There is a laboratory and clinical need to know the impact of direct oral anticoagulants (DOACs) on diagnostic tests to avoid misinterpretation of results. Although the regulatory labelling documents provide some information about the influences of each DOAC on diagnostic tests, these are usually limited to some of the most common tests and no head to head comparison is available. In this paper, we report the impact of DOACs on several thrombophilia tests, including assessment of antithrombin, protein S and protein C activity assays, detection of activated protein C resistance and assays used for lupus anticoagulant. Results are compared and discussed with data obtained from literature. The final goal of this comprehensive review is to provide practical recommendations for laboratories to avoid misdiagnosis due to oral direct factor Xa (FXa) or IIa (FIIa) inhibitors. Overall, oral direct FXa (apixaban, betrixaban, edoxaban and rivaroxaban) and FIIa (dabigatran) antagonists may affect clot‐based thrombophilia diagnostic tests resulting in false‐positive or false‐negative results. An effect on FIIa‐based thrombophilia diagnostic tests is observed with dabigatran but not with anti‐FXa DOACs and conversely for FXa‐based thrombophilia diagnostic tests. No impact was observed with antigenic/chromogenic methods for the assessment of protein S and C activity. In conclusion, interpretation of thrombophilia diagnostic tests results should be done with caution in patients on DOACs. The use of a device/chemical compound able to remove or antagonize the effect of DOACs or the development of new diagnostic tests insensitive to DOACs should be considered to minimize the risk of false results.

Adapted chromogenic anti-Xa assays are the most appropriate assays to estimate the concentration of betrixaban. Betrixaban significantly affects several haemostasis diagnostic tests and this needs to be taken into consideration when requesting and interpreting such tests.

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An accurate point-of-care test for detecting effective anticoagulation by direct oral anticoagulants (DOACs) in emergencies is an unmet need. We investigated the accuracy of a urinary qualitative strip test (DOAC Dipstick) to detect relevant DOAC exposure in patients who presented to an emergency department. In this prospective single-center cohort-type cross-sectional study, adults on DOAC treatment were enrolled. We assessed clinical sensitivity and specificity of DOAC Dipstick factor Xa and thrombin inhibitor pads to detect DOAC plasma levels ≥30 ng/mL using urine samples as the testing matrix. Liquid chromatography coupled with tandem-mass spectrometry was used as the reference standard method for plasma and urine measurement of DOAC concentrations. Of 293 patients enrolled, 265 patients were included in the analysis, of whom 92 were treated with rivaroxaban, 65 with apixaban, 77 with edoxaban, and 31 with dabigatran. The clinical sensitivity and specificity of the dipstick on urine samples to detect ≥30 ng/mL dabigatran plasma levels were 100% (95% confidence interval [CI]: 87–100%) and 98% (95% CI: 95–99%), respectively. The sensitivity and specificity of the dipstick to detect ≥30 ng/mL factor Xa inhibitor plasma levels were 97% (95% CI: 94–99%) and 69% (95% CI: 56–79%), respectively. The DOAC Dipstick sensitively identified effective thrombin and factor Xa inhibition in a real-world cohort of patients presenting at an emergency department. Therefore, the dipstick might provide a valuable test to detect relevant DOAC exposure in emergencies, although further studies will be needed to confirm these findings.

Introduction:Clot waveform analysis (CWA), a new methodology to assess coagulation process, can be usefully applied in various clinical settings. However, its clinical use is limited mainly because of the absence of standardization. No consensus exists regarding the wavelengths at which CWA has to be performed what is crucial for the sensitivity of the CWA. Objectives:The primary aim of this study is to determine which wavelength is the most sensitive and specific for CWA. Interindividual baseline absorbance will also be assessed as the impact of reagents from the intrinsic, extrinsic, and common coagulation pathway will be determined.Methods: Plasma samples were screened at wavelengths from 280 to 700 nm to provide absorbance spectra in clotted and nonclotted plasma. The interindividual variability of baseline absorbance was obtained by screening plasma from 50 healthy individuals at 340, 635, and 671 nm. The inner-filter effect of reagents was assessed in plasma or serum when appropriate at the same wavelengths. The reagents were those commonly used for activated partial thromboplastin time, prothrombin time, thrombin time, and dilute Russell's viper venom time.Results: Clotted plasma has higher absorbance value than nonclotted plasma (P < 0.01). The absorbance of all type of samples is higher at 340 nm than at >600 nm (P < 0.01). The interindividual variability at the different wavelengths was around 25%. However, except with the STA®-CKPrest® and STA®-NeoPTimal®, the reagents do not have a significant effect on the baseline absorbance. Conclusions:Wavelengths above 650 nm are recommended to perform CWA. Most of the commercialized reagents can be used for CWA. | 317EVRARD Et Al.

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Introduction Activated protein C (APC) resistance is a major risk factor of venous thrombosis which may be acquired by hormonal therapy or other causes. The FibWave, a sensitive global clot‐based assay design to analyze the coagulation kinetics in plasma, may be a good candidate to assess this prothrombotic state. This study aims to assess the suitability of the FibWave to differentiate the coagulation kinetics of women on oral contraceptives. Materials and methods Fifty‐four healthy volunteers were divided into 5 groups: men [n = 13], women not using hormonal contraception [n = 12], women using second [n = 12] or third generation [n = 12] combined oral contraceptives, and women using progestin only contraceptive [n = 5]. Patients with coagulation abnormalities were also assessed [n = 8]. The APC resistance was assessed on the FibWave using exogenous APC or Protac, and on the Calibrated Automated Thrombogram using the ETP‐based APC resistance assay. Results Either in presence or in absence of APC or Protac, the FibWave was able to detect a hypercoagulable state in plasma samples. All combined oral contraceptives showed a lower FW‐Max1, FW‐Max2, and FW‐Min2 percentage of inhibition and a lower FW‐Ttpeak ratio than the other groups. The sensitivity of the FibWave was similar to the one of the ETP‐based APC resistance assay. Conclusion The FibWave is able to differentiate APC resistance levels observed in women on combined oral contraceptive. The FW‐Max1, FW‐Max2, and to a lesser degree FW‐Min2 were identified as the most sensitive parameters with a similar performance to the ETP‐based APC resistance assay.