Richard Stephen Tayon
Coral Gables Hospital, United States
Title: When 80 mg a day of Warfarin is Not Enough: A Case for a Warfarin Resistant Dosing Algorithm
Biography
Biography: Richard Stephen Tayon
Abstract
A case is presented of a patient with lupus anticoagulant disorder that experiences treatment failure due to marked resistance to warfarin following standard algorithmic dosing. It is the opinion of the researcher that this patient may possess a genetic variation in the protein target for warfarin as is noted with VKORC1 D36 enzyme mutations. However, due to high cost and difficulty in obtaining genetic testing, this was not determined definitively. This case demonstrates the necessity for a standardized algorithm for dosing patients with severe warfarin resistance in situations where genetic testing is not afforded. Data was collected from 10/31/13 to 1/1/20 utilizing retrospective analysis. Data collected included: PTT, PT, INR, hemoglobin, hematocrit, and platelet results. Adverse treatment outcomes such as incidence of bleeding and thromboembolic events were examined. Through the course of 14 admissions and 266 hospital days, the daily warfarin dose ranged from 10 mg to 80 mg. Although the corresponding average INR was sub therapeutic (1.28 +0.17), the average hemoglobin (11.78 g/dL + 0.61), hematocrit (37.64% + 1.85), and platelet count (186.89 x 109/L + 22.12) results were all within normal limits. No adverse treatment outcomes were noted. In patients with sub therapeutic INR levels despite supra high dosages of warfarin, standard algorithmic dosing should be abandoned in favor of an individualized patient approach whereby employing clinical and demographic factors to predict a stable warfarin dose. Further research is needed into developing a predictive algorithm for dosing patients with severe warfarin resistance.