Comparative safety of direct oral anticoagulants and warfarin in venous thromboembolism: multicentre, population based, observational study

Safety and Effectiveness of Direct Oral Anticoagulants Versus Warfarin in Patients with Venous Thromboembolism using Real-World Data: A Systematic Review and Meta-Analysis

BACKGROUND

Direct oral anticoagulants (DOACs) have shown comparable efficacy and a superior safety profile in clinical trials for patients with venous thromboembolism (VTE). However, further study is needed to assess DOACs' effectiveness and safety compared to warfarin in a real-world context. Thus, this meta-analysis compares the effectiveness and safety of warfarin and DOACs in patients with VTE.

METHOD

A systematic review of the literature using PubMed and EMBASE was conducted from inception until June 2024. We examined observational studies that compared safety and effectiveness between DOACs and warfarin when used in treating VTE and reported adjusted hazard ratios (HRs) and/or odds ratios (ORs) for recurrent VTE, major bleeding, clinically relevant non-major bleeding, gastrointestinal bleeding, intracranial hemorrhage, and death from any cause. We then estimated the pooled effect using the random-effects model for meta-analysis.

RESULTS

A total of 25 studies were included in the current meta-analysis. DOAC therapy was associated with significantly lower risks of recurrent VTE (HR 0.76, 95% confidence interval [CI] 0.69-0.85), major bleeding (HR 0.77, 95% CI 0.72-0.83), clinically relevant non-major bleeding (HR 0.82, 95% CI 0.77-0.88), and gastrointestinal bleeding (HR 0.75, 95% CI 0.68-0.83) compared to warfarin. However, no statistically significant difference was observed in all-cause mortality between the two groups (HR 0.96, 95% CI 0.83-1.10).

CONCLUSION

This meta-analysis found that DOACs are associated with a significant reduction in VTE recurrence in addition to the known favorable safety profile when compared to warfarin.

Discovery of Heparin Mimetic, Potent, and Selective Inhibitors of Human Clotting Factor XIIIa

Factor XIIIa (FXIIIa) is a cysteine transglutaminase that catalyzes the last step in the coagulation process. An anion-binding site inhibition of FXIIIa is a paradigm-shifting strategy that may offer key advantages of controlled inhibition. Such an approach is likely to lead to novel FXIIIa inhibitors that do not carry bleeding risks. We previously reported a flavonoid trimer-based allosteric inhibitor of FXIIIa with moderate potency and selectivity. To further advance this approach, we evaluated a series of 27 variably sulfonated heparin mimetics against human FXIIIa. Only 13 molecules exhibited inhibitory activity at the highest concentration tested with IC50 values of 2-286 μM. Specifically, inhibitor 16 demonstrated an IC50 value of 2.4 ± 0.5 μM in a bisubstrate, fluorescence-based trans-glutamination assay. It also demonstrated a significant selectivity over other clotting factors including thrombin, factor Xa, and factor XIa as well as other cysteine enzymes including papain and tissue transglutaminase 2. Inhibitor 16 did not affect the viability of three human cell lines at a concentration that is 5-fold its FXIIIa-IC50. The molecule had a very weak effect on the activated partial thromboplastin time of human plasma at a concentration of >700 μM, further supporting its functional selectivity. Importantly, molecule 16 inhibited FXIIIa-mediated polymerization of fibrin(ogen) in a concentration-dependent manner as shown by the gel electrophoresis experiment. Michaelis-Menten kinetics revealed that the molecule competes with the Gln-donor protein substrate, i.e., dimethylcasein, but not with the Lys-donor small substrate, i.e., dansylcadaverine. Molecular modeling studies revealed that this type of molecule likely binds to an anion-binding site comprising the basic amino acids of Lys54, Lys61, Lys73, Lys156, and Arg244 among others. Overall, our work puts forward a new anion-binding site, selective, nontoxic, sulfonated heparin mimetic FXIIIa inhibitor 16 for further development as an effective and safer anticoagulant.

Comparative Outcomes of Peripheral Vascular Interventions in Patients on Chronic Anticoagulation with Factor Xa Inhibitors and Vitamin K Antagonists

BACKGROUND

In patients undergoing revascularization for peripheral arterial disease (PAD), low-dose Factor Xa inhibitors (FXaI) taken with aspirin improved limb and cardiovascular outcomes compared to aspirin alone. Furthermore, in atrial fibrillation and venous thromboembolism, FXaI are recommended over vitamin K antagonists (VKA) for chronic anticoagulation. While studies have evaluated different perioperative anticoagulation regimens in patients treated for PAD, the optimal regimen for chronic anticoagulation in patients with PAD undergoing peripheral vascular intervention (PVI) has not been determined. This analysis compares outcomes of patients after PVI that require chronic anticoagulation with FXaI and VKA.

METHODS

The Vascular Quality Initiative-PVI database was used. Patients consistently treated with FXaI or VKA before the procedure, at discharge, and on long-term follow-up were defined as those receiving chronic anticoagulation. Patient demographics, procedural details, and perioperative and long-term outcomes were compared between FXaI and VKA groups.

RESULTS

A total of 109,268 patients were analyzed, and 6,885 were chronically anticoagulated with FXaI (N = 2,427) or VKA (N = 4,458). Patients anticoagulated with VKA were more frequently males (65.3% vs. 61.0%, P < 0.001) with end-stage renal disease (9.7% vs. 4.6%, P < 0.001) and more likely to be treated for chronic limb-threatening ischemia (58.1% vs. 52.7%, P < 0.001). Rates of hematoma following PVI were significantly higher in patients taking VKA compared to FXaI (3.5% vs. 1.9%, P < 0.001). Multivariable logistic regression analysis showed that VKA were associated with increased perioperative hematoma than FXaI (odds ratio = 1.89 [1.30-2.82]). Compared to patients taking VKA, those receiving FXaI had lower rates of major amputation (6.7% vs. 8.4%, P = 0.020) and mortality (7.6% vs. 15.2%, P ≤ 0.001). Using Kaplan-Meier analysis, patients consistently anticoagulated with FXaI had improved amputation-free survival after PVI. Adjusting for significant patient and procedural characteristics, Cox proportional hazard regression demonstrated that there is an increased risk for major amputation or mortality in patients using VKA compared to FXaI (hazard ratio 1.61, [1.36-1.90]).

CONCLUSIONS

Chronic anticoagulation with FXaI as compared to VKA was associated with superior perioperative and long-term outcomes in patients with PAD undergoing PVI. FXaI should be the preferred agents over VKA for chronic anticoagulation in patients with PAD undergoing PVI.

Subsegmental Pulmonary Embolism

Subsegmental pulmonary embolism (SSPE) is increasingly diagnosed with the growing use and technological advancements of multidetector computed tomography pulmonary angiography. Its diagnosis is challenging, and some presumed SSPE may actually represent imaging artifacts. Indirect evidence and results from small observational studies suggest that SSPE may be more benign than more proximal pulmonary embolism, and may thus not always require treatment. Therefore, guidelines suggest to consider a management strategy without anticoagulation in selected patients with SSPE at low risk of recurrent venous thromboembolism (VTE), in whom proximal deep vein thrombosis is excluded. Recently, a large prospective study among low-risk patients with SSPE who were left untreated showed a higher VTE recurrence risk than initially deemed acceptable by the investigators, and thus was prematurely interrupted after recruitment of 97% of the target population. However, the risk-benefit ratio of anticoagulation for low-risk patients with SSPE remains unclear, and results from randomized trials are needed to answer the question about their optimal management.

Temporal trends in admissions for atrial fibrillation and severe bleeding in England: an 18-year longitudinal analysis

Objective. Temporal trends in admissions for atrial fibrillation (AF) and severe bleeding associated with AF vary worldwide. We aimed to explore their temporal trends in England and their relation to the introduction of DOACs in 2014 in the UK. Design. This longitudinal ecological study utilised aggregated data that was extracted from the Hospital Episode Statistics database, which captured annual admissions for AF and severe bleeding associated with AF between 2001 and 2018. Trends in admissions over the study period and across age groups, gender and regions in England were assessed. Results. In total, there were 11,292,177 admissions for AF and 324,851 admissions for severe bleeding associated with AF. There was a steady rise in admissions for AF from 2001 to 2017 (204,808 to 1,109,295; p for trend<.001). A similar trend was observed for severe bleeding (4940 to 30,169; p for trend <.001), but the increase dropped slightly between 2013 and 2014 and continued thereafter. Conclusions. There was a rise in admissions for AF and severe bleeding in England between 2001 and 2018. There is little evidence that the slight drop in admissions for severe bleeding between 2013 and 2014 may have been caused by the introduction of DOACs in 2014. Contributors to these trends need urgent exploration.

Economic Evaluation of Direct Oral Anticoagulants Compared to Warfarin for Venous Thromboembolism in Thailand: A Cost-Utility Analysis

BACKGROUND

Direct oral anticoagulants (DOACs) have been used for venous thromboembolism (VTE) in Thailand. However, they have not been listed in the National List of Essential Medicines (NLEM). A cost-effectiveness analysis is needed to aid policymakers in deciding whether DOACs should be listed in the NLEM. This study aimed to assess the cost-effectiveness of DOACs for patients with VTE in Thailand.

METHODS

A cohort-based state transition model was constructed from a societal perspective with a lifetime horizon. All available DOACs, including apixaban, rivaroxaban, edoxaban, and dabigatran, were compared with warfarin. A 6-month cycle length was used to capture all costs and health outcomes. The model consisted of nine health states, including VTE on treatment, VTE off treatment, recurrent VTE, clinically relevant non-major bleeding, gastrointestinal bleeding, intracranial bleeding, post-intracranial bleeding, chronic thromboembolic pulmonary hypertension, and death. All inputs were based on a comprehensive literature review. The model outcomes included total cost and quality-adjusted life-years (QALYs) with a 3% annual discount rate. A fully incremental cost-effectiveness analysis and the incremental cost-effectiveness ratio (ICER) per QALY gained were calculated at a willingness-to-pay (WTP) of THB 160,000/QALY ($5003). The robustness of the findings was assessed using deterministic and probabilistic sensitivity analyses.

RESULTS

All DOACs were associated with a decreased risk of VTE recurrence and intracranial hemorrhage. In the base-case analysis, apixaban could increase 0.16 QALYs compared with warfarin. An ICER for apixaban was 269,809 Thai baht (THB)/QALY ($8437/QALY). Rivaroxaban had a better QALY than warfarin at 0.09 QALYs with an ICER of 757,363 THB/QALY ($23,682/QALY). Edoxaban and dabigatran could also increase by 0.10 QALYs with an ICER of 709,945 THB ($22,200) and 707,145 THB ($22,122)/QALY, respectively. Our probabilistic sensitivity analyses indicated that warfarin had a 99.8% possibility of being cost-effective, while apixaban had a 0.2% possibility of being cost-effective at the current WTP. Other DOACs had no possibility of being cost-effective.

CONCLUSIONS

All DOACs were not cost-effective for VTE treatment at the current WTP in Thailand. Apixaban is likely to be the best option among DOACs.

Effectiveness and Safety of Direct Oral Anticoagulants Among Octogenarians with Venous Thromboembolism: An International Multidatabase Cohort Study

BACKGROUND

The effects of direct oral anticoagulants (DOACs) among octogenarian patients with venous thromboembolism remains poorly understood. To address this knowledge gap, our study aimed to assess the effectiveness and safety of DOACs compared to vitamin K antagonists (VKAs) among octogenarians with venous thromboembolism.

METHODS

We conducted an international cohort study using administrative health care databases from Québec, Canada, and Germany. We assembled 2 population-based cohorts of octogenarians with incident venous thromboembolism initiating treatment with DOACs or VKAs. The study period spanned from January 2012 to the most recent date of data availability (Québec: December 2016; Germany: December 2019). Using an as-treated exposure definition, we compared use of DOACs to use of VKAs, applying inverse probability of treatment weighting based on high-dimensional propensity scores to balance exposure groups. Cox proportional hazards models estimated site-specific hazard ratios (HRs) and 95% confidence intervals (CIs) of recurrent venous thromboembolism, major bleeding, and all-cause mortality. The results were meta-analyzed using random-effects models.

RESULTS

Overall, our study included 6737 octogenarians with venous thromboembolism (Québec: n = 2556; Germany: n = 4181) who initiated use of DOACs (n = 3778) or VKAs (n = 2959). When compared to VKAs, DOACs were associated with similar risks of recurrent venous thromboembolism (weighted HR, 0.80; 95% CI, 0.43-1.46; I² = 0.00), major bleeding (weighted HR, 0.96; 95% CI, 0.57-1.63; I² = 0.59), and all-cause mortality (weighted HR, 1.04; 95% CI, 0.81-1.34; I² = 0.00).

CONCLUSIONS

Among octogenarians with venous thromboembolism, DOACs showed a comparable effectiveness and safety compared to VKAs. Our results support the use of DOACs in this high-risk group.

Recurrent thromboembolism, bleeding, and mortality in Asian patients with venous thromboembolism receiving different oral anticoagulants: A nationwide analysis

Venous thromboembolism (VTE) is associated with a high risk of morbidity and mortality. However, data on the association between oral anticoagulants and the hazards of VTE complications in Taiwanese patients with VTE is limited. This study aimed to compare the hazards of recurrent VTE, bleeding, and mortality between patients with VTE receiving rivaroxaban, a non-vitamin K antagonist oral anticoagulant (NOAC), and those receiving heparin or low-molecular-weight heparin (LMWH) followed by warfarin. Patients with VTE treated with rivaroxaban, or heparin or LMWH followed by warfarin were enrolled from 2 million random samples from Taiwan's National Health Insurance database between 2013 and 2016. Hazards of recurrent VTE (deep vein thrombosis and pulmonary embolism), major bleeding, and mortality in rivaroxaban and warfarin users were investigated. Survival analyses were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). Users of rivaroxaban (183) and warfarin (456) were included in the study. Patients receiving rivaroxaban did not have significantly lower hazards of developing recurrent VTE (HR, 0.72 [CI, 0.37-1.37], P = .31) and mortality (HR, 0.86 [CI, 0.49-1.50], P = .59) than those receiving heparin or LMWH followed by warfarin. In addition, the hazard ratio of major bleeding was not significantly different between the 2 regimens (HR, 1.80 [CI, 0.39-8.29], P = .45). Rivaroxaban was not associated with lower risks of recurrent VTE and mortality and higher hazards of major bleeding than heparin or LMWH followed by warfarin in Taiwanese patients with VTE. Clinicians may tailor oral anticoagulants for VTE patients according to the patient's characteristics, cost-effectiveness and healthcare system policy.

Sulfonated non-saccharide molecules and human factor XIa: Enzyme inhibition and computational studies

Human factor XIa (FXIa) is a serine protease in the intrinsic coagulation pathway. FXIa has been actively targeted to develop new anticoagulants that are associated with a reduced risk of bleeding. Thousands of FXIa inhibitors have been reported, yet none has reached the clinic thus far. We describe here a novel class of sulfonated molecules that allosterically inhibit FXIa with moderate potency. A library of 18 sulfonated molecules was evaluated for the inhibition of FXIa using a chromogenic substrate hydrolysis assay. Only six molecules inhibited FXIa with IC₅₀ values of 4.6-29.5 μM. Michaelis-Menten kinetics indicated that sulfonated molecules are allosteric inhibitors of FXIa. Inhibition of FXIa by these molecules was reversed by protamine. The molecules also showed moderate anticoagulant effects in human plasma with preference to prolong activated partial thromboplastin time. Their binding to an allosteric site in the catalytic domain of FXIa was modeled to illustrate potential binding mode and potential important Arg/Lys residues. Particularly, inhibitor 16 (IC₅₀  = 4.6 µM) demonstrated good selectivity over a panel of serine proteases including those in the coagulation process. Inhibitor 16 did not significantly compromise the viability of three cell lines. Overall, the reported sulfonated molecules serve as a new platform to design selective, potent, and allosteric inhibitors of FXIa for therapeutic applications.

Effectiveness and Safety of Direct Oral Anticoagulants vs. Warfarin and Recurrence After Discontinuation in Patients With Acute Venous Thromboembolism in the Real World

BACKGROUND

The efficacy of direct oral anticoagulants (DOACs) compared with warfarin for the treatment of venous thromboembolism (VTE), and the recurrence of VTE after discontinuation of anticoagulation therapy in research are limited.

METHODS AND RESULTS

This retrospective study enrolled 893 patients with acute VTE between 2011 and 2019. The cohort was divided into the transient risk, unprovoked, continued cancer treatment, and cancer remission groups. The following were compared between DOACs and warfarin: composite outcome of all-cause death, VTE recurrence, bleeding and composite outcome of VTE-related death, recurrence and bleeding. In the continued cancer treatment group, more bleeding was seen in warfarin-treated patients than in patients treated with DOACs (53.2% vs. 31.2%, [P=0.048]). In addition, composite outcome of VTE-related death and recurrence after discontinuation of anticoagulation therapy (n=369) was evaluated. The continued cancer treatment group (multivariate analysis: HR: 3.62, 95% CI: 1.84-7.12, P<0.005) and bleeding-related discontinuation of therapy (HR: 2.60, 95% CI: 1.32-5.13, P=0.006) were independent predictors of the event after discontinuation of anticoagulation therapy. VTE recurrence after discontinuation of anticoagulation therapy in the cancer remission group was 1.6% and a statistically similar occurrence was found in the transient risk group (12.4%) (P=0.754).

CONCLUSIONS

DOACs may decrease bleeding incidence in patients continuing to receive cancer treatment. In patients with bleeding-related discontinuation of anticoagulation therapy, VTE recurrence may increase. Discontinuation of anticoagulant therapy might be a treatment option in patients who have completed their cancer treatment.

Association of Type of Oral Anticoagulant Dispensed With Adverse Clinical Outcomes in Patients Extending Anticoagulation Therapy Beyond 90 Days After Hospitalization for Venous Thromboembolism

IMPORTANCE

Guidelines for managing venous thromboembolism (VTE) recommend at least 90 days of therapy with oral anticoagulants. Limited evidence exists about the optimal drug for continuing therapy beyond 90 days.

OBJECTIVE

To compare having prescriptions dispensed for apixaban, rivaroxaban, or warfarin after an initial 90 days of anticoagulation therapy for the outcomes of hospitalization for recurrent VTE, major bleeding, and death.

DESIGN, SETTING, AND PARTICIPANTS

This exploratory retrospective cohort study used data from fee-for-service Medicare (2009-2017) and from 2 commercial health insurance (2004-2018) databases and included 64 642 adults who initiated oral anticoagulation following hospitalization discharge for VTE and continued treatment beyond 90 days.

EXPOSURES

Apixaban, rivaroxaban, or warfarin prescribed after an initial 90-day treatment for VTE.

MAIN OUTCOMES AND MEASURES

Primary outcomes included hospitalization for recurrent VTE and hospitalization for major bleeding. Analyses were adjusted using propensity score weighting. Patients were followed up from the end of the initial 90-day treatment episode until treatment cessation, outcome, death, disenrollment, or end of available data. Weighted Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% CIs.

RESULTS

The study included 9167 patients prescribed apixaban (mean [SD] age, 71 [14] years; 5491 [59.9%] women), 12 468 patients prescribed rivaroxaban (mean [SD] age, 69 [14] years; 7067 [56.7%] women), and 43 007 patients prescribed warfarin (mean [SD] age, 70 [15] years; 25 404 [59.1%] women). The median (IQR) follow-up was 109 (59-228) days for recurrent VTE and 108 (58-226) days for major bleeding outcome. After propensity score weighting, the incidence rate of hospitalization for recurrent VTE was significantly lower for apixaban compared with warfarin (9.8 vs 13.5 per 1000 person-years; HR, 0.69 [95% CI, 0.49-0.99]), but the incidence rates were not significantly different between apixaban and rivaroxaban (9.8 vs 11.6 per 1000 person-years; HR, 0.80 [95% CI, 0.53-1.19]) or rivaroxaban and warfarin (HR, 0.87 [95% CI, 0.65-1.16]). Rates of hospitalization for major bleeding were 44.4 per 1000 person-years for apixaban, 50.0 per 1000 person-years for rivaroxaban, and 47.1 per 1000 person-years for warfarin, yielding HRs of 0.92 (95% CI, 0.78-1.09) for apixaban vs warfarin, 0.86 (95% CI, 0.71-1.04) for apixaban vs rivaroxaban, and 1.07 (95% CI, 0.93-1.24) for rivaroxaban vs warfarin.

CONCLUSIONS AND RELEVANCE

In this exploratory analysis of patients prescribed extended-duration oral anticoagulation therapy after hospitalization for VTE, prescription dispenses for apixaban beyond 90 days, compared with warfarin beyond 90 days, were significantly associated with a modestly lower rate of hospitalization for recurrent VTE, but no significant difference in rate of hospitalization for major bleeding. There were no significant differences for comparisons of apixaban vs rivaroxaban or rivaroxaban vs warfarin.

Pharmacist monitoring of direct oral anticoagulants for American Indians and Alaska Natives in the outpatient setting

BACKGROUND

Direct oral anticoagulants (DOACs) call into question the role of traditional pharmacist-run clinics, and few studies have described the incorporation of DOAC's into traditional anticoagulation management services (AMS) OBJECTIVE: To describe the incorporation of DOACs into a pharmacist-run AMS for American Indian and Alaska Native (AI/AN) patients and determine outcomes related to adherence, follow-up, and pharmacist interventions.

PRACTICE DESCRIPTION

Traditional AMS embedded in ambulatory clinic. Warfarin managed by pharmacists under a collaborative practice agreement with supervising physician.

PRACTICE INNOVATION

DOACs incorporated into AMS by transitioning warfarin patients to rivaroxaban and apixaban and managing new patients with DOAC. Follow-up occurred via phone call and at longer intervals.

EVALUATION METHODS

Single-center, retrospective, observational analysis of AI/AN patients who were followed up by pharmacy AMS. The outcomes measured include adherence to DOAC therapy, number of telephonic encounters versus face-to-face visits, frequency of follow-up, types of interventions made at each visit, and an estimate of face-to-face clinic time savings.

RESULTS

A total of 50 patients were included for analysis. The average medication possession ratio was 91%. The majority of visits occurred over the phone (59%), and most follow-up visits occurred every 3 months (62%). The top 3 most frequent interventions were adherence education, initial DOAC education, and education on use of nonsteroidal anti-inflammatory drugs.

PRACTICE IMPLICATIONS

Traditional AMS can evolve by incorporating DOACs and maintaining follow-up.

CONCLUSION

Pharmacist monitoring of DOACs may promote high levels of adherence and lead to time savings by reducing the amount of time spent in traditional AMS.

Geriatric conditions do not predict stroke or bleeding in long-term care residents with atrial fibrillation

BACKGROUND

Long-term care (LTC) providers prescribe anticoagulation (AC) less frequently in residents with atrial fibrillation (AF) and geriatric conditions independent of CHA₂ DS₂ -VASc stroke risk score. Geriatric conditions include recent fall, activities of daily living dependency, mobility impairment, cognitive impairment, low body mass index, and weight loss. Multiple publications have suggested that patients with geriatric conditions are at increased risk for stroke. Understanding better the risk of stroke and bleeding in residents with AF and geriatric conditions would be valuable to LTC providers for AC decision-making.

METHODS AND RESULTS

We measured the association of geriatric conditions with composite of stroke/transient ischemic attack (TIA)/systemic embolism and bleeding in residents with AF and elevated stroke risk (CHA₂ DS₂ -VASc score ≥ 2) living in American LTC facilities in 2015. After merging nursing home assessments (Minimum Data Set) with medication and hospital utilization records, we identified 209,413 eligible residents. Using generalized estimating equations, we found that the incidence of stroke/TIA/systemic embolism ranged from 0.13% to 0.26% over 30 days (1.43%-3.08%/year) in residents off AC with and without geriatric conditions adjusting for other resident characteristics including CHA₂ DS₂ -VASc score and propensity to receive AC. Similarly, the monthly incidence of bleeding on AC ranged from 0.22% to 0.28% (2.61%-3.31%/year) without increased risk with geriatric conditions. Residents with a CHA₂ DS₂ -VASc score of ≥7 had a 2.4-fold increased risk of stroke compared with those with score of 2-4 (0.30% vs. 0.12%/month).

CONCLUSION

Calculating a CHA₂ DS₂ -VASc score can be helpful in AC decision-making for residents with and without geriatric conditions.

Evidence of the Different Associations of Prognostic Factors With Censoring Across Treatment Groups and Impact on Censoring Weight Model Specification: The Example of Anticoagulation in Atrial Fibrillation

Inverse probability of censoring weights (IPCWs) may reduce selection bias due to informative censoring in longitudinal studies. However, in studies with an active comparator, the associations between predictors and censoring may differ across treatment groups. We used the clinical example of anticoagulation treatment with warfarin or a direct oral anticoagulant (DOAC) in atrial fibrillation to illustrate this. The cohort of individuals initiating an oral anticoagulant during 2010-2016 was identified from the Régie de l'assurance maladie du Québec (RAMQ) databases. The parameter of interest was the hazard ratio (HR) of the composite of stroke, major bleeding, myocardial infarction, or death associated with continuous use of warfarin versus DOACs. Two strategies for the specification of the model for estimation of censoring weights were explored: exposure-unstratified and exposure-stratified. The HR associated with continuous treatment with warfarin versus DOACs adjusted with exposure-stratified IPCWs was 1.26 (95% confidence interval: 1.20, 1.33). Using exposure-unstratified IPCWs, the HR differed by 15% in favor of DOACs (1.41, 95% confidence interval: 1.34, 1.48). Not accounting for the different associations between the predictors and informative censoring across exposure groups may lead to misspecification of censoring weights and biased estimate on comparative effectiveness and safety.

The EHA Research Roadmap: Blood Coagulation and Hemostatic Disorders

In 2016, the European Hematology Association (EHA) published the EHA Roadmap for European Hematology Research1 aiming to highlight achievements in the diagnostics and treatment of blood disorders, and to better inform European policy makers and other stakeholders about the urgent clinical and scientific needs and priorities in the field of hematology. Each section was coordinated by 1-2 section editors who were leading international experts in the field. In the 5 years that have followed, advances in the field of hematology have been plentiful. As such, EHA is pleased to present an updated Research Roadmap, now including 11 sections, each of which will be published separately. The updated EHA Research Roadmap identifies the most urgent priorities in hematology research and clinical science, therefore supporting a more informed, focused, and ideally funded future for European hematology research. The 11 EHA Research Roadmap sections include Normal Hematopoiesis; Malignant Lymphoid Diseases; Malignant Myeloid Diseases; Anemias and Related Diseases; Platelet Disorders; Blood Coagulation and Hemostatic Disorders; Transfusion Medicine; Infections in Hematology; Hematopoietic Stem Cell Transplantation; CAR-T and Other Cell-based Immune Therapies; and Gene Therapy.

Use of direct oral anticoagulants in chronic thromboembolic pulmonary hypertension: a systematic review

Direct oral anticoagulants (DOACs) are being increasingly used in patients with chronic thromboembolic hypertension (CTEPH), however, the data on their safety and efficacy are scarce and contradictory. We systematically searched MEDLINE and Google Scholar databases from January 2010 to January 2021 for studies of DOACs in CTEPH. Three observational studies, 2 abstracts and one case series met our inclusion criteria. While these studies reported similar or even less rates of major bleeding in patients receiving DOACs compared with vitamin K antagonists, there were concerns about the possibility of increased risk of venous thromboembolism recurrence with DOAC therapy. Further studies are warranted to better define the role of DOACs in CTEPH.

Oral Anticoagulation Therapy for Venous Thromboembolism in Norway: Time Trends and Treatment Patterns

PURPOSE

Data describing treatment patterns of patients with venous thromboembolism (VTE) patients in Scandinavia are scarce. This study sought to address this scarcity by describing demographic and clinical characteristics, trends in the use of oral anticoagulants (OACs), and treatment patterns in patients treated for VTE in Norway between 2013 and 2017.

METHODS

Using data from Norway's nationwide registries, a cohort study included patients newly (after 2008) treated OACs who were diagnosed with VTE between January 2013 and December 2017 and were dispensed an OAC (warfarin, apixaban, rivaroxaban, dabigatran, or edoxaban) within 30 days. Patient characteristics and the percentage of patients with VTE who initiated treatment with each OAC for each calendar year were reported. Initial therapy persistence was assessed using Kaplan-Meier curves and compared between the OAC groups using the log-rank test.

FINDINGS

The comorbidity burden was similar between patients taking warfarin and those taking apixaban but lower among patients taking rivaroxaban. Direct oral anticoagulant (DOAC) use increased from 33.2% to 93.6% during the study period, whereas warfarin use decreased. Persistence was higher in the apixaban cohort compared with the warfarin cohort, with the difference mostly apparent after 6 months, whereas persistence was similar between the patients taking rivaroxaban and those taking warfarin.

IMPLICATIONS

Between 2013 and 2017, DOAC use among patients with VTEs increased markedly in Norway, whereas the use of warfarin decreased. Patients taking apixaban had higher persistence compared with those taking warfarin, whereas patients taking warfarin and those taking rivaroxaban had similar persistence. Further studies with longer follow-up are required to examine the use of extended OAC treatment for VTE.

Clinical protocols for oral anticoagulant reversal during high risk of bleeding for emergency surgical and nonsurgical settings: a narrative review

Background and objectives

Oral anticoagulants prevent thromboembolic events but expose patients to a significant risk of bleeding due to the treatment itself, after trauma, or during surgery. Any physician working in the emergency department or involved in the perioperative care of a patient should be aware of the best reversal approach according to the type of drug and the patient’s clinical condition. This paper presents a concise review and proposes clinical protocols for the reversal of oral anticoagulants in emergency settings, such as bleeding or surgery.

Contents

The authors searched for relevant studies in PubMed, LILACS, and the Cochrane Library database and identified 82 articles published up to September 2020 to generate a review and algorithms as clinical protocols for practical use. Hemodynamic status and the implementation of general supportive measures should be the first approach under emergency conditions. The drug type, dose, time of last intake, and laboratory evaluations of anticoagulant activity and renal function provide an estimation of drug clearance and should be taken into consideration. The reversal agents for vitamin K antagonists are 4-factor prothrombin complex concentrate and vitamin K, followed by fresh frozen plasma as a second-line treatment. Direct oral anticoagulants have specific reversal agents, such as andexanet alfa and idarucizumab, but are not widely available. Another possibility in this situation, but with less evidence, is prothrombin complex concentrates.

Conclusion

The present algorithms propose a tool to help healthcare providers in the best decision making for patients under emergency conditions.

Impact of anticoagulant exposure misclassification on the bleeding risk of direct oral anticoagulants

Aims

Drug exposure status based on routinely collected data might be misclassified when the database contains only prescriptions from 1 type of prescriber (e.g. general practitioner and not specialist). This study aims to quantify the impact of such exposure misclassification on the risk of major bleeding and stroke/transient ischaemic attack (TIA)associated with direct oral anticoagulants (DOACs) vs. vitamin K antagonists (VKAs).

Methods

Incident anticoagulant users (>12 mo free of anticoagulation use) in the Dutch PHARMO Database Network between 2008 and 2017 were included. Drug exposure was assessed using pharmacy dispensing information. The risks of hospital admission of major bleeding for DOAC vs. VKA users was assessed with Cox regression analysis, where exposure was based on all dispensings, on general practitioner (GP)‐prescribed dispensings only or on specialist‐prescribed dispensings only. Hazard ratios (HRs) were estimated also for hospitalization for gastrointestinal bleeding, intracranial bleeding and stroke/TIA.

Results

We included 99 182 VKA‐initiators and 21 795 DOAC‐initiators. Use of DOAC was associated with a lower risk of major bleeding compared to VKA use; HR 0.79 (95% confidence interval 0.70–0.90), 0.78 (0.68–0.91) and 0.62 (0.50–0.76), for exposure based on complete dispensing information, only GP‐ and only specialist‐prescribed dispensings, respectively. Similar results were found for the other bleeding outcomes. For stroke/TIA the HRs were 0.96 (0.84–1.09), 1.00 (0.84–1.18) and 0.72 (0.58–0.90), respectively.

Conclusion

Including only GP‐prescribed anticoagulant dispensings in this case did not materially impact the effect estimates compared to including all anticoagulant dispensings. Including only specialist‐prescribed dispensings, however, strengthened the effect estimates.

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. ​.

MAC Project-Monitoring Anticoagulant Therapy Observational Study: Rationale and Protocol

Real-life studies complement data from registrative trials. Because of the delayed registration of direct oral anticoagulants in Italy, scarce real-life data on such treatments is available for the Italian population. The aim of the MAC project is to collect real-life clinical information in unselected patients given oral anticoagulants for venous thromboembolism, during a 5-year follow-up period. This is a prospective-cohort, multi-center, observational study performed in four Italian centers. The estimated samples size is 4,000 patients. The efficacy outcomes are: incidence of symptomatic recurrent venous thromboembolism and of post-thrombotic syndrome. The safety outcomes are: incidence of major bleeding, clinically relevant non-major bleeding, minor bleeding, serious adverse events, and mortality. The MAC project has the potential to improve our understanding of the epidemiology and of the therapeutic strategies adopted in Italian patients with venous thromboembolism.

Clinical Trial Registration: WWW.ClinicalTrials.Gov, identifier: NCT0432939.

Comparative Safety of Smoking Cessation Pharmacotherapies During a Government-Sponsored Reimbursement Program

INTRODUCTION

The British Columbia Ministry of Health launched a Smoking Cessation Program on September 30, 2011, providing financial coverage for smoking cessation pharmacotherapies. Although pharmacotherapies have been shown to have a moderate short-term benefit as a quitting aid, substantial cardiovascular and neuropsychiatric safety concerns have been identified in adverse-reporting databases, leading to prescription label warnings by Health Canada and the U.S. Food and Drug Administration. However, recent studies indicate these warnings may be without merit. This study examined the comparative safety of medications commonly used to aid smoking cessation.

AIMS AND METHODS

Population-based retrospective cohort study using B.C. administrative data to assess the relative safety between varenicline, bupropion, and nicotine replacement therapies (NRTs). The primary outcome was a composite of cardiovascular hospitalizations. Secondary outcomes included mortality, a composite of neuropsychiatric hospitalizations, and individual components of the primary outcome. Statistical analysis used propensity score-adjusted log-binomial regression models. A sensitivity analysis excluded patients with a history of cardiovascular disease.

RESULTS

The study included 116 442 participants. Compared with NRT, varenicline was associated with a 10% 1-year relative risk decrease of cardiovascular hospitalization (adjusted risk ratio [RR] = 0.90, 95% confidence interval (CI): 0.82 to 1.00), a 20% 1-year relative risk decrease of neuropsychiatric hospitalization (RR: 0.80, CI: 0.7 to 0.89), and a 19% 1-year relative risk decrease of mortality (RR: 0.81, CI: 0.71 to 0.93). We found no significant association between NRT and bupropion for cardiovascular hospitalizations, neuropsychiatric hospitalizations, or mortality.

CONCLUSIONS

Compared with NRT, varenicline is associated with fewer serious adverse events and bupropion the same number of serious adverse events.

IMPLICATIONS

This study addresses the need for comparative safety evidence in a real-world setting of varenicline and bupropion against an active comparator. Compared with NRT, varenicline was associated with a decreased risk of mortality, serious cardiovascular events, and neuropsychiatric events during the treatment, or shortly after the treatment, in the general population of adults seeking pharmacotherapy to aid smoking cessation. These results provide support for the removal of the varenicline boxed warning for neuropsychiatric events and add substantively to the cardiovascular safety findings of previous observational studies and randomized clinical trials.

Clinical Surveillance vs. Anticoagulation For low-risk patiEnts with isolated SubSegmental Pulmonary Embolism: protocol for a multicentre randomised placebo-controlled non-inferiority trial (SAFE-SSPE)

INTRODUCTION

The clinical significance of subsegmental pulmonary embolism (SSPE) is currently unclear. Although growing evidence from observational studies suggests that withholding anticoagulant treatment may be a safe option in selected patients with isolated SSPE, most patients with this condition receive anticoagulant treatment, which is associated with a 90-day risk of recurrent venous thromboembolism (VTE) of 0.8% and major bleeding of up to 5%. Given the ongoing controversy concerning the risk-benefit ratio of anticoagulation for isolated SSPE and the lack of evidence from randomised-controlled studies, the aim of this clinical trial is to evaluate the efficacy and safety of clinical surveillance without anticoagulation in low-risk patients with isolated SSPE.

METHODS AND ANALYSIS

SAFE-SSPE (Surveillance vs. Anticoagulation For low-risk patiEnts with isolated SubSegmental Pulmonary Embolism, a multicentre randomised placebo-controlled non-inferiority trial) is an international, multicentre, placebo-controlled, double-blind, parallel-group non-inferiority trial conducted in Switzerland, the Netherlands and Canada. Low-risk patients with isolated SSPE are randomised to receive clinical surveillance with either placebo (no anticoagulation) or anticoagulant treatment with rivaroxaban. All patients undergo bilateral whole-leg compression ultrasonography to exclude concomitant deep vein thrombosis before enrolment. Patients are followed for 90 days. The primary outcome is symptomatic recurrent VTE (efficacy). The secondary outcomes include clinically significant bleeding and all-cause mortality (safety). The ancillary outcomes are health-related quality of life, functional status and medical resource utilisation.

ETHICS AND DISSEMINATION

The local ethics committees in Switzerland have approved this protocol. Submission to the Ethical Committees in the Netherlands and Canada is underway. The results of this trial will be published in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

NCT04263038.

Novel oral anticoagulants in intracardiac thrombosis resolution: a case series

Background

Vitamin K antagonists (VKAs) have been regarded as the therapy of choice for intracardiac thrombosis for decades based mostly on observational data. The advent of direct oral anticoagulants (DOACs) has displaced VKAs as the first-line therapy for multiple thrombotic disorders but not for intracardiac thrombosis. Although limited, there is growing evidence that DOACs are effective for intracardiac thrombosis and some data suggest that thrombus resolution might be superior to that with warfarin.

Case summary

Here, we present a series of six patients with left atrial appendage thrombi were treated with a venous thromboembolic dose of DOACs with resolution within 2–6 months with no reported complications.

Discussion

This case series adds to the accumulating evidence supporting the efficacy of DOACs in the treatment of intracardiac thrombi.

Anticoagulation in Italian patients with venous thromboembolism and thrombophilic alterations: findings from START2 register study

BACKGROUND

Randomised control trials have assessed the efficacy and safety of direct oral anticoagulants in the prophylaxis and treatment of venous thromboembolism (VTE). Positive but limited results have been reported in patients with inherited thrombophilia. Using an Italian, multicentre, prospective registry of consecutive patients presenting with symptomatic, acute VTE, we aimed to assess which factors are involved in making the choice of the drug that best fits the patient's risk profile in a large real-world setting of VTE patients.

MATERIALS AND METHODS

We investigated 4,866 VTE patients who took oral anticoagulants in the period between 2012 and April 2018 to prevent a new thromboembolic episode.

RESULTS

The large majority of patients who underwent thrombophilic screening, regardless of the results obtained, were prescribed direct oral anticoagulants rather than conventional anticoagulant therapy (p<0.001). During anticoagulation, bleeding events occurred more frequently in patients on conventional anticoagulant therapy (4.2%) than in those receiving direct oral anticoagulants (1.8%) and an increase in bleeding events was observed in patients who tested positive at the thrombophilic screening. Overall, a higher number of recurrent VTE was observed in patients not screened for thrombophilia (n=36; 1.7%) than in those screened (n=20; 0.7%; adjusted odds ratio: 2.2; 95% confidence interval: 1.2-4.1).

DISCUSSION

The present data confirm previous findings from other post-marketing registries and suggest that the choice of oral anticoagulation is strongly driven by patients' characteristics and VTE manifestations. Factors leading to the prescription of thrombophilic screening may identify a patient with a lower risk of VTE recurrence during anticoagulation.

Direct Oral Anticoagulant Use in Chronic Kidney Disease and Dialysis Patients With Venous Thromboembolism: A Systematic Review of Thrombosis and Bleeding Outcomes

OBJECTIVE

To evaluate how treatment with DOACs for VTE affects thrombosis and bleeding outcomes compared to warfarin in CKD and dialysis patients.

DATA SOURCES

A literature search was conducted for studies evaluating VTE and bleeding outcomes with DOAC use in CKD and dialysis patients. Searches conducted through EMBASE, MEDLINE/PubMed, Scopus, and Cochrane Central Register of Controlled Trials, from inception to September 22, 2020.

STUDY SELECTION AND DATA EXTRACTION

Randomized controlled trials, cohort studies, and case series with ≥10 patients included.

DATA SYNTHESIS

From 7286 studies, nine studies met inclusion criteria. There was no significant difference between DOACs (dabigatran, rivaroxaban, apixaban) and warfarin for reducing recurrent VTE and bleeding events in moderate CKD patients. The risk of overall major bleeding increased when the degree of kidney impairment increased. There was no significant difference between apixaban and warfarin for VTE outcomes in dialysis patients.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

There continues to be a controversial debate whether it may be more beneficial to use DOACs versus warfarin in CKD/dialysis patients with venous thromboembolism (VTE). The risk vs benefit of using DOACs in the CKD/ESKD population should continue to be evaluated for each individual patient.

CONCLUSION

Apixaban may be used cautiously as an alternative in acute VTE treatment in severe CKD patients. Insufficient evidence is available to suggest the use of dabigatran and rivaroxaban in this patient population. The benefit of using DOACs in this population for VTE treatment should be weighed against the potential bleeding risk in patients with CKD.

Compared to randomized studies, observational studies may overestimate the effectiveness of DOACs: a metaepidemiological approach

BACKGROUND AND OBJECTIVES

Randomized controlled trials (RCTs) are criticized for including patients who are overselected. Health authorities consequently encourage "real-world" postmarketing cohort studies. Our objective was to determine the differences between RCTs and observational studies as regards their populations and efficacy/safety results.

METHODS

A systematic review was conducted to identify RCTs and observational studies including patients with venous thromboembolism receiving direct oral anticoagulants or conventional treatment. Ratios of hazard ratio (RHR) comparing epidemiological studies (prospective and retrospective cohort studies and studies using living databases) with RCTs were computed.

RESULTS

Six RCTs (27,121 patients) and twenty observational studies (248,971 patients) were identified and analyzed. Prospective cohort studies seemed to recruit patients who were no less selected than those of RCTs whereas other types of observational studies may reflect the population treated in real life. Among observational studies, prospective cohort studies yielded the most favorable estimates of treatment effect compared with RCTs. These studies were associated with a nonsignificant 33% increase in efficacy estimate (RHR 0.67, [95% CI, 0.39-1.18]) but no effect on safety estimate. Studies using living databases were associated with nonsignificant trends toward a greater effect on efficacy (RHR 0.82, [0.66-1.01]) and a smaller effect on safety (RHR 1.33, [0.96-1.84]).

DISCUSSION

Overall, in this clinical setting, an exaggeration of the treatment efficacy estimate was seen with observational studies compared with RCTs.

CONCLUSIONS

As the presence of residual confounding cannot be excluded, these results should be interpreted cautiously.

Uninterrupted direct oral anticoagulant treatment during acute illness: Impact on clinical outcomes

BACKGROUND

Uninterrupted drug therapy during acute illness is often associated with pharmacokinetic and pharmacodynamic variations. Among warfarin treated patients, these changes are reflected in the INR. However, in the case of direct oral anticoagulants (DOACs), given that routine laboratory monitoring is not recommended, these changes may result in unforeseen thromboembolic or bleeding events.

OBJECTIVES

To determine the rate of thromboembolic (TEE) and bleeding events associated with uninterrupted DOAC compared to warfarin treatment during acute illness.

METHODS

A retrospective cohort study of patients treated with DOACs or warfarin, both at steady state, who were hospitalized for acute illness. Primary outcome was any TEE or major bleeding requiring re-hospitalization within one month from discharge. Secondary outcome was a composite of major bleeding and clinically relevant non-major bleeding (CRNMB) events.

RESULTS

A total of 410 patients continued oral anticoagulant treatment during their hospitalization, of whom 191 (46.6%) were on DOACs and 219 (53.4%) on warfarin, with a total of 18 (4.4%) events. Rates of TEE and major bleeding events did not differ between DOACs and warfarin treated patients (0.9% vs. 0.5% and 0.5% vs. 1%, respectively). Similarly, rate of secondary outcome was comparable between DOACs (4.7%) and warfarin (2.7%, p = 0.29). Sub-analyses demonstrated significantly higher rates among rivaroxaban (10.4%) treated patients compared to warfarin (p = 0.03).

CONCLUSION

Uninterrupted treatment with DOACs during acute illness is not associated with increased risk for re-hospitalizations due to bleeding or thromboembolic events compared to warfarin. Our results suggest a higher bleeding rate among rivaroxaban treated patients at high bleeding risk.

Recent advances in understanding, diagnosing and treating venous thrombosis

Focusing on the current state of the art, this article (a) describes recent advances in the understanding of the pathogenesis of venous thromboembolism (VTE), (b) discusses current approaches for the prevention, diagnosis and treatment of VTE, (c) outlines the role of aspirin for VTE prevention and treatment, and (d) highlights the unmet needs in VTE management and describes novel approaches to address them.

Prophylaxis with rivaroxaban after laparoscopic sleeve gastrectomy could reduce the frequency of portomesenteric venous thrombosis

INTRODUCTION

Portal and mesenteric venous thrombosis is a rare but potentially serious complication after laparoscopic sleeve gastrectomy. There are no consistent studies that prove the safety and effectiveness of oral anticoagulant thromboprophylaxis with rivaroxaban after laparoscopic sleeve gastrectomy. The objective was to evaluate the effect of rivaroxaban on the frequency of portal and mesenteric venous thrombosis and its safety profile after laparoscopic sleeve gastrectomy.

MATERIALS AND METHODS

This retrospective analysis of prospectively collected data includes all laparoscopic sleeve gastrectomies performed by a single surgeon at Pontificia Universidad Católica de Chile Hospital between January 2009 and June 2019. All patients received low molecular weight heparin thromboprophylaxis during the whole hospital stay. Between July 2012 and June 2019, patients received additional post-discharge thromboprophylaxis with rivaroxaban. Patient demographics, impaired renal, post-surgical portal and mesenteric venous thrombosis, and bleeding episodes were registered.

RESULTS

A total of 516 patients were identified; 95 patients were excluded. Results for 421 patients were analysed: 198 received only intrahospital thromboprophylaxis (group 1) and 223 received additional post-discharge thromboprophylaxis with rivaroxaban (group 2). There was no statistically significant difference between the two groups concerning age, sex and body mass index. In group 1, four cases of portal and mesenteric venous thrombosis were registered and no cases were reported in group 2 (p < 0.05). All cases occurred before 30 days after surgery. No bleeding episodes and no adverse reactions were detected in group 2.

CONCLUSIONS

Thromboprophylaxis during the whole hospital stay (two to three days), followed by rivaroxaban 10mg once daily for 10 days after discharge (completing in total 13-14 days of prophylaxis), could reduce cases of post-surgical portal and mesenteric venous thrombosis without an increase in bleeding complications.

Extended DOAC therapy in patients with VTE and potential risk of recurrence: A systematic review and meta-analysis

BACKGROUND

Guidelines recommend at least 3 months of anticoagulation for venous thromboembolism (VTE). Evidence supporting indefinite anticoagulation exists in certain conditions; however, for many patients, uncertainty regarding when to discontinue anticoagulation persists.

OBJECTIVE

We aimed to investigate the efficacy and safety of extended direct oral anticoagulants (DOAC) therapy in patients with VTE and clinical uncertainty regarding extended anticoagulation.

METHODS

We searched EMBASE, MEDLINE, PubMed, and Cochrane Central Register of Controlled Trials databases for randomized control trials examining extended anticoagulation with DOACs as compared to non-extended therapy for the treatment of VTE.

RESULTS

Of 560 citations identified by the search, three studies were eligible. Extended anticoagulation reduced VTE recurrence (relative risk [RR] 0.18, 95% confidence interval [CI] 0.12 to 0.25), and mortality (RR 0.39, 95% CI 0.19 to 0.80) with a low total number of deaths in the DOAC group (n = 12) versus placebo (n = 18). Extended anticoagulation increased clinically relevant non-major bleedings (RR 2.51, 95% CI 1.37 to 4.59). There was no difference in rates of major bleeding (RR 1.87, 95% CI 0.19 to 17.85); however, there was a low number of major bleeding events in both DOAC (n = 9) and placebo groups (n = 4). The results were mostly driven by one study (AMPLIFY-EXT), with significant heterogeneity between studies noticed when assessing bleeding outcomes.

CONCLUSION

Extended DOAC therapy for 1 year in patients with clinical uncertainty for ongoing anticoagulation can reduce VTE recurrence and mortality; however, it could increase clinically relevant non-major bleeding events.

Management of Outpatient Warfarin Therapy amid COVID-19 Pandemic: A Practical Guide

Many healthcare resources have been and continue to be allocated to the management of patients with COVID-19. Therefore, the ongoing care of patients receiving oral anticoagulation with warfarin is likely to be compromised amid this unprecedented crisis. This article discusses a stepwise algorithm for the management of outpatient warfarin therapy. Alternative management strategies are presented and discussed, including alternative pharmacological therapy options and self-monitoring. Our algorithm aims to help clinicians safely optimize the treatment of patients requiring anticoagulation therapy in the context of the global response to the current pandemic.

Management of Outpatient Warfarin Therapy amid COVID-19 Pandemic: A Practical Guide

Many healthcare resources have been and continue to be allocated to the management of patients with COVID-19. Therefore, the ongoing care of patients receiving oral anticoagulation with warfarin is likely to be compromised amid this unprecedented crisis. This article discusses a stepwise algorithm for the management of outpatient warfarin therapy. Alternative management strategies are presented and discussed, including alternative pharmacological therapy options and self-monitoring. Our algorithm aims to help clinicians safely optimize the treatment of patients requiring anticoagulation therapy in the context of the global response to the current pandemic.

Bleeding Risk in Nonvalvular Atrial Fibrillation Patients Receiving Direct Oral Anticoagulants and Warfarin: A Systematic Review and Meta-Analysis of Observational Studies

Introduction  In randomized trials in atrial fibrillation (AF) patients on direct oral anticoagulants (DOACs) have a lower risk of bleeding compared with warfarin. However, data from randomized trials may not extrapolate to general population. We aimed to determine the risk of bleeding in patients on DOACs in observational studies. Materials and Methods  Observational studies from 1990 to January 2019 were included. A pooled effect hazard ratio (HR) was calculated with a random effects model using the generic inverse variance method. Subgroup analyses according to previous anticoagulants exposure, study type, funding source, and DOAC type (direct thrombin inhibitors vs. factor Xa inhibitors) were conducted. Results  A total of 35 studies comprising 2,356,201 patients were included. The average pooled HR for observational data was 0.78 (95% confidence interval [CI] 0.71, 0.85). There were no statistically significant differences in pooled HR by previous exposure to anticoagulants, DOAC type (direct thrombin vs. factor Xa inhibitors), study type, and funding source. Among patients receiving factor Xa inhibitors, patients on apixaban had a lower risk of bleeding compared with warfarin (HR 0.60, 95% CI 0.50, 0.71, p  < 0.001) in contrast to those on rivaroxaban (HR 0.98, 95% CI 0.91, 1.06, p  = 0.60). Conclusion  In observational studies, AF patients on DOACs experience less bleeding events compared with warfarin; however, apixaban and dabigatran, but not rivaroxaban, have a lower risk of bleeding than warfarin.

Effectiveness and Safety of Apixaban for Treatment of Venous Thromboembolism in Daily Practice

Introduction  Phase 3 trials have shown comparable efficacy of direct oral anticoagulants (DOACs) and vitamin K antagonists in patients with acute venous thromboembolism (VTE), with less major bleeding events in patients randomized to DOAC treatment. With DOACs being increasingly used in clinical practice, evaluation of the DOACs in daily practice-based conditions is needed to confirm their safety and effectiveness. The aim of this study is to evaluate the effectiveness and safety of apixaban in VTE patients in daily practice. Methods  In this retrospective cohort study, consecutive patients diagnosed with VTE in two Dutch hospitals (Leiden University Medical Center, Leiden and Haga Teaching Hospital, The Hague) were identified based on administrative codes. We assessed recurrent VTE, major bleeding and mortality during a 3-month follow-up period in those treated with apixaban. Results  Of 671 consecutive VTE patients treated with apixaban, 371 presented with acute pulmonary embolism (PE) and 300 patients with deep-vein thrombosis. During 3 months treatment, 2 patients had a recurrent VTE (0.3%; 95% confidence interval [CI]: 0.08-1.1), 12 patients had major bleeding (1.8%; 95% CI: 1.0-3.2), and 11 patients died (1.6%; 95% CI: 0.9-2.9), of which one patient with recurrent PE and one because of a intracerebral bleeding. Conclusion  In this daily practice-based cohort, apixaban yielded a low incidence of recurrent VTE, comparable to the phase 3 AMPLIFY study patients. The incidence of major bleeding was higher than in the AMPLIFY-study patients, reflecting the importance of daily practice evaluation and the fact that results from phase III clinical studies cannot be directly extrapolated toward daily practice.

Has the introduction of direct oral anticoagulants (DOACs) in England increased emergency admissions for bleeding conditions? A longitudinal ecological study

OBJECTIVE

There is concern about long-term safety of direct oral coagulants (DOACs) in clinical practice. Our aim was to investigate whether the introduction of DOACs compared with vitamin-K antagonists in England was associated with a change in admissions for bleeding or thromboembolic complications.

SETTING

5508 General practitioner (GP) practices in England between 2011 and 2016.

PARTICIPANTS

All GP practices in England with a registered population size of greater than 1000 that had data for all 6 years.

MAIN OUTCOME MEASURE

The rate of emergency admissions to hospital for bleeding or thromboembolism, per 100 000 population for each GP practice in England.

MAIN EXPOSURE MEASURE

The annual number of DOAC items prescribed for each GP practice population as a proportion of all anticoagulant items prescribed.

DESIGN

This longitudinal ecological study used panel regression models to investigate the association between trends in DOAC prescribing within GP practice populations and trends in emergency admission rates for bleeding and thromboembolic conditions, while controlling for confounders.

RESULTS

For each additional 10% of DOACs prescribed as a proportion of all anticoagulants, there was a 0.9% increase in bleeding complications (rate ratio 1.008 95% CI 1.003 to 1.013). The introduction of DOACs between 2011 and 2016 was associated with additional 4929 (95% CI 2489 to 7370) emergency admissions for bleeding complications. Increased DOAC prescribing was associated with a slight decline in admission for thromboembolic conditions.

CONCLUSION

Our data show that the rapid increase in prescribing of DOACs after changes in National Institute for Health and Care Excellence guidelines in 2014 may have been associated with a higher rate of emergency admissions for bleeding conditions. These consequences need to be considered in assessing the benefits and costs of the widespread use of DOACs.

Impact of Anticoagulation on Mortality and Resource Utilization Among Critically Ill Patients With Major Bleeding

OBJECTIVES

Patients with major bleeding are commonly admitted to the ICU. A growing number are on either oral or parenteral anticoagulation, but the impact of anticoagulation on patient outcomes is unknown. We sought to examine this association between anticoagulation therapy and mortality, as well as the independent effects of warfarin compared to direct oral anticoagulants.

DESIGN

Analysis of a prospectively collected registry (2011-2017) of consecutive ICU patients admitted with major bleeding (as defined by International Society on Thrombosis and Haemostasis clinical criteria).

SETTING

Two hospitals within a single tertiary care level hospital system.

PATIENTS

We analyzed 1,598 patients identified with major bleeding, of which 245 (15.3%) had been using anticoagulation at the time of ICU admission. Of patients on anticoagulation, 149 were using warfarin, and 60 were using a direct oral anticoagulant.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The primary outcome, in-hospital mortality, was analyzed using a multivariable logistic regression model. Patients with anticoagulation-associated major bleeding had higher in-hospital mortality (adjusted odds ratio, 1.49; 95% CI, 1.16-1.92). Among survivors, anticoagulation use was associated with longer median hospital length of stay, and higher mean costs. No differences in hospital mortality were seen between warfarin- and direct oral anticoagulant-associated major bleeding. Patients with warfarin-associated major bleeding had longer median length of stay (11 vs 6 d; p = 0.02), and higher total costs than patients with direct oral anticoagulant-associated major bleeding.

CONCLUSIONS

Among ICU patients admitted with major bleeding, pre-admission anticoagulation use was associated with increased hospital mortality, prolonged length of stay, and higher costs among survivors. As compared to direct oral anticoagulants, patients with warfarin-associated major bleeding had increased length of stay and costs. These findings have important implications in the care of ICU patients with major bleeding.

Risk of Major Gastrointestinal Bleeding With New vs Conventional Oral Anticoagulants: A Systematic Review and Meta-analysis

BACKGROUND & AIMS

There is controversy over whether use of non-vitamin K antagonist oral anticoagulants (NOACs) associates with increased risk of major gastrointestinal bleeding (GIB) compared with conventional therapies (such as vitamin K antagonists or anti-platelet agents). We performed a systematic review and meta-analysis of data from randomized controlled trials and high-quality real-world studies.

METHODS

We performed a systematic search of the MEDLINE, EMBASE, Cochrane Library, and ClinicalTrials.gov Website databases (through Oct 12, 2018) for randomized controlled trials and high-quality real-world studies that reported major GIB events in patients given NOACs or conventional therapy. Relative risks (RRs) for randomized controlled trials and adjusted hazard ratios (aHRs) for real-world studies were calculated separately using random-effects models.

RESULTS

We analyzed data from 43 randomized controlled trials (183,752 patients) and 41 real-world studies (1,879,428 patients). The pooled major rates of GIB for patients on NOACs (1.19%) vs conventional treatment (0.92%) did not differ significantly (RR from randomized controlled trials, 1.09; 95% CI, 0.91-1.31 and aHR from real-world studies, 1.02; 95% CI, 0.94-1.10; P_interaction=.52). Rivaroxaban, but not other NOACs, was associated with an increased risk for major GIB (RR from randomized controlled trials, 1.39; 95% CI, 1.17-1.65 and aHR from real-world studies, 1.14; 95% CI, 1.04-1.23; P_interaction = .06). Analyses of subgroups, such as patients with different indications, dosage, or follow-up time, did not significantly affect results. Meta-regression analysis failed to detect any potential confounding to impact the primacy outcome.

CONCLUSIONS

In a systematic review and meta-analysis of data from randomized controlled trials and real-world studies, we confirmed that there is no significant difference in risk of major GIB between patients receiving NOACs vs conventional treatment. Rivaroxaban users had a 39% increase in risk for major GIB.

Periprocedural Direct Oral Anticoagulant Management: The RA-ACOD Prospective, Multicenter Real-World Registry

Introduction  There is scarce real-world experience regarding direct oral anticoagulants (DOACs) perioperative management. No study before has linked bridging therapy or DOAC-free time (pre-plus postoperative time without DOAC) with outcome. The aim of this study was to investigate real-world management and outcomes. Methods  RA-ACOD is a prospective, observational, multicenter registry of adult patients on DOAC treatment requiring surgery. Primary outcomes were thrombotic and hemorrhagic complications. Follow-up was immediate postoperative (24-48 hours) and 30 days. Statistics were performed using a univariate and multivariate analysis. Data are presented as odds ratios (ORs [95% confidence interval]). Results  From 26 Spanish hospitals, 901 patients were analyzed (53.5% major surgeries): 322 on apixaban, 304 on rivaroxaban, 267 on dabigatran, 8 on edoxaban. Fourteen (1.6%) patients suffered a thrombotic event, related to preoperative DOAC withdrawal (OR: 1.57 [1.03-2.4]) and DOAC-free time longer than 6 days (OR: 5.42 [1.18-26]). Minor bleeding events were described in 76 (8.4%) patients, with higher incidence for dabigatran (12.7%) versus other DOACs (6.6%). Major bleeding events occurred in 17 (1.9%) patients. Bridging therapy was used in 315 (35%) patients. It was associated with minor (OR: 2.57 [1.3-5.07]) and major (OR: 4.2 [1.4-12.3]) bleeding events, without decreasing thrombotic events. Conclusion  This study offers real-world data on perioperative DOAC management and outcomes in a large prospective sample size to date with a high percentage of major surgery. Short-term preprocedural DOAC interruption depending on the drug, hemorrhagic risk, and renal function, without bridging therapy and a reduced DOAC-free time, seems the safest practice.

Anticoagulants' Safety and Effectiveness in General Practice: A Nationwide Prospective Cohort Study

PURPOSE

Most real-world studies on anticoagulants have been based on health insurance databases or performed in secondary care. The aim of this study was to compare safety and effectiveness between patients treated with vitamin K antagonists (VKAs) and patients treated with direct oral anticoagulants (DOACs) in a general practice setting.

METHODS

The CACAO study (Comparison of Accidents and their Circumstances with Oral Anticoagulants) is a multicenter prospective cohort study conducted among ambulatory patients taking an oral anticoagulant. Participants were patients from the study's cross-sectional phase receiving oral anticoagulants because of nonvalvular atrial fibrillation, for secondary prevention of venous thromboembolism, or both. They were followed as usual for 1 year by their general practitioners, who collected data on changes in therapy, thromboembolic events, bleeding, and deaths. All events were adjudicated by an independent committee. We used a propensity score and a Cox regression model to derive hazard ratios.

RESULTS

Between April and December 2014, a total of 3,082 patients were included. At 1 year, 42 patients (1.7%) had experienced an arterial or venous event; 151 (6.1%) had experienced bleeding, including 47 (1.9%) who experienced major bleeding; and 105 (4.1%) had died. There was no significant difference between the VKA and DOAC groups regarding arterial or venous events, or major bleeding. The VKA group had a lower risk of overall bleeding (hazard ratio = 0.65; 95% CI, 0.43-0.98) but twice the risk of death (hazard ratio = 1.98; 95% CI, 1.15-3.42).

CONCLUSIONS

VKAs and DOACs had fairly similar safety and effectiveness in general practice. The substantially higher incidence of deaths with VKAs is consistent with known data from health insurance databases and calls for further research to understand its cause.

Comparison between direct factor Xa inhibitors and low-molecular-weight heparin for efficacy and safety in the treatment of cancer-associated venous thromboembolism: A meta-analysis

Aim of the Study

The role of direct-acting oral anticoagulants in the treatment of venous thromboembolism (VTE) in cancer patients compared with the current standard of low-molecular-weight heparin (LMWH) treatment remains unclear. This meta-analysis aimed to evaluate the efficacy and safety of direct factor Xa inhibitors compared with those of LMWH in the treatment of cancer-associated VTE.

Materials and Methods

We systematically searched PubMed, EMBASE, Cochrane library, and Web of Science for potential randomized controlled clinical trials and retrospective cohort studies. Data on recurrent VTE (efficacy) and major and minor bleeding events (safety) were extracted, and the odds risks (OR) were analyzed using a random-effect model.

Results

A total of nine studies involving 4208 cancer patients with VTE were included in these analyses. Pooled analysis showed that direct factor Xa inhibitors were significantly superior to LMWH in reducing the risk of recurrent VTE (OR = 0.67; 95% confidence interval [CI]: 0.54-0.82). There was no significant difference in the rate of major bleeding between the direct factor Xa inhibitor and LMWH treatments (OR = 1.25; 95% CI: 0.94-1.65). However, the rate of minor bleeding events was higher when a direct factor Xa inhibitor was used instead of LMWH (OR = 1.80; 95% CI: 1.05-3.07).

Conclusions

Direct factor Xa inhibitors are superior to LMWH in efficacy in the treatment of VTE in cancer patients, and the safety between the two regimens is comparable except for a slightly higher rate of minor bleeding when the former is used.

The prescription of direct oral anticoagulants in the elderly: An observational study of 19 798 Ambulatory subjects

OBJECTIVE

Direct oral anticoagulants (DOACs) are increasingly prescribed to elderly people, but the epidemiologic data for this population remains scarce. We compared the elderly population taking DOACs and those not taking DOACs (noDOAC).

METHOD

We included individuals over 75 years old, affiliated to Mutualité Sociale Agricole of Burgundy (a French regional health insurance agency), who had been refunded for a prescribed DOAC between 1st and 30th September 2017. The DAOC group (DAOCG) and noDOAC group (noDOACG) were compared in terms of demographic conditions, registered chronic diseases (RCD), and number and types of prescribed drugs. In the DOACG, we compared the type of prescribing physician and laboratory monitoring for novel prescriptions (initial) and prescription refills (≥ 3 months).

RESULTS

Of the 19 798 included patients, 1518 (7.7%) were prescribed DAOCs and 18 280 (92.3%) were not. Mean and median age was 85 years in the 2 groups (DOACG and noDOACG). In the DOACG, there were more men (50% vs 40.2%), more RCD (88.9% vs 68.7%) and more drugs per prescription (6 ± 2.8 vs 5 ± 2.9) (All P < .01). The DOACG also took more antihypertensive drugs. The most commonly prescribed DOACs were apixaban (42.9%) followed by rivaroxaban (38.4%) and dabigatran (18.6%). Complete blood count, serum creatinine and coagulation function tests were requested for 69.4%, 75% and 22.2%, respectively, of patients prescribed DAOCs.

CONCLUSIONS

The DOACG had more RCD and drugs per prescription than the noDOACG; routine laboratory monitoring was insufficient. What's known Platelet aggregation inhibitors (low-dose) are recommended for secondary prevention of cardiovascular events in patients suffering from symptomatic atherosclerosis. The main risk of this treatment is bleeding. What's new A prescription for platelet aggregation inhibitors was found in 34% of geriatric inpatients in this prospective study. Compliance to guidelines was better for symptomatic peripheral artery disease than for primary prevention in accordance with recent publications. Geriatric comorbidities had no impact on the prescription of platelet aggregation inhibitors. Underuse of platelet aggregation inhibitors was observed in 11.3% of cases and overuse in 13.7% of cases.

A synthetic heparin mimetic that allosterically inhibits factor XIa and reduces thrombosis in vivo without enhanced risk of bleeding

BACKGROUND

Human factor XIa (FXIa) is an actively pursued target for development of safer anticoagulants. Our long-standing hypothesis has been that allosterism originating from heparin-binding site(s) on coagulation enzymes is a promising approach to yield safer agents.

OBJECTIVES

To develop a synthetic heparin mimetic as an inhibitor of FXIa so as to reduce clot formation in vivo but not carry high bleeding risk.

METHODS

We employed a gamut of methods involving synthetic chemistry, biophysical biochemistry, enzyme assays, blood and plasma coagulation assays, and in vivo thrombosis models in this work.

RESULTS

Sulfated chiro-inositol (SCI), a non-saccharide mimetic of heparin, was synthesized in three steps in overall yields of >50%. SCI inhibited FXIa with potency of 280 nmol/L and preferentially engaged FXIa's heparin-binding site to conformationally alter its active site. SCI inhibition of FXIa could be rapidly reversed by common antidotes, such as protamine. SCI preferentially prolonged plasma clotting initiated with recalcification, rather than thromboplastin, alluding to its intrinsic pathway-based mechanism. Human blood thromboelastography indicated good ex vivo anticoagulation properties of SCI. Rat tail bleeding and maximum-dose-tolerated studies indicated that no major bleeding or toxicity concerns for SCI suggesting a potentially safer anticoagulation outcome. FeCl3 -induced arterial and thromboplastin-induced venous thrombosis model studies in the rat showed reduced thrombus formation by SCI at 250 μg/animal, which matched enoxaparin at 2500 μg/animal.

CONCLUSIONS

Overall, SCI is a highly promising, allosteric inhibitor of FXIa that induces potent anticoagulation in vivo. Further studies are necessary to assess SCI in animal models mimicking human clinical indications.

Standardized warfarin monitoring decreases adverse drug reactions

Background

While warfarin is the most commonly prescribed medication to prevent thromboembolic disorders, the risk of adverse drug reactions (ADR) poses a serious concern. This prospective study evaluated how primary care providers (PCP) and cardiologists at our Institution managed patients treated with warfarin with the goal of decreasing the number of warfarin ADRs.

Methods

A multidisciplinary anticoagulation task force was established at our Institution in 2014 to standardize warfarin monitoring and management. Between 2013 and 2017, we analyzed patients who were prescribed warfarin by their PCP or cardiologist upon hospital discharge and in the ambulatory setting to determine the international normalized ratio (INR) within 5, 10, and 30 days after discharge, time in therapeutic range (TTR), number of severe warfarin ADRs, and total and average cost reduction of all severe warfarin ADRs to determine whether there was an organizational cost savings following the implementation of standardized warfarin care.

Results

The warfarin ADR rate significantly decreased over the 5-year period, from 3.8 to 0.98% (p < 0.0001). The proportion of warfarin prescriptions out of all anticoagulants significantly decreased, from 72.2 to 42.1% (p < 0.001). The proportion of individuals who received an INR at 5, 10, and 30 days after hospital discharge compared to the total number of patients prescribed warfarin significantly increased (p < 0.001). The total cost of severe warfarin ADRs decreased by 57.6% between 2013 and 2017.

Conclusions

This study serves as a model to reduce the number of severe warfarin ADRs by the following tactics: (1) educating PCPs and cardiologists about evidence-based guidelines for warfarin management, (2) increasing the use of our Institution’s electronic warfarin module, and (3) enhancing patient compliance with obtaining INR.