This abstract was presented as a poster at the American Society for Clinical Laboratory Science annual meeting, Atlanta, July, 2015: McGlasson DL, Fritsma GA. Stable Dabigatran Levels in Anticoagulation Clinic Patients: An Unexpected Finding. Clin Lab Sci 2015; 28:159.
The dabigatran effect is rapid. Its half-life is 12–17 hours. Experts believe missed doses may lead to thrombosis. We evaluated plasma dabigatran levels on anticoagulation clinic patients monthly for 6 months. Subjects took 150 mg BID beginning one month prior. All subjects were >18 years old and had creatinine clearances >30 mL/min. No subjects were excluded for parallel medications or pre-existing conditions. We enrolled 64 males, mean age 77, and 38 females, mean age 76. Mean CHAD2DS2-VASc score was 3.2; mean BMI 29.8. Specimens from 72 subjects who completed the six-month cycle and 30 healthy controls taking no medication were analyzed. A 3.2% sodium citrate specimen from each subject on a monthly date within ± 5 days of the start date was collected. There was no monitoring the time subjects took medication. We prepared platelet poor plasma by immediate centrifugation and stored at –70⁰C. We assayed specimens using the APTT (APTT Automated, Stago); Ecarin Chromogenic Assay (ECA-T, Stago); Hemoclot Thrombin Inhibitor (HTI, Aniara); and Prothrombinase-induced clotting time (PiCT, Enzyme Research Laboratory). Testing was performed on a STAR-Evolution coagulometer. Reference intervals were computed from controls for the APTT (mean 30.7 s; ±2SD: 26.1–35.3 s); PiCT (mean 40.1 s; ±2SD: 29.4–50.7 s). Dabigatran subjects’ APTT range was 26.2–>300 s, mean 53.7 s >300 was assigned 301 s); PiCT range was 60.8–>301 s, mean 186.7 s; ECA-T range: 10–950 ng/mL, mean 177.6 ng/mL; HTI range 0.0–770 ng/mL, mean 185.3. A two-factor ANOVA (dabigatran, time) with repeated measures on all tests revealed no significant difference between monthly results within subjects (p=0.234) for any assay. Our data imply reproducibility in the absence of strict dosage time versus specimen collection time. This unexpected consequence implies a need for studies that determine dabigatran anticoagulant effect versus time subsequent to dosage.