Comparative Effectiveness and Safety of Low-Dose Oral Anticoagulants in Patients With Atrial Fibrillation

Aims: Observational studies of various dose levels of direct oral anticoagulants (DOACs) for patients with atrial fibrillation (AF) found that a high proportion of patients received a dose lower than the target dose tested in randomized controlled trials. There is a need to compare low-dose DOACs with warfarin or other DOACs on effectiveness and safety.Methods: Using administrative data from Quebec province, Canada, we built a cohort of new warfarin or DOAC users discharged from hospital between 2011 and 2017. We determined CHA2DS2-VASc and HAS-BLED scores, and comorbidities for 3-year prior cohort entry. The primary effectiveness endpoint was a composite of ischemic stroke/systemic embolism (SE), and secondary outcomes included a safety composite of major bleeding (MB) events and effectiveness composite (stroke/SE, death) at 1-year follow-up. We contrasted each low-dose DOAC with warfarin or other DOACs as references using inverse probability of treatment weighting to estimate marginal Cox hazard ratios (HRs).Results: The cohort comprised 22,969 patients (mean age: 80–86). We did not find a significant risk reduction for the stroke/SE primary effectiveness endpoint for DOACs vs. warfarin; however, we observed a significantly lower risk for low-dose dabigatran vs. warfarin (HR [95%CI]: 0.59 [0.42–0.81]) for effectiveness composite, mainly due to a lower death rate. The differences in effectiveness and safety composites between low-dose rivaroxaban vs. warfarin were not significant. However, low-dose apixaban had a better safety composite (HR: 0.68 [0.53–0.88]) vs. warfarin. Comparisons of dabigatran vs. apixaban showed a lower risk of stroke/SE (HR: 0.53 [0.30–0.93]) and a 2-fold higher risk of MB. The MB risk was higher for rivaroxaban than for apixaban (HR: 1.58 [1.09–2.29]).Conclusions: The results of this population-based study suggest that low-dose dabigatran has a better effective composite than warfarin. Compared with apixaban, low-dose dabigatran had a better effectiveness composite but a worse safety profile. Low-dose apixaban had a better safety composite than warfarin and other low-dose DOACs. Given that the comparative effectiveness and safety seem to vary from one DOAC to another, pharmacokinetic data for specific populations are now warranted.

Changes in Prescribing Antithrombotic Therapy in Patients with Atrial Fibrillation in the Multidisciplinary Hospital in Volgograd from 2012 to 2020

Aim. To study the frequency of prescribing antithrombotic agents in patients with non-valvular atrial fibrillation (AF) in real clinical practice, to evaluate changes of prescriptions from 2012 till 2020.Material and methods. The medical records of inpatients (Form 003/y) with the diagnosis AF, hospitalized in the cardiological department were analyzed. According to the inclusion criteria, the patients were over 18 years of age, established diagnosis of non-valvular AF. There were two exclusion criteria: congenital and acquired valvular heart disease and prosthetic heart valves. In retrospective analysis we have included 263 case histories in 2012, 502 ones in 2016 and 524 in 2020. CHA2DS2-VASc score was used for individual stroke risk assessment in AF. The rational use of the antithrombotic therapy was evaluated according with current clinical practice guidelines at analyzing moment.Results. During period of observation the frequency of antiplatelet therapy significantly decreased from 25,5% to 5,5% (р<0.001), decreased the frequency of administration of warfarin from 71,9% to 18,3% (р<0.001). The frequency of use of direct oral anticoagulants increased in 2020 compared to 2016 (р<0.001). For patients with a high risk of stroke anticoagulant therapy was administered in 71.8% of cases in 2012, 88.5% in 2016 and 92.5% in 2020. Before discharge from hospital majority of patients (72%) achieved a desired minimum international normalized ratio (INR) from 2.0 to 3.0 in 2012. In 2016 and 2020 an only 33% and 40.6% of patients achieved INR (2.0-3.0).Conclusion. Doctors have become more committed to following clinical guidelines during the period of the investigation. In 2020 antithrombotic therapy for atrial fibrillation was suitable according to current clinical guidelines.

Gastrointestinal Bleeding During Direct Oral Anticoagulants Therapy in Patients With Nonvalvular Atrial Fibrillation and Risk of Polypharmacy

Although concomitant medications have been raised as a factor affecting hemorrhage during direct oral anticoagulants (DOACs) therapy, details remain unelucidated. This study was conducted to clarify the relationship between concomitant medications with possible pharmacokinetic interactions and number of concomitant medications, and bleeding and embolism in patients with nonvalvular atrial fibrillation on DOACs. The subjects were 1,010 patients prescribed DOACs between April 2011 and June 2018. The study investigated their course between the first prescription and December 2018, including the presence or absence of clinically relevant bleeding, gastrointestinal bleeding (GIB), and major cardiovascular and cerebrovascular events (MACCE). Impacts of medications were evaluated by the general linear model with inverse probability-weighted propensity score. The observation period was 2,272 patient-years. The rate of bleeding was 4.7%/year, GIB was 2.8%/year, and MACCE was 2.0%/year. Taking 10 or more oral medications concurrently was a significant risk for GIB (hazard ratio, 2.046 [1.188–3.526]; p = 0.010). Nonsteroidal anti-inflammatory drugs (NSAIDs) was the only significant risk for GIB. Clinicians should be aware of gastrointestinal bleeding when using DOACs with patients taking more than 10 medications and/or NSAIDs.

Risk Factors for Post-Thrombotic Syndrome in Patients With a First Proximal Deep Venous Thrombosis Treated With Direct Oral Anticoagulants

The incidence of post-thrombotic syndrome (PTS) in patients with deep vein thrombosis (DVT) treated with direct oral anticoagulants (DOACs) remains a matter of debate. Hence, our endeavor to investigate a large cohort of patients with a first episode of proximal DVT treated with DOACs to ascertain the incidence and predisposing risk factors for PTS. All consecutive patients referred to the Thrombotic and Haemorrhagic Diseases Unit of Padova University Hospital (Italy) between January 2014 and January 2018 for a first episode of proximal DVT were considered for enrollment. Participants received DOACs for a minimum period of 3 months. PTS was assessed using the Villalta score up to 36 months after DVT diagnosis. Among 769 enrolled patients (M/F 353/416, age range 26–87 years), 152 (19.8%) developed PTS and 30 (3.9%) developed severe PTS. The adjusted hazard ratio was significant for obesity (1.64, 95% CI 1.28–2.39) and DVT site (femoral and/or iliac veins vs popliteal vein) (1.23, 95% CI 1.15–3.00). The incidence of PTS is not negligible in patients with proximal DVT despite the use of DOACs. We identified obesity and iliofemoral DVT as possible risk factors for PTS. Larger prospective studies are needed to confirm our findings and optimize therapeutic strategies.

Use of direct oral anticoagulants for postoperative venous thromboembolism prophylaxis after surgery for gynecologic malignancies

Venous thromboembolism is a preventable cause of postoperative mortality in patients undergoing surgery for malignancy. Current standard of care based on international guideline recommends 28 days of extended thromboprophylaxis after major abdominal and pelvic surgery for malignancies with unfractionated heparin or low molecular weight heparin. Direct oral anticoagulants have been approved for the treatment of venous thromboembolism in the general population. This regimen has a significant advantage over other types of anticoagulation regimens, particularly being administered by non-parenteral routes and without the need for laboratory monitoring. In this review, we evaluate the role of direct anticoagulation and provide an update on completed and ongoing clinical trials.

Direct Oral Anticoagulants versus Warfarin in Patients with Atrial Fibrillation: Patient-Level Network Meta-Analyses of Randomized Clinical Trials with Interaction Testing by Age and Sex

Background: Direct oral anticoagulants (DOACs) are preferred over warfarin for stroke prevention in atrial fibrillation (AF). Meta-analyses using individual patient data offer significant advantages over study-level data. Methods: We used individual patient data from the COMBINE AF database, which includes all patients randomized in the 4 pivotal trials of DOACs vs warfarin in AF (RE-LY, ROCKET AF, ARISTOTLE, ENGAGE AF-TIMI 48), to perform network meta-analyses using a stratified Cox model with random effects comparing standard-dose DOAC, lower-dose DOAC, and warfarin. Hazard ratios (95% CIs) were calculated for efficacy and safety outcomes. Covariate-by-treatment interaction was estimated for categorical covariates and for age as a continuous covariate, stratified by sex. Results: A total of 71,683 patients were included (29,362 on standard-dose DOAC, 13,049 on lower-dose DOAC, 29,272 on warfarin). Compared with warfarin, standard-dose DOACs were associated with a significantly lower hazard of stroke/systemic embolism (883/29312 [3.01%] vs 1080/29229 [3.69%]; HR 0.81, 95% CI 0.74-0.89), death (2276/29312 [7.76%] vs 2460/29229 [8.42%]; HR 0.92, 95% CI 0.87-0.97) and intracranial bleeding (184/29270 [0.63%] vs 409/29187 [1.40%]; HR 0.45, 95% CI 0.37-0.56), but no statistically different hazard of major bleeding (1479/29270 [5.05%] vs 1733/29187 [5.94%]; HR 0.86, 95% CI 0.74-1.01), whereas lower-dose DOACs were associated with no statistically different hazard of stroke/systemic embolism (531/13049 [3.96%] vs 1080/29229 [3.69%]; HR 1.06, 95% CI 0.95-1.19) but a lower hazard of intracranial bleeding (55/12985 [0.42%] vs 409/29187 [1.40%]; HR 0.28, 95% CI 0.21-0.37), death (1082/13049 [8.29%] vs 2460/29229 [8.42%]; HR 0.90, 95% CI 0.83-0.97), and major bleeding (564/12985 [4.34%] vs 1733/29187 [5.94%]; HR 0.63, 95% CI 0.45-0.88). Treatment effects for standard- and lower-dose DOACs versus warfarin were consistent across age and sex for stroke/systemic embolism and death, whereas standard-dose DOACs were favored in patients with no history of vitamin K antagonist use (p=0.01) and lower creatinine clearance (p=0.09). For major bleeding, standard-dose DOACs were favored in patients with lower body weight (p=0.02). In the continuous covariate analysis, younger patients derived greater benefits from standard-dose (interaction p=0.02) and lower-dose DOACs (interaction p=0.01) versus warfarin. Conclusions: Compared with warfarin, DOACs have more favorable efficacy and safety profiles among patients with AF.

Effectiveness and safety of oral anticoagulants in the treatment of acute venous thromboembolism: A nationwide comparative cohort study in France

Introduction: Data from clinical trials indicate that direct oral anticoagulants (DOACs) are non-inferior and safer than conventional therapy (low-molecular weight heparin followed by a vitamin K antagonist [VKA]) for treating venous thromboembolism (VTE), which includes deep vein thrombosis and pulmonary embolism (PE). This study compared the effectiveness and safety of DOACs and conventional therapy in a real-world setting. Materials and Methods: This observational study used French national claims data of adult, treatment-naïve patients diagnosed with VTE (majority PE) who were hospitalized and treated for VTE with a DOAC (apixaban or rivaroxaban) or VKAs during 2013–2018. Patients with active cancer were excluded. After propensity score matching for each DOAC-VKA comparison, risks of bleeding, recurrent VTE, and all-cause mortality were compared at 6 months. Cox proportional-hazards regression was used to estimate adjusted hazard ratios of the endpoints. Results: 58137 patients were included (10775 VKAs, 10440 apixaban, 36922 rivaroxaban). Propensity score-matched cohort sizes were 7503 for apixaban and 9179 for rivaroxaban. The hazard ratio (95% confidence interval) was significantly lower for apixaban than VKAs for bleeding requiring hospitalization (0.43 [0.32-0.59]), all-cause death (0.61 [0.51-0.74]), and first-recurrent VTE (0.67 [0.52-0.85]). The hazard ratio was also significantly lower for rivaroxaban than VKAs for all-cause death (0.63 [0.53-0.74]) but not for bleeding requiring hospitalization (0.86 [0.69-1.07]) or first-recurrent VTE (0.91 [0.74-1.13]). Conclusions: Apixaban was associated with superior safety and effectiveness than VKAs. All-cause mortality was lower in both DOACs than VKAs. Our results support recommendations to use DOACs over VKAs for the treatment of VTE.