Rapid dipstick test developed for DOAC levels


By Geir O'Rourke

25 Mar 2024

Researchers say they have developed an algorithm to support use of a simple dipstick test for DOAC levels, that can return a clinically-useful reading in 10 minutes.

The Australian and international team has presented early data showing promising sensitivity and specificity from the test, which uses a disposable strip to identify factor Xa or thrombin inhibitors in a urine sample.

Already approved for use in Australia, the test has a 10-minute reaction time at room temperature after urine immersion, at which point there is a specific colour change on the respective test pad if a DOAC is present. Other pads indicate urine colour and creatinine, each of each of which can impact testing accuracy.

If the test is negative (with normal creatinine pad results), then clinically significant DOAC levels (≥30 ng/mL) have been excluded, according to the team.

“This test excludes clinically relevant blood concentrations of DOACs, which can speed up clinical decision-making in critical medical situations such as major bleeding, acute ischaemic stroke with consideration for intravenous thrombolysis, or urgent surgical procedures,” they wrote in Thrombosis and Haemostasis (link here).

“Advantages of the method are that it does not require knowledge of the specific DOAC taken by the patient, is a point-of-care format, and has a rapid turnaround time, thereby enabling its use even in small facilities such as community hospitals.”

The authors performed a pooled analysis on five studies published in 2022 and 2023, comparing DOAC Dipstick with LC-MS/MS or DOAC-calibrated chromogenic assays.

Together, these indicated an acceptably high negative predictive value for exclusion of DOACs requiring verification of a match with the patient’s clinical picture (see table below).

Direct oral factor Xa inhibitors Mean (95% C) Direct oral thrombin inhibitor Mean (95% C)
Sensitivity 97.8 (95.6-99.0) 98.3 (91.0-100)
Negative predictive value 86.6 (76.0-93.7) 99.6 (97.7-100)
Positive predictive value 87.2 (83.7-90.1) 73.4 (63.7-83.2)
Specificity 50.0 (40.2-59.0) 91.8 (87.7-94 0.9)


Based on the studies, they proposed a decision-making algorithm to assist in the management of critically ill patients presenting to hospitals or urgent care centres not having available specific DOAC test within a short time frame and 24/7.

According to the algorithm, positive results should be supported by quantitative DOAC measurement where possible, but this would not always be necessary in the absence of available laboratory capacity, the authors said.

“If the laboratory can provide timely quantitative DOAC measurements, these results may provide additional guidance for determining the suitability of medical or surgical interventions, including DOAC reversal strategies,” they wrote.

“If timely testing cannot be performed by the laboratory, the decision to proceed with medical or surgical intervention should be based on the patient’s clinical history, including reversal strategies.”

“The proper course of action will depend on a host of factors including type of procedure needed, urgency of procedure, and on the availability of reversal agents. Unreliable dipstick results because of a low creatinine pad, abnormal urine colour pad, or other reasons for invalid pad results, e.g., expiry date of test strip passed or incorrect handling, should be interpreted as “positive” in the algorithm.”

The lead study author is general manager and founder of DOASENSE GmbH, manufacturer of the dipstick test.

Already a member?

Login to keep reading.

Email me a login link