Rivaroxaban versus warfarin for treatment and prevention of recurrence of venous thromboembolism in African American patients: a retrospective cohort analysis

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.

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.

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.

Rivaroxaban Versus Warfarin for Management of Obese African Americans With Non-Valvular Atrial Fibrillation or Venous Thromboembolism: A Retrospective Cohort Analysis

African Americans (AAs) and obese individuals have increased thrombotic risk. This study evaluated the effectiveness and safety of rivaroxaban versus warfarin in obese, AAs with nonvalvular atrial fibrillation (NVAF) or venous thromboembolism (VTE). Optum® De-Identified Electronic Health Record (EHR) data was used to perform separate propensity-score matched analyses of adult, oral anticoagulant (OAC)-naïve AAs with NVAF or acute VTE, respectively; who had a body mass index≥30kg/m² and ≥12-months EHR activity with ≥1-encounter before OAC initiation. Cox regression was performed and reported as hazard ratios (HRs) with 95% confidence intervals (CIs). For the NVAF analysis, 1,969 rivaroxaban- and 1,969 warfarin-users were matched. Rivaroxaban was not associated with a difference in stroke/systemic embolism versus warfarin (HR = 0.88, 95%CI = 0.60-1.28), but less major bleeding (HR = 0.68, 95%CI = 0.50-0.94) was observed. Among 683 rivaroxaban-users with VTE, 1:1 matched to warfarin-users, rivaroxaban did not alter recurrent VTE (HR = 1.36, 95%CI = 0.79-2.34) or major bleeding (HR = 0.80, 95%CI = 0.37-1.71) risk versus warfarin at 6-months (similar findings observed at 3- and 12-months). Rivaroxaban appeared to be associated with similar thrombotic, and similar or lower major bleeding risk versus warfarin in these obese, AA cohorts.

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.