Peak plasma concentration of direct oral anticoagulants in obese patients weighing over 120 kilograms: A retrospective study

Apixaban plasma concentrations in patients with obesity

PURPOSE

Routine therapeutic drug monitoring of apixaban is currently not recommended but may however be warranted in some situations and for some patient groups to provide better and safer treatment. Due to limited data on apixaban concentrations in different subpopulations, it is still unclear which group of patients could possibly gain from monitoring. The purpose of this study was to examine apixaban exposure in patients with obesity compared with normal-weight patients.

METHODS

Forty patients with obesity (mean BMI 39.4 kg/m2) and 40 controls with normal weight (mean BMI 23.4 kg/m2), treated with apixaban 5 mg twice daily were included. The patients were matched for age, sex, and renal function. Trough and peak apixaban concentrations were measured with LC‒MS/MS methodology.

RESULTS

The median trough concentrations in patients with obesity (58.7, range 10.7-200.7 ng/ml) were slightly higher than those in patients with normal weight (52.0, range 31.0-150.9 ng/ml) (p < 0.05). Notably, the variability in trough concentration was considerably higher in patients with obesity. Peak concentrations were similar in both groups, with a median of 124.5 ng/ml (range 82.0-277.5) and 113.5 ng/ml (range 75.5-334.6) in patients with obesity and normal weight, respectively.

CONCLUSION

Apixaban exposure did not vary substantially between obese and normal weight matched controls, implying that general dose adjustments are not required. However, vast interindividual variability was observed in patients with obesity, suggesting that measuring the concentrations could be valuable for specific patients. Further research is needed to identify which specific patients may benefit from this approach.

Efficacy and Safety of Direct Oral Anticoagulants versus Warfarin in Obese Patients (BMI ≥ 30 kg/m2) with Atrial Fibrillation or Venous Thromboembolism: An Updated Systematic Review and Meta-Analysis

Background: Real-world data show limited utilization of direct oral anticoagulants (DOACs) in obese patients (body mass index [BMI] ≥ 30 kg/m2) due to concerns regarding their efficacy and safety in this demographic. Aim: This review aimed to consolidate current evidence on the efficacy and safety of DOACs versus warfarin in obese patients with non-valvular atrial fibrillation (AF) or venous thromboembolism (VTE). The primary efficacy outcome assessed a composite of all-cause mortality, stroke, systemic embolism (SE), and myocardial infarction (MI). Methods: A systematic search was conducted in MEDLINE, SCOPUS, and Cochrane databases from inception to December 28, 2023. Data were synthesized using random-effects meta-analysis. Results: A total of 35 studies involving 434,320 participants were analyzed. DOAC use was associated with a significant reduction in the risk of the composite outcome (RR = 0.80, 95% CI [0.65, 0.98], I2 = 95%), hemorrhagic stroke (RR = 0.58, 95% CI [0.38, 0.88], I2 = 92%), major bleeding (RR = 0.76, 95% CI [0.63, 0.92], I2 = 94%), gastrointestinal bleeding (RR = 0.59, 95% CI [0.49, 0.72], I2 = 88%), and intracranial bleeding (RR = 0.45, 95% CI [0.34, 0.60], I2 = 44%) compared to warfarin. A non-significant benefit of DOACs was observed for all-cause mortality, MI, the composite of stroke or SE, ischemic stroke, SE, VTE, and minor bleeding compared to warfarin. Subgroup analysis indicated no significant effect modification based on the indication for anticoagulation or study design. Conclusions: DOACs demonstrated a favorable efficacy and safety profile in obese individuals compared to warfarin.

[Translation into French and republication of: "Management of cancer-associated thromboembolism in vulnerable population"]

Although all patients with cancer-associated thrombosis (CAT) have a high morbidity and mortality risk, certain groups of patients are particularly vulnerable. This may expose the patient to an increased risk of thrombotic recurrence or bleeding (or both), as the benefit-risk ratio of anticoagulant treatment may be modified. Treatment thus needs to be chosen with care. Such vulnerable groups include older patients, patients with renal impairment or thrombocytopenia, and underweight and obese patients. However, these patient groups are poorly represented in clinical trials, limiting the available data on which treatment decisions can be based. Meta-analysis of data from randomised clinical trials suggests that the relative treatment effect of direct oral factor Xa inhibitors (DXIs) and low molecular weight heparin (LMWH) with respect to major bleeding could be affected by advanced age. No evidence was obtained for a change in the relative risk-benefit profile of DXIs compared to LMWH in patients with renal impairment or of low body weight. The available, albeit limited, data do not support restricting the use of DXIs in patients with TAC on the basis of renal impairment or low body weight. In older patients, age is not itself a critical factor for choice of treatment, but frailty is such a factor. Patients over 70 years of age with CAT should undergo a systematic frailty evaluation before choosing treatment and modifiable bleeding risk factors should be addressed. In patients with renal impairment, creatine clearance should be assessed and monitored regularly thereafter. In patients with an eGFR less than 30mL/min/1.72m2, the anticoagulant treatment may need to be adapted. Similarly, platelet count should be assessed prior to treatment and monitored regularly. In patients with grade 3-4, thrombocytopenia (less than 50,000platelets/μL) treatment with a LMWH at a reduced dose should be considered. For patients with CAT and low body weight, standard anticoagulant treatment recommendations are appropriate, whereas in obese patients, apixaban may be preferred.

Pharmacokinetics of single-dose rivaroxaban under fed state in obese vs. non-obese subjects: An open-label controlled clinical trial (RIVOBESE-PK)

The evidence of rivaroxaban's pharmacokinetics in obese compared with non-obese populations remains inconclusive. We aimed to compare the pharmacokinetic profile of rivaroxaban between obese and non-obese populations under fed state. Participants who met the study's eligibility criteria were assigned into one of two groups: obese (body mass index ≥35 kg/m2) or non-obese (body mass index 18.5-24.9 kg/m2). A single dose of rivaroxaban 20 mg was orally administered to each participant. Nine blood samples over 48 h, and multiple urine samples over 18 h were collected and analyzed for rivaroxaban concentration using ultra-performance liquid chromatography coupled with tandem mass detector. Pharmacokinetic parameters were determined using WinNonlin software. Thirty-six participants were recruited into the study. No significant changes were observed between obese and non-obese participants in peak plasma concentration, time to reach peak plasma concentration, area under the plasma concentration-time curve over 48 h or to infinity, elimination rate constant, half-life, apparent volume of distribution, apparent clearance, and fraction of drug excreted unchanged in urine over 18 h. Rivaroxaban's exposure was similar between the obese and non-obese subjects, and there were no significant differences in other pharmacokinetic parameters between the two groups. These results suggest that dose adjustment for rivaroxaban is probably unwarranted in the obese population.

Direct Oral Anticoagulants: Navigating Through Clinical Challenges

PURPOSE

Direct oral anticoagulants (DOACs) have been approved, for over a decade, by both European and American medicine agencies, for treatment and prevention of several cardiovascular conditions. Since then, an increasing amount of data has been added to the medical literature day by day, resulting in a dichotomy in selection of the appropriate agent, dosage, and duration of treatment for special populations with multiple comorbidities. Considering these issues, we have prepared a comprehensive review for the clinical practitioner, to optimize the DOAC utilization in clinical practice.

METHODS

A thorough literature search and review was conducted, concerning mainly the last decade. Our review focused on the current guidelines and the most recently published studies in PubMed, Science Direct Scopus, and Google Scholar to date.

CONCLUSION

The purpose of this study is to provide guidance for healthcare professionals for making proper decisions when confronted with clinical challenges. Nevertheless, further research is required to establish DOAC superiority in complicated cases, where there is clinical uncertainty.

Head-to-head ex vivo comparison of clinically used direct anticoagulant drugs

An imbalance in coagulation is associated with cardiovascular events. For prevention and treatment, anticoagulants, currently mainly xabans and gatrans, are used. The purpose of the present study was to provide a head-to-head comparison since there are no studies directly evaluating these novel anticoagulants. An additional aim was to find whether selected anthropological and biochemical factors can affect their anticoagulant properties as they are used in fixed doses. In this cross-sectional study, blood from 50 generally healthy donors was collected, and coagulation responses to dabigatran, argatroban, rivaroxaban, and apixaban, at a concentration of 1 μM, were analyzed. Heparin was used as a positive control. Prothrombin time (PT) expressed as international normalized ratio (INR) and activated partial thromboplastin time (aPTT) were measured and compared. Rivaroxaban was the most active according to PT/INR while argatroban according to aPTT. The ex vivo anticoagulant effect measured by INR correlated inversely with body mass index (BMI) in all four anticoagulants tested. Shortening of aPTT was associated with higher cholesterol and triglyceride levels. No sex-related differences were observed in response to the anticoagulant treatments. As this was an ex vivo study and pharmacokinetic factors were not included, the influence of BMI is of high therapeutic importance.

Evaluation of Apixaban standard dosing in underweight patients with non-valvular atrial fibrillation: a retrospective cohort study

BACKGROUND

Recent guidelines recommend using direct oral anticoagulants (DOACs) as first-line agents in patients with non-valvular atrial fibrillation (NVAF). Research is currently investigating the use of Apixaban in underweight patients, with some results suggesting altered pharmacokinetics, decreased drug absorption, and potential overdosing in this population. This study examined the effectiveness and safety of standard Apixaban dosing in adult patients with atrial NVAF weighing less than 50 kg.

METHODS

This is a retrospective cohort study conducted at King Abdulaziz Medical City (KAMC); adult patients with a body mass index (BMI) below 25 who received a standard dose of Apixaban (5 mg twice daily) were categorized into two sub-cohorts based on their weight at the time of Apixaban initiation. Underweight was defined as patients weighing ≤ 50 kg, while the control group (Normal weight) comprised patients weighing > 50 kg. We followed the patients for at least one year after Apixaban initiation. The study's primary outcome was the incidence of stroke events, while secondary outcomes included bleeding (major or minor), thrombosis, and venous thromboembolism (VTE). Propensity score (PS) matching with a 1:1 ratio was used based on predefined criteria and regression model was utilized as appropriate.

RESULTS

A total of 1,433 patients were screened; of those, 277 were included according to the eligibility criteria. The incidence of stroke events was lower in the underweight than in the normal weight group at crude analysis (0% vs. 9.1%) p-value = 0.06), as well in regression analysis (OR (95%CI): 0.08 (0.001, 0.76), p-value = 0.002). On the other hand, there were no statistically significant differences between the two groups in the odds of major and minor bleeding (OR (95%CI): 0.39 (0.07, 2.03), p-value = 0.26 and OR (95%CI): 1.27 (0.56, 2.84), p-value = 0.40, respectively).

CONCLUSION

This exploratory study revealed that underweight patients with NVAF who received standard doses of Apixaban had fewer stroke events compared to normal-weight patients, without statistically significant differences in bleeding events. To confirm these findings, further randomized controlled trials with larger sample sizes and longer observation durations are required.

Castelino R, Inglis SC, Davidson PM, Ferguson C. Direct oral anticoagulant use in hospitalized patients with atrial fibrillation across body mass index categories: design and rationale for a retrospective cohort study

Background

Atrial fibrillation (AF) and obesity are common conditions globally; yet, there remains suboptimal pharmacological management contributing to high rates of hospitalization in patients with AF. The altered pathophysiology of both obese and underweight individuals may influence the pharmacology of medications, including those used to manage AF. This, in turn, increases the risk of adverse events and impacts patient risk for stroke and rehospitalization. Despite the well-established complications of obesity, research investigating the relationship between obesity and AF is scant.

Objectives

The primary aim of this study is to describe cardiovascular-related hospitalization in AF patients according to BMI categories. A secondary aim is to describe anticoagulant and antiarrhythmic prescribing practice patterns in patients with AF, according to the BMI category.

Design

A retrospective, exploratory descriptive observational cohort study, using routinely collected electronic medical record data from five public hospitals within a single health district, with a population dominantly that is culturally and linguistically diverse, and has a low socioeconomic status.

Methods and analysis

Data extraction will include a 24-month period (January 2017 to December 2018) with a 12-month follow-up. All adult (⩾18 years) patients at discharge diagnosed with AF, prescribed any oral anticoagulant and/or oral rate/rhythm control agent, will be eligible for inclusion.

Ethics and dissemination

Ethics approval from the health district and the University of Wollongong has been granted. Findings will seek to demonstrate associations between management strategies and patient outcomes, as well as describe patterns of acute care management from prescribers. These data will be used to inform and generate hypotheses for large-scale studies examining the impact of body weight on anticoagulation prescribing at national and global scales.

A Novel Body Mass Index-Based Thromboembolic Risk Score for Overweight Patients with Nonvalvular Atrial Fibrillation

BACKGROUND

A novel risk prediction model appears to be urgently required to improve the assessment of thrombotic risk in overweight patients with nonvalvular atrial fibrillation (NVAF). We developed a novel body mass index (BMI)-based thromboembolic risk score (namely AB2S score) for these patients.

METHODS

A total of 952 overweight patients with NVAF were retrospectively enrolled in this study with a 12-month follow-up. The primary endpoint was 1-year systemic thromboembolism and the time to thrombosis (TTT). The candidate risk variables identified by logistic regression analysis were included in the final nomogram model to construct AB2S score. The measures of model fit were evaluated using area under the curve (AUC), C-statistic, and calibration curve. The performance comparison of the AB2S score to the CHADS2 and CHA2DS2-VASc score was performed in terms of the AUC and decision analysis curve (DAC).

RESULTS

The AB2S score was constructed using 7 candidate risk variables, including a 3-category BMI (25 to 30, 30 to 34, or ≥35 kg/m2). It yielded a c-index of 0.885 (95% CI, 0.814-0.954) and an AUC of 0.885 (95% CI, 0.815-0.955) for predicting 1-year systemic thromboembolism in patients with NVAF. Compared to the CHADS2 score and CHA2DS2-VASc score, the AB2S score had greater AUC and DAC values in predicting the thromboembolic risk and better risk stratification in TTT (P <.0001, P =.082, respectively).

CONCLUSION

Our results highlighted the importance of a BMI-based AB2S score in determining systemic thromboembolism risk in overweight patients with NVAF, which may aid in decision-making for these patients to balance the effectiveness of anticoagulation from the underlying thrombotic risk.

Management of cancer-associated thromboembolism in vulnerable population

Although all patients with cancer-associated thrombosis (CAT) have a high morbidity and mortality risk, certain groups of patients are particularly vulnerable. This may expose the patient to an increased risk of thrombotic recurrence or bleeding (or both), as the benefit-risk ratio of anticoagulant treatment may be modified. Treatment thus needs to be chosen with care. Such vulnerable groups include older patients, patients with renal impairment or thrombocytopenia, and underweight and obese patients. However, these patient groups are poorly represented in clinical trials, limiting the available data, on which treatment decisions can be based. Meta-analysis of data from randomised clinical trials suggests that the relative treatment effect of direct oral factor Xa inhibitors (DXIs) and low molecular weight heparin (LMWH) with respect to major bleeding could be affected by advanced age. No evidence was obtained for a change in the relative risk-benefit profile of DXIs compared to LMWH in patients with renal impairment or of low body weight. The available, albeit limited, data do not support restricting the use of DXIs in patients with CAT on the basis of renal impairment or low body weight. In older patients, age is not itself a critical factor for choice of treatment, but frailty is such a factor. Patients over 70 years of age with CAT should undergo a systematic frailty evaluation before choosing treatment and modifiable bleeding risk factors should be addressed. In patients with renal impairment, creatine clearance should be assessed and monitored regularly thereafter. In patients with an eGFR<30mL/min/1.72m2, the anticoagulant treatment may need to be adapted. Similarly, platelet count should be assessed prior to treatment and monitored regularly. In patients with grade 3-4, thrombocytopenia (<50,000 platelets/μL) treatment with a LMWH at a reduced dose should be considered. For patients with CAT and low body weight, standard anticoagulant treatment recommendations are appropriate, whereas in obese patients, apixaban may be preferred.

Pharmacokinetics and pharmacodynamics of direct oral anticoagulants

INTRODUCTION

Direct oral anticoagulants (DOACs) have overtaken vitamin K antagonists to become the most widely used method of anticoagulation for most indications. Their stable and predictable pharmacokinetics combined with relatively simple dosing, and the absence of routine monitoring has made them an attractive proposition for healthcare providers. Despite the benefits of DOACs as a class, important differences exist between individual DOAC drugs in respect of their pharmacokinetic and pharmacodynamic profiles with implications for dosing and reversal in cases of major bleeding.

AREAS COVERED

This review summarizes the state of knowledge relating to the pharmacokinetics of dabigatran (factor IIa/thrombin inhibitor) and apixaban, edoxaban and rivaroxaban (factor Xa) inhibitors. We focus on pharmacokinetic differences between the drugs which may have clinically significant implications.

EXPERT OPINION

Patient-centered care necessitates a careful consideration of the pharmacokinetic and pharmacodynamic differences between DOACs, and how these relate to individual patient circumstances. Prescribers should be aware of the potential for pharmacokinetic drug interactions with DOACs which may influence prescribing decisions in patients with multiple comorbidities. In order to give an appropriate dose of DOAC drugs, accurate estimation of renal function using the Cockcroft-Gault formula using actual body weight is necessary. An increasing body of evidence supports the use of DOACs in patients who are obese, and this is becoming more routine in clinical practice.

Trends in prescribing and outcomes in obese versus non-obese patients receiving rivaroxaban therapy: an observational study using real-world data

PURPOSE

To investigate real-world prescribing trends and clinical outcomes based on body mass index (BMI) categorization in patients who received rivaroxaban therapy.

METHODS

This was a retrospective cohort study involving all patients who received rivaroxaban therapy across all Hamad Medical Corporation (HMC) hospitals from 2015 to 2020.

RESULTS

The number of patients initiated on rivaroxaban therapy significantly increased from 152 (3.3%) in 2015 to 1342 (28.9%) in 2020 (p <0.001). Within BMI categories, a similar increasing trend was observed in underweight, normal, and overweight patients, while from 2018 to 2020, there was a decreasing trend in rivaroxaban prescribing in all obese classes. The prevalence rate of all-cause mortality differed significantly between the BMI groups, with the highest mortality being among morbidly obese patients (BMI ≥ 40 kg/m2) (p< 0.001). On the other hand, no significant differences were found between the BMI groups in terms of bleeding, pulmonary embolism, deep vein thrombosis and stroke incidences. Multivariate logistic regression analyses showed that the likelihood of all-cause mortality was significantly higher in overweight and all categories of obese patients compared to underweight patients: overweight (OR: 5.3, 95% CI: 2.3-11.9, p< 0.001); obese class 1 (OR: 5.4, 95% CI: 2.3 - 12.2, p< 0.001); obese class 2 (OR: 6.5, 95% CI: 2.7 - 15.6, p< 0.001); and obese class 3 (OR: 3.7, 95% CI: 1.6 - 8.7, p = 0.003).

CONCLUSIONS

Rivaroxaban prescribing has significantly increased over the years across general population, with a noticeable decline in obese population during the last few years (from 2018 onwards). Furthermore, an appreciable association was evident between all-cause mortality and BMI of these patients.

Use of direct oral anticoagulants for venous thromboembolism treatment at extremes of body weight, renal and liver function: an illustrated review

Direct oral anticoagulants (DOACs) have been a welcome addition to clinical practice due to the practical advantages they confer over traditional anticoagulants. In many countries, DOACs are now used as first-line treatment for the management of venous thromboembolism (VTE). Traditional anticoagulants allow for a degree of individualization, either through monitoring the international normalized ratio in the case of vitamin-K antagonists or through dose titration according to bodyweight in the case of low-molecular-weight heparin. However, the use of fixed doses and removal of the need for routine monitoring has created uncertainty in prescribing DOACs for patients at the extremes of bodyweight, renal function, and patients with liver impairment, who were not well represented in the DOAC licensing clinical trials. The discipline of pharmacokinetics is concerned with the movement of drugs through the body. Although the extremes of bodyweight and renal and liver function will influence the pharmacokinetics of DOACs, are these changes significant enough to affect clinical outcomes of bleeding and thrombosis? In other words, can the fixed-dosing strategy of DOACs accommodate these differences in physiology? In this review, we recap key pharmacokinetic principles for drug dosing; review venous thromboembolism trial and real-world data on patients prescribed DOACs at the extremes of bodyweight, renal function, and liver function; relate this to the pharmacokinetic properties of DOACs; and summarize the state of the field and current unknowns.

Factor Xa inhibitors versus vitamin K antagonist in morbidly obese patients with venous thromboembolism: a systematic review and meta-analysis

INTRODUCTION

Guidelines have endorsed non-vitamin K antagonist oral anticoagulants (NOACs), consisting of factor Xa inhibitors (xabans) and direct thrombin inhibitors, as the first line of treatment in venous thromboembolism (VTE) and atrial fibrillation. However, morbidly obese patients were under-represented in landmark trials of NOACs. Therefore, this study aimed to systematically review and perform a meta-analysis of studies on xabans versus vitamin K antagonist (VKA) in this high-risk population with VTE.

METHODS

PubMed, Embase, Medline, Cochrane library, and Google Scholar databases were searched to identify studies that compared xabans and VKA in treating morbidly obese patients with VTE. Morbid obesity was defined as body weight ≥ 120 kg or BMI ≥ 40 kg/m². Outcomes of interest included recurrent VTE, major bleeding, and clinically relevant non-major bleeding (CRNMB).

RESULTS

Eight studies comprising 30,895 patients were included. A total of 12,755 patients received xabans while 18,140 received VKAs. No significant difference in the odds of recurrent VTE (OR 0.75, 95% CI 0.55-1.01) and CRNMB (OR 0.69, 95% CI 0.44-1.09) was observed between the xabans group and the VKA group. However, the xabans group was associated with lower odds of major bleeding (OR 0.70, 95% CI 0.59-0.83).

CONCLUSION

Xabans have lower odds of major bleeding but similar odds of recurrent VTE when compared with VKAs in treating VTE in morbidly obese patients. Large registry analyses or future randomized controlled trials will be helpful in confirming these findings.

Pharmacokinetics and Dosing Regimens of Direct Oral Anticoagulants in Morbidly Obese Patients: An Updated Literature Review

Data on the impact of morbid obesity (body mass index [BMI] ≥ 40 kg/m²) on the pharmacokinetics (PK), pharmacodynamics (PD) of direct oral anticoagulants (DOACs) are relatively limited, making it difficult to design optimal dosing regimens in morbidly obese patients.To review literature on PK/PD profile, efficacy, and safety of DOACs in venous thromboembolism (VTE) and nonvalvular atrial fibrillation (AF) patients with morbid obesity and make recommendations regarding optimal dosing regimens in these patient populations.A detailed literature search was conducted (from inception to June 22, 2022) for relevant articles involving PK/PD and clinical data on DOACs use in morbidly obese patients with VTE or AF, or healthy volunteers.A total of 28 studies were identified. DOAC-specific PK variations and clinical outcomes have been observed. Obesity may have a modest effect on PK/PD of dabigatran, apixaban, or rivaroxaban. Dabigatran was effective in AF patients with morbid obesity but might increase the risk of gastrointestinal bleeding. Standard dosing of apixaban or rivaroxaban is effective and safe for VTE and AF patients with morbid obesity. Trough edoxaban concentration and anti-Xa activity were similar in different BMI groups (18.5 to >40 kg/m²), and standard dosing of edoxaban may be effective and safe for AF patients.Current evidence suggests dabigatran should be used with caution in patients with AF as it might increase the risk of gastrointestinal bleeding; Standard dosing of apixaban or rivaroxaban can be used in VTE or AF patients; Standard dosing of edoxaban may be considered in AF patients.

Direct Oral Anticoagulants for Stroke Prevention in Special Populations: Beyond the Clinical Trials

Currently, direct oral anticoagulants (DOACs) are the first-line anticoagulant strategy in patients with non-valvular atrial fibrillation (NVAF). They are characterized by a more favorable pharmacological profile than warfarin, having demonstrated equal efficacy in stroke prevention and greater safety in terms of intracranial bleeding. The study population in the randomized trials of DOACs was highly selected, so the results of these trials cannot be extended to specific populations such as obese, elderly, frail, and cancer patients, which, on the other hand, are sub-populations widely represented in clinical practice. Furthermore, due to the negative results of DOAC administration in patients with mechanical heart valves, the available evidence in subjects with biological heart valves is still few and often controversial. We sought to review the available literature on the efficacy and safety of DOACs in elderly, obese, underweight, frail, cancer patients, and in patients with bioprosthetic heart valves with NVAF to clarify the best anticoagulant strategy in these special and poorly studied subpopulations.

The 5 most frequently asked questions about factor Xa inhibitors

Direct oral anticoagulants (DOACs) are commonly used oral factor Xa inhibitors in recent years. However, in some special clinical situations, the appropriate use of these anticoagulants may be of concern. In this article, we address the 5 commonly asked questions regarding their use for the treatment of venous thromboembolism, including in the setting of obesity, renal impairment, gastrointestinal (GI) malignancy, catheter-related thrombosis, and drug-drug interactions. Data on the use of DOACs in the presence of significant obesity or renal failure are mainly observational. Some DOACs are shown to have an increased risk of bleeding in patients with unresected luminal GI malignancy but not others, so selection of appropriate patients is the key. Furthermore, literature on the use of DOACs for catheter-related thrombosis or when drug-drug interactions are of concern is limited, and more research is welcome.

Tailored Direct Oral Anticoagulation in Patients with Atrial Fibrillation: The Future of Oral Anticoagulation?

Direct oral anticoagulants (DOAC) are currently the drug of choice for drug prevention of stroke or systemic embolism in patients with atrial fibrillation (AF). However, repeated ischemic stroke or systemic embolism and bleeding while on DOAC is still a challenging clinical phenomenon in the management of future long-term anticoagulation. It is not known whether tailoring the DOAC therapy to achieve optimal therapeutic drug levels could improve the clinical course of DOAC therapy. To be able to tailor the therapy, it is necessary to have a valid laboratory method for DOAC level assessment, to be aware of factors influencing DOAC levels and to have clinical options to tailor the treatment. Furthermore, the data regarding clinical efficacy/safety of tailored DOAC regimes are still lacking. This article reviews the current data on tailored direct oral anticoagulation in patients with AF.

Dilemmas Related to Direct-Acting Oral Anticoagulant Administration in Patients With Extreme Obesity

OBJECTIVE

The objective of the study was to discuss the controversies surrounding the use and dosing of direct-acting oral anticoagulants (DOACs) in obese patients recognizing the limitations of the existing evidence base that preclude strong recommendations.

DATA SOURCES

A literature search of MEDLINE was performed (2020 to end August 2022) subsequent to recent guidelines using the following search terms: direct acting anticoagulants, obesity, rivaroxaban, apixaban, edoxaban, dabigatran, dabigatran etexilate, and clinical practice guidelines.

STUDY SELECTION AND DATA ABSTRACTION

English-language studies and those conducted in adults were selected.

DATA SYNTHESIS

The available randomized studies evaluating DOACs had relatively small numbers of patients with more extreme forms of obesity (body mass index [BMI] > 40 kg/m²) and none of the larger studies had a specific focus on dosing DOACs in obese patients. Recent guidelines by the International Society on Thrombosis and Haemostasis (ISTH) have specific recommendations for dosing DOACs in obesity. There are pharmacokinetic/pharmacodynamic and observational studies published before and after the ISTH guidelines with a focus on DOAC dosing in obese patients that generally support the recommendations in the guidelines, but most involved small numbers of patients usually with BMIs <45 kg/m².

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

This review discusses DOAC dosing in obesity with important considerations for clinicians related to DOAC choice and dosing.

CONCLUSIONS

Dosing alterations of DOACs do not appear to be necessary when used for either prophylaxis or treatment in patients with BMIs up to approximately 45 to 50 kg/m², but research is needed for BMIs >50 kg/m².

Anticoagulation and BMI: effect of high body weight on the safety and efficacy of direct oral anticoagulants

Obesity is an epidemic with rising prevalence, and obese patients are predisposed to comorbid conditions that increase risk for thromboembolic events. It is critical to identify safe and effective anticoagulation therapy for use in this population. Direct oral anticoagulants (DOACs) are a preferred option for anticoagulation in patients of normal weight due to many benefits and equivalent safety and efficacy to their vitamin K antagonist counterparts. However, the safety and efficacy of DOACs in obese patients is not well understood. This review describes recent studies on the pharmacokinetics, safety and efficacy, and clinical outcomes of the DOACs apixaban, rivaroxaban, edoxaban and dabigatran in obese patient populations. DOACs may be a beneficial alternative to vitamin K antagonist therapy in obese patient populations.

Rivaroxaban Monotherapy in Atrial Fibrillation and Stable Coronary Artery Disease Across Body Mass Index Categories

Background

The AFIRE (Atrial Fibrillation and Ischemic Events With Rivaroxaban in Patients With Stable Coronary Artery Disease) trial showed both noninferiority for efficacy and superiority for safety endpoints of rivaroxaban monotherapy compared with those of rivaroxaban plus antiplatelet therapy (combination therapy) in patients with atrial fibrillation and stable coronary artery disease.

Objectives

This study sought to evaluate outcomes of rivaroxaban monotherapy in those patients across body mass index (BMI) categories.

Methods

Patients were categorized into 4 groups: underweight (BMI <18.5 kg/m²), normal weight (BMI 18.5 to <25 kg/m²), overweight (BMI 25 to <30 kg/m²), and obesity (BMI ≥30 kg/m²). Efficacy (a composite of all-cause death, myocardial infarction, unstable angina requiring revascularization, stroke, or systemic embolism) and safety (major bleeding defined according to International Society on Thrombosis and Haemostasis criteria) were compared between rivaroxaban monotherapy and combination therapy across BMI categories.

Results

This study analyzed 2,054 patients with a median age of 75.0 years and CHA₂DS₂-VASc score of 4. A significant interaction was not observed between BMI categories and effect of monotherapy for efficacy (P = 0.83) and safety (P = 0.07), although monotherapy was superior to combination therapy for efficacy in normal weight (HR: 0.64; 95% CI: 0.44-0.95) and safety in overweight (HR: 0.25; 95% CI: 0.10-0.62), whereas a significant difference in the endpoints was not observed in the other BMI categories.

Conclusions

Rivaroxaban monotherapy had a similar effect on prognosis across all BMI categories in patients with atrial fibrillation and stable coronary artery disease. (Atrial Fibrillation and Ischemic Events With Rivaroxaban in Patients With Stable Coronary Artery Disease [AFIRE]; UMIN000016612, NCT02642419).

Evaluation of safety and efficacy outcomes of direct oral anticoagulants versus warfarin in normal and extreme body weights for the treatment of atrial fibrillation or venous thromboembolism

Despite evolving evidence, the use of direct oral anticoagulants (DOACs) in patients with extremes of body weight remains controversial. This study aimed to measure the impact of DOACs compared to warfarin on safety and efficacy outcomes in extreme body weight patients. This multi-center, health system, retrospective study examined the outcomes of patients with all body weights and extreme body weights prescribed a DOAC (rivaroxaban, apixaban, dabigatran, edoxaban) or warfarin for atrial fibrillation or venous thromboembolism over a 9-year period. The primary outcome was a composite of thromboembolism, symptomatic recurrent VTE, or severe bleeding; analyzed by pre-determined BMI cutoffs. A total of 19,697 patients were included in the study: 11,604 in the DOAC group and in the 8093 in the warfarin group. 295 patients were underweight and 9108 patients were pre-obese to obese class 3. After adjusting for potential confounders, warfarin patients had higher odds of experiencing the composite outcome compared to DOAC patients (OR 1.337, 95% CI 1.212-1.475). Additionally, obese patients were 24.6% more likely to experience the outcome compared to normal BMI patients. Adjusted modeling showed that warfarin patients experienced higher bleed rates compared to DOAC patients (OR 1.432, 95% CI 1.266-1.620). Obese patients were less likely to be diagnosed with a bleed (OR 0.749, 95% CI 0.658-0.854), and underweight patients were more likely to be diagnosed with a bleed (OR 1.522, 95% CI 1.095-2.115) compared to normal BMI patients. In conclusion, DOACs for atrial fibrillation or VTE in patients with extreme body weights appear safe and effective when compared to warfarin.

Association of body mass index with outcomes in patients with newly diagnosed atrial fibrillation: GARFIELD-AF

Objective

While greater body mass index (BMI) is associated with increased risk of developing atrial fibrillation (AF), the impact of BMI on outcomes in newly diagnosed AF is unclear. We examine the influence of BMI on outcomes and whether this is modified by sex and evaluate the effect of non-vitamin K oral anticoagulants (NOACs) in patients with high BMI.

Methods

GARFIELD-AF is a prospective registry of 52 057 newly diagnosed AF patients. The study population comprised 40 482 participants: 703 underweight (BMI <18.5 kg/m²), 13 095 normal (BMI=18.5–24.9 kg/m²), 15 043 overweight (BMI=25.0–29.9 kg/m²), 7560 obese (BMI=30.0–34.9 kg/m²) and 4081 extremely obese (BMI ≥35.0 kg/m²). Restricted cubic splines quantified the association of BMI with outcomes. Comparative effectiveness of NOACs and vitamin K antagonists (VKAs) by BMI was performed using propensity score overlap-weighted Cox models.

Results

The median age of participants was 71.0 years (Q1; Q3 62.0; 78.0), and 55.6% were male. Those with high BMI were younger, more often had vascular disease, hypertension and diabetes. Within 2-year follow-up, a U-shaped relationship between BMI and all-cause mortality was observed, with BMI of ~30 kg/m² associated with the lowest risk. The association with new/worsening heart failure was similar. Only low BMI was associated with major bleeding and no association emerged for non-haemorrhagic stroke. BMI was similarly associated with outcomes in men and women. BMI did not impact the lower rate of all-cause mortality of NOACs compared with VKAs.

Conclusions

In the GARFIELD-AF registry, underweight and extremely obese AF patients have increased risk of mortality and new/worsening heart failure compared with normal or obese patients.

Prescribing direct-acting oral anticoagulants - mind the evidence gap

Direct-acting oral anticoagulants (DOACs) are licensed for the prevention of thromboembolism in non-valvular atrial fibrillation amongst other indications. Prescribers use information derived from the summary of product characteristics which is based on the key trials supporting the DOAC's market authorisation. However, prescribers may not be aware of the limitations within these trials regarding underrepresentation of patient populations commonly encountered in clinical practice and how this may adversely impact them. This review highlights the gaps in the licensing evidence using 4 clinical vignettes that explore prescribing challenges in older adults, female patients, patients with obesity and patients from non-Europid ethnic backgrounds.

Safety and efficacy of Apixaban and Rivaroxaban in obese patients with acute thrombosis/embolism

INTRODUCTION

Direct oral anticoagulants (DOACs) have significant advantages over vitamin K antagonists in the treatment of venous thromboembolism and as prophylaxis against recurrence. However, there is inadequate data to support the safety and efficacy of DOACs in the morbidly obese, and warfarin treatment is currently recommended by the International Society of Hemostasis and Thrombosis for this population.

MATERIALS AND METHODS

We performed a retrospective review of outcomes in 499 patients with BMI ≥ 40 kg/m² admitted from January 2013 to January 2020 with acute venous thromboembolism (VTE) and treated with either rivaroxaban (n=296) or apixaban (n=203).

RESULTS

There were 38 (7.6%) bleeding and clotting events within 60 days of the initiation of DOACs, of which 35 (7.0%) were bleeding events and 3 (0.6%) were clotting events. Patients treated with rivaroxaban had more bleeding episodes (23, 7.8% vs. 12, 5.9%) and higher mortality (21, 7.1% vs. 13, 6.4%) compared with those treated with apixaban; however, these differences were not statistically significant (p=.427 and p=.764, respectively). Most of the bleeding occurred in the genitourinary and gastrointestinal tracts.

CONCLUSIONS

Our study indicates that apixaban and rivaroxaban are not associated with an increase in VTE recurrence in the morbidly obese; however, bleeding rates were slightly higher in the rivaroxaban group compared to the apixaban group.

Morbidly Obese Patients Undergoing Primary Total Joint Arthroplasty May Experience Higher Rates of Venous Thromboembolism When Prescribed Direct Oral Anticoagulants vs Aspirin

BACKGROUND

Morbidly obese (body mass index [BMI] >40 kg/m²) patients undergoing total joint arthroplasty (TJA) are at high risk for postoperative venous thromboembolism (VTE); however, there is debate surrounding the optimal pharmacologic agent for prevention of VTE after TJA in this patient subset. Current guidelines recommend against direct-acting oral anticoagulants (DOACs) in patients of BMI >40 kg/m² due to low quality evidence justifying their use. We evaluated whether patients of BMI >40 kg/m² undergoing primary unilateral TJA would have increased risk of postoperative VTE if prescribed DOACs compared to non-DOAC agents such as aspirin.

METHODS

This retrospective study analyzed 897 patients of BMI >40 kg/m² undergoing primary unilateral TJA. Demographic and comorbidity-related variables were collected. The association between postoperative VTE and prophylactic pharmacologic agent prescribed was evaluated by multivariate logistic regression.

RESULTS

After controlling for comorbidities, we found that the sole use of DOACs, specifically apixaban, for VTE prophylaxis was associated with an increased risk of developing VTE compared to prophylaxis with aspirin alone in patients of BMI >40 kg/m² (odds ratio 2.962, P = .016). Regardless of VTE prophylactic agent, patients with BMI >40 kg/m² undergoing TKA had at least 4.5-fold increased odds of developing VTE compared to patients undergoing THA (OR 4.830, P = .019).

CONCLUSION

In our retrospective study of a large sample size of patients with BMI >40 kg/m², we found that the use of DOACs, specifically apixaban, for VTE prophylaxis following TJA was associated with increased odds of a VTE complication compared to the use of aspirin alone.

Carbamazepine, phenytoin, and oral anticoagulants: Drug‐drug interaction and clinical events in a retrospective cohort

BACKGROUND

Carbamazepine and phenytoin are potent inducers of enzymes that metabolize oral anticoagulants.

OBJECTIVES

To determine the clinical impact of drug-drug interactions between these anticonvulsants and oral anticoagulants, and whether they affect the treatment with direct oral anticoagulants (DOACs) or vitamin K antagonists (VKAs).

MATERIAL AND METHODS

Data on patients cotreated with carbamazepine or phenytoin and an oral anticoagulant were retrospectively retrieved from medical records from 2011 to 2020. Outcomes were time in therapeutic range (TTR), DOAC levels, thromboembolic events, major bleeding, and all-cause mortality.

RESULTS

Among 85 patients (37% female, median age 68 years) treated with carbamazepine (n = 43 [51%]) or phenytoin (n = 42 [49%]), 53 (62%) were initially treated with VKAs and 32 (38%) with DOACs. TTR in VKA patients was 63%, which improved in year 2. Four of seven trough and five of 12 peak DOAC plasma levels were lower than expected. The incidence rate (95% confidence interval) per 100 person-years for thromboembolism was 3.6 (3.1-4.2) for VKA patients and 4.4 (3.5-5.6) for DOAC patients; for major bleeding 1.8 (1.5-2.1) and 1.5 (1.2-1.9), and for all-cause mortality 3.6 (3.1-4.2) and 1.5 (1.2-1.9), respectively. Incidence rates between VKAs and DOACs and between carbamazepine and phenytoin were similar.

CONCLUSION

There was a high incidence of thromboembolism in patients cotreated with anticoagulants and carbamazepine or phenytoin. The incidence rates of thrombotic and bleeding events were similar between VKA and DOAC patients. DOAC levels were lower than expected in 47% of cases tested, without correlation with clinical outcomes.

Rivaroxaban Pharmacokinetics in Obese Subjects: A Systematic Review

INTRODUCTION

Venous thromboembolism (VTE) is a leading cause of morbidity and mortality globally. The direct oral anticoagulants, including rivaroxaban, are relatively novel therapeutic options in the treatment and prevention of VTE. There is a conflicting and inconclusive evidence surrounding the pharmacokinetics (PK) of rivaroxaban in patients with VTE who are obese.

OBJECTIVES

We conducted a systematic review to provide an overview, and to synthesize the available evidence in the current literature pertaining to rivaroxaban PK in obese subjects who are healthy or diseased.

METHODS

The PubMed, Embase, ScienceDirect, Rayyan, and Cochrane Library databases were systematically searched from 1 May 2021 through 28 February 2022. Studies investigating rivaroxaban PK in adult obese subjects were included in the review. Pertinent data, including anthropometric parameters, rivaroxaban dosage regimen, PK parameters, PK model, and outcome measures were extracted. Reference values of rivaroxaban PK parameters in the general population were used for comparison purposes. The review protocol was registered in the PROSPERO database (CRD42020177770).

RESULTS

In the 11 studies included in this systematic review, over 7140 healthy or diseased subjects received rivaroxaban therapy, with varying clinical indications in the diseased population. The reported PK parameters of rivaroxaban in obese subjects compared with reference values in the general population were variable. The reported values of the volume of distribution (V_d) among obese subjects (73.4-82.8 L) fell within the range of values reported/calculated for the general population (59.4-104 L), assuming complete bioavailability. However, some of the reported values of clearance (CL) in obese subjects (7.86-16.8 L.h^-1) do not fall within the range of values reported/calculated for the general population (5.57-11.3 L.h^-1). The reported maximum plasma concentrations in obese subjects versus the general population following a 10 mg dose were 149 vs. 143-180 µg.L^-1, and following a 20 mg dose were 214-305 vs. 299-360 µg.L^-1, respectively. The area under the plasma concentration versus time curves (AUC) over different intervals in obese subjects versus the general population following a 10 mg dose were 1155 (AUC from time zero to infinity [AUC_∞]) vs. 1029 (AUC_∞) µg.h.L^-1; and 1204-2800 (AUC from time zero to 24 h [AUC₂₄]) vs. 3200 (AUC₂₄) µg.h.L^-1, respectively, following a 20 mg dose. The reported values of half-life and time to reach the maximum plasma concentration in obese subjects versus the general population were not consistent across studies.

CONCLUSION

Variable changes and inconsistencies in different rivaroxaban PK parameters were reported in obese subjects. Further well-designed studies are warranted to better characterize the PK and clinical outcomes of rivaroxaban in subjects with obesity.

Dabigatran in cardiovascular disease management: A comprehensive review

Dabigatran, a direct thrombin inhibitor, has robust data for the treatment of deep venous thrombosis and pulmonary embolism, stroke prevention in non-valvular atrial fibrillation, and the prophylaxis of venous thromboembolism (VTE) after knee and hip replacement. Recent studies have evaluated dabigatran to determine its safety and efficacy in such conditions as VTE in malignancy, coronary artery disease, mechanical and bioprosthetic valves, and antiphospholipid syndrome. This article provides a comprehensive review on the role of dabigatran in various cardiovascular diseases.

Real life behaviour of direct oral anticoagulants in patients with nonvalvular atrial fibrillation and morbid obesity

Atrial fibrillation (AF) is the most prevalent arrhythmia worldwide and the main cause of anticoagulation, being direct oral anticoagulants (DOAC) increasingly used in this context. On the other hand, obesity is a known risk thromboembolic factor. In the clinical trials that led to the approval of DOAC for ischemic stroke prevention, patients with morbid obesity were underrepresented. The International Society of Thrombosis and Haemostasis suggests not using these drugs in morbid obese patients. Thus, the primary objectives of this study were to analyse the rates of mortality, thrombotic and haemorrhagic events in patients with morbid obesity. As secondary objectives, factors statistically associated with these events were analysed. Methods: multicentre retrospective study that included patients diagnosed with AF on treatment with DOAC from January 2013 to December 2016. The subgroup of patients with morbid obesity (BMI > 40 and / or weight > 120 kg) was analysed. Mean follow-up was 1.7 years. Results: Amongst 2,492 patients included in the study, 135 patients had morbid obesity (mean age was 71 ± 11 years). The mean scores of the CHA2DS2-VASc and HAS-BLED risk scales were 3.7 ± 1.6 and 2.2 ± 0.9, respectively. Neither differences were found regarding mortality (5.2 vs 6/100 patient-years, p = 0.662), ischemic stroke (0.8 vs 1.9/100 patient-years, p = 0.261) and major bleeding rates (3 vs 3.1/100 patient-years, p = 0.983) between morbidly obese population and general population. Nor was there an association found between the degree of obesity and any of the events studied. Conclusion: DOAC are safe and effective in morbidly obese patients.

Oral Anticoagulant Use in Morbid Obesity and Post Bariatric Surgery: A Review

Bariatric surgery has emerged as a therapy for obesity and the associated comorbidities. Obesity has been shown to be a risk factor for atrial fibrillation as well as venous thromboembolism, both of which are conditions that warrant anticoagulation. There is significant underrepresentation of the morbidly obese population in prospective trials that evaluated direct oral anticoagulants and vitamin K antagonists in atrial fibrillation and venous thromboembolism. We aim to review all the available data that assessed these oral anticoagulants in the morbidly obese population (body mass index >40 kg/m² and weight >120 kg) and in the post-bariatric surgery population. Our findings suggest that direct oral anticoagulants may be safe and effective for anticoagulation in morbidly obese patients for both atrial fibrillation and venous thromboembolism. However, warfarin is the preferred agent in the post-bariatric surgery population, given the limited number of studies on direct oral anticoagulants in this population. Further adequately powered randomized control trials are needed to confirm the safety and efficacy of these oral anticoagulants in the morbidly obese and post-bariatric surgery population.

Apixaban and rivaroxaban use for atrial fibrillation in patients with obesity and BMI ≥50 kg/m2

BACKGROUND

Apixaban and rivaroxaban are increasingly used for thromboembolism prophylaxis in patients with non-valvular atrial fibrillation (NVAF) and commonly in patients with obesity and body mass index (BMI) ≥50 kg/m² despite the limited data.

OBJECTIVES

This study aimed to establish the effectiveness and safety of apixaban and rivaroxaban in patients with NVAF and BMI ≥50 kg/m² .

METHODS

A single health-system, retrospective cohort study evaluated the effectiveness and safety of apixaban and rivaroxaban initiated in adult patients (≥18 years of age) with BMI ≥50 kg/m² and NVAF. Outcomes of ischemic stroke, systemic embolic events, and bleeding were compared to a cohort of patients with BMI 18 to 30 kg/m² .

RESULTS

After 1619 patient-years worth of follow-up in 595 patients, the primary endpoint of incidence of ischemic stroke was numerically similar in both groups, 1.3 per 100 patient-years in the BMI ≥50 kg/m²  group, compared to 2.0 per 100 patient-years in the BMI <30 kg/m²  group (RR 0.65, 95% CI 0.38-1.82, p = 0.544). Incidence of major bleeding and clinically relevant non-major bleeding was also numerically similar between the two groups.

CONCLUSIONS

This study demonstrated that apixaban and rivaroxaban in patients with a BMI ≥50 kg/m² for treatment of NVAF may be safe and effective at preventing thromboembolic events and had no increased risk of bleeding. Although, findings should be interpreted with caution and confirmed with additional studies. This study contributes to the growing body of evidence that direct oral anticoagulants (DOACs) may be effective and safe to use for the treatment of NVAF in patients with BMI ≥50 kg/m² .

Clinical outcomes of dabigatran use in patients with non-valvular atrial fibrillation and weight >120 kg

BACKGROUND

Patients with obesity were underrepresented in studies evaluating the safety and effectiveness of direct oral anticoagulants (DOAC) in patients with non-valvular atrial fibrillation (NVAF). This study compared clinical outcomes in patients with NVAF and weighing >120 kg and ≤120 kg who were receiving dabigatran.

MATERIALS AND METHODS

This retrospective, matched, longitudinal cohort study included patients from three integrated healthcare delivery systems. Patients ≥18 years of age with NVAF were included if between September 1, 2016 and June 30, 2019 they received dabigatran. Patients >120 kg and ≤120 kg were matched up to 1:6 on age, sex, and CHA₂DS₂-VASc score. Data were extracted from administrative databases. The primary outcome was a composite of ischemic stroke, clinically-relevant bleeding, systemic embolism, and all-cause mortality. Multivariable regression analyses were performed.

RESULTS

777 and 3522 patients >120 kg and ≤120 kg, respectively, were matched. The >120 kg group tended to be younger with a higher burden of chronic disease. There was no difference between groups in the composite outcome (adjusted hazard ratio [AHR] 1.10, 95% confidence interval 0.89-1.37) or individual components of the composite. A subanalysis of clinically-relevant bleeding identified that patients >120 kg were at a greater risk of gastrointestinal bleeding (AHR 1.44, 95% CI 1.01-2.05).

CONCLUSIONS

In patients with NVAF and >120 kg, dabigatran use was associated with a small increased risk of gastrointestinal bleeding but no differences in stroke, mortality or clinically-relevant bleeding. These findings suggest that dabigatran use is reasonable in patients with NVAF and weight >120 kg.

Apixaban and rivaroxaban in obese patients treated for venous thromboembolism: Drug levels and clinical outcomes

BACKGROUND

Direct oral anticoagulants (DOAC) use remains challenging in obese patients treated for Venous-Thrombo-Embolism (VTE) due to the paucity of prospective and dedicated studies.

OBJECTIVE

To assess rivaroxaban and apixaban concentrations at different time-points after intake, in obese patients followed at a thrombosis center and treated for VTE; to define factors associated with DOAC levels outside the on-therapy ranges; and to evaluate bleeding and thrombosis rates during follow-up.

METHODS

Observational prospective study in two French University hospitals. Apixaban or rivaroxaban concentrations were measured after the first visit, regardless of last intake in obese patients receiving DOAC for VTE. Concentrations were compared to published reference values for non-obese patients. Demographic, clinical, biological and therapeutic data were collected. Univariate and multivariate analyses were performed to identify factors associated to DOAC concentrations outside the on-therapy ranges.

RESULTS

Out of the 146 patients included, 22 (15%) had DOAC concentrations outside the on-therapy ranges, mainly in the rivaroxaban group (n = 17). Age ≤ 63 years, use of rivaroxaban and time since last intake ≤8 h were associated with DOAC concentrations outside the on-therapy ranges, in multivariable analysis. During the median follow-up of 16 months, two (1%) patients receiving apixaban had recurrent VTE. No patient had major bleeding, 11 (8%) patients had minor bleeding.

CONCLUSION

In this specific prospective bi-centric study dedicated to VTE obese patients, use of DOACs at fixed doses led to concentrations similar to those of non-obese patients in a high proportion of patients, without any effect of the BMI, and with risk-benefit profile comparable to non-obese patients.

Assessment of exposure to direct oral anticoagulants in elderly hospitalised patients

It is unclear whether elderly patients established on direct oral anticoagulants (DOACs) have greater exposure to these drugs, which could subsequently increase their risk of bleeding. We assessed DOAC exposure and factors affecting it in a real-world elderly cohort of patients. For this, 151 medically stable hospital inpatients (76 established on apixaban, 61 on rivaroxaban, 14 on dabigatran) with a median [interquartile range (IQR)] age of 84 (78-89) years were recruited. Patients provided blood samples for measurement of peak and trough plasma DOAC concentrations. There was up to 48-fold and 13-fold variation in trough and peak plasma drug concentrations respectively. A significantly greater proportion of patients on apixaban had peak plasma drug concentrations within the reported ranges compared to those on either rivaroxaban or dabigatran (82·9% vs. 44·3% vs. 64·3% respectively; P < 0·001). A third of the variability in DOAC plasma concentrations was attributed to the influences of DOAC dosage, renal function and gender. To what extent the observed increases in DOAC exposure in the older patients is the cause of their increased risk of bleeding, which could potentially be ameliorated by dosing titration, requires further investigation.

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.

Effectiveness and Safety of Direct Oral Anticoagulants in Patients with Nonvalvular Atrial Fibrillation and Weighing ≥ 120 Kilograms versus 60-120 Kilograms

BACKGROUND

Direct oral anticoagulants (DOACs) have become favorable choices for anticoagulation due to their fixed-dose schedule, limited need for monitoring, and non-inferiority or superiority to warfarin. DOACs are currently not recommended in patients with a body weight ≥ 120 kg or body mass index ≥ 40 kg/m² due to limited data regarding safety and efficacy.

OBJECTIVE

The aim of this study was to compare the safety and efficacy of DOACs in patients with nonvalvular atrial fibrillation (NVAF) and weighing ≥ 120 kg with those weighing < 120 kg.

METHODS

A single-center, retrospective study was conducted in patients weighing ≥ 120 kg who received either apixaban, dabigatran, or rivaroxaban for stroke risk reduction in NVAF, and matched to patients who weighed < 120 kg. The primary outcome was the incidence of stroke, deep vein thrombosis, pulmonary embolism, or myocardial infarction, while the safety outcome was the incidence of major or clinically relevant non-major bleeding based on the International Society on Thrombosis and Haemostasis (ISTH) definitions.

RESULTS

A total of 318 patients weighing ≥ 120 kg with NVAF and meeting the inclusion criteria were evaluated and matched with 318 patients weighing < 120 kg. The primary outcome occurred in 2.5% of patients in the ≥ 120 kg group and in 3.1% of patients in the < 120 kg group (p = 0.632). The safety outcome occurred in 5.3% and 6.6% of patients in these respective groups (p = 0.503).

CONCLUSION

Apixaban, dabigatran, or rivaroxaban may be well-tolerated and effective anticoagulant options in patients with NVAF weighing ≥ 120 kg.

The Importance of Appropriate Dosing of Nonvitamin K Antagonist Oral Anticoagulants for Stroke Prevention in Patients with Atrial Fibrillation

Preventing thromboembolic events, while minimizing bleeding risks, remains challenging when managing patients with atrial fibrillation (AF). Several factors contribute to current dosing patterns of nonvitamin K antagonist oral anticoagulants (NOACs), including patient characteristics, comorbidities, and physician judgment. Application of NOAC doses inconsistent with the drug labels may cause patients to receive either subtherapeutic (increasing stroke risk) or supratherapeutic (increasing bleeding risk) anticoagulant levels. In clinical practice, under- or over-dosing of NOACs in patients with AF is not uncommon. This analysis of prospective and retrospective registry and database studies on NOAC use in patients with AF (with at least 250 patients in each treatment arm) showed that under-dosing may be associated with reduced effectiveness for stroke prevention, with similar or even increased bleeding than with the standard dose. This may reflect underlying conditions and patient factors that increase bleeding despite NOAC dose reduction. Such factors could drive the observed overuse of reduced NOAC dosages, often making the prescription of reduced-dose NOAC an intentional label deviation. In contrast, over-dosing more likely occurs accidentally; instead of providing benefits, it may be associated with worse safety outcomes than the standard dose, including increased bleeding risk and higher all-cause mortality rates. This review summarizes the main findings on NOAC doses usually prescribed to patients with AF in clinical practice.

Oral anticoagulant use in patients with morbid obesity: A systematic review and meta-analysis

OBJECTIVES

Obesity is associated with increased risks of atrial fibrillation (AF) and venous thromboembolism (VTE) for which anticoagulation is commonly used. However, data on the efficacy and safety of oral anticoagulants in patients with morbid obesity are limited.

METHODS

We conducted a systematic review and meta-analysis to evaluate the efficacy and safety of direct oral anticoagulants (DOACs) or vitamin K antagonists (VKAs) for AF or VTE in patients with morbid obesity.

RESULTS

We included 3 randomized controlled trials (5 studies) and 18 observational studies in adult patients with a body weight ≥ 120 kg, body mass index (BMI) ≥ 40 kg/m2 or classified as morbid obesity who received DOACs or VKAs for AF or VTE (N=77,687). The primary efficacy outcome was stroke/systemic embolism or recurrent VTE, and the primary safety outcome was major bleeding. DOACs were associated with a pooled incidence rate of stroke/systemic embolism of 1.16 per 100 person-years, compared to 1.18 with VKAs. The incidence of recurrent VTE on DOACs was 3.83 per 100 person-years, compared to 6.81 on VKAs. In both VTE and AF populations, DOACs were associated with lower risks of major bleeding compared to VKAs. However, all observational studies had moderate to serious risks of bias.

CONCLUSIONS

Patients with morbid obesity on DOACs had similar risks of stroke/systemic embolism, lower rates of recurrent VTE and major bleeding events compared to those on VKAs. However, the certainty of evidence was low given that studies were mostly observational with high risk of confounding.

Pharmacokinetics of Direct Oral Anticoagulants in Patients With Atrial Fibrillation and Extreme Obesity

PURPOSE

Direct oral anticoagulants (DOACs) are recommended in preference to vitamin K antagonists (VKAs) for stroke prevention in patients with atrial fibrillation (AF) eligible for oral anticoagulation therapy; however, data and clinical experiences supporting the use of DOACs in patients with a body mass index ≥40 kg/m² or weight >120 kg remain limited. The aim of this study was to evaluate the pharmacokinetic properties of DOACs in patients with AF and extreme obesity.

METHODS

We enrolled all consecutive patients with AF and extreme obesity undergoing treatment with DOACs followed up at Monaldi Hospital, Naples, Italy. To determine peak plasma and trough levels of DOACs, plasma samples were collected at 2nd, 4th, 6th, and 12th hours from the last dose intake in patients receiving apixaban and dabigatran and at the 2nd, 4th, 6th, and 24th hours in those receiving edoxaban and rivaroxaban. The DOACs' peak and trough plasma levels obtained from our study population were compared with those sourced from pharmacokinetic studies among patients without obesity, defined as a normal reference range in the literature. If at least 1 peak or trough plasma level was found ​​below or above the normal reference ranges, the patients were classified as having out-of-range DOAC plasma levels. Study population was then divided into in-range and out-of-range groups. Baseline characteristics, including DOAC treatment, were compared between the 2 groups. Univariate and multivariate logistic regression analysis were performed to identify baseline variables associated with DOACs' plasma concentration out of the expected range.

FINDINGS

A total of 58 patients (mean [SD] age, 70.93 [8.73] years; 40% female) with extreme obesity (mean [SD] body mass index. 44.43 [3.54] kg/m²) and AF while undergoing DOAC treatment were included in the present study. In 9 patients (15.5 %), the DOAC plasma concentrations were out of the expected ranges (out-of-range group);, indicating a greater likelihood of edoxaban 30 mg treatment (33% vs 2%; P < 0.01) and inappropriate DOAC underdosing (56% vs 4%; P < 0.005) compared with the in-range group. According to the multivariate logistic analysis (P = 0.0011), the inappropriate DOAC underdosing (hazard ratio = 29.37; P = 0.0002) was an independent predictor of DOAC plasma levels out of the expected ranges.

IMPLICATIONS

Patients with extreme obesity and AF who were receiving DOAC therapy had DOAC plasma concentrations in the expected range. The inappropriate DOAC underdosing seems to be the only independent clinical factor associated with a plasma concentration of the drug out of the expected range.

Use of direct oral anticoagulants in patients with obesity for treatment and prevention of venous thromboembolism: Updated communication from the ISTH SSC Subcommittee on Control of Anticoagulation

Although direct-acting oral anticoagulants (DOACs) have widespread first-line use for treatment and prevention of venous thromboembolism (VTE), uncertainty remains regarding their efficacy and safety in patients with obesity. We reviewed available data for use of DOACs for VTE treatment and prevention in patients with obesity, including phase 3, phase 4, meta-analyses, and pharmacokinetic and pharmacodynamics studies. In addition, we reviewed available data regarding DOACs in bariatric surgery. We provide updated guidance recommendations on using DOACs in patients with obesity for treatment and prevention of VTE, as well as following bariatric surgery.

Impact of Weight on Clinical Outcomes of Edoxaban Therapy in Atrial Fibrillation Patients Included in the ETNA-AF-Europe Registry

Background: Extremes of body weight may alter exposure to non-vitamin K antagonist oral anticoagulants and thereby impact clinical outcomes. This ETNA-AF-Europe sub-analysis assessed 1-year outcomes in routine care patients with atrial fibrillation across a range of body weight groups treated with edoxaban. Methods: ETNA-AF-Europe is a multinational, multicentre, observational study conducted in 825 sites in 10 European countries. Overall, 1310, 5565, 4346 and 1446 enrolled patients were categorised into ≤60 kg, >60–≤80 kg (reference weight group), >80–≤100 kg and >100 kg groups. Results: Patients weighing ≤60 kg were older, more frail and had a higher CHA₂DS₂-VASc score vs. the other weight groups. The rates of stroke/systemic embolism, major bleeding and ICH were low at 1 year (0.82, 1.05 and 0.24%/year), with no significant differences among weight groups. The annualised event rates of all-cause death were 3.50%/year in the overall population. After adjustment for eGFR and CHA₂DS₂-VASc score, the risk of all-cause death was significantly higher in extreme weight groups vs. the reference group. Conclusions: Low rates of stroke and bleeding were reported with edoxaban, independent of weight. The risk of all-cause death was higher in extremes of weight vs. the reference group after adjustment for important risk modifiers, thus no obesity paradox was observed.

Body Mass Index Influence on the Clinical Outcomes for Nonvalvular Atrial Fibrillation Patients Admitted to a Hospital Treated with Direct Oral Anticoagulants: A Retrospective Cohort Study

BACKGROUND

Considering that the current fixed dose of direct oral anticoagulants (DOACs) might have insufficient anticoagulation effect for overweight patients, the aim of this study was to compare the effectiveness and safety of anticoagulation between dabigatran and rivaroxaban in different body mass index (BMI) population.

METHODS

We conducted a retrospective cohort study of 2402 DOAC anticoagulated patients with atrial fibrillation who underwent catheter ablation (1290 dabigatran, 53.7% and 1112 rivaroxaban, 46.3%) between January 2017 and December 2018. Patients were distributed based on the BMI into nonobese (1362, BMI <25 kg/m2), preobese (521, BMI 25.0-29.9 kg/m2), class I obese (344, BMI 30.0-34.9 kg/m2) and class II+ obese (175, BMI ≥35.0 kg/m2). We collected information regarding clinical features, laboratory data, bleeding complications and systemic embolic events from the electrical medical records system during 12 months.

RESULTS

The incidence of systemic embolism and stroke complications was higher in the class II+ obese group (P=0.001 and P=0.003). The incidence of bleeding complications and the levels of anticoagulation parameters under the bleeding threshold were similar among the four groups (P>0.05). Cumulative Kaplan-Meier analysis illustrated that rivaroxaban-treated patients who belonged to higher BMI subgroups were more likely to experience shorter time to thrombosis (TTT) (12-month TTT rates of 0.5% for nonobese vs 1.7% for class I obese patients, HR=3.716, P=0.005; 12-month TTT rates of 0.5%, for nonobese vs 4.0% for class II+ obese patients, HR=6.843, P=0.001). However, no statistical significant difference in terms of the time to bleeding complications and the time to cumulative events among the four groups was observed. By multivariate analysis, a higher BMI value (BMI ≥25 kg/m2) (P=0.019; OR=2.094, 95%CI: 1.129-3.883) was an independent predictor for thrombosis in patients treated with dabigatran or rivaroxaban. Positive linear relationship was observed between BMI levels and occurrence rate of thrombosis and bleeding in under anticoagulation patients with NVAF (R2=0.451 and R2=0.383, respectively).

CONCLUSION

The fixed dose of 15 mg rivaroxaban might carry a risk of under exposure, which would lead to an increase of thromboembolic complications in patients with high BMI. Therefore, rivaroxaban dose increase was suggested for obese patients. Use of DOACs appears to have considerable safety in obese patients.

The Pharmacology, Efficacy, and Safety of Rivaroxaban in Obese Patient Populations

Cardiovascular disease (CVD) remains the leading cause of death in the USA. Several risk factors have been identified, and obesity has become one of prominent concern. Excessive weight is considered a risk factor for CVD based on evidence linking it to a hypercoagulable state. Considering the prevalence of CVD and obesity in the USA, along with the increased risk for thrombus-related events, anticoagulation plays a significant role in prevention and treatment. Direct oral anticoagulants have taken the place of many traditional anticoagulants. Considering the recently approved indications and continued postmarketing studies conducted with rivaroxaban, this updated review provides data on the overall impact of obesity on this compound. This includes data obtained from both healthy obese volunteers and obese patients with various CVD conditions enrolled in rivaroxaban clinical trials, along with data obtained from postmarketing real-world evidence studies. Assessment of the clinical pharmacology and population pharmacokinetics in obese individuals revealed no clinically relevant effects of increased weight. Additionally, subgroup analyses from each of the pivotal phase III trials supporting the current approved labeling also demonstrated consistent efficacy and safety results in obese patients. Lastly, these findings are further supported by several recent real-world evidence studies assessing the continued effectiveness and safety of rivaroxaban. In conclusion, rivaroxaban’s overall pharmacological and clinical profile remained consistent in obese adults when assessed in both drug development and postmarketing studies, supporting the premise that higher weight does not necessitate adjustment in either dose strength or regimen.

Evaluation of Anti-Xa Apixaban and Rivaroxaban Levels With Respect to Known Doses in Relation to Major Bleeding Events

BACKGROUND

Although not routinely recommended, anti-Xa level monitoring for apixaban or rivaroxaban may be useful in certain clinical scenarios. There are currently no laboratory standards, therapeutic ranges, or proven correlation between anti-Xa levels and clinical outcomes.

OBJECTIVE

This study describes the utilization, application, and association of anti-Xa levels with clinical outcomes in patients receiving apixaban or rivaroxaban.

METHODS

This retrospective, descriptive study included adult inpatients within the Houston Methodist System on apixaban or rivaroxaban with at least one anti-Xa level ordered subsequent to administered doses. The primary endpoint was major bleeding according to International Society on Thrombosis and Haemostasis criteria. Secondary endpoints included reasons for anti-Xa level ordering, anti-Xa levels at different time intervals post-dose, and thrombotic events. Pre-specified subgroup analyses were performed to further evaluate the primary endpoint.

RESULTS

The study population consisted of 169 patients and 234 anti-Xa levels. Twenty-nine levels were obtained in context of major bleeding. The majority of levels were not drawn as peak levels 2-4 hours post-dose, however remained quantifiable above typical observed levels within this timeframe and well beyond 24 hours post-dose. Patient characteristics with major bleeding included elderly age, acute renal impairment, and low body weight. At least 14 unique reasons for anti-Xa level ordering were identified. Twenty-nine levels were associated with thrombotic events.

CONCLUSION

Anti-Xa levels may be useful for assessment of current drug concentrations, immediate safety of therapy, and guidance for possible clinical interventions. Dose titration and reversal therapies based on anti-Xa level results in major bleeding warrant further research.

Outcomes of Direct Oral Anticoagulants in Atrial Fibrillation Patients Across Different Body Mass Index Categories

OBJECTIVES

This study sought to evaluate direct oral anticoagulant (DOAC) outcomes (vs. warfarin) in patients with atrial fibrillation (AF) across body mass index (BMI) categories, including ≥40 and <18.5 kg/m².

BACKGROUND

Clinical trials have not systematically tested the fixed DOAC dosing in underweight and morbidly obese patients.

METHODS

We retrospectively included consecutive patients with nonvalvular AF with CHA₂DS₂-VASc (Congestive heart failure, Hypertension, Age ≥75, Diabetes, Stroke/transient ischemic attack/systemic thromboembolism, Vascular disease, Age 65-74, Sex) of ≥1 receiving OACs at our hospital system (2010-2018). Patients were categorized into groups 1 (underweight: BMI of <18.5 kg/m²), 2 (normal/overweight: BMI of 18.5 to <30 kg/m²), 3 (grade 1/2 obesity: BMI of 30 to <40 kg/m²), and 4 (grade 3 obesity: BMI of ≥40 kg/m²). We further classified patients by DOAC versus warfarin use. Outcomes were ischemic stroke, significant bleeding events (i.e., resulting in hospitalization), and mortality.

RESULTS

We included 36,094 patients with a mean age of 74 ± 11 years and CHA₂DS₂-VASc of 3.4 ± 1.5. Groups 1 through 4 included 455 (1.3%), 18,339 (50.8%), 13,376 (37.1%), and 3,924 (10.9%) patients, respectively. DOAC use ranged from 49% to 56%. At 3.8 follow-up years, with multivariable Cox regression, DOACs (vs. warfarin) were associated with lower risk of ischemic stroke, bleeding, and mortality across all BMI groups, with hazard ratios (HRs) of 0.73 (95% confidence interval [CI]: 0.63 to 0.85), 0.75 (95% CI: 0.64 to 0.87), 0.75 (95% CI: 0.65 to 0.88), and 0.75 (95% CI: 0.64 to 0.87) (p < 0.001 for all) for ischemic stroke; 0.42 (95% CI: 0.19 to 0.92), 0.41 (95% CI: 0.19 to 0.89), 0.45 (95% CI: 0.20 to 1.00), and 0.43 (95% CI: 0.20 to 0.94) (p < 0.05 for all) for bleeding; and 0.90 (95% CI: 0.68 to 1.19; p = 0.5), 0.70 (95% CI: 0.66 to 0.75; p < 0.0001), 0.65 (95% CI: 0.60 to 0.71; p < 0.0001), and 0.66 (95% CI: 0.56 to 0.77; p < 0.0001) for mortality, in groups 1 to 4, respectively.

CONCLUSIONS

In patients with nonvalvular AF, DOACs compared to warfarin were associated with better safety and effectiveness across all BMI categories, including underweight and morbidly obese patients.

Efficacy and safety of direct oral anticoagulant in morbidly obese patients with atrial fibrillation: systematic review and meta-analysis

AIMS

We conducted a systematic review and meta-analysis on 3 outcomes. We assessed the efficacy and safety of direct oral anticoagulants (DOAC) compared to vitamin K antagonists (VKA) in morbidly obese patients with atrial fibrillation (AF). We compared the efficacy and safety of DOAC in obese patients and non-obese patients with AF. Finally, we updated the current knowledge of outcomes of AF patients with obesity compared to normal-weight patients regardless of anticoagulation type.

METHODS AND RESULTS

Using PubMed and Embase, we searched for literature published from inception to August 2020 for studies conducted in morbidly obese patients with AF who used DOACs and/or VKA for stroke or systemic embolism (stroke/SE) prevention that report efficacy and/or safety data. GRADE assessment was performed to determine the quality of the meta-analysis results. DOAC was not statistically different from VKA in reducing stroke/SE with RR of 0.85 (95%CI: 0.56 to 1.29; very low certainty evidence). Major bleeding risk was lower in the DOAC groups with RR of 0.62 (95%CI: 0.48 to 0.80; low certainty evidence). Obese patients with AF who used DOACs had lower risk of stroke/SE and similar major bleeding risk compared to nonobese patients with RR of 0.77 (95%CI: 0.70 to 0.84; low certainty evidence) and 1.02 (95%CI: 0.94 to 1.09; low certainty evidence), respectively. Obese patients with AF who used any type of anticoagulant had lower risk of stroke/SE compared to normal-weight patients with RR of 0.62 (95%CI: 0.57 to 0.69; low certainty evidence).

CONCLUSIONS

The use of DOACs in morbidly obese patients maybe reasonable if needed, but more dedicated studies are needed to make a more robust recommendation.

Direct Oral Anticoagulants Plasma Levels Measurement: Clinical Usefulness from Trials and Real-World Data

Measurement of direct oral anticoagulants (DOACs) activity is not routinely necessary. Indeed, evaluation of DOACs plasmatic concentration is discouraged for the majority of patients, due to the lack of outcome data supporting this approach. Nevertheless, DOAC measurements may be useful in emergency situations such as serious bleeding events, need for urgent invasive procedures, and acute ischemic stroke or in managing anticoagulation in "special populations" not adequately studied in clinical trials, for example the very elderly or those at the extremes of body weight. The aim of this review is to describe and summarize the methods for DOACs activity evaluation and the settings in which their plasma level measurement may be indicated, analyzing indications from scientific societies and evidence from clinical trials, as well as real world data on the usefulness of DOACs plasma levels "monitoring."