Abstract
Assessing bleeding duration in patients on direct oral anticoagulants (DOACs) is crucial for evaluating reversal strategies, yet no standardized methods are currently available for clinical trials. We investigated a non-invasive, reproducible bleeding model based on a routine dental cleaning procedure, aiming to provide a clinically meaningful endpoint for testing DOAC antidots. We enrolled 90 subjects in this prospective observational pilot study: 49 not receiving DOACs (group 1; 30 female, 19 male; mean age: 40.7 ± 16 years) and 41 on DOACs (group 2; 22 female, 19 male; mean age: 71.3 ± 20.4 years). Mouth-rinse samples were collected before and at 5-minute intervals for up to 60 min following bleeding-on-probing assessment, periodontal staging, and dental cleaning. Red blood cell (RBC) counts in these samples were determined using a hemocytometer. Bleeding cessation was defined as an RBC count below 150 cells/µL. Reaching this threshold within 15 min was defined as the clinical endpoint (EP). In group 1, 83.7% reached the EP (group 1a (without gingivitis): 90.9%; group 1b (with gingivitis): 77.8%). In group 2, only 39% reached the EP (group 2a (without gingivitis): 60%; group 2b (with gingivitis): 32.3%; p < 0.001 vs. group 1). The most relevant comparison for future antidote trials is between group 1b (non-DOAC with gingivitis) and group 2b (DOAC with gingivitis; p < 0.001). This model offers a standardized, non-invasive, and clinically relevant approach to monitor bleeding in DOAC-treated patients. The defined clinical endpoint (≤ 150 RBC/µL after 15 min) could serve as a useful surrogate for evaluating the efficacy of temporary DOAC reversal agents.