B blood type is a strong risk factor for venous thromboembolism recurrence

Abstract

Background: Non-O blood type patients are at higher risk of first venous thromboembolic event compared to others. However, only little is known about ABO blood type and risk of venous thromboembolism (VTE) recurrence. In this study, we sought to determine the impact of ABO blood type on VTE recurrence. Methods and results: We prospectively recruited 130 consecutive patients with a first episode of pulmonary embolism (PE) (CT scan-documented). Patients lost to follow-up within 12 months after anticoagulation therapy discontinuation were excluded from the study. We finally analysed prospective data from 100 patients with extensive follow-up. Mean follow-up was 35 months [33.3-36.7]. PE was unprovoked in 48 patients (48%) and mean anticoagulation duration was 5.3±2.2 months. The rate of recurrence was 10.2% per patient and per year (31 recurrences, 31%). B blood type patients had a 2.6-fold increased risk of developing VTE recurrence (95% CI 1.1-6.1, p=0.04). In a bivariate COX model, B blood type remained a strong predictor of VTE recurrence (HR 2.7, 95% CI 1.1-6.2, p=0.02). A and AB blood types were not associated with VTE recurrence. Non-O blood type patients tended to relapse more frequently than O patients (HR 2.1, 95% CI 0.8-5.0, p=0.09). Interestingly, in women, non-O blood type was associated with a 4.9-fold increase in VTE recurrence (95% CI 1.1-21.4, p=0.01). VTE recurrence rate and B blood type VTE recurrence rate and B blood type Conclusion: Non-O blood types, beyond being involved in occurrence of VTE, contribute to the risk of VTE recurrence. B blood type is strongly associated with VTE recurrence, and can identify patients at high risk who could benefit from long-term anticoagulation therapy after a first VTE event.