Application of DOAC Score for the risk-stratification of major bleeding in patients with venous thromboembolism on direct oral anticoagulants: insight from the COMMAND VTE Registry-2
Authors: Nishimoto Y , Chatani R , Kaneda K , Ikeda N , Kobayashi Y , Ikeda S , Kim K , Takase T , Tsuji S , Oi M , Takada T , Otsui K , Watanabe T , Yamada T , Yamashita Y 
Published: October 2024

Abstract

Background/Introduction
Bleeding complications are still a major concern in anticoagulation therapy for venous thromboembolism (VTE), even in the direct oral anticoagulant (DOAC) era. Thus, the risk stratification of bleeding during anticoagulation therapy is essential, although most of currently available bleeding risk scores have been developed from patients receiving vitamin K antagonists, which could have limited validity in those receiving DOACs. Very recently, the DOAC Score has been developed to predict major bleeding in patients with atrial fibrillation on DOACs; however, the score has not yet been validated in patients with VTE.

Purpose
The present study aimed to evaluate the usefulness of the DOAC Score in patients with VTE, using a large-scale multicenter observational database of patients with VTE.

Methods
The COMMAND VTE Registry-2 is a multicenter registry enrolling 5197 consecutive acute symptomatic VTE patients among 31 centers in Japan between January 2015 and August 2020. The present study population was consisted of 3539 patients with VTE who received DOACs and had a calculated DOAC Score. The eligible patients were classified into 5 risk categories: very low (score 0–3), low (score 4–5), moderate (6–7), high (score 8–9), and very high (score ≥10). We used the Kaplan-Meier method to estimate the cumulative incidence and assessed the discriminatory ability of the DOAC Score for major bleeding at 1 year by calculating the area under the receiver operating characteristic curve. We also assessed the discriminatory ability of the VTE-BLEED and RIETE scores.

Results
In the present study population, the very low-risk group accounted for 1437 patients (41%), low-risk group for 828 (23%), moderate-risk group for 812 (23%), high-risk group for 326 (9.2%), and very high-risk group for 136 (3.8%). The proportion of anemia was highest in the very high-risk group (71%) and lowest in the very low-risk group (47%). The prevalence of active cancer was highest in the low-risk group (36%) and lowest in the very high-risk group (18%). During the first year of anticoagulation therapy, major bleeding occurred in 180 patients. The cumulative 1-year incidence of major bleeding seemed to be different according to the 5 groups, but the risks could not be well-stratified (Figure 1). The discriminating power of the DOAC Score was relatively low with a C-statistic of 0.52 (95% CI, 0.48–0.57) (Figure 2), while those of VTE-BLEED and RIETE scores were modest with C-statistics of 0.66 (95% CI, 0.60–0.73) and 0.67 (95% CI, 0.64–0.71), respectively.

Conclusions
The risk of 1-year major bleeding on DOACs in patients with VTE was not well-stratified according to the risk categories by the DOAC Score, which might suggest that patients with VTE have different risk factors for bleeding on DOACs as compared to those with atrial fibrillation. A new bleeding risk score for DOAC specifically in patients with VTE would be warranted in the future.Figure 1Figure 2