Non-Vitamin K Antagonist Oral Anticoagulants (NOACs) Versus Warfarin in Patients with Atrial Fibrillation and (Morbid) Obesity or Low Body Weight: a Systematic Review and Meta-Analysis

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.

Efficacy of human prothrombin complex concentrate in the treatment of warfarin overdose in patients receiving warfarin for mechanical heart valve replacement

Warfarin, a widely utilized anticoagulant, is paramount for preventing thromboembolic events in patients with mechanical heart valve replacements. However, its narrow therapeutic index can lead to over-anticoagulation and overdose, resulting in serious health risks. This study examines the efficacy of human prothrombin complex concentrate (PCC) in managing warfarin overdose, in comparison with traditional treatments. A retrospective analysis was conducted on 162 adults who presented with warfarin overdose (INR > 5.0) at a tertiary care hospital between 2016 and 2020. Participants were divided into 2 groups-those treated with PCC (n = 57) and those treated with conventional methods (n = 105), including vitamin K and fresh frozen plasma. The primary outcome was the rate of reaching the target (International Normalized Ratio) INR within 24 hours. Secondary outcomes included transfusion requirements, thromboembolic events, adverse reactions, 30-day mortality, and length of hospital stay. PCC demonstrated significant efficacy, with 89.5% of patients achieving the target INR within 24 hours, compared to 64.8% in the control group (P < .05). The PCC group also had reduced transfusion requirements and a shorter average hospital stay. There was no significant difference in thromboembolic events or adverse reactions between the 2 groups, and the reduced 30-day mortality in the PCC group was not statistically significant. Human prothrombin complex concentrate is associated with rapid reaching the target INR, decreased transfusion needs, and shortened hospitalization, making it a promising option for warfarin overdose management. While the results are encouraging, larger, multicenter, randomized controlled trials are necessary to further validate these findings and optimize PCC administration protocols.

Comparative Effectiveness and Safety of Direct Oral Anticoagulants in Low Body Weight Patients with Atrial Fibrillation: A Systematic Review and Meta-analysis

INTRODUCTION

Direct oral anticoagulant (DOAC) agents are established as the anticoagulation strategy of choice for a variety of clinical risks. Despite this, uncertainty still exists with regard to their efficacy and safety for the prevention of stroke and systemic embolism in some patient populations; most notably those with low body weight (LBW) (<60 kg or body mass index [BMI] <18 kg/m2). Currently, there is a paucity of trial and non-trial data to support a prescriptive recommendation for their use in these patient cohorts. We have carried out a pooled systematic review of the most up to date published data of patients stabilized on various DOAC analogs with the view to ascertaining the exact matrices of their efficacy and safety in these cohorts of patients.

METHODS

We initially carried out a comprehensive search of databases from inception to June 2023 for eligible studies exploring the efficacy and safety of various analogs of direct oral anticoagulants in patients with atrial fibrillation who had low body weight. Databases accessed include PubMed, EMBASE, the Science Citation Index, the Cochrane Database of Systematic Reviews, and the Database of Abstracts of Reviews of Effectiveness. We carried out a weighted comparison of derived pooled odd ratios (with their corresponding confidence intervals) of mortality outcomes between various DOACs using the random effects model.

RESULTS

Thirteen studies (n = 165,205 patients) were included in our meta-analysis. DOAC analogs were associated with increased stroke-related events, composite outcome, and mortality in low body weight patients compared to non-low body weight patients (odds ratio [OR] 1.50, 95% confidence interval [CI] 1.17-1.92), (OR 1.55, 95% CI 1.29-1.86), (OR 2.92, 95% CI 1.87-4.58), respectively. There was no significant difference in the safety outcome (major bleeding events) between the DOAC analogs (OR 1.19, 95% CI 0.93-1.52).

DISCUSSION

In this meta-analytical review comprising both real-world and randomized controlled studies, the use of DOAC analogs in low body weight patients (body weight of <60 kg or BMI<18 kg/m2) with atrial fibrillation was associated with increased risks of stroke-related events, composite outcomes, and mortality compared to non-low body weight cohorts patients. At the same time, there was no significant difference in terms of major bleeding events. This finding has provided the first resolution of pervading uncertainty surrounding the use of DOAC analogs in these patient cohorts and suggests the need for follow-up confirmatory systematic studies in this group of patients.

Direct-Acting Oral Anticoagulants in patients at extremes of body weight: a review of pharmacological considerations and clinical implications

Patients at extremes of body weight are underrepresented in randomized controlled trials of direct-acting oral anticoagulants (DOACs). Therefore, their optimal anticoagulant treatment remains a topic of debate. The aim of this narrative review is to summarize the evidence on the pharmacokinetic and pharmacodynamic profile of DOACs for treating patients at extremes of body weight in venous thromboembolism (VTE) and in the prevention of cardioembolic stroke in nonvalvular atrial fibrillation (NVAF). A literature search was conducted in the main bibliographic databases, and the most relevant reviews and original articles on the topic were selected. Although data in these patient groups are limited, apixaban and rivaroxaban show a favorable pharmacokinetic and pharmacodynamic profile in obese VTE treatment and NVAF patients and, in the case of apixaban, also in underweight patients. In particular, these drugs demonstrated comparable efficacy and safety to standard therapy. Very few data were available for dabigatran and edoxaban; the latter drug was safer at a lower dose, mainly in underweight patients. Our findings are in line with the last International Society of Haemostasis and Thrombosis position paper and European Heart Rhythm Association 2021 practical guide, suggesting the use of apixaban and rivaroxaban in morbidly obese patients (>120 kg or body mass index ≥40 kg/m 2 ) and the reduced dosage of edoxaban in low-weight patients. Future studies should focus on large populations of patients at extremes of body weights to acquire more clinical and pharmacokinetic evidence on all available DOACs, especially those currently less investigated.

Safety and efficacy of oral anticoagulants in extreme weights

BACKGROUND

The 2021 International Society on Thrombosis and Haemostasis' (ISTH) recommends standard doses of apixaban and rivaroxaban regardless of high body mass index (BMI) and weight, but had not compare DOACs head-to-head in obesity or address underweight patients.

METHODS

Our aim is to evaluate the safety and efficacy of DOACs in underweight and obese patients compared to warfarin. The primary endpoints include incidence of thromboembolic and bleeding events. Descriptive statistics was used for continuous variables. The Kruskal-Wallis test was used to compare the four-groups for continuous measures and the chi-square test or Fisher's exact test was used to analyze categorical data. The chi-square test or Fisher's exact test, was used for categorical variables, and the Mann-Whitney test (the non-parametric counterpart to the two-sample t-test) for continuous data.

RESULTS

Of 2940 patients receiving anticoagulation for venous thromboembolism (VTE) treatment or atrial fibrillation (AF), 492 met eligibility criteria. Within each group, 248 patients received warfarin, 101 received apixaban, 100 received rivaroxaban and 43 received dabigatran. Patients were characterized in 4 body mass index (BMI) categories, in which 80 were underweight and 412 were obese.

CONCLUSIONS

When each DOAC was compared to warfarin in rates of VTE, apixaban showed statistically significant lower rate of VTE (p = 0.0149). However, no statistical significance was identified in the rate of VTE between DOACs combined vs. warfarin (p = 0.1529). When each DOAC was compared to warfarin, apixaban showed the lowest rate of overall bleeding (p = 0.0194). However, no statistical difference in the rate of bleeding was observed between DOACs combined vs. warfarin (p = 0.3284). Patients with extreme body weights requiring anticoagulation for VTE and AF may safety benefit from DOAC therapy. This evaluation showed apixaban with the lowest rate of VTE and bleeding compared to warfarin, rivaroxaban, and dabigatran. These results provide experience for the clinician to use DOACs, particularly apixaban, in underweight and obese populations.

Mitral Regurgitation and Body Mass Index Increase the Predictability of Perioperative Bleeding in Anticoagulated Patients With Nonvalvular Atrial Fibrillation

Background

Catheter ablation (CA) effectively restores sinus rhythm in atrial fibrillation (AF) but causes a short-term fluctuation in the coagulation state. Potential risk factors and better management during this perioperative period remain understudied.

Methods

We consecutively included 940 patients with nonvalvular AF who received CA at Fuwai Hospital, Beijing, China. Patients were divided into two groups according to their bleeding status during 3 months' anticoagulation. Any adverse events related to bleeding in the 3 months were evaluated. The HAS-BLED score and ABC-bleeding score, as well as other potential factors, were explored to predict bleeding risk.

Results

In this observational study, 8.0% and 0.9% of the whole population suffered from bleeding and thromboembolic events, respectively. After adjusting for known factors related to bleeding, mitral regurgitation (MR, p for trend &lt;0.001) and body mass index (BMI, odds ratio (OR) = 0.920, 95% CI 0.852–0.993, p = 0.033) were the most significant ones. C-indexes of the HAS-BLED score and ABC-bleeding score for bleeding were 0.558 (0.492–0.624) and 0.585 (0.515–0.655), respectively. The incorporation of MR and BMI significantly improved the predictive value based on HAS-BLED score (C-index = 0.650, 95% CI 0.585–0.715, p = 0.004) and ABC-bleeding score (C-index = 0.671, 95% CI 0.611–0.731, p &lt; 0.001). The relative risk of mild-moderate MR was 4.500 (95% CI 1.625–12.460) in patients with AF having HAS-BLED = 1 and 4.654 (95% CI 1.496–14.475) in HAS-BLED ≥ 2, while it was not observed in patients with HAS-BLED = 0 (p = 0.722).

Conclusion

More severe MR and lower BMI are associated with a higher incidence of perioperative bleeding, which helps improve the predictability of increased individual bleeding risk of a patient with nonvalvular AF who has received CA therapy and oral anticoagulants.

The value and limitations of new oral anticoagulant plasma level assessments

The class of new oral anticoagulants (NOACs) has been developed to provide reliable oral anticoagulation without the need for therapeutic drug monitoring. Based on phase I and II trials and pharmacokinetic and pharmacodynamic modeling, fixed drug doses have been selected for large phase III clinical trials for each currently available NOAC. In these trials, the use of the fixed dose without plasma level assessments was shown to be at least as effective and at least as safe as vitamin K antagonists with continuous therapeutic drug monitoring. Real world evidence reaffirms that the use of a fixed NOAC dose without plasma level assessment is safe and effective in a large variety of patients. Nevertheless, measurement of NOAC plasma levels can add information that may be useful in some clinical scenarios. This review discusses the possible use cases, the limitations, and the practical implementation of measuring NOAC plasma concentrations.

Non-Vitamin K Antagonists Versus Warfarin in Patients with Atrial Fibrillation and Bioprosthetic Valves: A Systematic Review and Meta-Analysis

BACKGROUND

Patients with atrial fibrillation and bioprosthetic valves are at high risk for thromboembolic events. The pooled efficacy and safety of non-vitamin K oral anticoagulants (NOACs), as a class, relative to warfarin in this population is not well-known. We aimed to compare the efficacy and safety of NOACs relative to warfarin in patients with bioprosthetic valves or valve repair.

METHODS

We systematically searched EMBASE, PubMed, and Cochrane databases for randomized controlled trials comparing NOACs to warfarin in patients with atrial fibrillation and bioprosthetic valves or valve repair. We pooled outcomes for stroke or systemic embolism, ischemic stroke, hemorrhagic stroke, and major bleeding.

RESULTS

We included 4 trials with 1379 patients, of whom 723 (52.4%) received a NOAC. Mean follow-up ranged from 90 days to 2.8 years. In the pooled analysis, stroke or systemic embolism was significantly lower in patients treated with NOACs (1.9%) compared with warfarin (3.7%) (odds ratio [OR] 0.43; 95% confidence interval [CI] 0.22-0.85; P = .02). Ischemic stroke (OR 0.72; 95% CI 0.18-2.93), hemorrhagic stroke (OR 0.18; 95% CI 0.03-1.05), cardiovascular death (OR 0.78; 95% CI 0.38-1.62), and all-cause mortality (OR 0.94; 95% CI 0.55-1.62) were not significantly different among groups. Major bleeding was significantly lower in patients treated with NOAC (2.8%) compared with warfarin (4.7%) (OR 0.49; 95% CI 0.28-0.88; P = .02).

CONCLUSIONS

In patients with atrial fibrillation and bioprosthetic valves or valve repair, NOACs are associated with a reduced incidence of thromboembolic events and major bleeding as compared with warfarin. Thus, NOACs may be considered a preferred option for this patient population.

Effectiveness and Safety of Rivaroxaban versus Warfarin Among Nonvalvular Atrial Fibrillation Patients with Obesity and Polypharmacy

Background

Current evidence suggests that rivaroxaban may be well tolerated and effective in patients with nonvalvular atrial fibrillation (NVAF) and obesity; however, there is limited evidence on the impact of polypharmacy in this population. This study evaluated real-world clinical outcomes with rivaroxaban versus warfarin in patients with NVAF and obesity according to the number of concurrent medications.

Methods

This retrospective cohort study identified patients with one or more pharmacy claim for rivaroxaban or warfarin from two large claims databases. Patients were required to have an atrial fibrillation diagnosis, body mass index ≥ 30 kg/m² and the presence of polypharmacy (1–4, 5–9, or ≥ 10 concurrent medications). Outcomes of stroke, systemic embolism, and major bleeding were compared between the rivaroxaban and warfarin cohorts after propensity score matching (PSM).

Results

A total of 95,875 patients were identified with one or more claim for either rivaroxaban or warfarin. After PSM, patient characteristics were balanced between cohorts (n = 21,547 in each cohort). The overall composite risk of stroke and systemic embolism was significantly lower in the rivaroxaban cohort compared with the warfarin cohort (hazard ratio [HR] 0.77, 95% confidence interval [CI] 0.70–0.84; p < 0.001). The risks of ischemic stroke, hemorrhagic stroke, and systemic embolism separately were also significantly reduced with rivaroxaban. Major bleeding risk was similar between cohorts (HR 0.93, 95% CI 0.81–1.06; p = 0.2842), and results were consistent across the three polypharmacy groups.

Conclusions

In this real-world study of NVAF patients with obesity, rivaroxaban was associated with lower risks of stroke and systemic embolism and similar risk of major bleeding versus warfarin across polypharmacy categories.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40256-021-00520-7.

Healthcare Resource Utilization and Costs of Rivaroxaban Versus Warfarin Among Nonvalvular Atrial Fibrillation Patients with Obesity and Diabetes

INTRODUCTION

Nonvalvular atrial fibrillation (NVAF) is associated with a substantial economic burden, particularly in patients with comorbid conditions. This study compared healthcare resource utilization (HRU) and costs of rivaroxaban and warfarin in patients with NVAF, obesity, and diabetes.

METHODS

A de-identified healthcare claims database was used to identify adult patients newly initiating rivaroxaban or warfarin and having at least one medical claim with a diagnosis of AF, obesity determined by validated algorithm, and at least one claim with a diagnosis of diabetes or for antidiabetic medication from December 2011 to March 2020. Propensity score matching was used to balance the treatment cohorts on the basis of demographics and baseline characteristics. All-cause and NVAF-related HRU rates and costs were compared between treatments using rate ratios, and mean cost differences were calculated on a per patient per year (PPPY) basis.

RESULTS

A total of 9999 matched pairs of patients with NVAF, obesity, and diabetes were identified in the rivaroxaban and warfarin cohorts. Rate ratios of all-cause HRU were significantly reduced with rivaroxaban versus warfarin in all healthcare settings evaluated, except emergency room visits. The greatest impact was on physician office visits followed by hospital outpatient and inpatient visits. NVAF-related HRU was significantly lower for rivaroxaban versus warfarin in all care settings. Consistent with these findings, the length of hospital stay was significantly reduced by approximately 4 days among all patients for both all-cause and NVAF-related hospitalizations in the rivaroxaban cohort compared with the warfarin cohort. Rivaroxaban was associated with reductions in all-cause total healthcare costs by more than $5000 PPPY and NVAF-related medical costs by approximately $1100 PPPY.

CONCLUSION

In comparison with warfarin, rivaroxaban reduced HRU and costs, particularly hospital inpatient and outpatient visits and physician office visits, in patients with NVAF and comorbidities of obesity and diabetes.

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.

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.