Direct Oral Anticoagulant Agents: Pharmacologic Profile, Indications, Coagulation Monitoring, and Reversal Agents

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.

Association of direct oral anticoagulant and delayed bleeding with pharmacokinetics after endoscopic submucosal dissection

BACKGROUND AND AIMS

Pharmacokinetic parameters, such as drug plasma level at trough, time to maximum plasma concentration (Tmax), and coagulation factor Xa (FXa) activity generally predict factors for the anticoagulant effects of direct oral anticoagulants (DOACs). Although GI bleeding is a major adverse event after endoscopic submucosal dissection (ESD), little is known about the association between post-ESD bleeding in patients taking DOACs and the pharmacologic parameters. This study aimed to evaluate pharmacologic risk factors for post-ESD bleeding in patients taking DOACs.

METHODS

We prospectively evaluated the incidence of post-ESD bleeding in patients taking DOACs between April 2018 and May 2022 at 21 Japanese institutions and investigated the association with post-ESD bleeding and pharmacologic factors, including plasma concentration and FXa activity at trough and Tmax.

RESULTS

The incidence of post-ESD bleeding was 12.8% (14 of 109; 95% confidence interval [CI], 7.2-20.6). Although plasma DOAC concentration and plasma level/dose ratio at trough and Tmax varied widely among individuals, a significant correlation with plasma concentration and FXa activity was observed (apixaban: correlation coefficient, -0.893; P < .001). On multivariate analysis, risk factors for post-ESD bleeding in patients taking DOACs were higher age (odds ratio [OR], 1.192; 95% CI, 1.020-1.392; P = .027) and high anticoagulant ability analyzed by FXa activity at trough and Tmax (OR, 6.056; 95% CI, 1.094-33.529; P = .039).

CONCLUSIONS

The incidence of post-ESD bleeding in patients taking DOACs was high, especially in older patients and with high anticoagulant effects of DOACs. Measurement of pharmacokinetic parameters of DOACs may be useful in identifying patients at higher risk of post-ESD bleeding.

Racial and Ethnic Disparities in Initiation of Direct Oral Anticoagulants Among Medicare Beneficiaries

Importance

The influence of race and ethnicity on initiation of direct oral anticoagulants (DOACs) is relatively understudied in Medicare data.

Objective

To investigate disparities in the initiation of DOACs compared with warfarin by race, ethnicity, and social vulnerability.

Design, Setting, and Participants

This retrospective cohort study used a 50% sample of Medicare fee-for-service data from January 1, 2010, to December 31, 2019 (mean patient enrollment duration, 7.7 years). Analysis took place between January 2023 and February 2024. A cohort of older adults (aged ≥65 years) with atrial fibrillation who newly initiated warfarin or DOACs (dabigatran, rivaroxaban, apixaban, and edoxaban) was identified.

Exposure

Patients were classified as non-Hispanic White, non-Hispanic Black, and Hispanic.

Main Outcomes and Measures

The likelihood of starting use of DOACs compared with warfarin was modeled, adjusting for race, ethnicity, age, sex, county-level social vulnerability, and other clinical factors.

Results

Among 950 698 anticoagulation initiations, consisting of 680 974 DOAC users and 269 724 warfarin users (mean [SD] age, 78.5 [7.6] years; 52.6% female), 5.2% were Black, 4.3% were Hispanic, and 86.7% were White. During the 10-year study period, DOAC use increased for all demographic groups. After adjustment, compared with White patients, Black patients were 23% less likely (adjusted odds ratio [AOR, 0.77; 95% CI, 0.75-0.79) and Hispanic patients were 13% less likely (AOR, 0.87; 95% CI, 0.85-0.89) to initiate DOAC use. Disparities in DOAC initiation were greatest among Black patients in the earlier years but attenuated during the study period. For instance, in 2010, the OR of Black patients initiating DOACs was 0.54 (95% CI, 0.50-0.57), attenuating linearly over time to 0.69 by 2013 (95% CI, 0.65-0.74) and 0.83 (95% CI, 0.78-0.89) by 2017. By 2019, these differences became nonsignificant (OR, 1.08; 95% CI, 0.99-1.18).

Conclusions and Relevance

In this cohort study of Medicare patients with atrial fibrillation, Black and Hispanic patients were less likely to initiate DOACs for atrial fibrillation, although these differences diminished over time. Identifying the factors behind these early disparities is crucial for ensuring equitable access to novel therapies as they emerge for Black and Hispanic populations.

Management of patients with proximal femur fractures under DOACs

PURPOSE

In the past, preinjury direct oral anticoagulant (DOAC) intake has led to delays in time to surgery (TTS) in patients with proximal femur fractures and delays in surgery have been associated with impaired outcomes. Although healthcare institutions/federal committees have set rules for treatment within 24 h of injury, comprehensive guidelines for the perioperative management of these patients, in particular when on preinjury DOACs, are still lacking. This contribution aims to summarize the current evidence on the safe time window for surgery in patients with proximal femur fractures on preinjury DOACs and to outline therapeutic options if emergency DOAC reversal becomes necessary.

METHODS

Narrative review based upon selective review of the pertinent literature.

RESULTS

For the majority of patients with proximal femur fractures and on preinjury DOACs, early surgery appears safe as soon as medical clearance has been obtained. There may be an increase in the need for blood products but with data not yet conclusive. Work-up including assessment of remaining anticoagulant activity and potential reversal should be restricted to patients at risk for bleeding complications, in particular in the presence of renal/hepatic impairment. Methodology for rapid assessment of DOACs including quantitative/qualitative concentration levels is work in progress. In the case of bleeding, rapidly acting reversal agents are available.

CONCLUSION

Preinjury DOAC use should not routinely delay surgery in patients with proximal femur fractures.

How I treat pediatric venous thromboembolism in the DOAC era

ABSTRACT

The direct oral anticoagulants (DOACs) rivaroxaban and dabigatran are newly licensed for the treatment and prevention of venous thromboembolism (VTE) in children and mark a renaissance in pediatric anticoagulation management. They provide a convenient option over standard-of-care anticoagulants (heparins, fondaparinux, and vitamin K antagonists) because of their oral route of administration, child-friendly formulations, and significant reduction in monitoring. However, limitations related to therapeutic monitoring when needed and the lack of approved reversal agents for DOACs in children raise some safety concerns. There is accumulating experience of safety and efficacy of DOACs in adults for a broad scope of indications; however, the cumulative experience of using DOACs in pediatrics, specifically for those with coexisting chronic illnesses, is sparse. Consequently, clinicians must often rely on their experience for treating VTE and extrapolate from data in adults while using DOACs in children. In this article, the authors share their experience of managing 4 scenarios that hematologists are likely to encounter in their day-to-day practice. Topics addressed include (1) appropriateness of indication; (2) use for special populations of children; (3) considerations for laboratory monitoring; (4) transition between anticoagulants; (5) major drug interactions; (6) perioperative management; and (7) anticoagulation reversal.

An Update on Betrixaban, The Challenging Anticoagulant Agent for Extended Venous Thromboembolism Prophylaxis

ABSTRACT

Venous thromboembolism (VTE) is a prevalent yet preventable cause of death, particularly among hospitalized patients. Studies have shown that the risk of VTE remains high for up to 6 months after discharge, highlighting the need for extended thromboprophylaxis as a viable treatment approach. Despite the availability of several anticoagulant drugs such as vitamin K antagonists, heparinoids, rivaroxaban, apixaban, edoxaban, and dabigatran, none of them has received approval from the US Food and Drug Administration for long-term thromboprophylaxis. However, an emerging factor Xa inhibitor called betrixaban has shown promising results in Phase II and phase III trials, positioning itself as the first and only US Food and Drug Administration-approved anticoagulant for extended thromboprophylaxis in hospitalized patients after discharge. Betrixaban offers distinct pharmacological characteristics, including a long half-life, low renal excretion, and unique hepatic metabolism, making it an attractive option for various theoretical uses. Numerous articles have been published discussing the safety and efficacy of betrixaban, all of which have emphasized its usefulness and practicality. However, there has been limited discussion regarding its weaknesses and areas of ambiguity. Therefore, this article aimed to explore the challenges faced during the approval process of betrixaban and provide a comprehensive review of the literature on its advantages and disadvantages as a long-term prophylaxis approach for VTE. Furthermore, we aim to identify the ambiguous points that require further investigation in future studies.

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.

Comparative Effectiveness of Anticoagulants in Patients With Cancer-Associated Thrombosis

Importance

Patterns of clinical utilization and comparative effectiveness of anticoagulants for cancer-associated thrombosis (CAT) remain largely unexplored.

Objectives

To assess patterns of and factors associated with anticoagulant use and to evaluate the comparative effectiveness of contemporary anticoagulants in patients with active cancer in a clinical setting.

Design, Setting, and Participants

This retrospective cohort study obtained deidentified OptumLabs electronic health record claims data from January 1, 2012, to September 30, 2019. Adult patients (≥18 years of age) with a primary cancer diagnosis (except skin cancer) during at least 1 inpatient or 2 outpatient visits within 6 months before the venous thromboembolism (VTE) date were included. Data were analyzed from April 2020 to September 2021.

Exposures

The patients were grouped according to the anticoagulant prescribed: (1) direct oral anticoagulants (DOACs), (2) low-molecular-weight heparin (LMWH), and (3) warfarin.

Main Outcomes and Measures

Odds ratios (ORs) were used to present the association between factors of interest and utilization of anticoagulants. Main efficacy outcomes included risk of VTE recurrence and all-cause mortality. Main safety outcomes included the risk of hospitalization due to major bleeding. Relative treatment effect estimates were expressed as hazard ratios (HRs) with 95% CIs.

Results

This study included 5100 patients (mean [SD] age, 66.3 [12.3] years; 2670 [52.4%] women; 799 [15.7%] Black, 389 [7.6%] Hispanic, and 3559 [69.8%] White individuals). Overall, 2512 (49.3%), 1488 (29.2%), and 1460 (28.6%) filled prescriptions for DOACs, LMWH, and warfarin, respectively. The median (IQR) treatment duration was 3.2 (1.0-6.5) months for DOACs, 3.1 (1.0-6.8) months for warfarin, and 1.8 (0.9-3.8) months for LWMH. Patients with lung (OR, 2.07; 95% CI, 1.12-3.65), urological (OR, 1.94; 95% CI,1.08-3.49), gynecological (OR, 4.25; 95% CI, 2.31-7.82), and colorectal (OR, 2.26; 95% CI, 1.20-4.32) cancer were associated with increased prescriptions for LMWH compared with DOACs. LMWH (HR, 1.47; 95% CI, 1.14-1.90) and warfarin (HR, 1.46; 95% CI, 1.13-1.87) were associated with an increased risk of VTE recurrences compared with DOACs. LMWH was associated with an increased risk of major bleeding (HR, 2.27; 95% CI, 1.62-3.20) and higher all-cause mortality (HR, 1.61; 95% CI, 1.15-2.25) compared with DOACs.

Conclusions and Relevance

In this comparative effectiveness study of claims-based data, patients with CAT received anticoagulation for a remarkably short duration in clinical settings. DOACs was associated with a lower risk of VTE recurrence, major bleeding, and mortality. Warfarin may still be considered for patients with contraindications to DOACs and those with poor persistence on LMWH.

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.

The methods for removal of direct oral anticoagulants and heparins to improve the monitoring of hemostasis: a narrative literature review

The assessment of hemostasis is necessary to make suitable decisions on the management of patients with thrombotic disorders. In some clinical situations, for example, during thrombophilia screening, the presence of anticoagulants in sample makes diagnosis impossible. Various elimination methods may overcome anticoagulant interference. DOAC-Stop, DOAC-Remove and DOAC Filter are available methods to remove direct oral anticoagulants in diagnostic tests, although there are still reports on their incomplete efficacy in several assays. The new antidotes for direct oral anticoagulants - idarucizumab and andexanet alfa - could be potentially useful, but have their drawbacks. The necessity to remove heparins is also arising as heparin contamination from central venous catheter or therapy with heparin disturbs the appropriate hemostasis assessment. Heparinase and polybrene are already present in commercial reagents but a fully-effective neutralizer is still a challenge for researchers, thus promising candidates remain in the research phase.

Incidence and Predictors of Switching and Dose Change of Direct Oral Anticoagulants among Elderly Patients with Nonvalvular Atrial Fibrillation: A 5-Year Analysis of a Large Administrative Database

In the last decade, novel oral anticoagulants (NOACs) have emerged as prominent therapeutic options in non-valvular atrial fibrillation (NVAF). We analysed the clinical burden and the switching rate between all available NOACs, and their dosage change over a period of 5 years in a representative population of patients with NVAF aged between 70 and 75 years. Methods and Results: This is a retrospective observational study on administrative databases, covering approximately 6.2 million health-assisted individuals by the Italian National Health System (around 11% of the entire Italian residents). Out of 4640 NVAF patients treated with NOACs and aged 70-75 years in 2017, 3772 (81.3%) patients were still in treatment with NOAC up to 2021 and among them, 3389 (73.0%) patients remained in treatment with the same NOAC during 2017-2021. In fact, 10.2% of patients switched NOAC type and 10.3% changed the dose of the same NOAC. Overall, after switching, the dabigatran and rivaroxaban groups lost, respectively, 13.5% and 2.8% of patients, while apixaban and edoxaban resulted in a relative percentage increase of 6.8% and 44.6% of patients, respectively. By a logistic regression analysis, the treatment with rivaroxaban, apixaban, and edoxaban (respect to dabigatran) was associated with a significant risk reduction of switch of 57%, 68%, and 44%, respectively. On the other hand, several features of high risk were associated with dose reduction. Conclusions. In our 5-year analysis of a large administrative database, a switching among NOACs or a change in NOAC dosages occurred in around 20% of elderly patients with NVAF. The type of NOAC was associated with a high switching rate, while several characteristics of high risk resulted as predictors of dose reduction of NOACs. Moreover, a worsening trend of clinical conditions occurred in patients maintaining the same NOAC treatment across 2017-2021.

Antithrombotics and Gastrointestinal Prophylaxis: A Systematic Review

Antithrombotic medications include both antiplatelet and anticoagulants and are used for a wide variety of cardiovascular conditions. A common complication of antithrombotic use is gastrointestinal bleeding. As a result, gastrointestinal prophylaxis is a common consideration for patients on a single or combination antithrombotic regimen. Prophylaxis is typically achieved through use of either proton pump inhibitors or histamine 2 receptor antagonists. Current recommendations for use of gastrointestinal prophylaxis with concomitant use of antithrombotic medications are scarce. In this systematic review, we explore the current evidence and recommendations regarding gastrointestinal prophylaxis for patients on antiplatelet or anticoagulant therapy as well as combination regimens.

Direct oral anticoagulant agents might be safe for patients undergoing endovenous radiofrequency and laser ablation

OBJECTIVE

Studies assessing the effect of the use of anticoagulant agents on endovenous thermal ablation (ETA) have been limited to patients taking warfarin. Thus, the aim of the present study was to assess the efficacy and safety of ETA for patients taking direct oral anticoagulants (DOACs). We hypothesized that the outcome of ETA for patients taking DOACs would not be superior to the outcomes for patients taking DOACs.

METHODS

We performed a retrospective review to identify patients who had undergone radiofrequency ablation or endovenous laser ablation with 1470-nm diode laser fibers for symptomatic great or small saphenous venous reflux from 2018 to 2020. The patients were dichotomized into those who had received a therapeutic dose of DOACs periprocedurally and those who had not (control group). The outcomes of interest included the rates of treated vein closure at 7 days and 9 months and the incidence of deep vein thrombosis (DVT), endothermal heat-induced thrombosis (EHIT), and bleeding periprocedurally.

RESULTS

Of the 301 patients (382 procedures), 69 patients (87 procedures) had received DOACs and 232 control patients (295 procedures) had not received DOACs. The patients receiving DOACs were more often older (mean age, 65 years vs 55 years; P < .001) and male (70% vs 37%; P < .001), with a higher prevalence of venous thromboembolism and more severe CEAP (clinical, etiologic, anatomic, pathophysiologic) classification (5 or 6), than were the control patients. Those receiving DOACs were more likely to have had a history of DVT (44% vs 6%; P < .001), pulmonary embolism (13% vs 0%; P < .001), and phlebitis (32% vs 15%; P < .001). Procedurally, radiofrequency ablation had been used more frequently in the control group (92% vs 84%; P = .029), with longer segments of treated veins (mean, 38 mm vs 35 mm, respectively; P = .028). No major or minor bleeding events nor any EHIT had occurred in either group. Two patients in the control group (0.7%) developed DVT; however, no DVT was observed in those in the DOAC group (P = .441). At 9 months, the treated vein had remained ablated after 94.4% of procedures for patients receiving DOACs and 98.4% of the control group (P = .163). On multivariable analysis, DOAC usage was not associated with an increased risk of vein recanalization (hazard ratio, 5.76; 95% confidence interval, 0.57-58.64; P = .139). An increased preprocedural vein diameter and the use of endovenous laser ablation were associated with an increased risk of recanalization.

CONCLUSIONS

In our study of patients who had undergone ETA for symptomatic saphenous venous reflux, the periprocedural use of DOACs did not adversely affect the efficacy of endovenous ablation to ≥9 months. Furthermore, DOAC use did not confer an additional risk of bleeding, DVT, or EHIT periprocedurally. DOACs may be safely continued without affecting the efficacy and durability of ETA.

Prescribing Trends of Oral Anticoagulants from 2010 to 2020 in Shanghai, China: A Retrospective Study

Aim

Non-vitamin K antagonist oral anticoagulants (NOACs) were developed as an alternative to warfarin to prevent thromboembolism in patients with atrial fibrillation (AF), prosthetic heart valves, venous thromboembolism (VTE), or other thrombotic disorders. The aim of this study is to explore the trends in prescribing OACs, including warfarin and NOACs, in Shanghai, China.

Methods

Prescription data of OACs were retrospectively collected from Rx Analysis System from 2010 to 2020 in Shanghai, China. Comparisons were made on the trends of each OACs according to different indications, age groups, and hospital grades. The costs and the contribution of individual OACs were also explored.

Results

Growing trends in overall prescriptions for OACs were observed. The prescriptions of NOACs were significantly increased since 2016, while the prescriptions of warfarin kept decreasing since 2017. A highly statistically significant increase in prescriptions of Rivaroxaban was observed from 2016 to 2020 (P < .001). Despite the price reduction of rivaroxaban in 2018, the total cost of rivaroxaban continued to rise (P < .001). Rivaroxaban emerged as a preferred NOAC in both indications of AF and VTE, and accounted for more than three-quarters of the total costs for OACs since 2019. Compared with rivaroxaban, the prescription numbers of dabigatran and apixaban were much smaller, and the growth of prescriptions were much slower. Differences in prescribing patterns in different indications, age groups, and grades of hospitals were also founded.

Conclusion

There has been a rapid increase in the use of OAC over the last 11 years in Shanghai, China. NOACs have been adopted rapidly, and have been gradually replacing warfarin. Warfarin remains the top choice for certain patients with valvular heart disease. Future studies are warranted considering changes in the OAC use in a larger scale, as well as the rationality and its influence factors on OAC use.

Do Apixaban Plasma Levels Relate to Bleeding? The Clinical Outcomes and Predictive Factors for Bleeding in Patients with Non-Valvular Atrial Fibrillation

Apixaban can significantly prevent stroke events in patients with non-valvular atrial fibrillation (NVAF), as can be observed from the large, randomized, controlled trial conducted in the present study. However, the real-world evidence of bleeding events related to the apixaban plasma levels in Asian populations is limited. This study aimed to investigate the apixaban plasma levels and clinical outcomes among NVAF patients receiving apixaban, including determining the risk factors associated with bleeding during routine care. Seventy-one patients were included in the study. The median values were 112.79 (5–95th percentiles: 68.69–207.8) μg/L and 185.62 (5–95th percentiles: 124.06–384.34) μg/L for the apixaban trough (C_trough) and apixaban peak plasma levels (C_peak), respectively. Stroke and bleeding were found in 8 (11.27%) and 14 patients (19.72%), respectively. There was no statistical significance for C_trough and C_peak in the stroke and non-stroke groups, respectively. The median of C_trough (139.15 μg/L) in patients with bleeding was higher than that in the non-bleeding group (108.14 μg/L), but there was no statistical significance. However, multivariate analyses showed that bleeding history (odds ratio (OR): 17.62; 95% confidence interval (CI): 3.54–176.64; and p-value = 0.002) and C_trough (OR: 1.01; 95%: CI 1.00–1.03; and p-value = 0.038) were related to bleeding events. Almost all of the patients presented apixaban plasma levels within the expected range. Interestingly, bleeding events were associated with the troughs of the apixaban plasma levels and bleeding history.

Correcting Coagulopathy for Image-Guided Procedures

Patients with acquired coagulopathy often require percutaneous image-guided invasive procedures for urgent control of hemorrhage or for elective procedures. Routine preprocedural evaluation of coagulopathy previously focused on absolute prothrombin time, partial thromboplastin time, international normalized ratio, and platelet count values. Now viscoelastic testing and greater understanding of patient- and drug-specific changes in coagulation profiles can yield better coagulation profile data. More specific reversal agents and profiles combine for less generalized and more titrated transfusion or correction algorithms. This article reviews procedural and patient-specific factors for defining both hemorrhagic risk and correction strategies.

Pathophysiology and Management of Hypercoagulation in Infectious Diseases

Numerous systemic infections may have hypercoagulation as one of the complications, which may range from asymptomatic presentation of elevation of biochemical markers of coagulation such as that of fibrin and thrombin generation, to a much severe, symptomatic, life-threatening, disseminated intravascular coagulation (DIC), which results in the formation of thrombi in the microvasculature of various organs. This phenomenon contributes to increase in morbidity and mortality in various infectious diseases. The current review discusses various mechanisms of hypercoagulation during infections such as tissue factor activation, endothelial cell activation, inhibition of physiological anticoagulant pathways, and fibrinolysis inhibition. The review also discusses pathophysiological changes in the coagulation system and its management in the recent pandemic of COVID-19. The article also discusses role of various parenteral and oral anticoagulants in the management of infectious diseases. The review provides clinical data on various anticoagulants used during hospitalization and extended prophylaxis for the management of venous thromboembolism in various infections.

Methodology Because this is a review of published literature and no humans or animals were involved, ethical committee approval was not required and patient consent was not required.

Incremental net monetary benefit of direct oral anticoagulants for the prevention of venous thromboembolism after total knee or hip replacement: A systematic review and meta-analysis

INTRODUCTION

This meta-analysis was conducted to quantitatively pool the incremental net benefit (INB) of using direct oral anticoagulants (DOACs) for the prevention of venous thromboembolism (VTE) in patients undergoing total knee or hip replacements (TKR or THR).

MATERIALS AND METHODS

We performed a comprehensive search in several databases published before June 2021. Studies were included if they were cost-effectiveness analyses reporting cost per quality-adjusted life-year or life-year of DOACs compared to low molecular-weight heparins (LMWHs) or other anticoagulant agents for the prevention of VTE after TKR or THR. Risk of bias was also assessed using the biases in economic studies (ECOBIAS) checklist. Various monetary units were converted to purchasing power parity, adjusted to 2020 US dollars. The INBs were pooled across studies using a random-effects model, stratified by high-income countries (HICs) and low- and middle-income countries (LMICs). Heterogeneity was assessed using the I² statistic.

RESULTS

A total of 49 comparisons (TKR = 25 and THR = 24) from 16 studies was included. In HICs, DOACs were cost-effective compared to LMWHs from the health care system/payer perspective for the prevention of VTE after both TKR and THR with corresponding INBs (95 % CI; I²) of $231.91 ($178.71, $285.11; 0 %) and $254.99 ($159.20, $350.77; 27.79 %), respectively. In LMICs, DOACs were not cost-effective compared to LMWHs for both TKR and THR with the INBs of $94.13 (-$40.21, $228.47; 97.04 %) and $80.55 (-$157.37, $318.47; 99.78 %), respectively. No evidence of small-study effects was identified in any analyses. The cost-effectiveness of using DOACs for TKR and THR in HICs was robust across a series of sensitivity analyses.

CONCLUSIONS

DOACs were cost-effective as compared to LMWHs for VTE prophylaxis following TKR and THR surgeries in HICs. Further studies from LMICs are warranted.

Perioperative management of antithrombotic therapy: a case-based narrative review

The periprocedural management of patients who are receiving vitamin K antagonists, direct oral anticoagulants and antiplatelet therapy is a common and challenging clinical scenario as the decision to interrupt or continue these medications is anchored on patient and procedure-related risks for bleeding and thrombosis. Adding to the complexity of clinical management is the fact that anticoagulants have varied pharmacokinetic and pharmacodynamic properties and indications for clinical use. In many minimal-bleed-risk procedures, anticoagulants can be safely continued, without interruption, whereas in cases where anticoagulants cannot be safely continued, the timing of interruption and resumption, as well as the need for heparin bridging requires consideration. Perioperative antithrombotic management scenarios occur most often in patients with atrial fibrillation, mechanical heart valves, coronary stents, and cerebrovascular disease as such patients are likely to be prescribed anticoagulant and/or antiplatelet therapy. The objective of this case-based narrative review is to provide a practical evidence-based approach to the perioperative management of patients on anticoagulation and antiplatelet therapy. Four clinical scenarios will be provided: (1) managing patients in whom anticoagulants can be continued; (2) perioperative management of direct oral anticoagulants; (3) management of patients on dual antiplatelet therapy; and (4) anticoagulant management for emergency or urgent surgery.

Rivaroxaban Pharmacokinetics in Obese Subjects: A Systematic Review

INTRODUCTION

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

Evaluation of direct oral anticoagulant use on thromboelastography in an emergency department population

BACKGROUND

Direct oral anticoagulant (DOAC) use presents a challenge to all providers involved in emergency care of patients since widely accepted laboratory tests to assess the level of anticoagulation for such medications are lacking. Viscoelastic tests such as thromboelastography (TEG) tests are increasingly used throughout major trauma centers to help guide resuscitation efforts in patients presenting with trauma and/or hemorrhagic shock.

OBJECTIVE

The primary outcome compared TEG parameters between emergency department trauma patients reporting DOAC therapy and known normal TEG parameter values. The secondary outcome evaluated patients who reported time of last known DOAC dose within a preferred time frame of <12 h for once daily dosing DOAC therapy or < 6 h for twice daily dosing DOAC therapy.

METHODS

This single-center, retrospective cohort study assessed TEG values in patients receiving DOAC therapy and compared these to institution TEG ranges considered normal. TEG values of reaction time (R time), kinetics (K), alpha angle (AA), maximum amplitude (MA), and percent lysis in 30 min (LY30) were collected for patients reporting DOAC therapy.

RESULTS

40 patients were included in this study. 19 patients reported apixaban therapy and 21 reported rivaroxaban therapy. 5 (12.5%) patients had an elevated R time and 1 (2.5%) patient had a reduced MA. All other TEG values did not suggest hypocoagulability. For the secondary outcome assessing patients reporting last known dose within the preferred time frame, only the R time was elevated in 2 (14.3%) patients. Lastly, in a subgroup analysis of patients with elevated low-molecular-weight heparin (LMWH) orAnti- Xa levels, the R time was the only parameter affected in 25% of patients.

CONCLUSION

TEG values were typically not affected by rivaroxaban or apixaban use in an emergency department trauma population suggesting that TEG is not sensitive for Xa inhibitor detection and should not be relied upon for assessing anticoagulation in such settings.

Required warfarin dose and time in therapeutic range in patients with diagnosed Nonalcoholic Fatty Liver Disease (NAFLD) or Nonalcoholic Steatohepatitis (NASH)

Warfarin has been widely used to treat thromboembolism. The effect of nonalcoholic fatty liver disease (NAFLD) or nonalcoholic steatohepatitis (NASH), on warfarin dosing remains unknown. This study aims to examine the effects of NAFLD/NASH on the average daily dose (ADD) of warfarin and the time in therapeutic range (TTR). This is a retrospective study utilizing an administrative data. We included patients with at least 2 months of warfarin dispensing and two subsequent consecutive INR measures. The ADD of warfarin to achieve therapeutic range INR levels, and TTR were compared between patients with and without NAFLD/NASH in four subgroups of patients accounting for the presence of obesity and diabetes. Generalized linear models (GLM) with Propensity score (PS) fine stratification were applied to evaluate the relative differences (RD) of warfarin ADD and TTR (>60%) in four subgroups. A total of 430 NAFLD/NASH patients and 38,887 patients without NAFLD/NASH were included. The ADD and TTR, were not significant in the overall cohort between those with and without NAFLD/NASH. However, GLM results in patients without diabetes or obesity (N = 26,685) showed a significantly lower warfarin ADD (RD: -0.38; 95%CI: -0.74–-0.02) and shorter TTR (OR: 0.71; 95%CI: 0.52–0.97) in patients diagnosed with NAFLD/NASH. The effects of NAFLD/NASH on warfarin dose or TTR were observed in patients without obesity and diabetes. Obesity and diabetes appear to be significant modifiers for the effects of NAFLD/NASH on warfarin dose and TTR.

Patients' adherence to oral anticoagulants therapy: Comparison between vitamin K antagonists and direct oral anticoagulants

BACKGROUND

Patient's adherence to oral anticoagulant therapy is essential to prevent and treat thrombotic events.

METHODS

To assess the patients' adherence Morisky Medication Adherence Scale 8-items was used. The target population included 785 consecutive outpatients, of whom 384 were on Vitamin K Antagonists and 401 on Direct Oral Anticoagulants. Moreover, we evaluate which variable among age, gender, having experienced a thrombotic episode, time in the therapeutic range for patients on Vitamin K Antagonists, being naive and once versus twice daily drug assumption for patients on Direct Oral Anticoagulants, could affect adherence to therapy.

RESULTS

Morisky Medication Adherence Scale 8-items score was 8 in both groups. The intentional non-adherence obtained the lowest score while the unintentional non-adherence is the most frequent problem in patients treated with either Vitamin K Antagonists or Direct Oral Anticoagulants. Age > 75 years, male gender, having experienced a thrombotic episode, being naive and assuming Direct Oral Anticoagulants twice a day were significantly associated with a higher risk to forget assuming the oral anticoagulant, to have more difficulty in remembering to take it or to bring it in case of travel or leaving home. A low percentage of time in therapeutic range was associated with a not regularly assumption of the anticoagulants.

CONCLUSION

Patients treated with Vitamin K Antagonists or Direct Oral Anticoagulants show a good adherence and persistence to their oral anticoagulant therapy. Several factors have been identified to affect patients' adherence and deserve a careful attention by the doctors at the Anticoagulation Clinic.

Management of Patients Receiving Direct Oral Anticoagulants Scheduled for Radical Prostatectomy: An Update of a Prospective Assessment

BACKGROUND

In the perioperative setting, temporary interruption of direct oral anticoagulants (DOACs) is mandatory. However, the safety of these recommendations is largely based on nonurological surgical experiences.

OBJECTIVE

To verify the safety of these recommendations in patients undergoing radical prostatectomy (RP).

DESIGN, SETTING, AND PARTICIPANTS

A total of 5317 patients underwent RP in our tertiary care centre between December 2017 and February 2020. Of them, 107 consecutive patients had DOACs in standard preoperative medication. DOAC intake was stopped 2-3 d before RP. Postoperatively, patients received weight- and risk-adapted low-molecular-weight heparin (LMWH). DOAC intake was restarted, and administration of LMWH was stopped the 3rd day after surgery. For comparison, we performed 1:2 propensity-score matching (DOAC:non-DOAC), which resulted in 321 consecutive patients.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Perioperative outcomes and 30-d morbidity were compared between both cohorts. The Wilcoxon rank sum test and the Pearson's chi-square test were used.

RESULTS AND LIMITATIONS

The median age of patients with DOACs was 68 yr. Sixty-six patients (61.7%) stopped DOAC intake 48 h and 41 patients (38.3%) 72 h before RP. In comparison with the matching cohort, the median blood loss during RP, median duration of surgery, and median duration of hospitalisation did not differ in a statistically significant fashion. Similarly, there was no significant difference in 30-d morbidity between groups. Importantly, the rate of bleeding and thromboembolic complications did likewise not differ significantly, though it is a nonrandomised and retrospective study.

CONCLUSIONS

Standardised perioperative management of DOACs is important to minimise bleeding and thromboembolic complications. RP can be performed with a low perioperative complication risk if patients are adherent to our presented algorithm.

PATIENT SUMMARY

We looked at peri- and postoperative complications and compared direct oral anticoagulant (DOAC) and non-DOAC patients. We found no significant difference in thromboembolic and bleeding complications between the groups. We conclude that our regime is safe.

Quantification of direct-acting oral anticoagulants: Application of a clinically validated liquid chromatography-tandem mass spectrometry method to forensic cases

In certain forensic cases, a quantification of direct-acting oral anticoagulants (DOACs) can be necessary. We evaluate the applicability of a previously described liquid chromatography-tandem mass spectrometry (LC-MS/MS) methodology for the determination of DOACs in plasma to postmortem specimen. Postmortem internal quality control (PIQC) samples were prepared in pooled blank postmortem heart blood, femoral blood, cerebrospinal fluid (CSF), and urine as well in plasma. To examine the application of the clinical method to forensic cases, the main validation parameters were reinvestigated using PIQC samples. Postmortem samples of 12 forensic cases with evidence of previous rivaroxaban intake and unknown bleeding disorders were analyzed. Interday variability remained within the acceptance criterion of ±15%. Matrix effects were comparable in blank plasma and postmortem matrix extracts. After 4 weeks of storage in the refrigerator, no relevant decrease of DOACs was evident. After 96 h of storage at room temperature, a slight decrease in edoxaban concentration was observed in CSF and urine, while plasma edoxaban decreased by about 50%. Median (range) rivaroxaban concentrations determined in specimen of forensic cases were as follows: heart blood (n = 6), 17.2 ng/ml (<LOQ, 56.6 ng/ml); femoral blood (n = 12), 27.6 ng/ml (<LOQ, 110.5 ng/ml); CSF (n = 7), 11.7 ng/ml (<LOQ, 17.5 ng/ml); urine (n = 6), 275.7 ng/ml (14.5-870.9 ng/ml). The median heart/femoral blood rivaroxaban ratio was 1.2 (n = 5). Exemplary, a forensic case with detection of edoxaban in femoral blood, CSF, and urine, is presented. DOACs can be detected in postmortem heart and femoral blood, CSF, and urine specimen by LC-MS/MS. Based on limited forensic cases, no significant redistribution was evident for rivaroxaban, which was found at highest concentrations in urine.

Real-World Analysis of Potential Pharmacokinetic and Pharmacodynamic Drug Interactions with Apixaban in Patients with Non-Valvular Atrial Fibrillation

Purpose

We conducted this study to assess the real-world prevalence, nature, predictors, and clinical necessity of apixaban pharmacokinetic (PK) and pharmacodynamic (PD) drug interactions in patients with non-valvular atrial fibrillation (NVAF) at a tertiary medical institution in Saudi Arabia.

Patients and Methods

An observational retrospective cohort analysis was conducted in adult patients diagnosed with NVAF receiving apixaban for stroke prevention from the period of June 2015 to May 2019.

Results

Of the 1271 patients included in the analysis, 611 (48.1%) patients had potential PD– or PK–drug interactions with apixaban. Of those, 490 (38.6%) patients had potential PD drug–drug interactions (DDIs) and 121 (9.5%) patients had potential PK-DDIs. PD-DDIs with apixaban were mainly with antiplatelet therapy followed by non-steroidal anti-inflammatory drugs and antidepressants. PK-DDIs with apixaban were mainly with combined P-gp/CYP3A4 inhibitors or inducers. History of minor bleeding was positively correlated with PD-DDIs with apixaban, ß coefficient = 0.455 (OR 1.58; 95% CI 1.01–2.45); p<0.05. History of acute coronary syndrome was positively correlated with PD-DDIs with apixaban, ß coefficient = 0.515 (OR 1.60; 95% CI 1.36–1.99); p<0.05. History of heart failure was positively correlated with PK-DDIs with apixaban, ß coefficient = 0.459 (OR 1.58; 95% CI 1.07–2.35); p<0.05. Almost 15% of the included patients had no clinical indication to receive the potential interacting drug with apixaban and about 20% of them were assuming an inappropriate apixaban dose according to the product package insert.

Conclusion

Pharmacodynamics and pharmacokinetics interactions are common in more than half of the patients with NVAF receiving apixaban for stroke prevention in this real-world analysis. Some of these interacting medications are not indicated. Drug–drug interactions should always be considered and monitored with apixaban with a regular assessment of the need for any interacting medication.

Warden B. Direct Oral Anticoagulant Use: A Practical Guide to Common Clinical Challenges

Direct oral anticoagulants ( DOAC s) have quickly become attractive alternatives to the long‐standing standard of care in anticoagulation, vitamin K antagonist. DOAC s are indicated for prevention and treatment of several cardiovascular conditions. Since the first approval in 2010, DOAC s have emerged as leading therapeutic alternatives that provide both clinicians and patients with more effective, safe, and convenient treatment options in thromboembolic settings. With the expanding role of DOAC s, clinicians are faced with increasingly complex decisions relating to appropriate agent, duration of treatment, and use in special populations. This review will provide an overview of DOAC s and act as a practical reference for clinicians to optimize DOAC use among common challenging scenarios. Topics addressed include (1) appropriate indications; (2) use in patients with specific comorbidities; (3) monitoring parameters; (4) transitioning between anticoagulant regimens; (5) major drug interactions; and (6) cost considerations.

Warden B. Direct Oral Anticoagulant Use: A Practical Guide to Common Clinical Challenges

Direct oral anticoagulants (DOACs) have quickly become attractive alternatives to the long-standing standard of care in anticoagulation, vitamin K antagonist. DOACs are indicated for prevention and treatment of several cardiovascular conditions. Since the first approval in 2010, DOACs have emerged as leading therapeutic alternatives that provide both clinicians and patients with more effective, safe, and convenient treatment options in thromboembolic settings. With the expanding role of DOACs, clinicians are faced with increasingly complex decisions relating to appropriate agent, duration of treatment, and use in special populations. This review will provide an overview of DOACs and act as a practical reference for clinicians to optimize DOAC use among common challenging scenarios. Topics addressed include (1) appropriate indications; (2) use in patients with specific comorbidities; (3) monitoring parameters; (4) transitioning between anticoagulant regimens; (5) major drug interactions; and (6) cost considerations.

Variability in international normalized ratio and activated partial thromboplastin time after injury are not explained by coagulation factor deficits

BACKGROUND

Conventional coagulation assays (CCAs), prothrombin time (PT)/international normalized ratio (INR) and activated partial thromboplastin time (aPTT), detect clotting factor (CF) deficiencies in hematologic disorders. However, there is controversy about how these CCAs should be used to diagnose, treat, and monitor trauma-induced coagulopathy. Study objectives were to determine whether CCA abnormalities are reflective of deficiencies of coagulation factor activity in the setting of severe injury.

METHODS

Patients without previous CF deficiency within a prospective database at an ACS-verified Level I trauma center had CF activity levels, PT/INR, aPTT, and fibrinogen levels measured upon emergency department arrival from 2014 to 2017. Linear regression assessed how CF activity explained the aPTT and PT/INR variation. Prolonged CCA values were set as INR greater than 1.3 and aPTT greater than 34 seconds. CF deficiency was defined as less than 30% activity, except for fibrinogen, defined as less than 150 mg/dL.

RESULTS

Sixty patients with a mean age of 35.8 (SD, 13.6) years and median New Injury Severity Score of 32 (interquartile range, 12-43) were included; 53.3% sustained blunt injuries, 23.3% required massive transfusion, and mortality was 11.67%. Overall, 44.6% of the PT/INR variance and 49.5% of the aPTT variance remained unexplained by CF activity. Deficiencies of CFs were: common pathway, 25%; extrinsic pathway, 1.7%; and intrinsic pathway, 6.7%. The positive predictive value for CF deficiencies were: (1) PT/INR greater than 1.3:4.4% for extrinsic pathway, 56.5% for the common pathway; (2) aPTT greater than 34 seconds:16.7% for the intrinsic pathway, 73.7% for the common pathway.

CONCLUSION

Almost half of the variances of PT/INR and aPTT were unexplained by CF activity. Prolonged PT/INR and aPTT were poor predictors of deficiencies in the intrinsic or extrinsic pathways; however, they were indicators of common pathway deficiencies.

LEVEL OF EVIDENCE

Prognostic, level III.

Efficacy of local tranexamic acid treatment for prevention of bleeding after dental procedures: A systematic review and meta-analysis

Background/purpose

Tranexamic acid (TA) is one of the commonly used local hemostatic agents for dental procedures and a previous study has demonstrated a significantly lower incidence of post-procedural bleeding (PPB) in patients taking warfarin and received local TA treatment after the dental procedures than those who took warfarin and did not receive local TA treatment. However, it is still unknown whether post-procedural local TA treatment can lower the bleeding risk to the same level as individuals who do not take oral anticoagulant (OAC). The current study aimed to compare the PPB risk in patients who took OAC and received local TA treatment after the dental procedures and individuals who did not take OAC and underwent similar dental procedures.

Materials and methods

We systematically searched primary researches from two databases and four eligible cohort studies were identified. The bleeding incidence was collected from each study and the pooled odds ratio (OR) and 95% confidence interval (CI) of PPB were calculated using Mantel-Haenzel method.

Results

The analysis revealed a higher risk of PPB in patients who took OAC and received local TA treatment after the dental procedures than individuals who did not take OAC and underwent similar dental procedures with the pooled OR of 2.4, although the pooled effect estimate had a relatively wide 95% CI with non-statistically difference (0.69–8.12).

Conclusion

This study results serve as a reminder to dentists that the increased risk of PPB in those who took OAC is not entirely resolved by the local TA treatment.

Pharmacokinetics of anticoagulants apixaban, dabigatran, edoxaban and rivaroxaban in elderly Japanese patients with atrial fibrillation treated in one general hospital

Steady-state plasma concentrations of anticoagulants and the time since the previous administration in mainly outpatients with atrial fibrillation administered standard or reduced doses were analyzed for 110 elderly Japanese subjects (mean age, 76 years) treated with apixaban (2.5 or 5.0 mg twice daily), dabigatran etexilate (110 or 150 mg twice daily), edoxaban (30 or 60 mg once daily) or rivaroxaban (10 or 15 mg once daily) at one general hospital. The pharmacokinetics in patients treated with standard and reduced doses of the four anticoagulants using liquid chromatography-tandem mass spectrometry was compared with the concentration ranges estimated using physiologically based pharmacokinetic modeling. Reduced doses of anticoagulants resulted in relatively small pharmacokinetic variations compared with the standard dose. Statistical analyses revealed that renal impairment is likely not the sole determinant factor for high plasma concentrations of apixaban, dabigatran, edoxaban and rivaroxaban. Patients with atrial fibrillation should be treated with the correct doses of oral anticoagulants as specified in the package inserts (e.g. reduced doses for elderly patients, patients with low body weights and in combination with P-glycoprotein inhibitor drugs) to avoid excessive or insufficient doses of direct oral anticoagulants.