OC 17.5 - Direct Oral Anti-Coagulant (DOAC) external quality assessment (EQA) scheme assay results and interpretations from UKNEQAS BC DOAC Survey 19 2021.

Background: DOAC EQA scheme requires participants to perform DOAC assays and results are performance assessed.

Aims: The assay interpretation is a recent addition to the NEQAS BC programme with clinical and laboratory staff being asked to provide interpretations.

Methods: Data were collected as part of the DOAC exercise survey 19. Participants were asked to provide interpretations from: below level of detection; anticoagulant present at sub-therapeutic level; anticoagulant detected , unable to state if therapeutic; anticoagulant present at therapeutic level or anticoagulant present at supra-therapeutic level. The clinical scenario associated with Survey 19 stated that the patient had taken dose of anticoagulant three hours before medical assessment.

Results: The interpretations for the DOAC assays were either from: anticoagulant nurses (2%) ; biomedical scientists (34%) ; clinicians (33%) or clinical scientists (9%). 22% of participants did not provide an interpretation.
From the interpretative data returned on Survey 19, none of the participants interpreted the assays results as below the level of detection. The majority of interpretations returned for dabigatran, apixaban and edoxaban indicated that levels of the drug were at a therapeutic level. The returns for rivaroxaban interpretation included 45% of participants who had indicated that the drug was at a level above the therapeutic range.
In clinical scenarios that state the level of drug is unknown, an interpretation of “anticoagulant detected, unable to state if therapeutic” might stimulate the requesting clinician to review the time and dosage administered to the patient.

Conclusion(s): DOAC monitoring is not required for the vast majority of patients receiving these anticoagulants. However measuring DOAC levels is indicated in some settings including but not exclusively: bleeding risk; thrombotic risk; compliance and or accurate interpretation of other laboratory assays. Our data indicate that there is currently substantial variability in how the same levels of DOACs is interpreted.