(A-092) Vitamin K Antagonists And Direct Oral Anticoagulants Are Equal For Recurrent Venous Thromboembolism Prevention In Patients With Anorexia Nervosa: A Nationwide Cohort Study

Background: Anorexia nervosa (AN) is associated with an increased risk of venous thromboembolism (VTE), likely due to AN’s effects on hemostasis and behavior. When treating this patient population, an unusual pharmacokinetic profile, e.g., low volume of distribution or erratic food intake, may affect both efficacy and safety of oral anticoagulants.

Objectives: To evaluate the risk of recurrent VTE and severe bleeding in AN patients treated with either vitamin K antagonists (VKAs) or direct oral anticoagulants (DOACs), to inform clinical decision-making.

Methods: We conducted an active-comparator, new-user cohort study using Danish nationwide registries from 1995–2019. All female individuals with AN and a validated first-ever VTE diagnosis, followed by a first-ever prescription for either VKAs or DOACs within six months, were included with cohort entry at the date of the first VTE diagnosis. The primary outcome was the first recurrent VTE >14 days after cohort entry. Severe bleeding was included as a secondary outcome. Hazard ratios (HRs) were calculated using Cox proportional hazards models, adjusting for age and contraceptive use.

Results: Of 67 patients (median age: 30 years), 46 received VKAs, and 21 received DOACs. Recurrent VTE occurred in 24% of the VKA-users and 33% of the DOAC-users (adjusted HR: 1.7; 95% CI: 0.7–4.5). No severe bleeding events were recorded. Subgroup analyses suggested a higher recurrence risk among DOAC users below 30 years (aHR: 2.5; 95% CI: 0.6–11.1). The median time to first recurrent VTE was 51 days for VKA-users and 35 for DOAC-users. Sensitivity analyses limited to patients treated after DOAC market entry in 2009 showed no marked differences in recurrence rates between groups (aHR 1.2 (95% CI: 0.4-3.3).

Conclusions: VKAs and DOACs appear to have comparable safety profiles for preventing recurrent VTE in AN patients. The high recurrence rate and the absence of bleeding incidents could suggest a liability to undertreat this population, but the study is limited by imprecision of calculated estimates and a risk of misclassification of the primary outcome. Our findings underscore the need for further research into the pharmacokinetic profile of AN patients to optimize treatment for this population.