Performance Characteristics of DOAC Dipstick in Determining Direct Oral Anticoagulants in Urine

Pearls and Pitfalls in the Measurement of Direct Oral Anticoagulants

Due to their widespread use, testing for direct oral anticoagulants (DOACs) has become urgent in certain clinical situations. Screening based on widely available, rapid, and simple hemostasis assays such as prothrombin time, activated partial thromboplastin time, or even diluted Russel Viper venom time may provide sufficient evidence of "over-coagulation" and could be used "in small/peripheral/spoke laboratories" as an emergency strategy, but is not thought to be reliable for driving clinical decision making. Given their good correlation with plasma concentration, urine dipsticks may be considered a valuable alternative for emergency screening, although their performance is dependent on renal function, may vary depending on the time since the last urination, and there may be problems of interfacing with the laboratory/hospital information system. Separation methods based on liquid chromatography and mass spectrometry may be clinically questionable, since they measure the concentration rather than the actual inhibitory effect of DOACs, are relatively expensive, cumbersome and time consuming, and therefore seem unsuitable for most conditions requiring urgent clinical decision making. A proposed approach therefore involves establishing a network of routine clinical laboratories, designating a reference center where DOAC tests could be available 24/7, establishing a clear diagnostic care pathway for ordering the tests from the laboratory and standard operating procedures for performing them, the use of the diluted thrombin time for dabigatran and anti-FXa assays (drug-calibrated) for rivaroxaban, apixaban, and edoxaban, as well as providing expert advice throughout the testing process, from ordering to interpretation of results.

Evidence-based Management of Major Bleeding in Patients Receiving Direct Oral Anticoagulants: An Updated Narrative Review on the Role of Specific Reversal Agents

The indications of direct oral anticoagulants (DOACs) have expanded over the past 15 years. DOACs are effective and safe oral anticoagulants associated with lower bleeding risks and mortality than vitamin K antagonists. However, DOAC users are prone to a considerable bleeding risk, which can occur at critical sites or lead to severe life-threatening conditions. Recent statistics indicated that major bleeding occurs in up to 6.62 DOAC users per 100 treatment years. With the increased use of DOACs in clinical practice, DOAC-associated major bleeding is expected to be encountered more frequently in the emergency department. The current international guidelines recommend specific reversal agents for the management of DOAC users with severe bleeding to reverse the anticoagulant effect and restore normal hemostasis. An individualized assessment was incorporated in specific clinical situations to guide the decision pathway of major bleeding management. However, specific reversal agents are unavailable or have limited availability in many countries, which is expected to negatively impact the clinical outcomes of DOAC-associated major bleeding. Limited real-world evidence is available from these countries regarding the clinical outcomes of patients with DOAC-associated major bleeding. This narrative review provided an updated assessment of the evidence-based approaches for the management of major bleeding in DOAC users. We also explored the clinical outcomes of patients with major bleeding from clinical settings where specific reversal agents are unavailable.

Patients' Plasma Activity of Heparin, low-Molecular-Weight Heparin or no Anticoagulants on Urine Based DOAC Test Strips

DOAC Dipstick determines specifically the presence and absence of direct oral anticoagulants (DOACs) from patients’ urine samples and handmade test strips performed as well as the commercial version. To compare plasma activity (chromogenic substrate assays) from plasma samples with results from urine samples (DOAC test strips) of patients treated with heparin, low-molecular weight heparin (LMWH) and without anticoagulation. Plasma anti-factor Xa (aXa) activity was determined by Coamatic chromogenic substrate assay and compared to the presence of anticoagulants in urine by DOAC test strips. Patients were treated for least 5 days and samples were taken 4 hrs after administration in comparison to no treatment with an anticoagulant (n = 42). A total of 100 patients were included treated with heparin (n = 29), LMWH nadroparin (n = 29) or no anticoagulants (n = 42). Plasma aXa levels of patients treated with heparin (2 × 7.500 IU daily subcutaneously, 12 male, age 67.4 ± 11.5 years) were 0,18 IU/ml ± 0,15 IU/ml (mean, standard deviation), with LMWH (1 × 3000 IU daily subcutaneously, 15 male, age 64.2 ± 14.1 years) 0,17 IU/ml ± 0,16 IU/l, and with no anticoagulants (28 male, age 64.2 ± 15.6 years) 0,02 IU/ml ± 0.01 IU/ml. All factor Xa and thrombin inhibitor pad results of test strips were negative. We conclude that DOAC Dipstick has a high probability of not detecting heparin and LMWH in patients on treatment as well as in urine samples of patients not treated with an anticoagulant.

Evaluation of DOAC Dipstick Test for Detecting Direct Oral Anticoagulants in Urine Compared with a Clinically Relevant Plasma Threshold Concentration

Measuring direct oral anticoagulant (DOAC) concentrations might be necessary in certain clinical situations but is not routinely performed. The DOAC Dipstick is a new rapid test for detecting DOACs in urine. The aim of this study was to evaluate the possible uses and limitations of the DOAC Dipstick and to compare visual analysis and DOASENSE Reader analysis of DOAC Dipstick pads. Plasma and urine samples were collected from 23 patients taking DOACs. DOAC concentrations in plasma and urine were measured by chromogenic substrate assays and in urine also by the DOAC Dipstick. Plasma concentrations were dichotomized at a threshold of ≥30 ng/mL. Patient samples were compared with samples from control individuals not using anticoagulants (n = 10) and with DOASENSE control urines. The Combur-10 test was used to measure parameters that may affect urine color and hence the interpretation of the DOAC Dipstick result. DOAC Dipstick test results were positive in 21/23 patient urine samples at a plasma DOAC concentration of ≥30 ng/mL and in 2/23 patient urine samples at a plasma DOAC concentration of <30 ng/mL. Inter-observer agreement was above 90% for visual analysis of patient urine samples and was 100% for DOASENSE Reader analysis of patient urines and for analysis of control group urines and DOASENSE control urines. Abnormalities in urine color detected by the Combur-10 test did not affect the DOAC Dipstick results. DOAC Dipstick detects DOACs in urine at a plasma threshold of ≥30 ng/mL. Positive DOAC Dipstick results should be confirmed by measuring DOAC plasma concentration.

Detection of Direct Oral Anticoagulants in Patient Urine Samples by Prototype and Commercial Test Strips for DOACs - A Systematic Review and Meta-analysis

The DOAC Dipstick accurately detects the presence or absence of factor Xa (DXI) and thrombin inhibitor (DTI) classes of direct oral anticoagulants (DOACs) in patients' urine samples on DOAC treatment. The aim of the study was to systematically review the literature and compare the performance of prototype and commercial test strips with a meta-analysis.

A systematic literature search of electronic databases PubMed (MEDLINE) and Cochrane Library was performed. Heterogeneity between studies was calculated using the Chi-squared test and the I ² index. A random effects model was used to pool data to compare the performance of prototype and commercial test strips.

Using PRISMA reporting guidelines, four of 1,081 publications were eligible for inclusion in the meta-analysis: three reporting on prototype (DXI n  = 658, DTI n  = 586) and one on commercial test strips (DXI n  = 451, DTI n  = 429). Sensitivity and specificity of DXI and DTI detection did not differ significantly between the prototype and commercial test strips. Odds ratios were 0.718 and 0.365 for sensitivity and 1.211 and 1.072 for specificity of DXI and DTI (p-values between 0.3334 and 1.000), respectively. The pooled sensitivity and specificity values for DXI were 0.968 ( p  = 0.1290, I ² 47.1%) and 0.979 ( p  = 0.1965, I ² 35.9%), and for DTI 0.993 ( p  = 0.1870, I ² 37.5%) and 0.993 ( p  = 0.7380, I ² 0%), respectively.

Prototype and commercial DOAC test strips did not differ in their ability to detect DXI and DTI in patient urine samples. This supports the confidence in use of the DOAC Dipstick test, although it needs to be validated in specific patient populations.