Analysis of adherence to therapy comparing DOAC Dipstick test with plasma concentration of rivaroxaban and apixaban in outpatients with venous thromboembolic disease

Objective The efficacy and safety of direct oral factor Xa inhibitors rivaroxaban and apixaban (DXI) in patients with venous thromboembolism (VTE) is closely related to patient’s adherence to therapy. Objective documentation of drug intake may be a useful tool for patients’ education and improvement of adherence to treatment.

We aim to analyze the accuracy of DOAC Dipstick near-patient device compared to plasma concentration for evaluation of the presence of rivaroxaban or apixaban in the urine in outpatients with VTE.

Material and Methods A prospective observational ongoing cohort study is performed including patients on active DXI treatment for secondary prevention of VTE. All participants were routinely assessed for concentration of rivaroxaban or apixaban in plasma using the specific chromogenic assays based on the measurement of the anti-Xa activity. Renal function was assessed by using the Cockroft –Gault equation. DOAC Dipstick test was performed from patients’ urine samples and visual evaluation of pads’ colors for factor Xa and thrombin inhibitors was performed by trained medical staff according the instructions for use.

Results Interim analysis was performed after enrolment of 41 patients (female/male 15/31, age 55 ± 14 years, mean and standard deviation). Of these, 19.5% (n=8) were treated for deep vein thrombosis (DVT), 12.1% (n=5) for pulmonary embolism (PE), 41.4% (n=17) for recurrent DVT, 19.5% (n=5), for cancer-associated thrombosis, 2% (n=1) for cerebral thrombosis and 2% (n=1) for ocular thrombosis and were treated with rivaroxaban (76%, n=31) and apixaban (24%, n= 10) patients. All patients had normal renal function. The anti Xa levels ranged from 20-418 UI/mL (median value 131.36 ±113.95). The factor Xa inhibitor pad of urine samples was as correct positive in 40/41 cases (almost 98%) and false negative in 1/41 cases (2%) as compared with plasma anti-Xa levels. Thrombin inhibitor pad was negative in all cases.

Conclusion The DOAC Dipstick qualitative test results demonstrated at least 95% correct positive and correct negative results for DXI rivaroxaban and apixaban in urine samples compared to quantitative plasma concentrations. The ongoing study should provide specific data for validation of the device as an easy-to-use and accurate tool assessing adherence to DOAC treatment

Publication History

Article published online:
18 June 2021