Effect of extremes of body weight on drug level in patient treated with standard dose of rivaroxaban for venous thromboembolism; real life experience

Real life results of direct-acting oral anticoagulants recommended-dose in obese vs normal-weight patients with venous thromboembolism

BACKGROUND

There is scarce evidence on the effectiveness and safety of recommended-dose direct acting oral anticoagulants (DOACs) in obese patients with venous thromboembolism (VTE).

MATERIAL AND METHODS

We used the data in the RIETE registry to compare the rates of VTE recurrences and major bleeding during long-term therapy with DOACs at recommended doses in patients with body mass index ≥30 kg/m2 (obese) vs. those with BMI 18.5-24.9 kg/m2 (normal weight). We performed regression models with competing risks for death.

RESULTS

From January 2013 through October 2022, 2885 obese patients and 2676 with normal weight in RIETE received rivaroxaban (n = 3020), apixaban (n = 1754), edoxaban (n = 636) or dabigatran (n = 151). Median age was 63 years and 52 % were female. At baseline, obese patients were more likely to have diabetes (18.6 % vs. 8.4 %), hypertension (51.9 % vs. 31.4 %) or pulmonary embolism (67.7 % vs. 61 %), and less likely to have renal insufficiency (5.3 % vs. 16 %) or anaemia (21.8 % vs. 28 %%). During anticoagulation (median, 147 vs. 101 days), the obese had a similar rate of VTE recurrences (1.71 vs. 2.14 events per 100 patients-years; hazard ratio (HR): 0.81; 95 % CI: 0.49-1.34) or major bleeding (1.45 vs. 1.76 per 100 patients-years; HR: 0.91; 95 % CI: 0.52-1.59) than those with normal weight. These findings persisted after multivariable analysis (recurrent VTE, HR: 0.80; 95 % CI: 0.48-1.32; major bleeding, HR: 1.11; 95 % CI: 0.60-2.07).

CONCLUSION

The use of DOACs at recommended doses in obese patients with VTE was associated with similar rates of VTE recurrences or major bleeding than in patients with normal weight.

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.

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.

Generic Methods for Simultaneous Analysis of Four Direct Oral Anticoagulants in Human Plasma and Urine by Ultra-High Performance Liquid Chromatography-Tandem Mass Spectrometry

The new direct oral anticoagulants (DOACs) are increasingly used to treat and prevent thromboembolic disorders, and monitoring concentrations may be valuable in some special scenarios to prevent clinical adverse events. This study aimed to develop generic methods for the rapid and simultaneous analysis of four DOACs in human plasma and urine. Protein precipitation and one-step dilution were used to prepare the plasma and urine; the extracts were injected to ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) for analysis. Chromatographic separation was performed on an Acquity™ UPLC BEH C₁₈ column (2.1 × 50 mm, 1.7 μm) with gradient elution of 7 min. A triple quadrupole tandem mass spectrometer with an electrospray ionization source was employed to analyze DOACs in a positive ion mode. The methods showed great linearity in the plasma (1~500 ng/mL) and urine (10~10,000 ng/mL) for all analytes (R² ≥ 0.99). The intra- and inter-day precision and accuracy were within acceptance criteria. The matrix effect and extraction recovery were 86.5~97.5% and 93.5~104.7% in the plasma, while 97.0~101.9% and 85.1~99.5% in the urine. The stability of samples during the routine preparation and storage were within the acceptance criteria of less than ±15%. The methods developed were accurate, reliable, and simple for the rapid and simultaneous measurement of four DOACs in human plasma and urine, and successfully applied to patients and subjects with DOACs therapy for anticoagulant activity assessment.

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

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

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

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

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

BACKGROUND

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

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

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

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

AIMS

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

METHODS AND RESULTS

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

CONCLUSIONS

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

Direct Oral Anticoagulants in the Treatment of Venous Thromboembolism: Use in Patients with Advanced Renal Impairment, Obesity, or Other Weight-Related Special Populations

There are currently more than 7 million patients taking a direct oral anticoagulant (DOAC), with more new prescriptions per year than warfarin. Despite impressive efficacy and safety data for the treatment of venous thromboembolism, patients with obesity or advanced renal impairment represented a small portion of the patients enrolled in the phase 3 clinical trials. Therefore, to evaluate the potential use of DOACs in these special populations, clinicians need to have an understanding of the pharmacokinetics and pharmacodynamics of these agents in these settings. Since data from randomized controlled trials are limited, data from observational trials are helpful in gaining comfort with the use of DOACs in these special populations. Selecting the appropriate dose for each agent is imperative in achieving optimal patient outcomes. We provide an extensive review of the pharmacokinetics, pharmacodynamics, phase 3 clinical trials, and observational studies on the use of DOACs in patients with advanced renal impairment, obesity, or other weight-related special populations to provide clinicians with a comprehensive understanding of the data for optimal drug and dose selection.

Direct oral anticoagulant therapy in patients with morbid obesity after intermediate- or high-risk pulmonary emboli

There is little reported on the efficacy and safety of direct oral anticoagulants (DOACs) in morbid obesity after venous thromboembolism (VTE). In this observational study, patients were followed up after intermediate- or high-risk pulmonary embolism (PE) at the University of Rochester Pulmonary Hypertension Clinic 2-4 months after the initial event. All patients had echocardiography and V/Q imaging regardless of symptoms. Outcomes of interest were the rates of recurrent VTE, thrombus resolution and development of chronic thromboembolic pulmonary hypertension (CTEPH) in patients with morbid obesity treated with a DOAC compared to treatment with vitamin K antagonists and to non-morbidly obese patients after PE. Using the electronic medical record, recurrent events were assessed up to 12 months after the event. 107 patients (body mass index (BMI)>40 kg·m^-2, n=32; BMI 30-39.9 kg·m^-2, n=39; BMI<30 kg·m^-2, n=36) attended follow-up appointments after treatment for PE. A DOAC was used in 70 patients (BMI>40 kg·m^-2, n=19; BMI 30-39.9 kg·m^-2, n=27; BMI<30 kg·m^-2, n=24). There were no recurrent events within the first 12 months of initial diagnosis based on symptoms and imaging in any patient. There was no difference in rate of residual unmatched perfusion defect with DOACs or conventional anticoagulation (49% versus 49%). This finding remained in the subset of morbidly obese patients (47% versus 50%). For the overall cohort, there was no difference in the rate of CTEPH development based on anticoagulation with a DOAC (5% versus 8% with warfarin). There were no major bleeding complications with a DOAC. DOAC therapy appears to be effective and safe in morbid obesity even after intermediate- or high-risk PE. ​.

Safety and efficacy of direct oral anticoagulants across body mass index groups in patients with venous thromboembolism: a retrospective cohort design

Current literature on the safety and efficacy of direct oral anticoagulants (DOACs) in patients of extreme weights are limited, however, they are still being prescribed in these populations. The objective of this study is to describe the safety and efficacy of DOAC therapy in patients of extreme weights for the treatment of venous thromboembolism (VTE) using body mass index (BMI) groups. A multi-site, retrospective cohort design at four hospitals was performed. Patients who experienced an initial VTE between November 2012 and August 2017 and placed on a DOAC were included. Patients were defined as: extremely obese (EO) if BMI ≥ 40 kg/m², obese if BMI 30-39.9 kg/m², normal/overweight if BMI 18.5-29.9 kg/m², and underweight if BMI < 18.5 kg/m². The primary efficacy outcome of recurrent VTE and primary safety outcome of major bleeding (MB) within 12 months were compared between weights. Univariate statistical tests and multivariate logistic regression analyses were performed. Rates of recurrent VTE showed no significant differences (p = 0.58) across groups; 7.8% (11/142) EO, 4.7% (18/383) obese, 5.2% (27/517) normal/overweight, and 5.9% (1/17) underweight. Proportions of MB were overall significantly different (p = 0.026); 6.3% (9/142) EO, 10.4% (40/383) obese, 10.1% (52/517) normal/overweight, and 29.4% (5/17) underweight. EO and obese patients had similar odds of MB compared to normal/overweight (OR 0.61, 95% CI [0.29, 1.26] and OR 1.04, 95% CI [0.67, 1.61]). Underweight patients showed larger odds of MB compared to normal/overweight (OR 3.73, 95% CI [1.26, 11.0]). This study found that recurrence of VTE was not associated with BMI. However, the proportions of major bleeding were statistically different among the BMI categories.

Dosage of Anticoagulants in Obesity: Recommendations Based on a Systematic Review

Anticoagulants are frequently used as thromboprophylaxis and in patients with atrial fibrillation (AF) or venous thromboembolism (VTE). While obesity rates are reaching epidemic proportions worldwide, the optimal dosage for obese patients has not been established for most anticoagulants, including low-molecular-weight heparin (LMWH), non-vitamin K antagonist oral anticoagulants (NOAC), and pentasaccharides (fondaparinux). The aim of the present systematic review was to summarize the current knowledge and provide recommendations on dosage of LMWH, NOAC, and fondaparinux in obese patients (body mass index [BMI] ≥ 30 kg/m² or body weight ≥ 100 kg). Based on a systematic search in PubMed and Embase, a total of 72 studies were identified. For thromboprophylaxis with LMWH in bariatric surgery (n = 20 studies), enoxaparin 40 mg twice daily, dalteparin 5,000 IE twice daily, or tinzaparin 75 IU/kg once daily should be considered for patients with BMI ≥ 40 kg/m². For thromboprophylaxis with LMWH in nonbariatric surgery and in medical inpatients (n = 8 studies), enoxaparin 0.5 mg/kg once or twice daily or tinzaparin 75 IU/kg once daily may be considered in obese patients. For treatment with LMWH (n = 18 studies), a reduced weight-based dose of enoxaparin 0.8 mg/kg twice daily should be considered in patients with BMI ≥ 40 kg/m², and no dose capping of dalteparin and tinzaparin should be applied for body weight < 140 kg. As regards NOAC, rivaroxaban, apixaban, or dabigatran may be used as thromboprophylaxis in patients with BMI < 40 kg/m² (n = 4 studies), whereas rivaroxaban and apixaban may be administered to obese patients with VTE or AF, including BMI > 40 kg/m², at standard fixed-dose (n = 20 studies). The limited available evidence on fondaparinux (n = 3 studies) indicated that the treatment dose should be increased to 10 mg once daily in patients weighing > 100 kg.

Direct oral anticoagulants in the treatment of acute venous thromboembolism in patients with obesity: A systematic review with meta-analysis

BACKGROUND

Direct oral anticoagulants' (DOAC) pharmacokinetics are affected by obesity. Their efficacy and safety in obesity (BMI≥30 kg/m²) and morbid obesity (BMI≥40 kg/m²) are still unclear in the treatment of venous thromboembolism (VTE).

OBJECTIVES

To compare the efficacy/safety of DOAC versus vitamin K antagonist (VKA)/low molecular weight heparin (LMWH) for the treatment of VTE in patients with obesity and morbid obesity. The primary efficacy/safety outcomes were VTE recurrence and major bleeding (MB). Clinically relevant non-MB and mortality were also evaluated.

METHODS

A systematic literature search (MEDLINE, EMBASE, CENTRAL, Web of Science) identified studies evaluating DOAC in the treatment of VTE in patients with obesity and reporting one of the outcomes. Relative risks (RR) and 95 % confidence intervals (CI) were estimated using the Mantel-Haenszel method.

RESULTS

We included 21 studies (50,360pts) of which 16,150 patients had a BMI≥30 kg/m² and 6443 patients had a BMI≥40 kg/m². VTE recurrence was similar with DOAC compared to VKA/LMWH in patients with obesity (RR 1.03;95 %CI 0.93-1.15;p = 0.55) and morbid obesity (RR 1.06;95 %CI 0.94-1.19;p = 0.35). DOAC were also associated with a reduction in MB (RR 0.57;95 %CI 0.34-0.94;p = 0.03 and RR 0.71;95 %CI 0.50-1.00;p = 0.05 in patients with obesity and morbid obesity, respectively). Subgroup analyses comparing randomized controlled trials to observational studies showed consistent results. No difference was observed in regards of clinically relevant non-MB and mortality.

CONCLUSION

There is no signal for differences in VTE recurrence in patients with obesity and morbid obesity treated with DOAC compared to VKA/LMWH, while DOAC likely reduce the risk of MB compared to VKA/LMWH.

How I treat obese patients with oral anticoagulants

Obesity has become a major threat to health worldwide. The prevalence of obesity is rapidly increasing, so much so that the World Health Organization has declared obesity as a global epidemic. Obesity is associated with multiple health problems, including venous thromboembolism and atrial fibrillation, both of which are treated with anticoagulation. However, obesity and treatments for obesity such as bariatric surgery can influence absorption, excretion, pharmacokinetics, and pharmacodynamics of various anticoagulants. This results in uncertainty regarding the best antithrombotic strategies in this population, particularly in the morbidly obese. In the recent years, several studies have attempted to investigate anticoagulation use in this population and provided more insight. Herein, we present 4 cases of anticoagulant use in the obese to illustrate the common challenges faced by clinicians and discuss our approach. Whenever possible, we provide a review of the literature and base our recommendations on the best available evidence.

Direct Oral Anticoagulant Concentrations in Obese and High Body Weight Patients: A Cohort Study

BACKGROUND

 Direct oral anticoagulants (DOACs) are prescribed for atrial fibrillation (AF) and venous thromboembolism (VTE) and both occur more frequently in obese patients. Outcomes from DOAC trials included few individuals ≥ 120 kg leading to uncertainty whether high body weight (BW) reduces DOAC concentrations.

OBJECTIVES

 This article investigates the relationship between factor Xa (FXa) inhibitor concentrations, BW, and renal function, and compares them in high BW patients with unselected populations.

METHODS

 Consecutive patients in two United Kingdom centers, weighing ≥ 120 kg receiving 5 mg twice daily apixaban or 20 mg once daily rivaroxaban for AF or VTE were prospectively included. Peak or trough concentrations were measured using specific chromogenic assays, expressed in mean or median (5th-95th percentiles). On-therapy range was the interval from the 5th percentile trough concentration to the 95th percentile peak concentration.

RESULTS

 One hundred patients were included; age range: 23 to 78 years, 31% were women, 58% had AF, creatinine clearance range: 67 to 474 mL/min. Median BW was 139 kg, and 84% had body mass index (BMI) ≥ 40 kg/m². DOAC peak and trough concentrations varied from 44 to 727 and 14 to 299 ng/mL, respectively. There was no linear relationship between FXa inhibitor concentrations at peak or trough and BW or BMI, and creatinine clearance. Apixaban troughs in AF and rivaroxaban peaks in VTE were lower than in unselected populations. However, only two trough concentrations were below the expected range, and 109/116 were within the on-therapy range.

CONCLUSION

 These data indicated that obese or high BW patients generally achieve therapeutic FXa inhibitor concentrations. However, further investigations assessing clinical outcomes are required.

Monitoring of rivaroxaban levels in patients with class III obesity

PURPOSE

There is little evidence to guide the use of direct oral anticoagulants (DOACs) in patients with class III obesity. Clinicians face the dilemma that using DOACs in patients with class III obesity may not provide adequate anticoagulation, while avoiding DOACs may deprive them of a useful therapeutic option. We present 2 cases describing our experience navigating rivaroxaban use in patients with class III obesity and review available case reports of measurement of rivaroxaban levels using a calibrated anti-factor Xa assay.

SUMMARY

In patient case 1, the rivaroxaban trough level was within the reference range, and therapy was continued. In patient case 2, the rivaroxaban trough level was below the reference range, and the patient's anticoagulation therapy was switched to warfarin. No thromboembolic events were noted in the 2 patients more than 1 year (15 and 22 months, respectively) after initiation of anticoagulation therapy. Because of the many advantages associated with use of DOACs instead of vitamin K antagonists, further research is critical to enabling clinicians to use DOACs more confidently in a broader population.

CONCLUSION

When monitoring rivaroxaban therapy in patients with class III obesity, there is uncertainty regarding clinical interpretation of drug levels that fall outside of established reference ranges, and monitoring is not standardized or widely available. In addition to case reports found in the literature, the presented cases highlight these challenges and differing clinical decisions made when evaluating rivaroxaban levels in patients with class III obesity.

Direct Oral Anticoagulants in Obesity: An Updated Literature Review

OBJECTIVE

To review literature on the use of direct-acting oral anticoagulants (DOACs) in patients with high body weight (BW) and/or high body mass index (BMI) and to make recommendations regarding use in this patient population.

DATA SOURCES

A search using PubMed was conducted (inception to April 13, 2020) using the term DOAC AND the terms obesity OR body weight. A separate search was also conducted with individual DOACs (dabigatran, apixaban, rivaroxaban, edoxaban) and the aforementioned terms.

STUDY SELECTION AND DATA EXTRACTION

Studies included examined the effect of BW and/or BMI on DOAC pharmacokinetics, efficacy, or safety. Included studies had DOAC indications of prevention of stroke in nonvalvular atrial fibrillation, or treatment or long-term prevention of venous thromboembolism.

DATA SYNTHESIS

The efficacy and safety of DOACs in patients with high BW/BMI has not yet been elucidated by randomized trials; however, 2016 international guidelines suggest avoiding their use in patients with a BW >120 kg or BMI >40 kg/m². Since 2016, several studies have been published examining use of DOACs in this patient population.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

This review thoroughly discusses the literature on DOACs in patients with a BW >120 kg or BMI >40 kg/m² pre-2016 and post-2016 guidelines.

CONCLUSIONS

Evidence indicates that each DOAC may have differences in outcomes when used in patients with a high BW/BMI. Currently, low-quality data are available that support avoiding dabigatran and considering apixaban or rivaroxaban; lack of sufficient data preclude a recommendation for edoxaban use in this patient population.

Rivaroxaban Versus Warfarin for Stroke Prevention and Venous Thromboembolism Treatment in Extreme Obesity and High Body Weight

Background: Limited clinical data exist describing the use of direct-acting oral anticoagulants (DOACs) in patients with body mass index (BMI) >40 kg/m2 or body weight >120 kg. Thus, DOAC therapy in this population remains controversial. Objectives: To investigate rivaroxaban as a safe and effective alternative to warfarin for venous thromboembolism (VTE) treatment and prevention of stroke in patients with atrial fibrillation identified as extremely obese or of high body weight. Methods: A retrospective chart review was performed at 2 academic medical centers in patients ≥18 years old and BMI >40 kg/m2 or weight >120 kg, newly initiated on warfarin or rivaroxaban for atrial fibrillation or VTE treatment. The primary end point was incidence of clinical failure, defined as VTE recurrence, stroke incidence, and mortality, within 12 months of initiation. Secondary end points included length of stay (LOS) and bleeding complications. Results: A total of 176 patients were included, with 84 and 92 patients in the rivaroxaban and warfarin arms, respectively. Clinical failure was lower in the rivaroxaban group but did not reach statistical significance when compared with warfarin (5% vs 13%; P = 0.06). LOS was significantly shorter in the rivaroxaban arm (2 days [1-3] vs 4 days [2-7], P < 0.0001). Percentage of bleeding complications was higher in the rivaroxaban arm but not statistically significant (8% vs 2%, P = 0.06). Conclusion and Relevance: Although not statistically significant, rivaroxaban trended toward a lower incidence of clinical failure while demonstrating a significantly shorter LOS when compared with warfarin for VTE treatment or atrial fibrillation in morbidly obese or high-body-weight patients.

Morbidly Obese Patient on Rivaroxaban Presents With Recurrent Upper Extremity Deep Vein Thrombosis: A Case Report

A morbidly obese patient with history of deep vein thrombosis and pulmonary embolism was diagnosed with an acute left upper extremity deep vein thrombosis and started on rivaroxaban. Three months later, the patient returned with swelling in the right arm and was found to have a right brachial thrombosis. Anticoagulant therapy was switched to a low-molecular-weight heparin, and patient was discharged on enoxaparin along with an order to follow-up with a hematologist. Subanalyses from randomized controlled trials, pharmacokinetic/pharmacodynamic, and real-world studies suggest that rivaroxaban may be effective and safe in morbidly obese patients for primary and secondary prevention of venous thromboembolism. However, the Scientific and Standardization Committee of the International Society on Thrombosis and Haemostasis does not recommend the use of direct-acting oral anticoagulants in this population. If used, drug levels should be monitored to guide the therapy. Due to the disparity in data to show efficacy and safety of rivaroxaban in morbidly obese subjects, the interpatient variability of rivaroxaban’s effects in subjects, and the lack of defined therapeutic range for rivaroxaban drug concentration, rivaroxaban should be used cautiously in this population.

Anticoagulation at the extremes of body weight: choices and dosing

INTRODUCTION

The landscape of therapeutic anticoagulation has changed dramatically over the past decade, with availability of direct oral anticoagulants (DOACs), which inhibit factor Xa or thrombin. However, the optimal anticoagulant agent and dosing strategy for patients at both extremes of body weight has not been established for any anticoagulant, including DOACs, vitamin K antagonists (VKA), and the various heparin options. Areas covered: This paper reviews available evidence to assist clinicians in prescribing of anticoagulation therapy at the extremes of body weight. Expert commentary: There are limited data to guide prescribing of all available anticoagulants at the extremes of weight and further research regarding efficacy and safety outcomes in these groups is required. Laboratory monitoring to guide dosing of traditional anticoagulants provides reassurance of 'predictable' efficacy. In contrast agents that are not routinely monitored by laboratory testing provide greater challenges. For example, underweight patients are at risk of receiving higher drug exposures of DOACs, whereas the use of fixed dose DOACs in obese patients may be associated with lower drug exposures.

Comparing the Efficacy and Safety of Direct Oral Anticoagulants With Warfarin in the Morbidly Obese Population With Atrial Fibrillation

BACKGROUND

The International Society of Thrombosis and Haemostasis recommends avoiding direct oral anticoagulants (DOACs) in morbidly obese patients with a body mass index (BMI) >40 kg/m² or weight >120 kg because of limited clinical data in this group of patients.

OBJECTIVES

The objective of this study was to evaluate the efficacy and safety of DOACs in morbidly obese patients with atrial fibrillation or flutter.

METHODS

A retrospective, single-center cohort study was conducted of patients older than 18 years, with BMI >40 kg/m² or weight >120 kg, who were diagnosed as having atrial fibrillation or flutter and who received warfarin or DOACs (ie, dabigatran, rivaroxaban, or apixaban). The primary efficacy outcome was the incidence of ischemic stroke or transient ischemic attack (TIA), whereas the primary safety outcome was the incidence of major bleeding.

RESULTS

A total of 64 patients in each group were included in the study analysis. The incidence rate of ischemic stroke or TIA was 1.75%/year in the DOAC group compared with 2.07%/year in the warfarin group (rate ratio = 0.84; 95% CI = 0.23 to 3.14; P = 0.80). The incidence rate of major bleeding was 2.18%/year in the DOAC group, compared with 4.97%/year in the warfarin group (rate ratio = 0.44; 95% CI = 0.15 to 1.25; P = 0.11). Conclusion and Relevance: Apixaban and rivaroxaban may be considered as alternatives to warfarin for atrial fibrillation or flutter in morbidly obese patients. Dabigatran use in morbidly obese patients needs caution until further studies are conducted.

Use of direct oral anticoagulants in antiphospholipid syndrome

The direct oral anticoagulants (DOACs) are therapeutic alternatives to warfarin and other vitamin K antagonists (VKAs), and constitute the standard of care for many indications. VKAs constitute the conventional therapy for the treatment and secondary thromboprophylaxis of thrombotic antiphospholipid syndrome (APS), but are often problematic, owing to the variable sensitivity of thromboplastins to lupus anticoagulant. Thus, the International Normalized Ratio may not accurately reflect anticoagulation intensity, or be clinically effective. Definition of the current role of DOACs in the treatment of APS is based on limited clinical trial data and information from other sources, including manufacturers' data, case series or cohort studies, and expert consensus. The Rivaroxaban in Antiphospholipid Syndrome (RAPS) randomized controlled trial (RCT), which had a laboratory surrogate primary outcome measure, suggests that rivaroxaban has the potential to be an effective and convenient alternative to warfarin in thrombotic APS patients with a single venous thromboembolism event requiring standard-intensity anticoagulation. However, further studies, in particular to provide better long-term efficacy and safety data, are needed before it can be widely recommended. APS patients are clinically heterogeneous, with the risk of recurrent thrombosis and the intensity of anticoagulation being influenced by their clinical phenotype and risk profile. DOAC trials involving homogeneous thrombotic APS populations, with the antiphospholipid antibody status well defined, will help to optimize the appropriate treatment in APS patient subgroups. Ongoing and emerging DOAC RCTs should provide further information to guide the use of DOACs in APS patients. Optimal identification of APS patients is a key step in working towards improved therapeutic strategies in these individuals.

Non-vitamin K antagonist oral anticoagulants for pulmonary embolism: who, where and for how long?

INTRODUCTION

Acute pulmonary embolism (PE) is a relatively common cardiopulmonary emergency that is a major cause of hospitalization and morbidity and is the primary cause of mortality associated with venous thromboembolism (VTE). During the last decade, one of the biggest changes in the management of PE has been the approval of four non-vitamin K antagonist oral anticoagulants (NOACs; apixaban, dabigatran, edoxaban and rivaroxaban) for the treatment of PE and deep vein thrombosis and secondary prevention of VTE. Areas covered: This article reviews the evolving management of PE in the NOAC era and addresses three fundamental questions: who should receive NOACs over conventional heparin/vitamin K antagonist regimens for the treatment of acute PE; should patients be treated as inpatients or outpatients; and how long should patients be treated to reduce the risk of recurrence? Expert commentary: The management of PE is changing. NOACs provide new anticoagulant treatment options for patients with PE, based on Phase III clinical study results. The consistent efficacy and safety profile of NOACs across many PE patient subgroups, including the elderly, fragile patients, those with active cancer and high-risk (right ventricular dysfunction) patients, suggests NOAC use will increase among these patients.

The impact of body weight on rivaroxaban pharmacokinetics

BACKGROUND

There is concern amongst clinicians that the fixed dosing strategy of rivaroxaban for the treatment of venous thromboembolism (VTE) might not be optimal in those patients under or overweight.

OBJECTIVE

To develop a pharmacokinetic model for rivaroxaban, based on real-world patients, specifically focusing on the impact of patients' body weight on rivaroxaban pharmacokinetics.

PATIENTS/METHODS

One hundred and one patients prescribed rivaroxaban prophylactic or treatment doses for the prevention or treatment of VTE were recruited at a London teaching hospital. Subjects had up to 3 rivaroxaban concentrations measured during a single dosing period (trough, 1 and 3 hours post dose). Population pharmacokinetic analyses was conducted to develop a rivaroxaban model, which was subsequently evaluated.

RESULTS

A one-compartment model with between-subject variability on rivaroxaban clearance and volume of distribution, with a combined (additive and proportional) error model, best fitted the data. Following a full covariate analysis, creatinine clearance on rivaroxaban clearance was found to be the significant covariate impacting on the pharmacokinetic profile of rivaroxaban in the dataset.

CONCLUSIONS

Our results suggest that the most important covariate impacting on rivaroxaban pharmacokinetics is creatinine clearance and the weight alone has little effect. These findings are in line with previous studies for rivaroxaban. Larger datasets, from real-world patients who are followed longitudinally, should be conducted to provide front-line clinicians with further reassurance when prescribing rivaroxaban for the acute management of VTE.