Impact of DOAC Dipstick test and relation to plasma and urine concentrations to exclude the presence of clinically relevant concentrations of DOACs in real-life patient setting – study protocol and case reports

Objective Rapid and accurate testing for direct oral anticoagulants (DOACs) is required to facilitate medical decision making in specific emergency and other medical situations. The relation of its qualitative results to quantitative plasma concentrators remains to be determined. The objective of the study is to examine whether results of DOAC Dipstick can be used to exclude the presence of clinically relevant concentrations of the three DOACs (dabigatran, rivaroxaban and apixaban).

Material and Methods The one centre study aims to include patients treated with rivaroxaban, apixaban and dabigatran admitted with neurologic and cardiovascular diseases to general wards of Sestre Milosrdnice University Hospital Center at Zagreb. The study is the part of the research project IP-2016-06-8208, LAB-NOAC funded by Croatian Science Foundation. Between 120 and 180 patients will be included treated with rivaroxaban 15 or 20 mg od, apixaban 5 mg bid and dabigatran 110 or 150 mg bid. DOAC Dipstick test is performed by visual colour identification of the pads of DOAC Dipstick and by semi-automatic DOASENSE Reader as described in the respective instructions for use. The visual and reader evaluation of colours of pads of DOAC Dipstick for presence or absence of DOACs is performed independently by two trained medical persons. Concentration of rivaroxaban, apixaban and dabigatran are performed from plasma and urine samples using LC-MS/MS and of plasma samples using specific chromogenic assays and a set of coagulation assays. Data will be analysed at the end of the study.

Results At present 13 patients are included treated with rivaroxaban and apixaban. Methods are easy to perform. Anticoagulation was switched in 3 patients from rivaroxaban to dabigatran for minor bleeding or other minor side effects as decided by the treating physician. The day after switching DOAC Dipstick test revealed presence of both factor Xa and thrombin inhibitor by color identification of the pads with visual and reader evaluation.

Conclusion The case reports indicate that DOAC Dipstick may be positive for rivaroxaban and dabigatran following switching of DOACs. Further assessment of plasma concentrations may be required if the presence of factor Xa and thrombin inhibitors are found by DOAC Dipstick test before further medical decision-making. A relation of plasma and urine tests and DOAC Dipstick results will be analyzed after termination of the study.

Publication History

Article published online:
18 June 2021