*Purpose: This study describes the comparative safety and efficacy of direct acting oral anticoagulants (DOACs) relative to warfarin following liver transplantation, at a large academic transplant center.

*Methods: This was a single-center, retrospective cohort review of adult liver transplant recipients prescribed either a DOAC or warfarin between January 2014 and January 2018. Patients were excluded if they had active cancer or discontinued anticoagulation therapy prior to 60 days for a reason other than acute bleeding or thrombosis. Patients receiving DOACs were matched with warfarin treated controls using an exact greedy matching algorithm based upon the following clinical parameters: donor type, age, history of hepatocellular carcinoma, indication for anticoagulation, HAS-BLED score, timing of anticoagulation, and duration of anticoagulation. Matched patients were then followed from the time of anticoagulation initiation, until treatment discontinuation or study conclusion. The primary endpoint for this review was the incidence of clinically significant bleeding between the two treatment groups. Secondary endpoints included incidence of major bleeding, incidence of new thrombotic complications, and change in calcineurin inhibitor trough/dose ratios at 30-days post-DOAC initiation.

*Results: A total of 27 patients prescribed DOACs were identified for inclusion in the study. Among these patients, there were 4 episodes of clinically significant bleeding and 4 instances of new or recurrent thrombosis over a median of 351 (61-784) anticoagulation days. Exact warfarin matches could be found for 20 out of the 27 patients originally managed with DOACs. Demographic and clinical characteristics were similar between the two treatment groups at baseline. At the conclusion of the study review period, the DOAC treated patients were found to have significantly lower rates of clinically significant bleeding (3 events vs. 10 events; p = 0.01) and major bleeding (0 events vs. 4 events). No statistically significant differences were found in the rates of new or recurrent thrombotic events between the DOAC and warfarin arms (4 events vs. 3 events; p = 0.67), and no differences were observed in tacrolimus trough/dose ratios at 30-days following DOAC initiation. After logistic regression, treatment assignment with warfarin continued to be associated with a significantly higher odds of clinically significant bleeding (OR = 12.1; CI 1.4-106.3).

*Conclusions: In our patient cohort, DOAC use resulted in similar efficacy relative to warfarin in preventing new or recurrent thrombosis, but was associated with less clinically significant bleeding. A variety of clinical and patient specific risk factors still bear consideration when selecting between the various anticoagulant options.

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