Potential usefulness of activated charcoal (DOAC remove®) for dRVVT testing in patients receiving Direct Oral AntiCoagulants

Introduction: Lupus Anticoagulant testing using dilute Russell Viper Venom Time (dRVVT) is challenging in patients receiving Direct Oral AntiCoagulants (DOAC) due to potential false positive results. In a multicenter study, we evaluated the in vitro removal of DOAC by activated charcoal (DOAC remove (R)), allowing reliable dRVVT testing. Materials and methods: Patient samples were analyzed before and after treatment with DOAC remove (R): 49 apixaban, 48 rivaroxaban, 24 dabigatran and 30 none. DOAC plasma concentrations were measured using anti-Xa or diluted thrombin time assays. In a subset of 28 samples, DOAC concentrations were also measured using HPLC-MS/MS following treatment with DOAC remove (R). DRVVT was performed using STA-Staclot dRVVT Screen (R)/Confirm (R) (Stago) or LAC-Screening (R)/Confirmation (R) (Siemens). Results: Baseline median [min-max] concentrations were 94 [< 20-479] for apixaban, 107 [< 20-501] for rivaroxaban and 135 ng/mL [< 20-792] for dabigatran; dRVVT screen ratio/confirm ratio was positive in 47, 90 and 42% of apixaban, rivaroxaban and dabigatran samples. Treatment with DOAC remove (R) did not affect dRVVT results in non-DOAC patients while it resulted in DOAC concentrations < 20 ng/mL in 82, 98 and 100% of samples, respectively. Concentrations were < 5 ng/mL with HPLC-MS/MS in 5 out of 10, 8 out of 10 and 7 out of 8 samples, respectively. DOAC remove (R) corrected DOAC interference with dRVVT assays in 76, 85 and 95% of the patients, respectively. Conclusion: For dRVVT testing in DOAC patients, we suggest the use of DOAC remove (R) for every rivaroxaban sample, whereas it might only be used in positive apixaban and dabigatran samples. A residual DOAC interference cannot be ruled out in case of persisting dRVVT positive results after treatment with DOAC remove (R).