inconsistent dosing both higher and lower than label. Female sex and higher weight were significantly associated with dosing lower than label, as were heart failure, vascular or liver disease, and bleeding history. Dosing higher than label was significantly associated with male sex, race (African American/Black), weight < 60 kg, and use of drugs with potential drug-drug interactions. When prescribed by primary care physicians, DOAC doses were 37% (95% CI, 27-49%) more likely to be lower than label and 30% (95% CI, 16-46%) more likely to be higher than label than when prescribed by cardiologists or electrophysiologists. Label-inconsistent dosing varied (6.7 to 15.8%) across participating systems.

CONCLUSIONS

DOAC dosing inconsistent with label varied by demographics, clinical characteristics, prescriber specialty, and healthcare system, suggesting a need to monitor and assess dosing decisions in NVAF. Identification of variables associated with dosing inconsistencies may enable targeted interventions to ensure label-consistent dosing in vulnerable populations.

A Descriptive Analysis of Direct Oral Anticoagulant Drugs Dosing Errors Based on Spontaneous Reports from the EudraVigilance Database

Direct oral anticoagulant drugs (DOACs) interfere with the coagulation process, thus improving patient care for those who require anticoagulant treatment. This study presents a descriptive analysis of adverse reactions (ADRs) attributed to DOAC dosage errors (overdose, underdose, and improper dose). The analysis was performed based on the Individual Case Safety Reports from the EudraVigilance (EV) database. Results show that data reported for rivaroxaban, apixaban, edoxaban, and dabigatran are mostly regarding underdosing (51.56%) compared to overdosing (18.54%). The most dosage error reports were identified for rivaroxaban (54.02%), followed by apixaban (33.61%). Dabigatran and edoxaban had similar percentages (6.26% and 6.11%, respectively) regarding dosage error reports. Since coagulation issues can become life-threatening events, and factors such as advanced age and renal failure can influence the pharmacokinetics of drugs, the correct usage of DOACs is of utmost importance for the management and prevention of venous thromboembolism. Thus, the collaboration and the complementarity of knowledge of physicians and pharmacists may offer a reliable solution for DOAC dose management and improve patient care.

Challenges and Possible Solutions to Direct-Acting Oral Anticoagulants (DOACs) Dosing in Patients with Extreme Bodyweight and Renal Impairment

This article aims to highlight the dosing issues of direct oral anticoagulants (DOACs) in patients with renal impairment and/or obesity in an attempt to develop solutions employing advanced data-driven techniques. DOACs have become widely accepted by clinicians worldwide because of their superior clinical profiles, more predictable pharmacokinetics, and hence more convenient dosing relative to other anticoagulants. However, the optimal dosing of DOACs in extreme bodyweight  patients and patients with renal impairment is difficult to achieve using the conventional dosing approach. The standard dosing approach (fixed-dose) is based on limited data from clinical studies. The existing formulae (models) for determining the appropriate doses for these patient groups leads to suboptimal dosing. This problem of mis-dosing is worsened by the lack of standardized laboratory parameters for monitoring the exposure to DOACs in renal failure and extreme bodyweight patients. Model-informed precision dosing (MIPD) encompasses a range of techniques like machine learning and pharmacometrics modelling, which could uncover key variables and relationships as well as shed more light on the pharmacokinetics and pharmacodynamics of DOACs in patients with extreme bodyweight or renal impairment. Ultimately, this individualized approach-if implemented in clinical practice-could optimise dosing for the DOACs for better safety and efficacy.

Effectiveness and safety of low-dose versus standard-dose rivaroxaban and apixaban in patients with atrial fibrillation

BACKGROUND

Low-dose direct oral anticoagulant (DOAC) use is quite prevalent in clinical practice, but evidence of its effectiveness and safety compared with high-dose DOAC in patients with atrial fibrillation (AF) remains limited. We aimed to assess the effectiveness and safety of low-dose and high-dose DOACs in patients with AF with similar baseline characteristics.

METHODS

We used a cohort of hospitalized patients with a primary or secondary diagnosis of AF after discharge to the community, whose data were stored in the Quebec administrative databases, from 2011 to 2017. Older adults with AF newly prescribed with rivaroxaban (15 or 20 mg) or apixaban (2.5 mg or 5 mg) were classified as under treatment (UT) and intent to treat (ITT). We used an inverse probability treatment weighting study of new users of rivaroxaban and apixaban to address confounding by indication. The primary effectiveness outcome was ischemic stroke/systemic embolism (SE), while the primary safety outcome was major bleeding (MB). We used Cox proportional models to estimate the marginal hazard ratios (HRs).

FINDINGS

A total of 1,722 and 4,639 patients used low-dose and standard-dose rivaroxaban, respectively, while 3,833 and 6,773 patients used low-dose and standard-dose apixaban, respectively. No significant difference was observed in the incidence of comparative stroke/SE and MB between low-dose and standard-dose rivaroxaban, except for the risk of acute myocardial infarction (AMI), which was increased with the low dose in the UT analysis. For apixaban, no difference was found in the bleeding rates, but the risk of stroke/SE (HR: 1.95; 95% confidence interval (CI): 1.38-2.76) and death (HR: 1.99; 95% CI: 1.46-2.70) were greater in the low-dose group than in the standard-dose group in the UT analysis. Similar results were observed for the ITT analysis.

CONCLUSION

No significant differences were observed in the effectiveness or safety outcome between low-dose and standard-dose rivaroxaban, except for AMI. However, low-dose apixaban was associated with a greater risk of stroke/SE and death without a reduction in the bleeding rates.

Preferences for and use of oral anticoagulants for stroke prevention in atrial fibrillation under real-world conditions in Germany: A survey among physicians

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Based on a nationwide quantitative online survey among office-based physicians in Germany, we found a high divergence between preference for and use of treatment options for stroke prevention in atrial fibrillation.

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In particular, vitamin K antagonists were used more often than preferred whereas non-vitamin K oral anticoagulants, on average, were used less often than preferred.

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Oral anticoagulant attributes and patient characteristics related to efficacy and safety, as well as patients’ kidney function were most important when selecting a specific oral anticoagulant.

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Federal and regional governance instruments likely influenced treatment decision-making process.

In Germany, there is little real-world evidence on physicians’ choice of oral anticoagulants (OACs). Our study aimed at assessing preferences for and prescribing patterns of treatment options for stroke prevention in atrial fibrillation in clinical practice in Germany.

We conducted a nationwide quantitative online survey among office-based physicians in Germany. Physicians were asked about their preference for and use of treatment options as well as factors influencing their choice of a specific OAC.

A total of n = 953 physicians was surveyed in September and October 2020 (general physicians: 36.0%; internists: 37.3%; cardiologists: 23.7%; neurologists: 10.5%; multiple specialties possible). Preference and use were highest for non-vitamin K oral anticoagulants (NOACs); followed by vitamin K antagonists (VKAs). Most preferred OACs were apixaban (39.3%), rivaroxaban (28.5%) and edoxaban (14.7%). Most used OACs were apixaban (24.3%), rivaroxaban (21.2%) and phenprocoumon (21.4%). NOACs were preferred more often than used (85.6% > 68.6%). VKAs were preferred less often than used (9.6% < 23.5%). OAC attributes and patient characteristics related to efficacy and safety, as well as patients’ kidney function were most important when selecting a specific OAC. Federal and regional governance instruments likely influenced treatment decision-making.

We found a high divergence between preferences for and use of available treatment options in clinical practice. Further exploration of the importance of OAC attributes, patient characteristics as well as federal and regional governance instruments for physicians’ choice of a specific OAC may help to further optimize the healthcare of patients with atrial fibrillation in the long-term.