Use of the direct oral anticoagulants in obese patients: guidance from the SSC of the ISTH

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.

Evaluation of modified fixed dose four-factor prothrombin complex concentrate for warfarin reversal

Non-activated four-factor prothrombin complex concentrate (4 F-PCC) has emerged as the preferred reversal strategy for patients on warfarin with life-threatening bleeding. Current dosing recommendations for 4 F-PCC require pre-treatment international normalized ratio (INR) and bodyweight values, resulting in ordering and administration delays. Studies have shown that alternative dosing regimens are safe and efficacious. This retrospective, single-center, pre- and post-protocol analysis was conducted to assess the efficacy of a pharmacist driven modified fixed-dose 4 F-PCC regimen versus package insert weight- and INR-based dosing regimen for warfarin reversal. The primary outcome was achievement of INR less than two. Secondary outcomes included dose and cost of 4 F-PCC, a time analysis, incidence of concomitant vitamin K administration, and incidence of thrombosis within seven days of 4 F-PCC. There were 195 patients included in the analysis, with 74 in the pre-cohort and 121 in the post-cohort. Baseline characteristics were similar between cohorts with the most common indication for warfarin use being atrial fibrillation (48.6% versus 47.1%) and reversal being intracerebral hemorrhage (68.9% versus 43.0%). Achievement of the primary endpoint occurred in 92% versus 95% (p = 0.097) of patients. A statistically significant difference was seen between cohorts regarding median dose and cost of 4 F-PCC administered (p < 0.001). Eleven thromboembolic events occurred with three events in the pre-cohort and eight events in the post-cohort (p = 0.453). A fixed-dose of 1500IU of 4 F-PCC was effective in reversing INR to less than two in most patients regardless of reversal indication with minimal thrombotic risks.

Safety and efficacy of direct oral anticoagulants in comparison to warfarin in obese patients with atrial fibrillation: A systematic review and meta-analysis

Background and Aim

Obesity affects nearly 650 million adults worldwide, and the prevalence is steadily rising. This condition has significant adverse effects on cardiovascular health, increasing the risk of hypertension, coronary artery disease, heart failure, and atrial fibrillation (AF). While anticoagulation for obese patients with AF is a well-established therapy for the prevention of thromboembolism, the safety and efficacy of different anticoagulants in this specific population are not well explored. This meta-analysis aimed to compare direct oral anticoagulants (DOAC) to vitamin K antagonists in obese populations with AF.

Methods

The PRISMA guidelines were followed for this meta-analysis, registered in PROSPERO (CRD42023392711). PubMed, PubMed Central, Embase, Cochrane Library, and Scopus databases were searched for relevant articles from inception through January 2023. Two independent authors screened titles and abstracts, followed by a full-text review in Covidence. Data were extracted in Microsoft Excel and analyzed using RevMan v5.4 using odds ratio as an effect measure.

Results

Two thousand two hundred fifty-nine studies were identified from the database search, and 18 were included in the analysis. There were statistically significant reductions in the odds of ischemic and hemorrhagic stroke in the DOAC group compared with the VKA group (OR 0.70, CI 0.66-0.75) and (OR 0.47, CI 0.35-0.62), respectively. In addition, the DOAC group exhibited lower odds of systemic embolism (OR 0.67, CI 0.54-0.83), major bleeding (OR 0.62, CI 0.54-0.72), and composite outcome (OR 0.72, CI 0.63-0.81).

Conclusion

Based on the findings from this meta-analysis, DOACs demonstrate superior safety and efficacy in obese patients with AF compared with VKAs. These results may have significant implications for guiding anticoagulation strategies in this patient population.

Factor Xa Inhibitors versus warfarin in patients with morbid obesity and atrial fibrillation

PURPOSE

Factor Xa Inhibitors have emerged as a first-line agent in the management of non-valvular atrial fibrillation (NVAF), but there is a need for additional data surrounding their use in the morbidly obese population. The purpose of this study was to evaluate whether Factor Xa Inhibitors are as safe and effective as warfarin for the treatment of NVAF in individuals with a BMI ≥ 40 kg/m2 and/or weight ≥ 120 kg.

METHODS

This was a multi-center retrospective cohort study comparing the use of Factor Xa Inhibitors (apixaban and rivaroxaban) to warfarin for the management of NVAF in adult patients with a BMI ≥ 40 kg/m2 and/or weight ≥ 120 kg. The primary outcomes were stroke or systemic embolism and major bleeding within 12 months.

RESULTS

A total of 3,156 patients were included in the final analysis; 1,396 in the warfarin group and 1760 in the Factor Xa Inhibitor group. The mean weight and BMI of the overall cohort was 134.1 kg and 44.7 kg/m2, respectively. There was no difference in stroke or systemic embolism (OR 1.21, 95% CI 0.78-1.85) or major bleeding (OR 0.99, 95% CI 0.65 - 1.53) with Factor Xa Inhibitors compared to warfarin after controlling for covariates.

CONCLUSION

This analysis of real-world data suggests no difference in bleeding or thrombotic outcomes for severely obese patients with NVAF taking Factor Xa Inhibitors compared to warfarin. Overall, our study adds further data to support the use of Factor Xa Inhibitors as an alternative to warfarin in severely obese patients with NVAF.

Efficacy and Safety of Non-Vitamin-K Antagonist Oral Anticoagulants Versus Warfarin Across the Spectrum of Body Mass Index and Body Weight: An Individual Patient Data Meta-Analysis of 4 Randomized Clinical Trials of Patients With Atrial Fibrillation

BACKGROUND

The efficacy and safety of non-vitamin-K antagonist oral anticoagulants (NOACs) across the spectrum of body mass index (BMI) and body weight (BW) remain uncertain.

METHODS

We analyzed data from COMBINE AF (A Collaboration Between Multiple Institutions to Better Investigate Non-Vitamin K Antagonist Oral Anticoagulant Use in Atrial Fibrillation), which pooled patient-level data from the 4 pivotal randomized trials of NOAC versus warfarin in patients with atrial fibrillation. The primary efficacy and safety outcomes were stroke or systemic embolic events (stroke/SEE) and major bleeding, respectively; secondary outcomes were ischemic stroke/SEE, intracranial hemorrhage, death, and the net clinical outcome (stroke/SEE, major bleeding, or death). Each outcome was examined across BMI and BW. Because few patients had a BMI <18.5 kg/m2 (n=598), the primary analyses were restricted to those with a BMI ≥18.5 kg/m2.

RESULTS

Among 58 464 patients, the median BMI was 28.3 (interquartile range, 25.2-32.2) kg/m2, and the median BW was 81.0 (interquartile range, 70.0-94.3) kg. The event probability of stroke/SEE was lower at a higher BMI irrespective of treatment, whereas the probability of major bleeding was lower at a higher BMI with warfarin but relatively unchanged across BMI with NOACs. NOACs reduced stroke/SEE overall (adjusted hazard ratio [HRadj], 0.80 [95% CI, 0.73-0.88]; P<0.001), with a generally consistent effect across BMI (Ptrend across HRs, 0.48). NOACs also reduced major bleeding overall (HRadj, 0.88 [95% CI, 0.82-0.94]; P<0.001), but with attenuation of the benefit at a higher BMI (trend test across BMI [Ptrend], 0.003). The overall treatment effects of NOACs versus warfarin for secondary outcomes were consistent across BMI, with the exception of the net clinical outcome and death. While these outcomes were overall reduced with NOACs (net clinical outcome, HRadj, 0.91 [95% CI, 0.87-0.95]; P<0.001; death, HRadj, 0.91 [95% CI, 0.86-0.97]; P=0.003), these benefits were attenuated at higher BMI (Ptrend, 0.001 and 0.08, respectively). All findings were qualitatively similar when analyzed across BW.

CONCLUSIONS

The treatment effect of NOACs versus warfarin in atrial fibrillation is generally consistent for stroke/SEE across the spectrum of BMI and BW, whereas the reduction in major bleeding is attenuated in those with higher BMI or BW. Death and the net clinical outcome are overall reduced with NOACs over warfarin, although there remain uncertainties for these outcomes at a very high BMI and BW.

European expert consensus recommendations on the primary care use of direct oral anticoagulants in patients with venous thromboembolism

BACKGROUND

Direct oral anticoagulants for the treatment of venous thromboembolism are supported by robust clinical trial evidence. Despite published guidance, general practitioners are faced with increasingly complex decisions and implementation remains sub-optimal in certain real-world scenarios.

METHODS

A two stage formal consensus exercise was performed to formulate consensus statements and a summary guide, facilitating optimal management of direct oral anticoagulants in venous thromboembolism patients by generalist physicians across Europe. An online questionnaire distributed to a broad panel (Phase 1), followed by a virtual panel discussion by an expert group (Phase 2) were conducted. Phase 1 statements covered nine management domains, and were developed via a literature review and expert steering committee. Participants rated statements by their level of agreement. Phase 1 responses were collated and analysed prior to discussion and iterative refinement in Phase 2.

RESULTS

In total 56 participants from across Europe responded to Phase 1. The majority had experience working as general practitioners. Consensus indicated that direct oral anticoagulants are the treatment of choice for managing patients with venous thromboembolism, at initiation and for extended treatment, with a review at three to six months to re-assess treatment effect and risk profile. Direct oral anticoagulant choice should be based on individual patient factors and include shared treatment choice between clinicians and patients; the only sub-group of patients requiring specific guidance are those with cancer.

CONCLUSION

Results demonstrate an appreciation of best practices, but highlight challenges in clinical practice. The patient pathway and consensus recommendations provided, aim to highlight key considerations for general practice decision making, and aid optimal venous thromboembolism treatment.

Obesity: the perfect storm for heart failure

Obesity condition causes morphological and functional alterations involving the cardiovascular system. These can represent the substrates for different cardiovascular diseases, such as atrial fibrillation, coronary artery disease, sudden cardiac death, and heart failure (HF) with both preserved ejection fraction (EF) and reduced EF. Different pathogenetic mechanisms may help to explain the association between obesity and HF including left ventricular remodelling and epicardial fat accumulation, endothelial dysfunction, and coronary microvascular dysfunction. Multi-imaging modalities are required for appropriate recognition of subclinical systolic dysfunction typically associated with obesity, with echocardiography being the most cost-effective technique. Therapeutic approach in patients with obesity and HF is challenging, particularly regarding patients with preserved EF in which few strategies with high level of evidence are available. Weight loss is of extreme importance in patients with obesity and HF, being a primary therapeutic intervention. Sodium-glucose co-transporter-2 inhibitors have been recently introduced as a novel tool in the management of HF patients. The present review aims at analysing the most recent studies supporting pathogenesis, diagnosis, and management in patients with obesity and HF.

[Bariatric surgery and drugs: Review of the literature and Adverse Drug Reactions analysis in French National Pharmacovigilance Database]

INTRODUCTION

Bariatric surgery is the only treatment for severe obesity (BMI>35kg/m2) currently recognized as effective both in achieving tangible and lasting weight loss, and in improving obesity-related comorbidities such as type 2 diabetes, hypertension, and cardiovascular complications. Bariatric surgery, like any other surgery of the digestive tract, can have an impact on nutrient absorption, as well as on drug absorption. The literature on drug management in bariatric surgery patients concerned mainly of case reports and retrospective studies involving a small number of patients. No official guidelines are available.

METHODS

We conducted a literature search on the consequences of bariatric surgery in terms of drug bioavailability and/or effect. The Medline® (PubMed) database was searched using the following keywords: "bariatric surgery", "bioavailability", "gastric bypass", and "obesity". We completed this review with an analysis of reports of adverse drug reactions (ADRs) in post-bariatric surgery patients for obesity registered in the National pharmacovigilance database (PVDB). We selected all cases with the mention of "bariatric surgery and/or gastrectomy" as "medical history". After reading the cases, we excluded those in which the patient had undergone surgery for an indication other than obesity, where the route of administration was other than oral, and cases in which ADRs resulted from voluntary overdose, attempted suicide, allergy, switch to Levothyrox® new formulation, meningioma under progestative drugs, inefficacy related to generic substitution and medication error.

RESULTS

The literature search identified mainly "case report" about the impact of bariatric surgery on so-called "narrow therapeutic window" drugs. We identified 66 informative cases out of a total of 565 cases selected (11%) in the PVDB. Nevertheless, the information does not allow a clear relationship between the occurrence of the ADR and the influence of bariatric surgery.

CONCLUSION

There is a lack of official information and/or recommendations on medication use in subjects who have undergone bariatric surgery. Apart from under-reporting, ADRs reports remain largely uninformative. Health professional and patients would be awareness for improving, quantitatively and qualitatively the reporting of ADRs in this population.

Efficacy, safety, and feasibility of Apixaban for postoperative venous thromboembolism prophylaxis following open gynecologic cancer surgery at a comprehensive cancer center

OBJECTIVES

To evaluate safety, efficacy, and feasibility of apixaban for postoperative venous thromboembolism (VTE) prophylaxis following open gynecologic cancer surgery at a comprehensive cancer center.

METHODS

This retrospective, cohort study included patients with gynecologic cancer who underwent open surgery between 3/2021 and 3/2023 and received 28-day postoperative VTE prophylaxis. Patients on therapeutic anticoagulation preoperatively were excluded. Predictors of 90- and 30-day VTE and 30-day bleeding events were determined using multivariable logistic regression, adjusting for known confounders.

RESULTS

452 patients were included in the cohort: 348 received apixaban and 104 received enoxaparin. Those who received enoxaparin were more likely to be American Society of Anesthesiologists class III/IV (compared to I/II) (p = 0.033), current or former smokers (p = 0.012) and have a higher BMI (p < 0.001), Charlson Comorbidity Index (p = 0.005), and age (p = 0.046). 30-day VTE rate was significantly lower in the apixaban group (0.6%) compared to the enoxaparin group (6.2%) (adjusted OR 0.13, 95% CI 0.03-0.56; p = 0.006). 90-day VTE rate was 2.7% and 6.2% in the apixaban and enoxaparin groups, respectively (adjusted OR 0.85, 95% CI 0.38-1.92; p = 0.704). Major bleeding complications (2.4% vs. 2.0%) and minor bleeding complications (0.9% vs. 3.0%) were similar in the apixaban and enoxaparin groups, respectively, on multivariate analyses. The median patient out of pocket cost was $10 (IQR 0.0-40.0) for apixaban and $20 (IQR 3.7-67.7) for enoxaparin (p = 0.001).

CONCLUSIONS

Our findings along with previously published data suggest that apixaban should be considered the standard of care for VTE prophylaxis in patients undergoing open surgery for gynecologic malignancies.

Comparing the Clinical Outcomes Observed with Rivaroxaban Versus Warfarin for the Management of Obese Patients with Non-valvular Atrial Fibrillation: a Systematic Review and Meta-analysis

BACKGROUND

Atrial fibrillation (AF) is an irregular heart rhythm which is becoming more and more common in this new era. Obesity is a risk factor for cardiovascular events, and obese patients are more at risk for stroke. The Framingham Heart Study demonstrated an increase in the developmental risk of AF by 4% for every unit (kg/m2) increase in body mass index (BMI). An anticoagulant is often required for the management of such patients. In this analysis, we aimed to systematically compare the clinical outcomes which were associated with rivaroxaban versus warfarin for the treatment of obese patients with non-valvular AF.

METHODS

PubMed, EMBASE, Web of Science, http://www.

CLINICALTRIALS

gov , Google Scholar, and Cochrane Central were the searched databases. Clinical outcomes including stroke, systemic embolism, and major bleeding were the endpoints. In this study, dichotomous data were analyzed by the RevMan software version 5.4. Risk ratio (RR) with 95% confidence interval (CI) was used for result interpretation.

RESULTS

Ten studies consisting of a total number of 168,081 obese participants were included whereby 81,332 participants were treated with rivaroxaban and 86,749 participants were treated with warfarin. The risks of ischemic (RR: 0.79, 95% CI: 0.74-0.84; P = 0.00001) and hemorrhagic stroke (RR: 0.61, 95% CI: 0.48-0.76; P = 0.0001) as well as systemic embolism (RR: 0.73, 95% CI: 0.62-0.87; P = 0.0004) were significantly lower with rivaroxaban compared to warfarin for the management of these obese patients with non-valvular AF. Rivaroxaban was also associated with a significantly lower risk of major bleeding (RR: 0.75, 95% CI: 0.65-0.87; P = 0.0001).

CONCLUSION

Based on this analysis, rivaroxaban seemed to be a better option in comparison to warfarin, due to its association with significantly lower risks of stroke and bleeding outcomes in obese patients with non-valvular AF. However, this hypothesis should further be confirmed in larger clinical trials.

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.

Oral Anticoagulants Beyond Warfarin

Direct oral anticoagulants (DOACs) have largely replaced vitamin K antagonists, mostly warfarin, for the main indications for oral anticoagulation, prevention and treatment of venous thromboembolism, and prevention of embolic stroke in atrial fibrillation. While DOACs offer practical, fixed-dose anticoagulation in many patients, specific restrictions or contraindications may apply. DOACs are not sufficiently effective in high-thrombotic risk conditions such as antiphospholipid syndrome and mechanical heart valves. Patients with cancer-associated thrombosis may benefit from DOACs, but the bleeding risk, particularly in those with gastrointestinal or urogenital tumors, must be carefully weighed. In patients with frailty, excess body weight, and/or moderate-to-severe chronic kidney disease, DOACs must be cautiously administered and may require laboratory monitoring. Reversal agents have been developed and approved for life-threatening bleeding. In addition, the clinical testing of potentially safer anticoagulants such as factor XI(a) inhibitors is important to further optimize anticoagulant therapy in an increasingly elderly and frail population worldwide.

Anti-Xa Monitoring of Apixaban (ZyQuis) in Venous Thrombo-Embolism and Atrial Fibrillation

Apixaban is a direct oral Xa inhibitor and is indicated for the treatment of venous thrombo-embolism (VTE) and prevention of stroke in atrial fibrillation (AF). Recently, a generic (ZyQuis, Zydus Lifesciences Limited, India) has received Food and Drug Administration approval. While bioequivalence has been demonstrated with Eliquis (Bristol-Myers Squibb/Pfizer, UK), it is necessary to monitor its effectiveness prior to acceptance in medical practice. This prospective study independently evaluated Apixaban (ZyQuis) at two accredited laboratories. Participants were converted from Warfarin or Rivaroxaban to Apixaban 5 mg bd for a duration of one month. Peak anti-Xa levels were measured 3-4 h post the morning dose. The samples were processed on the Atellica COAG 360 (Siemens Healthineers, Marburg, Germany) analyzers with a chromogenic anti-Xa assay (Innovance, reference interval 69-321 ng/mL). There were 26 participants; 5 men, 21 women; mean ± standard deviation age of 46 ± 12 years. Indications for anticoagulation included: VTE (88.5%) and AF (11.5%). 69.2% of the participants had at least one comorbidity. 96.2% of the anti-Xa levels were within the laboratory's 95% reference interval. Mean anti-Xa activity was 191 ± 69 ng/mL and 186 ± 68 ng/mL measured at respective laboratories. Mean differences in anti-Xa measurements represented by Bland-Altman statistics were small (bias of -2.6%, 95% confidence interval -1.11 to -4.09) and a strong correlation was observed on Deming regression analysis (0.995). Apixaban (ZyQuis) was effective for the management of VTE and AF as evidenced by anti-Xa activity.

Dysregulated coagulation system links to inflammation in diabetic kidney disease

Diabetic kidney disease (DKD) is a significant contributor to end-stage renal disease worldwide. Despite extensive research, the exact mechanisms responsible for its development remain incompletely understood. Notably, patients with diabetes and impaired kidney function exhibit a hypercoagulable state characterized by elevated levels of coagulation molecules in their plasma. Recent studies propose that coagulation molecules such as thrombin, fibrinogen, and platelets are interconnected with the complement system, giving rise to an inflammatory response that potentially accelerates the progression of DKD. Remarkably, investigations have shown that inhibiting the coagulation system may protect the kidneys in various animal models and clinical trials, suggesting that these systems could serve as promising therapeutic targets for DKD. This review aims to shed light on the underlying connections between coagulation and complement systems and their involvement in the advancement of DKD.

Direct Oral Anticoagulants for the Treatment of Venous Thromboembolism in Obesity

Background: Direct oral anticoagulants (DOACs) are known to have similar efficacy with a decreased risk of bleeding when compared to warfarin for the treatment of venous thromboembolism (VTE). In patients with obesity, there are limited data regarding the safety and efficacy of DOACs. Despite concerns for both under- and over-dosing patients with extremes of body weight, there are no dose adjustment recommendations in the package inserts for any of the DOACs. Objective: To evaluate the safety and efficacy of DOACs versus warfarin for the treatment of VTE in patients with obesity. Methods: This single-center, retrospective cohort study included obese patients initiated on DOAC or warfarin therapy for VTE from January 2015 to January 2022. Patients with cancer, hypercoagulable disorders, end-stage kidney disease, or pregnancy were excluded. The primary endpoint was VTE recurrence. Secondary endpoints included major and minor bleeding. Results: A total of 120 patients met criteria for inclusion. Ninety-two received DOAC therapy and 28 received warfarin. The primary endpoint occurred in 4 patients in the DOAC group and 3 patients in the warfarin group (P = 0.35). Major bleeding occurred in 2 patients. Minor bleeding events occurred in 10 (8.33%) patients. Of those, 6 (6.5%) events occurred in patients receiving a DOAC and 4 (14.3%) events occurred in patients receiving warfarin (P = 0.28). Limitations of this study include the retrospective single-center study design. Conclusions: There was a comparable risk of bleeding and recurrent VTE between DOACs and warfarin in patients initiated on therapy for VTE.

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.

Comparing Safety and Efficacy of Direct Oral Anticoagulants Versus Warfarin in Extreme Obesity

Background: Limited clinical data exists regarding use of direct oral anticoagulants (DOACs) in extreme obesity, specifically those ≥140 kg or having a body mass index (BMI) ≥ 50 kg/m2. Objective: Evaluate the safety and efficacy of DOACs in extreme obesity. Patients/Methods: A retrospective chart review was performed at a single center of patients aged 18-89 years and weight ≥140 kg or BMI ≥50 kg/m2 receiving warfarin or DOAC therapy. Patients were followed for 1 year from prescribing/study inclusion. The primary outcome was the difference in rates of any bleed (composite of major, nonmajor clinically relevant, or minor bleeding events as defined by International Society of Thrombosis and Haemostasis (ISTH) criteria) between groups. Secondary outcomes included individual components of the composite primary outcome and effectiveness in preventing thrombotic events within 12 months. Post-hoc multivariate analysis evaluated potential predictors of bleeding events within overall patient population. Results: Two-hundred eighty-five patients were included, 80 and 205 in the DOAC and warfarin groups, respectively. Rates of any documented bleeding event were comparable in DOAC and warfarin groups (17.5% vs 17.1%, P > .05). No significant difference in rates of minor (P = .067), nonmajor clinically relevant (P = .825), and major (P = 1) bleeding events were observed. Two thrombotic events occurred in the warfarin group compared to none in the DOAC group. Increasing weight was associated with bleeding events in multivariate analysis. Conclusions: This data did not demonstrate a difference in safety or efficacy outcomes between DOACs and warfarin when utilized in patients with extreme obesity.

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.

Construction of a risk scoring system using clinical factors and RYR2 polymorphisms for bleeding complications in patients on direct oral anticoagulants

Introduction: Bleeding is one of the most undesirable complications of direct oral anticoagulants (DOACs). While the ryanodine receptor (RYR2) has been related to cardiac diseases, research on bleeding complications is lacking. This study aimed to elucidate the association between RYR2 and bleeding risk to develop the risk scoring system in patients treated with DOACs. Methods: This study was a retrospective analysis of prospectively collected samples. We selected ten SNPs within the RYR2 gene, and two models were constructed (Model I: demographic factors only, Model II: demographic and genetic factors) in multivariable analysis. Independent risk factors for bleeding were used to develop a risk scoring system. Results: A total of 447 patients were included, and 49 experienced either major bleeding or clinically relevant non-major bleeding. In Model I, patients using rivaroxaban and experiencing anemia exhibited an increased bleeding risk after adjusting for covariates. Upon incorporating genetic factors into Model I, a significant association with bleeding was also observed in cases of overdosing on DOACs and in patients with a creatinine clearance (CrCl) < 30 mL/min, in addition to rivaroxaban and anemia (Model II). Among genetic factors, RYR2 rs12594 GG, rs17682073 AA, rs3766871 GG, and rs6678625 T alleles were associated with bleeding complications. The area under the receiver operating characteristic curve (AUROC) of Model I was 0.670, whereas that of Model II increased to 0.803, demonstrating better performance with the inclusion of genetic factors. Using the significant variables in Model II, a risk scoring system was constructed. The predicted bleeding risks for scores of 0, 1-2, 3-4, 5-6, 7-8, and 9-10 points were 0%, 1.2%, 4.6%, 15.7%, 41.7%, and 73.3%, respectively. Conclusion: This study revealed an association between RYR2 and bleeding complications among patients taking DOACs and established a risk scoring system to support individualized DOAC treatment for these patients.

A Real-World Comparison of Apixaban and Rivaroxaban in Obese and Morbidly Obese Patients With Nonvalvular Atrial Fibrillation

Background: Contemporary guidelines for managing nonvalvular atrial fibrillation (NVAF) include apixaban and rivaroxaban as first-line anticoagulation treatment options. Minimal guidance is available regarding selecting anticoagulants for patients with class I-III obesity. Objective: This study aims to evaluate the comparative effectiveness and safety of apixaban and rivaroxaban in both obese and morbidly obese patients with NVAF. Methods: A retrospective cohort study was conducted at an outpatient cardiovascular clinic after Institutional Review Board approval. Patients were eligible if they were ≥18 years of age, had a BMI ≥30 kg/m2, and took apixaban or rivaroxaban for NVAF for ≥3 months. The primary endpoint was the composite rate of stroke, transient ischemic attack (TIA), myocardial infarction (MI), or presence of atrial thrombosis. Bleeding events were evaluated as the primary safety endpoint. Results: Combined, the cohorts consisted of 303 obese or morbidly obese patients. The primary composite endpoint occurred in 3.8% of patients taking apixaban and 1.7% of patients taking rivaroxaban (P = .28). Both clinically relevant, non-major and major bleeding occurred more often in the apixaban arm, but this difference was not statistically significant; however, bleeding risk may have been skewed due to differences in baseline characteristics. Conclusion and Relevance: For obese and morbidly obese patients prescribed either apixaban or rivaroxaban for NVAF, rates of stroke, TIA, MI, and atrial thrombosis did not differ. The preferred DOAC for patients with class I-III obesity remains elusive, but current data points to a patient-centered approach for anticoagulant selection.

Management of Patients Treated with Direct Oral Anticoagulants in Clinical Practice and Challenging Scenarios

It is well established that direct oral anticoagulants (DOACs) are the cornerstone of anticoagulant strategy in atrial fibrillation (AF) and venous thromboembolism (VTE) and should be preferred over vitamin K antagonists (VKAs) since they are superior or non-inferior to VKAs in reducing thromboembolic risk and are associated with a lower risk of intracranial hemorrhage (IH). In addition, many factors, such as fewer pharmacokinetic interactions and less need for monitoring, contribute to the favor of this therapeutic strategy. Although DOACs represent a more suitable option, several issues should be considered in clinical practice, including drug-drug interactions (DDIs), switching to other antithrombotic therapies, preprocedural and postprocedural periods, and the use in patients with chronic renal and liver failure and in those with cancer. Furthermore, adherence to DOACs appears to remain suboptimal. This narrative review aims to provide a practical guide for DOAC prescription and address challenging scenarios.

Effectiveness and safety of non-vitamin K antagonist oral anticoagulant in the treatment of patients with morbid obesity or high body weight with venous thromboembolism: A meta-analysis

BACKGROUND

Venous thromboembolism (VTE) poses a significant health risk to patients with morbid obesity or high body weight. Non-vitamin K antagonist oral anticoagulants (NOACs) are emerging treatments, but their effectiveness and safety compared with vitamin K antagonists (VKAs) in this population are yet to be thoroughly studied.

METHODS

We conducted a systematic review and meta-analysis, adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Four electronic databases were searched for relevant studies comparing the efficacy and safety of NOACs and VKAs in treating patients with VTE with a body mass index > 40 kg/m2 or body weight > 120 kg. Eligible studies were scored for quality using the Newcastle-Ottawa Scale.

RESULTS

Thirteen studies were included. The meta-analysis results showed that compared to VKAs, NOACs significantly decreased the risk of VTE occurrence (odds ratio = 0.72, 95% CI: 0.57-0.91, I2 = 0%, P < .001) and were associated with a lower risk of bleeding (odds ratio = 0.74, 95% CI: 0.58-0.95, I2 = 0%, P < .05). Subgroup analysis showed that in the cancer patient subgroup, both risks of VTE occurrence and bleeding were lower in the NOAC group than in the VKA group. In patients without cancer, the risk of VTE was significantly lower in the NOAC group.

CONCLUSION

NOACs appear to be more effective and safer than VKAs in patients with morbid obesity or a high body weight with VTE. However, further large-scale randomized controlled trials are required to confirm these findings.

DOACs use in extreme body-weighted patients: results from the prospective START-register

BACKGROUND

Direct oral anticoagulants (DOACs) are widely used for the treatment of venous thromboembolism (VTE) and for stroke prevention in atrial fibrillation (AF). However, evidence in obese and underweight patients is limited. We assessed the safety and effectiveness of DOACs and vitamin K antagonists (VKAs) in patients  ≥ 120 kg or ≤ 50 kg enrolled in an observational prospective cohort study, the START-Register.

METHODS

Adult patients started on anticoagulant therapy were followed up for a median of 1.5 years (IQR 0.6-2.8). Primary efficacy outcome was the occurrence of VTE recurrence, stroke and systemic embolism. Primary safety outcome was major bleeding (MB).

RESULTS

10,080 AF and VTE patients were enrolled between March 2011 and June 2021, 295 patients weighted  ≤ 50 kg and 82 patients ≥ 120 kg. Obese patients were significantly younger than underweight patients. Rates of thrombotic events were low and similar between DOACs and VKAs in underweight patients (1 event on DOACs therapy [0.9% 95% CI 0.11-5.39] and 2 on VKAs [1.1% 95% CI 0.01-47.68]) and in overweight patients (0 events on DOACs, 1 on VKAs [1.6%, 95% CI 0.11-5.79]. Two MB events occurred on DOACs (1.9%, 95% CI 0.38-6.00) and 3 on VKAs (1.6%, 95% CI 0.04-22.06) in the underweight group; 1 MB on DOACs (5.3% 95% CI 0.33-16.68) and 2 on VKAs (3.3%, 95% CI 0.02-130.77) in the overweight group.

CONCLUSIONS

DOACs seem to be effective and safe also for the treatment of patients with extreme body weights, both underweight and overweight. Further prospective studies are needed to support these findings.

Effectiveness and Safety of Direct Oral Anticoagulants for Stroke Prevention in Atrial Fibrillation Patients With Extreme Obesity

Direct oral anticoagulants (DOACs) are a favored treatment to prevent stroke in patients with atrial fibrillation (AF). There are limited data concerning the efficacy and safety of DOACs in obese. Obesity leads to wide structural and physiological changes that may affect the pharmacokinetics and pharmacodynamics of drugs. The optimal dosing strategies for DOACs in this significant and growing sub-group remain unknown. The study aimed to evaluate on a large scale the safety and efficacy of DOAC treatment in extreme obese patients with AF. In this retrospective cohort study, we included patients with AF treated with DOACs. Patients were divided according to body mass index (BMI). Study outcomes included stroke, major bleeding, and death. Between 2012 and 2017, 5183 patients with AF were included in the analysis (2,688, 2137, and 358 patients had a BMI <30, 30 to 40, and >40 accordingly). There was no significant difference in the prevalence of ischemic events (9.9%, 8.2%, and 7.5% of patients with BMI <30, 30 to 40, and >40, respectively, p = 0.088), major bleeding events (13%, 14.1%, and 11.2% of patients with BMI <30, 30 to 40, and >40, respectively, p value = 0.257) or net ischemic and major bleeding events (18.7%, 18.7%, and 15.4% of patients with BMI <30, 30 to 40, and >40 respectively, p = 0.297) between the BMI groups. In conclusion, DOACs treatment for prevention of ischemic events in AF is effective and safe through the BMI spectrum, including extreme obesity.

Therapeutic Drug Monitoring of Direct Oral Anticoagulants in Patients with Extremely Low and High Body Weight-Pilot Study

Phase III clinical trials for individual direct oral anticoagulants (DOACs) contained a limited representation of subjects with abnormal body weight, which were mostly limited to a BMI > 40 kg/m2, or body weight > 120 kg for obese subjects, and <50 kg for underweight subjects. Although low or high body weight is not a contraindication to DOACs therapy, it can significantly affect the safety and effectiveness of treatment. Due to the limited amount of clinical data on the use of DOACs in extremely abnormal weight ranges, optimal pharmacotherapy in this group of patients is a matter of controversy. The objective of this study was to evaluate the pharmacokinetics of DOAC properties in patients with abnormal body weight beyond the established cut-off points in the phase III studies for rivaroxaban, apixaban, and dabigatran. In total, 38 patients took DOACs for at least 12 months for non-valvular atrial fibrillation in 2019-2021. Blood samples were collected before the planned intake of the drug and 4 h after its administration. The determined concentrations of DOACs were statistically analyzed in relation to body weight, age, and eGFR (estimated Glomerular Filtration Rate). Among subjects taking apixaban, rivaroxaban, and dabigatran, the smallest representation of patients who achieved therapeutic concentrations were those treated with dabigatran. The population of people with abnormal body weight is a potential risk group of patients, in which some of them do not reach the therapeutic range of DOACs.

The Effectiveness and Safety of Direct Oral Anticoagulants in Obese Patients With Atrial Fibrillation: A Network Meta-Analysis

Atrial fibrillation (AF) is a cardiac condition characterized by an irregular heart rhythm, which is increasingly prevalent in the modern era. All international guidelines strongly advise the administration of anticoagulants to individuals with AF who are at high risk of stroke. These guidelines recommend the use of direct oral anticoagulants (DOACs) over warfarin because warfarin is significantly associated with increased rates of major bleeding, numerous interactions with food and drugs, and the necessity for frequent monitoring. The aim of this study is to compare the effectiveness and safety of direct oral anticoagulants (DOACs) in obese patients with atrial fibrillation. Two authors independently conducted a comprehensive literature search using electronic databases including PubMed, CINAHL, and EMBASE from inception to June 1, 2023. The efficacy outcome assessed in this meta-analysis included the composite of stroke and systemic embolism. For safety analysis, major bleeding events were compared among the study groups. Eleven studies fulfilled all the inclusion criteria and were included in the present meta-analysis enrolling 144,502 patients. In this study, DOACs demonstrate superior efficacy in preventing stroke/systemic embolism compared to warfarin. Among the DOACs, apixaban emerged as the most effective, followed by rivaroxaban, warfarin, and dabigatran. In terms of safety, apixaban was also found to be the most favorable treatment option, followed by rivaroxaban, dabigatran, and warfarin. In summary, our study concludes that apixaban exhibited greater effectiveness and safety when compared to other DOACs and warfarin in obese patients with AF.

Practices, beliefs, and attitudes of clinicians in prescribing direct oral anticoagulants for obese adults with atrial fibrillation: a qualitative study

BACKGROUND

Atrial fibrillation (AF) and obesity affect over 60 and 650 million people, respectively.

AIM

This study aimed to explore clinician practices, beliefs, and attitudes towards the use of direct oral anticoagulants (DOACs) in obese adults (BMI ≥ 30 kg/m²) with AF.

METHOD

Semi-structured interviews via video conference were conducted with multidisciplinary clinicians from across Australia, with expertise in DOAC use in adults with AF. Clinicians were invited to participate using purposive and snowball sampling techniques. Data were analysed in NVIVO using thematic analysis.

RESULTS

Fifteen clinicians including cardiologists (n = 5), hospital and academic pharmacists (n = 5), general practitioners (n = 2), a haematologist, a neurologist and a clinical pharmacologist participated. Interviews were on average 31 ± 9 min. Key themes identified were: Health system factors in decision-making Disparities between rural and metropolitan geographic areas, availability of health services, and time limitations for in-patient decision-making, were described; Condition-related factors in decision-making Clinicians questioned the significance of obesity as part of decision-making due to the practical limitations of dose modification, and the rarity of the extremely obese cohort; Decision-making in the context of uncertainty Clinicians reported limited availability, reliability and awareness of primary evidence including limited guidance from clinical guidelines for DOAC use in obesity.

CONCLUSION

This study highlights the complexity of decision-making for clinicians, due to the limited availability, reliability and awareness of evidence, the intrinsic complexity of the obese cohort and limited guidance from clinical guidelines. This highlights the urgent need for contemporary research to improve the quality of evidence to guide informed shared decision-making.

Assessment of delayed bleeding after endoscopic submucosal dissection of early-stage gastrointestinal tumors in patients receiving direct oral anticoagulants

Delayed bleeding is a major and serious adverse event of endoscopic submucosal dissection (ESD) for early-stage gastrointestinal tumors. The rate of post-ESD bleeding for gastric cancer is higher (around 5%-8%) than that for esophagus, duodenum and colon cancer (around 2%-4%). Although investigations into the risk factors for post-ESD bleeding have identified several procedure-, lesion-, physician- and patient-related factors, use of antithrombotic drugs, especially anticoagulants [direct oral anticoagulants (DOACs) and warfarin], is thought to be the biggest risk factor for post-ESD bleeding. In fact, the post-ESD bleeding rate in patients receiving DOACs is 8.7%-20.8%, which is higher than that in patients not receiving anticoagulants. However, because clinical guidelines for management of ESD in patients receiving DOACs differ among countries, it is necessary for endoscopists to identify ways to prevent post-ESD delayed bleeding in clinical practice. Given that the pharmacokinetics (e.g., plasma DOAC level at both trough and T_max) and pharmacodynamics (e.g., anti-factor Xa activity) of DOACs are related to risk of major bleeding, plasma DOAC level and anti-FXa activity may be useful parameters for monitoring the anti-coagulate effect and identifying DOAC patients at higher risk of post-ESD bleeding.

Direct oral anticoagulants and warfarin safety in rural patients with obesity

BACKGROUND

Direct oral anticoagulants (DOACs) are often used in patients with atrial fibrillation or flutter instead of warfarin and although supporting evidence is limited, available studies suggest this may be an acceptable route of care. Our study assessed the question: are DOACs as effective and safe as warfarin in patients with atrial fibrillation and class III obesity specifically in a rural population?

METHODS

A retrospective analysis was conducted by examining the first 6-12 months of therapy with a DOAC (apixaban or rivaroxaban) or warfarin in patients with weight >120kg or class III obesity. Events of interest, thrombosis and bleeding, were documented for analysis. The risk and odds of events of interest for both groups were calculated and compared.

RESULTS

Characteristics of both arms were similar (DOAC n=42; warfarin n=43). A lack of thrombosis events limited efficacy analysis. A total of 22 bleeds occurred with 8 in patients prescribed a DOAC (7 minor; 1 major) and 14 in those prescribed warfarin (12 minor; 2 major). Weight in kg (p<0.001), BMI (p=0.013) and HAS-BLED score (p=0.035) were predictive of a first bleeding event in patients prescribed warfarin. The odds ratio for any type of bleed on DOAC vs warfarin was 0.55 (0.180-1.681; 95% CI).

CONCLUSIONS

In patients with atrial fibrillation and class III obesity, regarding safety, DOACs appear to be non-inferior to warfarin during the first six to 12 months of therapy in our rural population - consistent with other analyses; however, the lack of thrombosis events limited the efficacy analysis.

DOAC compared with warfarin for VTE in patients with obesity: a retrospective cohort study conducted through the VENUS network

The effectiveness and safety of direct oral anticoagulants (DOAC) compared with warfarin remains uncertain in obese patients. We assessed the comparative effectiveness and safety of DOACs with warfarin for the treatment of VTE among obese patients. This multi-center retrospective cohort study included adults with a BMI ≥ 35 kg/m2 or weight ≥ 120 kg prescribed either DOAC (apixaban, dabigatran, edoxaban, rivaroxaban) or warfarin for a VTE diagnosis. The primary outcome was the 12-month rate of recurrent VTE. The secondary outcome was the 12-month rate of major bleeding. Among 5626 patients, 67% were prescribed warfarin and 33% were prescribed a DOAC. The 12-month VTE recurrence rate was 3.6% (67/1823) for patients treated with DOAC compared with 3.8% (143/3664) for patients treated with warfarin [odds ratio for recurrent VTE on warfarin versus DOAC (OR) (95% CI).07 (0.80, 1.45)]. The 12-month major bleeding rate was 0.5% (10/1868) for patients on DOAC versus 2.4% (89/3758) on warfarin [OR 4.25 (2.19, 8.22)]. Similar proportions of recurrent VTE occurred across BMI thresholds on DOAC and warfarin: for BMI ≥ 35 kg/m2 (N = 5412), 3.6% versus 3.8%, respectively [OR 1.08 (0.80, 1.46)]; for BMI ≥ 40 kg/m2 (N = 2321), 4.4% versus 3.5%, respectively [OR 0.80 (0.51, 1.26)]; and for BMI ≥ 50 kg/m2 (N = 560), 3.1% versus 3.7%, respectively [OR 1.18 (0.39, 3.56)]. Similar proportions of recurrent VTE occurred in patients with obesity treated for VTE with DOACs and warfarin. DOACs were associated with lower major bleeding compared to warfarin in patients with obesity and VTE.

A review of venous thromboembolism in India

Venous thromboembolism (VTE), which entails the formation of a thrombus (blood clot) in a vein, has a significant disease burden worldwide. While VTE has traditionally been considered to predominantly affect Caucasian populations, recent studies have indicated a gradual shift in the disease burden towards Asian populations, with added significance of it being a key driver of post-operative mortality. It is imperative to develop a sound understanding of the various factors that affect VTE in stratified local populations. However, there is a glaring paucity of quality data on VTE and its ramifications among Indians - both in terms of quality of life and cost of healthcare. This review aims to throw light on the disease burden, epidemiology, risk factors, environmental factors, food and nutrition that plays a key role in VTE. We also explored the association of VTE with coronavirus disease 2019 to grasp the interplay between the two most significant public health crises of our time. It is vital to place a special emphasis on future research on VTE in India to plug the gaps, which exist in our current knowledge of the disease, particularly with respect to Indian population.

Pharmacist Practice Patterns Regarding Direct Oral Anticoagulants for Treatment of Venous Thromboembolism

Background: Direct oral anticoagulants (DOACs) are increasingly prescribed for the treatment of venous thromboembolism (VTE). However, little is known regarding pharmacists' practice patterns and preferences in clinical areas of contention, such as initiation dosing, obesity, and renal impairment. Objective: To determine pharmacist trends in practice regarding DOACs for the treatment of VTE overall and within areas of clinical controversy. Methods: An electronic survey was distributed to pharmacists in the United States through national and state pharmacy organizations. Responses were collected for 30 days. Results: One hundred fifty-three complete responses were submitted. The majority of pharmacists preferred apixaban (90.2%) for the oral treatment of venous thromboembolism. When initiating apixaban or rivaroxaban for a new VTE, 76% and 64% of pharmacists surveyed, respectively, state the duration of the initiation dose phases are reduced if the patient received parenteral anticoagulation. Fifty-eight percent of pharmacists used body mass index to evaluate the appropriateness of DOACs in obese patients whereas 42% used total body weight. Preference for rivaroxaban (31.4%) was higher in this population compared to the global population (10%). Apixaban was preferred for patients with renal impairment (92.2%). However, as creatinine clearance as calculated by the Cockcroft-Gault equation (CrCl) reduced to ≤15 milliliters/minute (mL/min), preference for warfarin increased (36%). Conclusion: This national survey of pharmacists demonstrated an overall preference for apixaban and significant variability in practice patterns regarding DOACs for patients with new VTE, patients with obesity, and patients with renal impairment. Further research is warranted to evaluate the efficacy and safety of DOAC initiation dosing phase modifications. Prospective evaluations of DOACs in obese and renal dysfunction populations would confirm the safety and efficacy of DOACs in these populations.

Circulating adipokine concentrations and the risk of venous thromboembolism: A Mendelian randomization and mediation analysis

Background: Previous observational studies have suggested that circulating adipokine concentrations are related to a greater risk of venous thromboembolism (VTE). However, it remained unclear whether these observations reflect causality.

Objective: This study aimed to investigate the causal relationship between circulating adipokine concentrations (including adiponectin, leptin, PAI-1, MCP-1, leptin receptor, and RETN) and the risk of VTE and its subtypes (DVT and PE) and to determine whether circulating adipokine concentrations are a mediator of venous thromboembolic events in obese patients.

Methods: We used Mendelian randomization (MR) analyses to determine the effects of the body mass index (BMI), adiponectin, leptin, PAI-1, MCP-1, leptin receptor, and RETN levels on VTE, DVT, and PE in a cohort of 11,288 VTE cases, 5,632 DVT cases, 5,130 PE cases, and 254,771 controls. We then assessed the proportion of the effect of obesity on VTE, DVT, and PE explained by circulating leptin levels.

Result: Genetically predicted higher BMI was related to increased VTE (OR = 1.45, p &lt; 0.001), DVT (OR = 1.63, p &lt; 0.001), and PE (OR = 1.37, p &lt; 0.001) risk, and higher circulating leptin levels increase odds of VTE (OR = 1.96, q &lt; 0.001), DVT (OR = 2.52, q &lt; 0.001), and PE (OR = 2.26, q = 0.005). In addition, we found that the causal effect between elevated serum adiponectin and the decreased risk of VTE (OR = 0.85, p = 0.013, q = 0.053) and PE (OR = 0.81, p = 0.032, q = 0.083) and between MCP-1 and the reduced risk of VTE (OR = 0.88, p = 0.048, q = 0.143) is no longer significant after FDR adjustment. In MR mediation analysis, the mediation effect of circulating leptin levels in the causal pathway from BMI to PE was estimated to be 1.28 (0.95–1.71, p = 0.10), accounting for 39.14% of the total effect.

Conclusion: The circulating leptin level is a risk factor for VTE, DVT, and PE, but it might be a potential mediator of BMI on the risk of PE, and thus, interventions on the circulating leptin level in obesity might reduce the risk of PE. Adiponectin is a potential protective factor for both VTE and PE.

Personalizing Direct Oral Anticoagulant Therapy for a Diverse Population: Role of Race, Kidney Function, Drug Interactions, and Pharmacogenetics

Oral anticoagulants (OACs) are commonly used to reduce the risk of venous thromboembolism and the risk of stroke in patients with atrial fibrillation. Endorsed by the American Heart Association, American College of Cardiology, and the European Society of Cardiology, direct oral anticoagulants (DOACs) have displaced warfarin as the OAC of choice for both conditions, due to improved safety profiles, fewer drug-drug and drug-diet interactions, and lack of monitoring requirements. Despite their widespread use and improved safety over warfarin, DOAC-related bleeding remains a major concern for patients. DOACs have stable pharmacokinetics and pharmacodynamics; however, variability in DOAC response is common and may be attributed to numerous factors, including patient-specific factors, concomitant medications, comorbid conditions, and genetics. Although DOAC randomized controlled trials included patients of varying ages and levels of kidney function, they failed to include patients of diverse ancestries. Additionally, current evidence to support DOAC pharmacogenetic associations have primarily been derived from European and Asian individuals. Given differences in genotype frequencies and disease burden among patients of different biogeographic groups, future research must engage diverse populations to assess and quantify the impact of predictors on DOAC response. Current under-representation of patients from diverse racial groups does not allow for proper generalization of the influence of clinical and genetic factors in relation to DOAC variability. Herein, we discuss factors affecting DOAC response, such as age, sex, weight, kidney function, drug interactions, and pharmacogenetics, while offering a new perspective on the need for further research including frequently excluded groups.

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.

Direct Oral Anticoagulants in Obese Patients with Venous Thromboembolism: Results of an Expert Consensus Panel

In clinical practice, direct oral anticoagulants (DOACs) are increasingly used for venous thromboembolism treatment and prevention. A substantial proportion of patients with venous thromboembolism are also obese. International guidance published in 2016 stated that DOACs could be used in standard doses in patients with obesity up to a body mass index [BMI] of 40 kg/m², but should not be used in those with severe obesity (BMI > 40 kg/m²) owing to limited supporting data at the time. Although updated guidance in 2021 removed this limitation, some healthcare providers still avoid DOACs even in patients with lower levels of obesity. Furthermore, there are still evidence gaps regarding treatment of severe obesity, the role of peak and trough DOAC levels in these patients, use of DOACs after bariatric surgery, and appropriateness of DOAC dose reduction in the setting of secondary venous thromboembolism prevention. This document describes proceedings and outcomes of a multidisciplinary panel convened to review these and other key issues regarding DOAC use for treatment or prevention of venous thromboembolism in individuals with obesity.

Transferability of Published Population Pharmacokinetic Models for Apixaban and Rivaroxaban to Subjects with Obesity Treated for Venous Thromboembolism: A Systematic Review and External Evaluations

Apixaban and rivaroxaban have first-line use for many patients needing anticoagulation for venous thromboembolism (VTE). The pharmacokinetics of these drugs in non-obese subjects have been extensively studied, and, while changes in pharmacokinetics have been documented in obese patients, data remain scarce for these anticoagulants. The aim of this study was to perform an external validation of published population pharmacokinetic (PPK) models of apixaban and rivaroxaban in a cohort of obese patients with VTE. A literature search was conducted in the PubMed/MEDLINE, Scopus, and Embase databases following the PRISMA statement. External validation was performed using MonolixSuite software, using prediction-based and simulation-based diagnostics. An external validation dataset from the university hospitals of Brest and Rennes, France, included 116 apixaban pharmacokinetic samples from 69 patients and 121 rivaroxaban samples from 81 patients. Five PPK models of apixaban and 16 models of rivaroxaban were included, according to the inclusion criteria of the study. Two of the apixaban PPK models presented acceptable performances, whereas no rivaroxaban PPK model did. This study identified two published models of apixaban applicable to apixaban in obese patients with VTE. However, none of the rivaroxaban models evaluated were applicable. Dedicated studies appear necessary to elucidate rivaroxaban pharmacokinetics in this population.

Challenges in Cardiovascular Evaluation and Management of Obese Patients: JACC State-of-the-Art Review

Many unique clinical challenges accompany the diagnosis and treatment of cardiovascular disease (CVD) in people living with overweight/obesity. Similarly, physicians encounter numerous complicating factors when managing obesity among people with CVD. Diagnostic accuracy in CVD medicine can be hampered by the presence of obesity, and pharmacological treatments or cardiac procedures require careful adjustment to optimize efficacy. The obesity paradox concept remains a source of confusion within the clinical community that may cause important risk factors to go unaddressed, and body mass index is a misleading measure that cannot account for body composition (eg, lean mass). Lifestyle modifications that support weight loss require long-term commitment, but cardiac rehabilitation programs represent a potential opportunity for structured interventions, and bariatric surgery may reduce CVD risk factors in obesity and CVD. This review examines the key issues and considerations for physicians involved in the management of concurrent obesity and CVD.

First National Consensus on the Safe Practice of Medical Tourism for Bariatric Surgery in Mexico

BACKGROUND

Medical tourism is increasing every year, especially in fields such as bariatric surgery. Global concerns rely on the fact of its safety, mainly because of a lack of standardization, unknown number of cases, and the type of specialists performing such procedures. Mexico continues to be among the top countries receiving patients from abroad, but there is no national consensus, guidelines, or recommendations about the practice in such fields.

METHODS

A group of 32 bariatric surgeons with an accumulated experience of 25,196 procedures in the medical tourism modality were gathered to perform a national consensus in bariatric surgery tourism. The Delphi methodology was used for this project, with a total of 52 items applied. A consensus was reached when the experts' position was ≥ 70% for each statement. The items included pre- and postoperative phases, patient selection, follow-up, and ethical and legal considerations.

RESULTS

Of the 52 statements, 40 (76.9%) reached a consensus of ≥ 70%; 36 in favor, 5 against, and 11 with indeterminate responses.

CONCLUSIONS

Although more than two-thirds of the statements related to high standard practice reached a consensus, weak points in the medical tourism modality were identified. This first consensus serves to establish the basis of safe practices, eventually reach national guidelines, and define the top standards of care when performing bariatric surgery tourism.

A Systematic Review of Warfarin Use in Post-Bariatric Surgery Patients: Cases Compiled From a Literature Review

OBJECTIVE

The objective of this review was to provide dosing recommendations for percentage change in weekly warfarin dose and rates of thrombotic and bleeding events in patients requiring long-term warfarin therapy after bariatric surgery.

DATA SOURCES

A comprehensive literature search of PubMed (through April 5, 2021), Cochrane Library, and Google Scholar (through April 5, 2021) databases was completed using the keywords warfarin OR vitamin k antagonist AND bariatric surgery.

STUDY SELECTION AND DATA EXTRACTION

Retrospective studies and matched-cohort studies evaluating preoperative and postoperative use of warfarin after bariatric surgery for obesity were considered. Weekly dose defined as sum of daily doses of warfarin for 7 consecutive days was a required outcome to be considered in this review. Patients were excluded from review if post-operative dosage change was not reported.

DATA SYNTHESIS

Six studies were included with a total of 160 patients who met the criteria. A decrease in average warfarin dose was seen in all studies, with the largest decrease occurring at 1 month postsurgery followed by an upward trend toward baseline about 90 days postsurgery. While thrombotic events were observed in none of the patients, there was an increased risk of bleeding in patients, particularly in those who underwent roux-en-y gastric bypass (RYGB) surgery.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

The study provides a specific warfarin dosing titration regimen, as well as embolic and bleed risk in post-bariatric surgery population.

CONCLUSIONS

Clinicians may consider lowering warfarin weekly dose by about 25% immediately postsurgery, with doses approaching closer to baseline about 90 days postsurgery.

Management of venous thromboembolism in morbidly obese patients: a 10-year review

Obesity is a known risk factor for venous thromboembolism (VTE) and poses a unique set of challenges in anticoagulation management. We report a 10-year experience of VTE management in morbidly obese patients. We conducted a retrospective analysis of VTE presentations to Northern Health, Victoria, Australia, from January 2011 to December 2020, with median follow-up of 44 months. Morbidly obese patients (defined as weighing > 120 kg) were compared to those ≤ 120 kg. Patients with active malignancy were excluded. 194 VTE cases with weight > 120 kg were compared to 2168 cases weighing ≤ 120 kg. Patients > 120 kg were more likely to present with unprovoked VTE (59.3% vs. 45.2%, p < 0.001) and major VTE (74.7% vs. 67.4%, p = 0.028). Overall, patients > 120 kg were more likely to develop VTE recurrence after anticoagulation cessation (7.80 vs. 3.92 per 100-patient-years, HR 1.97, 95%CI 1.29-3.00), while there were no significant differences in major bleeding or 30-day all-cause mortality. There were no significant differences in outcomes in patients > 120 kg treated with warfarin compared to direct oral anticoagulants (DOAC), or when comparing those treated with an uncapped (1 mg/kg BD) vs. capped (< 1 mg/kg) enoxaparin dosing regimen. Morbid obesity is associated with increased clot burden at presentation and VTE recurrence following anticoagulation cessation, without significant differences in bleeding compared to those ≤ 120 kg. There were no significant differences in morbidly obese patients' outcomes when treated with warfarin or DOAC, or when treated with an uncapped or capped enoxaparin dosing strategy. Larger randomised controlled trials evaluating the safety of DOACs and different enoxaparin dosing strategies in patients > 120 kg are warranted.

Apixaban and Rivaroxaban Anti-Xa Concentration Utilization in Clinical Practice

ABSTRACT

Drug-specific anti-Xa concentrations can be used to assess the presence of drug effects; however, there is inadequate guidance for clinicians on the interpretation and clinical application of these results. The purpose of this study is to review patients' first apixaban and rivaroxaban anti-Xa concentrations to identify indications for monitoring and common therapeutic interventions made based on the results. In addition, we compared bleeding and thrombotic outcomes between the obesity group body mass index ≥40 kg/m 2 and the standard group body mass index 25-39.9 kg/m 2 . A retrospective analysis was conducted at a large academic medical center from January 1, 2020, to December 31, 2020. Primary outcomes were indications for anti-Xa concentrations and interventions on results. A total of 180 patients were included in the analysis, with 119 patients (66%) in the apixaban group and 61 patients (34%) in the rivaroxaban group. The most common indications for anti-Xa concentrations were extreme body weight (23%) and concern for bleeding (22%). About half of the anti-Xa concentrations resulted in therapy changes including holding for procedure, switching to heparin or enoxaparin, holding for an elevated anti-Xa concentration or concern for bleeding, adjusting direct-acting oral anticoagulant dose, or switching to an alternative oral anticoagulant. There were no differences in bleeding complications (5% [2] vs. 16% [14], P = 0.11) or thrombotic complications (8% [3] vs. 9% [8], P = 0.85) between the obesity group and the standard group. Despite the lack of validation of therapeutic ranges for anti-Xa concentrations, this study showed clinical situations where anti-Xa concentration monitoring can be of value.

Warfarin Time in Therapeutic INR Range and Direct Oral Anticoagulant Adherence for Venous Thromboembolism Across the Spectrum of Weight and Body Mass Index: Findings from Veterans Health Administration

The evidence of direct oral anticoagulants (DOACs) usage for venous thromboembolism (VTE) in patients at extremes of body weight or mass index is limited. In such situations, warfarin may be more frequently used. We investigated warfarin time in the therapeutic international normalized ratio range (TTR) and DOAC adherence based on the calculated proportion of days covered (PDC) by pill coverage from a DOAC prescription in patients with VTE across all body sizes. Using data from the Veterans Health Administration (VA), we identified first-time patients with VTE between 2013 and 2018 treated with warfarin or DOACs. We analyzed 28,245 patients with warfarin TTR (N  =  10,167) or DOAC PDC(N  =  18,078). For warfarin-treated patients after index VTE, mean TTR was lower over shorter treatment durations (TTR 30 vs TTR 180 [mean  ±  SD]: 43.8% ± 33.5% vs 58.8% ± 23.5%). Mean TTR over 180 days after VTE was lowest for patients <60 kg (TTR 180 [mean  ±  SD]: <60kg: 49.3% ± 24.2% vs ≥60 to <100 kg: 57.8% ± 23.4%; P < .0001). For DOAC-treated patients over 180 days after index VTE, mean PDC was lowest for patients <60 kg (PDC 180 [mean  ±  SD]: < 60kg: 76.9% ± 33.2% vs ≥ 60 to <100 kg: 83.6% ± 27.7%; P < .0001).Most DOAC-treated patients attained sufficient adherence across the body size spectrum while warfarin-treated patients <60kg were at risk for low TTR.

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.

Safety and efficacy of apixaban, dabigatran and rivaroxaban in obese and morbidly obese patients with heart failure and atrial fibrillation: A real-world analysis

BACKGROUND

Atrial fibrillation and heart failure are combined risk factors for thromboembolic events. Obese and morbidly obese individuals have been underrepresented in clinical trials studying safety and efficacy of direct oral anticoagulants (DOACs).

OBJECTIVES

Study the comparative safety and efficacy of DOACs in obese and morbidly obese patients with atrial fibrillation or flutter, and concomitant congestive heart failure.

METHODS

In the present single-center retrospective observational study, patients with an ICD-9 code of atrial fibrillation or atrial flutter, and congestive heart failure on a DOAC (apixaban[n = 155], rivaroxaban[n = 335], dabigatran[n = 393]) were followed for a median 12.5 months (IQR: 22.1 months). Obesity was defined as a body mass index, BMI ≥ 30 and < 40 kg/m² [n = 614], and morbid obesity as BMI ≥ 40 kg/m² [n = 269]. Clinical endpoints were grouped into safety (composite of intracranial-hemorrhage, gastrointestinal-bleeds, hemorrhagic-stroke, and other bleeds), and efficacy (composite of ischemic-stroke and systemic-embolism) endpoints. Cox proportional hazard models were used to compare safety, efficacy, and all-cause mortality outcomes.

RESULTS

In obese patients, no statistical difference was observed in efficacy of DOACs. A statistical difference was observed in the safety of DOACs in obese patients. Apixaban was found to be safer than dabigatran [hazard ratio [HR] 0.37 (0.16-0.87), p = .02] and rivaroxaban [HR 0.29 (0.12-0.67), p = .004]. In morbidly obese patients, there was no overall statistical difference in the efficacy or safety of DOACs.

CONCLUSION

In obese patients with congestive heart failure and atrial fibrillation or atrial flutter on DOACs, apixaban has the most favorable safety profile compared to rivaroxaban and dabigatran.

Evaluation of Patient Characteristics Linked to Major Bleeding Events in Patients Prescribed Direct Oral Anticoagulants

INTRODUCTION

Direct oral anticoagulants (DOACs) demonstrated similar efficacy and lower risk of intracranial hemorrhage than warfarin in patients with atrial fibrillation and venous thromboembolism. Given the lack of data identifying risk factors in patients who bled while on a DOAC, we sought to investigate these characteristics.

MATERIALS AND METHODS

This retrospective chart review was approved by the Mass General Brigham Institutional Review Board and assessed patients who experienced bleeding events while on DOAC therapy from 6/1/2015 to 7/1/2020. Patient characteristics were evaluated, including age, sex, body mass index (BMI), renal function, concomitant therapies, and baseline comorbidities.

RESULTS

Eighty-seven patients were included for analysis, with a median age of 75.8 years. Most patients were female (51.7%) and 24 (27.6%) had a BMI >30. At time-of-event, 21 patients (24.1%) had acute kidney injury. Thirty-three patients (37.9%) were on concomitant antiplatelet therapy (APT), with 31 (35.6%) on single APT and 2 on dual APT. Pertinent comorbidities included hypertension (74.7%), ischemic cerebrovascular accident (28.7%), thyroid abnormality (23.0%), active cancer (14.9%), and anemia (13.8%). Eleven patients (12.6%) had a prior bleeding event. Most patients were on apixaban (69.0%) for the indication of stroke prevention in nonvalvular atrial fibrillation/flutter (72.4%). FDA-approved dosing was used in most patients (92.0%), and all deviations reflected underdosing. Most bleeding events were defined as major (95.4%), occurred at a critical organ site (72.4%), and developed spontaneously (58.6%).

CONCLUSIONS

These data provide insight into characteristics of patients who experience bleeding events while on DOAC therapy. Understanding these potential risk factors may optimize the safe use of these agents.

Strategies involving low-molecular-weight heparin for the treatment and prevention of venous thromboembolism in patients with obesity: A systematic review and meta-analysis

INTRODUCTION

Recent studies have indicated that the dosage of LMWH in patients with specific weights may be controversial. Therefore, we conducted a meta-analysis to explore an appropriate dosage of LMWH for the prevention and treatment of venous thromboembolism (VTE) in patients with obesity.

MATERIALS AND METHODS

We searched the PubMed, EMBASE, and Cochrane Library databases up to July 23, 2022. Study selection, bias analysis, and information extraction were performed by three independent reviewers. The occurrence or recurrence of VTE and bleeding events were the primary outcomes we assessed.

RESULTS

Eleven studies (a total of 6266 patients) were included in the prevention group, and 6 studies (a total of 3225 patients) were included in the treatment group. For VTE prophylaxis, compared with the standard-dosage group, the high-dosage group had a lower incidence of VTE (OR: 0.47, 95% CI: 0.27-0.82, P=0.007) and a similar incidence of bleeding events (OR: 0.86, 95% CI: 0.69-1.08, P=0.020). For VTE therapy, compared to the standard-dosage group, the reduced-dosage group had a similar incidence of VTE recurrence (OR: 0.86, 95% CI: 0.11-6.84, P=0.89) but a lower incidence of bleeding events (OR: 0.30, 95% CI: 0.10-0.89, P=0.03).

CONCLUSION

In patients with obesity, increasing the dosage of LMWH is a more appropriate option for the prevention of VTE. Due to the limited evidence, reducing the therapeutic dosage of LMWH requires careful consideration. Larger-scale, well-designed randomized controlled trials are necessary.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/display_record.php?, identifier ID=CRD42022298128.