Lupus anticoagulant testing during anticoagulation, including direct oral anticoagulants

Lupus Anticoagulant Testing in Challenging Situations: Navigating Complexities

The laboratory diagnosis of antiphospholipid syndrome (APS) relies on detecting persistent antiphospholipid antibodies (aPL), including lupus anticoagulant (LA) as one of the three laboratory criteria. LA is a well-established risk factor in APS and the cornerstone of APS diagnosis, identifying triple-positive patients. LA testing is supported by testing guidelines, but challenges remain with LA measurement, which is complex and susceptible to numerous pitfalls and interferences. A nuanced understanding of the technical and interpretative aspects of LA testing is crucial for accurate diagnosis. Limited to specific patient populations, the timing of testing in relation to clinical events is essential to avoid false results, and only persistent LA positivity is considered diagnostic. Proper sample preparation, choice of assays, test procedure, cutoff values, and strategies to handle anticoagulant therapy interference pose significant challenges in LA testing. While advances in the harmonization of test procedures and testing guidelines have improved diagnostic reliability, the complex nature of LA demands careful consideration of methodological issues and potential interferences, underscoring the importance of expertise and interdisciplinary communication in achieving accurate results. Interpretative comments and close interaction between clinical pathologists and clinicians are mandatory for diagnosis and patient management. This paper will focus on the technical aspects of the laboratory method and the interpretation of LA results in the diagnosis of APS with attention to specific situations where LA testing is difficult.

Update on the Laboratory Diagnosis of Lupus Anticoagulant: Current Challenges and Clinical Involvement

Lupus anticoagulant (LAC) is a heterogeneous mix of autoimmune antibodies that prolongs phospholipid-dependent clotting assays. Its diagnosis can be a real challenge in the hemostasis laboratory. In this review, the author describes the main pitfalls affecting the preanalytical phase and how to proceed to reduce interferences. Because of the heterogeneity of these autoantibodies, two assays with different mechanism of action should be performed to detect the majority of LACs. The dilute Russell's viper venom test and the use of a reagent very sensitive to LAC derived from the activated partial thromboplastin time, using silica as the activator, are the most frequent techniques. The algorithms for LAC detection are reported here, and every laboratory is encouraged to introduce its own diagnostic procedure. Results should be expressed in ratio to reduce inter- and intravariability. In addition, the effect of anticoagulation in LAC assays and possible strategies for a correct diagnosis are provided.

Enhancing Lupus Anticoagulant Testing with Machine Learning: Deep Neural Networks Match Expert Performance without the Need for Feature Selection

BACKGROUND

The lupus anticoagulant (LAC) is an important laboratory criterion in the diagnosis of antiphospholipid antibody syndrome. LAC testing at the Mayo Clinic Special Coagulation Laboratory includes up to 13 tests, which are interpreted by trained physicians to identify the presence of LAC and rule out anticoagulant interferences. This feasibility study explored the use of two deep neural network (DNN) architectures for multilabel classification of LAC profiles as a first step toward automating interpretation.

METHODS

Seven thousand two hundred and two retrospective cases were randomly split (64:16:20) for training, validation, and test, respectively. LAC positivity by dilute Russell's viper venom time (LAC-DRVVT) and activated partial thromboplastin time (LAC-APTT) and the presence of warfarin (WAR) and heparin (HEP) were adjudicated by one expert. DNN architectures included: single-output DNNs using domain-knowledge input feature selection and a single-column multioutput DNN using all 13 inputs.

RESULTS

Domain-knowledge-naïve multioutput DNN achieved similar or improved performance for all 4 label prediction tasks compared with domain knowledge optimized DNNs: F1 scores of 0.977 vs 0.968 for LAC-DRVVT, 0.954 vs 0.945 for LAC-APTT, 0.961 vs 0.957 for HEP, and 0.995 vs 0.977 for WAR, respectively.

CONCLUSIONS

The comparable performance of the 4 domain knowledge optimized DNNs and the multioutput DNN using all 13 input features suggests that the DNN may learn feature importance or mapping to a task without explicit input selection. Given its relative simplicity and versatility, the multioutput DNN is the preferred choice for implementation in a clinical laboratory to standardize LAC diagnosis.

Impact of the 2023 ACR/EULAR Classification Criteria on START2 Antiphospholipid Registry

INTRODUCTION

The recently published ACR/EULAR classification criteria score (3 points or more) both clinical and laboratory criteria to define the presence of antiphospholipid syndrome (APS). The clinical criteria have been better defined while laboratory criteria remain the same [lupus anticoagulant (LA), anticardiolipin (aCL) and anti ß2-Glycoprotein I (aß2GPI) antibodies] but with different impact (points) on the classification of patients. APS is excluded if more than 3 years separate positive test for antiphospholipid antibodies (aPL) and clinical manifestation.

METHODS

The present study evaluates how many patients would be excluded by the new criteria among those enrolled as APS in the START 2 antiphospholipid registry. The analysis includes 380 patients (274 APS and 106 carriers).

RESULTS

Of 274 patients classified as APS, 118 (43%) did not match the new ACR/EULAR criteria for various reasons. First, the determination of aCL and aß2GPI antibodies was performed by automated instrumentations not allowed in the new criteria. Second, laboratory test score was less than 3 and this was due to an isolated IgM aCL or IgM aß2GPI in most cases and to isolated LA unconfirmed after 12 weeks in few cases. Third, 2 patients had a positive laboratory tests more than 3 years after the clinical event. Of the 106 carriers, 62% had aCL and aß2GPI determined by ELISA thus meeting the ACL/EULAR laboratory criteria but were negative for clinical criteria.

DISCUSSION

This study shows that many patients classified as APS in the START 2 registry do not match the classification using the new ACR/EULAR criteria.

The New Occurrence of Antiphospholipid Syndrome in Severe COVID-19 Cases with Pneumonia and Vascular Thrombosis Could Explain the Post-COVID Syndrome

Introduction: The classification of antiphospholipid syndrome (APS) comprises clinical criteria (vascular thrombosis or obstetric complications throughout life) and laboratory criteria (antiphospholipid antibodies (aPLs) positivity, confirmed at least twice at 12-week interval). Methods: In 100 patients admitted to the hospital with COVID-19 pneumonia, thrombosis and pregnancy complications were recorded during the hospital stay and in personal medical history. They were tested for nine types of aPLs at four time points (admission, deterioration, discharge, and 3-month follow-up): anticardiolipin (aCL), anti-β2-glycoproteinI (anti-β2GPI), and antiphosphatidylserine/prothrombin (aPS/PT) isotypes IgM/IgG/IgA. Results: During hospitalization, aPLs were detected at least once in 51% of patients. All 7% of deceased patients tested negative for aPLs upon admission, and only one patient became aCL IgG positive as his condition worsened. In 83.3% of patients, intrahospital thrombosis was not related to aPLs. One patient with pulmonary artery and cerebral artery thrombosis was given an APS diagnosis (triple aPLs positivity on admission, double on follow-up). Personal anamnesis (PA) for thromboembolism was verified in 10 patients, all of whom tested negative for aPLs at admission; however, transition to aPLs positivity at discharge (as the disease subsided) was seen in 60% of patients: three of six with arterial thrombosis (at follow-up, two did not appear, and one was negativized) and three of four with deep vein thrombosis (one was confirmed at follow-up and diagnosed with APS, one was negativized, and one did not appear). At admission, the majority of the aPLs were of the aCL IgG class (58.8%). Unexpectedly, as the COVID-19 disease decreased, anti-β2GPI IgG antibodies (linked with thromboses) became newly positive at discharge (14.9%), as confirmed at follow-up (20.8%). Conclusion: The incidence of APS in our cohort was 2.0%, whereas in the general population, it ranges from 0.001% to 0.002%. The incidence might have increased even more if the four aPLs-positive patients with intrahospital thrombosis/history of thrombosis had attended follow-up. Recommendation: All patients with severe COVID-19 or post-COVID syndrome should be evaluated for current/previous thrombosis and tested for aPLs at least twice: at admission to the hospital and at discharge, then retested 3 months later in positive cases in order to be given the appropriate therapy.

An update on laboratory detection and interpretation of antiphospholipid antibodies for diagnosis of antiphospholipid syndrome: guidance from the ISTH-SSC Subcommittee on Lupus Anticoagulant/Antiphospholipid Antibodies

Antiphospholipid syndrome (APS) diagnosis is dependent on the accurate detection and interpretation of antiphospholipid antibodies (aPL). Lupus anticoagulant (LA), anticardiolipin antibodies (aCL), and anti-beta2 glycoprotein I antibodies (aβ2GPI) remain the cornerstone of the laboratory part of APS diagnosis. In the 2023 American College of Rheumatology (ACR)/European Alliance of Associations for Rheumatology (EULAR) APS classification criteria, the type of laboratory parameters remain essentially unchanged compared with the updated Sapporo classification criteria, and aCL and aβ2GPI measurement are still restricted to enzyme-linked immunosorbent assays (ELISAs) with moderate and high titer aPL thresholds defined as 40 and 80 Units, respectively, and a cutoff calculated by the 99th percentile has been abandoned. We must differentiate between classification criteria and assessment of aPL in clinical care. Classification criteria are strict and meant for participant inclusion in studies and trials to study homogeneous populations of patients. In contrast, laboratory detection for APS diagnosis in daily practice is broader, meant to diagnose each APS patient to optimize their management. Nowadays, there is increasing use of measurement of aPL by methods other than ELISAs , the semiquantitative reporting of titers is a matter of debate, as well as the role of the isotypes immunoglobulin (Ig)M and IgA, and the role of other aPL, such as antiphosphatidylserine (aPS)/prothrombin (PT) antibodies. Patients diagnosed with the disease may or may not fulfill the classification criteria, and inappropriate use of classification criteria may lead to mis(under)diagnosis. The aim of this guidance, based on literature and expert opinion, is to provide guidance recommendations for laboratory workers and clinicians on routine diagnostic assessment of patients with suspected APS.

Evaluation of MRX PT DOAC as a new screening method for detecting interferences in thrombophilia analyses

BACKGROUND

Direct oral anticoagulants (DOACs) can interfere with coagulation analyses, causing erroneous results such as false-positive lupus anticoagulant and false-normal antithrombin, threatening patient safety when overlooked. A test using a prothrombin time quotient method to detect DOAC presence in plasma samples is now commercially available, the MRX PT DOAC, with the result expressed as Clot Time Ratio (CTR).

OBJECTIVES

Evaluate the ability of MRX PT DOAC to identify interfering apixaban or rivaroxaban concentrations, identify non-interfering or interfering patient samples, and detect whether a patient is on DOAC treatment.

METHODS

An MRX PT DOAC reference interval was established, and MRX PT DOAC results related to FXa inhibitor concentrations. MRX PT DOAC patient plasma results were related to indications of analytical interference with lupus anticoagulant and antithrombin analyses and with the patients' anticoagulant drug use, according to medical records.

RESULTS

The MRX PT DOAC CTR reference interval was 0.98-1.38. MRX PT DOAC apixaban and rivaroxaban interference detection sensitivity was 1.00 (0.96 - 1.0). For subgroups from 315 patient plasma samples, the negative predictive values estimates were 0.84 or above (95% confidence interval minimum 0.64) for excluding analysis interference with the lupus anticoagulant and antithrombin analyses and for excluding DOAC treatment as per medical records. All 9 interference-indicating DOAC samples were identified for the lupus anticoagulant analyses, 5 out of 11 for antithrombin.

CONCLUSIONS

The MRX PT DOAC is a potential screening tool for interference. Confirming results in a larger DOAC patient group and further investigating the antithrombin interference detection uncertainty is important.

Impact of Lupus Anticoagulant on INR Using Recombinant Prothrombin Time Reagent

BACKGROUND Lupus anticoagulants (LA) can interfere with routine coagulation tests such as the activated partial thromboplastin time (aPTT) and prothrombin time (PT). The international normalized ratio (INR) is derived from PT and is used to monitor warfarin therapy. A positive LA result is one of the laboratory criteria of the 2023 ACR/EULAR antiphospholipid syndrome (APS) classification criteria. We report a case in which LA interfered with INR measurement in an APS patient. CASE REPORT Our patient was a 45-year-old man who had experienced multiple episodes of thromboembolism. His INR was consistently high, despite not being on any anticoagulant. Our laboratory used a recombinant PT reagent, Siemens Healthineers Dade® Innovin® on a fully automated coagulometer, the Sysmex CS-2500. PT measurements were repeated using 2 different analyzers, the Sysmex CA-104 and Werfen ACL Top 550 CTS. The PT results were 40.5 s (reference range (RR): 9.3-10.8 s) and 56 s, using Sysmex CS2500 and CS104, respectively. However, the PT was 13.4 s (RI: 10.3-12.7 s) using Werfen ACL Top 550 CTS. We retested the sample using Thromborel® S, a tissue-derived PT reagent, and PT was found to be within the reference range. The patient tested positive for LA, anti-cardiolipin, and anti-beta2 glycoprotein I antibodies. CONCLUSIONS LA can falsely prolong the PT when a recombinant PT reagent is used. When we retested the plasma using a tissue-derived PT reagent - Thromborel® S - PT was within normal limits. Thus, it is important to acknowledge that LA can react differently with different PT reagents.

Coagulation Profile of Convalescent Plasma Donors and Recipients

Convalescent plasma (CP) therapy for COVID-19 infection may have favorable safety but varying efficacy, with concerns about its procoagulant impact. We investigated whether administration of CP to hospitalized patients affects their coagulation profile. Fifty-four patients randomized in a double-blinded fashion received either placebo, low-titer CP (LCP) or high-titer CP (HCP). Donor blood samples were obtained at the time of the plasmapheresis, while recipient blood samples were collected before infusion, one day post-infusion and between two and six days after infusion. Routine laboratory follow-up, coagulation biomarkers, antiphospholipid antibodies, and thrombin generation (TG) were assessed. CP donors had normal blood cell counts and coagulation profiles, without differences between LCP and HCP donors at the baseline. All CP recipients were on low-molecular-weight heparin thromboprophylaxis at the time of the infusion. Despite randomization, the HCP group had lower baseline (p = 0.004) and Day 1 platelet counts (p = 0.019) than the LCP group. Von Willebrand antigen (VWF:Ag) levels clearly exceeded normal without differences at baseline. At Day 1, LCP recipients had higher VWF:Ag (mean ± SD 224 ± 15%) than HCP recipients (210 ± 8%) (p = 0.012). In all groups, overall 80% lupus anticoagulant was positive. Baseline TG variables were comparable, but again LCP recipients exhibited higher endogenous thrombin potential (ETP) (1313 ± 535 nM.min) (p = 0.038) and peak TG (184 ± 106 nM) (p = 0.037) than the HCP group (870 ± 425 nM.min and 86 ± 54 nM). Our findings show that LCP increases VWF:Ag levels and enhances TG despite the thromboprophylaxis. These results suggest that HCP induces less hypercoagulability than LCP, which may contribute to the variability in CP efficacy.

Innovative Diagnostic Solutions in Hemostasis

Hemostasis describes the process of blood clotting homeostasis. Hemostasis reflects a balance of procoagulant and anticoagulant mechanisms that aim to prevent both bleeding and thrombosis. If hemostasis is disrupted, and bleeding or thrombosis occur, then laboratory testing may ensue to either diagnose the reason for bleeding or thrombosis, or to manage patients under therapy or treatment for bleeding or thrombosis. A wide range of tests of hemostasis are available to laboratories and to clinicians, from routine coagulation assays to specialized hemostasis assays and platelet function. In the current narrative review, we highlight some of the history of innovative diagnostic solutions, such as the integration of chemiluminescence and flow cytometry in the hemostasis diagnostic armamentarium, as well as providing a glimpse to the possible future of diagnostic hemostasis testing. Future directions include the potential for artificial intelligence in diagnostics, the development of more global test systems that can assess both primary and secondary hemostasis, and several innovations to enable the ongoing evolution of therapies to rebalance hemostasis and requiring precise monitoring. This review underscores the ongoing need for innovation to enhance the diagnostic landscape of hemostasis, ensuring better patient outcomes through more accurate and efficient diagnostic methods.

The Performance of 2023 American College of Rheumatology (ACR) / European Alliance of Associations for Rheumatology (EULAR) Antiphospholipid Syndrome Classification Criteria in a Real-World Rheumatology Department

Background

Antiphospholipid Syndrome (APS) is one of the most common acquired causes of hypercoagulability. The 2023 American College of Rheumatology (ACR) / European Alliance of Associations for Rheumatology (EULAR) APS Classification Criteria were specified as new APS classification criteria with high specificity for use in observational studies and research. The primary objective of this study was to evaluate the performance of the 2023 ACR/EULAR APS classification criteria in a real-world rheumatology department.

Methods

This is a retrospective, single-center study evaluating the sensitivity and specificity of the 2006 revised Sapporo and 2023 ACR/EULAR APS classification criteria in patients diagnosed with APS through clinical evaluation. A total of 184 patients, 103 of whom were diagnosed with APS, were included in the study.

Results

The 2023 ACR/EULAR APS classification criteria demonstrate higher specificity 98.8% (95% CI 93.3-99.8) and positive predictive value (PPV) 98.7% (95% CI 93.2-99.8). The revised Sapporo criteria exhibit higher sensitivity 90.3% (95% CI 83-96.6), negative predictive value (NPV) 88.1% (95% CI 79.4-93.4), and accuracy 90.8% (95% CI 85.7-94.1). When the diagnosis of APS was accepted according to the revised Sapporo criteria, the sensitivity of the 2023 ACR/EULAR APS classification criteria was 77% (95% CI 67.8-84.2), specificity 97.6% (95% CI 91.7-99.3), PPV 97.5% (95% CI 69.3-84.9) and NPV 78.1% (95% CI 69.3-84.9).

Conclusion

The 2023 ACR/EULAR APS classification criteria have low sensitivity and high specificity compared to the revised Sapporo APS classification criteria. The increase in specificity is due to risk assessment in thromboses and strict obstetric and laboratory criteria.

Variable Performance of Lupus Anticoagulant Testing: The Australasian/Asia-Pacific Experience

Lupus anticoagulant (LA) is one of three tests identified as laboratory criteria for definite antiphospholipid syndrome (APS). The other two tests are anticardiolipin antibody (aCL) and anti-β2-glycoprotein I (aβ2GPI) antibody. The presence of LA is assessed using clot-based tests, while the presence of aCL and aβ2GPI is assessed by immunological assays. Since no test can be considered 100% sensitive or specific for LA, current guidelines recommend using two different clot-based assays reflecting different principles, with the dilute Russell viper venom time (dRVVT) and activated partial thromboplastin time (aPTT) recommended. Initially, LA-sensitive reagents are used to screen for LA, and then, in "screen-positive" samples, LA-"insensitive" reagents are used to confirm LA. Because LA assays are based on clot detection, anything that can interfere with fibrin clot development may affect test results. In particular, in addition to LA, the tests are also sensitive to the presence of a wide range of clinical anticoagulants, reflecting preanalytical issues for testing. We provide updated findings for LA testing in our geographic region, using recent data from the Royal College of Pathologists of Australasia Quality Assurance Programs, an international external quality assessment program with approximately 120 participants. Data show a wide variety of assays in use, especially for aPTT testing, and variable outcomes in reported numerical values with these assays when assessing proficiency samples. dRVVT testing mostly comprised reagents from three main manufacturing suppliers, which also showed differences in numerical values for the same homogeneous tested samples. Nevertheless, despite the use of different test reagents and processes, >98% of participants correctly identified LA-negative samples as LA-negative and LA-positive samples as LA positive. We hope our findings, reflecting on the heterogeneity of test processes and test data, help improve diagnostic testing for LA in the future.

Multifocal Renal Infarction and Diabetic Ketoacidosis: Diagnostic Challenges and Anticoagulation Management in a Complex Case

BACKGROUND Incidental findings of renal infarct secondary to thrombosis in acutely ill patients present a unique challenge in diagnosis. We present a case of idiopathic renal infarct to highlight its workup and management and encourage further investigation of renal infarctions. CASE REPORT A 68-year-old woman with a past medical history of diet-controlled diabetes, hypertension, and hyperlipidemia presented to the Emergency Department (ED) for abdominal pain. She was found to be in diabetic ketoacidosis with pyelonephritis, so she was admitted to the Intensive Care Unit (ICU) for insulin and dextrose drip. Due to her abdominal pain, she underwent computed tomography (CT) of her abdomen and pelvis with contrast. This revealed multifocal infarcts of her right kidney with noncalcified thrombus at the proximal right renal artery. Subsequent CT angiography confirmed a right renal artery thrombus. She was started on subcutaneous enoxaparin and downgraded to basic level of care. Her history was negative for prior thrombosis, hypercoagulable state, and abdominal trauma. Echocardiogram and limited hypercoagulable workup were largely unremarkable. A multidisciplinary team evaluated the patient and recommended no surgical intervention. Following downgrade from the ICU, the patient was transitioned from enoxaparin to apixaban. She was discharged with plans for anticoagulation for 6 months, aspirin daily, and repeat CT angiogram abdomen/pelvis in 1 month. CONCLUSIONS This case illustrates the difficulties in elucidating the cause of incidental renal thrombosis in an acutely ill patient. Diagnostic workup is limited in the inpatient setting, but therapeutic anticoagulation remains the standard of treatment regardless of etiology.

Thrombosis in Antiphospholipid Syndrome: Current Perspectives and Challenges in Laboratory Testing for Antiphospholipid Antibodies

Antiphospholipid syndrome (APS) diagnosis hinges on identifying antiphospholipid antibodies (aPL). Currently, laboratory testing encompasses lupus anticoagulant (LA), anticardiolipin (aCL), and anti-β2-glycoprotein I antibodies (aβ2GPI) IgG or IgM, which are included in the APS classification criteria. All the assays needed to detect aPL antibodies have methodological concerns. LA testing remains challenging due to its complexity and susceptibility to interference from anticoagulant therapy. Solid phase assays for aCL and aβ2GPI exhibit discrepancies between different assays. Antibody profiles aid in identifying the patients at risk for thrombosis through integrated interpretation of all positive aPL tests. Antibodies targeting domain I of β2-glycoprotein and antiphosphatidylserine-prothrombin antibodies have been evaluated for their role in thrombotic APS but are not yet included in the APS criteria. Detecting these antibodies may help patients with incomplete antibody profiles and stratify the risk of APS patients. The added diagnostic value of other methodologies and measurements of other APS-associated antibodies are inconsistent. This manuscript describes laboratory parameters useful in the diagnosis of thrombotic APS and will concentrate on the laboratory aspects, clinical significance of assays, and interpretation of aPL results in the diagnosis of thrombotic APS.

Detection of direct oral anticoagulants with the diluted Russel's viper venom time

INTRODUCTION

The activity of direct oral anticoagulants (DOAC) is important in acute clinical situations. Recent studies have suggested a strong influence of DOAC on the diluted Russel's Viper Venom Time (dRVVT). Therefore, it may be a suitable screening parameter for antithrombotic plasma activity of different DOAC. This prospective study aims to evaluate the sensitivity and specificity of dRVVT to detect residual DOAC activity at recommended plasma level thresholds.

METHODS

A total of 80 patients were recruited, with 20 each treated with one of the four approved DOAC (apixaban, edoxaban, rivaroxaban or dabigatran), respectively. Blood plasma was collected before (baseline), at plasma peak time, and 6 and 12 h after DOAC. DRVVT was measured using the screen (LA1) and confirm (LA2) assay for lupus anticoagulant and compared with DOAC plasma levels. A reference range was calculated based on the dRVVT values of 61 healthy blood donors.

RESULTS

All DOAC significantly prolonged the dRVVT especially at higher DOAC plasma levels. The LA1 time ≥41 s had a sensitivity ≥98% to detect edoxaban, dabigatran and rivaroxaban plasma levels ≥30 ng/mL but it was only 87% for apixaban. Sensitivity was ≥98% for all DOAC with the LA2 assay ≥36 s. The negative predictive value of a DOAC plasma level <30 ng/mL and dRVVT LA2 <36 s was 99%.

CONCLUSIONS

The dRVVT confirm assay (LA2) reliably detects residual DOAC plasma levels ≥30 ng/mL and could be useful to rapidly rule out relevant DOAC activity in emergency situations and to guide treatment decisions.

Testing for the lupus anticoagulant: the good, the bad, and the ugly

Lupus anticoagulant (LA) represents 1 of the laboratory criteria for classification of patients as having definite antiphospholipid syndrome (APS). The other 2 laboratory criteria are anticardiolipin antibodies and anti-beta2-glycoprotein I antibodies. At least 1 of these antiphospholipid antibody (aPL) tests need to be positive, with evidence of persistence, together with evidence of at least 1 clinical criterion for APS, before a patient can be classified as having definite APS. LA and other aPL assays are also important for diagnosis or exclusion of APS, as well as for risk stratification, with triple-positive patients carrying the greatest risk. Whereas LA is identified through "uncalibrated" clot-based assays, the other aPL assays (anticardiolipin and anti-beta2-glycoprotein I antibodies) represent immunological assays, identified using calibrated solid-phase methods. Because LA is identified using clot-based assays, it is subject to considerable preanalytical and analytical issues that challenge accurate detection or exclusion of LA. In this narrative review, we take a look at the good, the bad, and the ugly of LA testing, primarily focusing on the last 10 years. Although harmonization of LA testing as a result of International Society on Thrombosis and Haemostasis guidance documents and other international activities has led to improvements in LA detection, many challenges remain. In particular, several anticoagulants, especially direct oral anticoagulants and also vitamin K antagonists, given as therapy to treat the pathophysiological consequences of aPL, especially thrombosis, interfere with LA assays and can generate false-positive or false-negative LA findings. Overcoming these diagnostic errors will require a multifaceted approach with clinicians and laboratories working together.

Ischemic Stroke as an Initial Manifestation of Antiphospholipid Syndrome in an Adolescent: A Case Report

Cerebrovascular diseases in pediatric patients are relatively rare. Ischemic stroke in adolescents is associated with a poor prognosis. The most common causes include systemic diseases, such as heart disease and hypercoagulation disorders. It is important to mention that one of the most common acquired hypercoagulation states is the antiphospholipid syndrome (APS). Patients with this disease may present stroke as the first clinical manifestation, which not only increases morbidity in these patients but presents a diagnostic challenge. This case presents one example of how APS can present as a pediatric stroke. The diagnostic approach should always be through the presence of specific antibodies accompanied by the presence of a thromboembolic episode proven by catheterization or an imaging study. In the brain, the preferred imaging study is magnetic resonance imaging. Management is based on anticoagulation therapy and continuous monitoring in the intensive care unit.

A comparative in vitro study of the anticoagulant effect of branded versus generic rivaroxaban

BACKGROUND

Several generic formulations of rivaroxaban were recently marketed to be used interchangeably with their branded equivalent. However, there have been no previously published studies that directly compared the in vitro anticoagulant effect of branded vs. generic rivaroxaban. The aim of this in vitro study was to compare the effects of three raw rivaroxaban materials, obtained from the branded (Xarelto®) and two generic (Rivarolto® and Rivaroxaban Sandoz®) rivaroxaban formulations on an array of coagulation assays.

METHODS

A pool of normal plasma was spiked with several concentrations of the three rivaroxaban (range 50-750 ng/ml). The concentrations were assessed with a rivaroxaban calibrated anti-Xa assay and confirmed by ultra-high-performance liquid chromatography-mass spectrometry coupled with tandem mass spectrometry (UHPLC-MS/MS). The following assays were performed: Prothrombin time (PT), activated Partial Thromboplastin time (aPTT), Diluted Russell's Viper Venom Test (dRVVT), Thrombin time (TT), Clauss Fibrinogen, Factor VII, VIII and IX assays, and thromboelastography.

RESULTS

The results obtained by the three rivaroxaban at similar concentrations were comparable. Increasing concentrations of the three rivaroxaban showed a strong positive correlation with the PT, aPTT and dRVVT assays (r > 0.95, p < 0.01 for all), and a strong negative correlation with the Factors assays (r < -0.95, p < 0.01 for all). TT and Clauss Fibrinogen were not affected by rivaroxaban. No significant difference was identified in the mean assays' results obtained by the three rivaroxaban.

CONCLUSION

This study showed that the branded and generic rivaroxaban exert an identical in vitro anticoagulant effect across a wide range of concentrations.

Simplified Method for Removing Direct Oral Anticoagulant Interference in Mechanical Coagulation Test Systems-A Proof of Concept

BACKGROUND

Direct oral anticoagulants (DOACs) cause unwanted interference in various hemostasis assays, including lupus anticoagulant (LA) testing, where false positive and false negative identification may occur. DOAC Stop (DS) is an activated charcoal (AC) product used to specifically and effectively adsorb DOACs from test plasma. This process normally requires plasma treatment, centrifugation and plasma separation prior to tests, but inexperienced operators may also inadvertently transfer residual AC particles, thereby potentially adversely affecting clot detection.

METHODS

We hypothesized that residual DS might not be problematic for mechanical clot detection. We therefore investigated the potential impact of DS and a new DS liquid (DS-L) product on clotting tests using a mechanical clot detection system. Varying concentrations of DS were added to normal and abnormal plasmas with and without DOAC presence. Clotting tests including PT, APTT and dRVVT were performed directly in the analyzer without plasma/DS centrifugation.

RESULTS

DS up to double the recommended treatment level had only minor effects on all test results, despite completely obscuring visibility in the plasma/reagent mix. This confirms that the centrifugation step may be able to be omitted when using mechanical detection systems.

CONCLUSIONS

Should DS carryover into treated plasmas occur, this should not cause issues with testing performed on mechanical clot-sensing devices. Moreover, we hypothesize that DS can be used directly in these systems, without the need for centrifugation, thereby simplifying its many potential applications.

Viewpoint: Lupus anticoagulant detection and interpretation in antiphospholipid syndrome

Lupus anticoagulant (LA) is a well-established risk factor for the clinical manifestations of antiphospholipid syndrome (APS). Accurate LA detection is an essential prerequisite for optimal diagnosis and management of patients with APS or aPL carriers. Variability remains a challenge in LA testing, with reliable detection influenced by multiple factors, including pre-analytical conditions, anticoagulation treatment, choice of tests and procedures performed, as well as interpretation of results, that can lead to false-positives or negatives. A standardised approach to LA testing, following current guidance, based on published data and international consensus, and with attention to detail, is required to underpin accurate detection of LA. Future work should focus on better characterisation of the nature of LA, which may ultimately lead to improved diagnosis and management of patients with APS and aPL carriers. This article reviews current practice and challenges, providing an overview on detection of LA.

Key Issues at the Forefront of Diagnosis and Testing for Antiphospholipid Syndrome

Antiphospholipid syndrome (APS) is an autoimmune disorder characterized by antiphospholipid antibodies associated with thrombosis and pregnancy complications. Catastrophic APS is a severe form involving multiple organ systems with a high mortality rate. The pathogenesis involves antiphospholipid antibodies which target phospholipid-binding proteins and damage endothelial cells thus activating coagulation, triggering a pro-thrombotic state. Laboratory tests for antiphospholipid antibody detection include lupus anticoagulant testing in the coagulation laboratory and serological detection of anticardiolipin and anti-beta 2 glycoprotein I antibodies. Despite recent updates in the diagnostic criteria for APS the recent decades and our improved knowledge of this disease, there remain several key issues pertaining to diagnosis and testing with potential implications to patient management. Here we briefly review APS pathophysiology, strengths and weaknesses of classification criteria, laboratory challenges leading to test interpretation, and clinical management of this complex condition.

Prevalence of antiphospholipid antibody syndrome misclassification in an academic health system

PURPOSE

Antiphospholipid Antibody Syndrome (APS) is a complex autoimmune disorder that includes a combination of laboratory criteria and clinical events (thrombosis, pregnancy complications). Accurate classification is essential, as APS patients may have limited oral anticoagulant options and requires indefinite anticoagulation. The prevalence of inaccurate APS misclassification is unknown. This study sought to determine the proportion of patients in an academic health-system who formally met APS criteria.

METHODS

This retrospective cohort study included any patient within the University of Utah Health system who had an International Classification of Diseases-10 code for APS, between January 1, 2016 and June 30, 2020. Manual chart review was performed to assess the appropriateness of the APS classification by laboratory and clinical criteria.

RESULTS

Of the 184 patients identified, 59 (32.1 %) formally met APS criteria, while 69 (37.5 %) did not meet criteria. The remaining 56 (30.4 %) patients lacked enough information in their medical records to decide on appropriateness of APS classification. The most prevalent reason for inappropriate APS classification in the 69 patients identified was incorrect interpretation of lab values as positive (62; 89.9 %), followed by lack of repeat confirmation testing (32; 46.4 %).

CONCLUSION

The results of this single-center study indicate that only one-third of patients with presumed APS met classification criteria. This was predominantly due to incorrect collection or interpretation of APS laboratory data. One-third had insufficient medical record data to determine APS classification, which impairs clinical decision-making. This suggests more education or implementation of anticoagulation stewardship is needed to ensure accurate APS classification and proper management of anticoagulation therapy.

Antiphospholipid Antibodies and Vascular Thrombosis in Patients with Severe Forms of COVID-19

Antiphospholipid antibodies (aPLA) are a laboratory criterion for the classification of antiphospholipid syndrome (APS) and are known to cause clinical symptoms such as vascular thrombosis or obstetric complications. It is suggested that aPLA may be associated with thromboembolism in severe COVID-19 cases. Therefore, we aimed to combine clinical data with laboratory findings of aPLA at four time points (admission, worsening, discharge, and 3-month follow-up) in patients hospitalized with COVID-19 pneumonia. In 111 patients with COVID-19 pneumonia, current and past history of thrombosis and pregnancy complications were recorded. Nine types of aPLA were determined at four time points: anticardiolipin (aCL), anti-β2-glycoprotein I (anti- β2GPI), and antiphosphatidylserine/prothrombin (aPS/PT) of the IgM, IgG, or IgA isotypes. During hospitalization, seven patients died, three of them due to pulmonary artery thromboembolism (none were aPLA positive). Only one of the five who developed pulmonary artery thrombosis was aPLA positive. Out of 9/101 patients with a history of thrombosis, five had arterial thrombosis and none were aPLA positive at admission and follow-up; four had venous thrombosis, and one was aPLA positive at all time points (newly diagnosed APS). Of these 9/101 patients, 55.6% were transiently aPLA positive at discharge only, compared to 26.1% without a history of thrombosis (p = 0.041). Patients with severe forms of COVID-19 and positive aPLA should receive the same dose and anticoagulant medication regimen as those with negative aPLA because those antibodies are mostly transiently positive and not linked to thrombosis and fatal outcomes.

Close link between antiphosphatidylserine/prothrombin antibodies, lupus anticoagulant, and activated protein C resistance in tetra antiphospholipid antibody-positive subjects

BACKGROUND

Most of the carriers/patients triple-positive for antiphospholipid antibodies (lupus anticoagulant [LAC], immunoglobulin G [IgG]/immunoglobulin M [IgM] anticardiolipin, and anti-β2-glycoprotein I antibodies) are tetra-positive, being positive for antiphosphatidylserine/prothrombin (aPS/PT) antibodies. The relationship between aPS/PT titer, LAC potency, and resistance to activated protein C (aPC-R) has not been investigated.

OBJECTIVES

The aim of this study was to clarify the mutual interdependence of these parameters in tetra-positive subjects.

METHODS

Twenty-three carriers and 30 patients with antiphospholipid syndrome, none of whom were being treated with anticoagulants, and 30 age- and sex-matched controls were studied. Detection of aPS/PT, LAC, and aPC-R in each individual was performed with established methods in our laboratory. Carriers and patients were positive for IgG or IgM aPS/PT or for both isotypes without significant difference. Since both IgG and IgM aPS/PT have anticoagulant activity, we used the sum of their titers (total aPS/PT) for the correlation studies.

RESULTS

Total aPS/PT in all individuals studied exceeded that in controls. There was no difference in total aPS/PT titers (P = .72), LAC potency (P = .56), and aPC-R (P = .82) between antiphospholipid antibody-carriers and patients with antiphospholipid syndrome. There was a significant correlation between total aPS/PT and LAC potency (r = 0.78; P < .0001) and between total aPS/PT titers and aPC-R (r = 0.80; P < .0001). LAC potency also was correlated significantly with aPC-R (r = 0.72; P < .0001).

CONCLUSION

This study shows that there is interdependence between aPS/PT, LAC potency, and aPC-R.

Lupus Anticoagulant Detection under the Magnifying Glass

Diagnosis of antiphospholipid syndrome (APS) requires the presence of a clinical criterion (thrombosis and/or pregnancy morbidity), combined with persistently circulating antiphospholipid antibodies (aPL). Lupus anticoagulant (LA) is one of the three laboratory parameters (the others being antibodies to either cardiolipin or β2-glycoprotein I) that defines this rare but potentially devastating condition. For the search for aCL and aβ2-GP-I, traditionally measured with immunological solid-phase assays (ELISA), several different assays and detection techniques are currently available, thus making these tests relatively reliable and widespread. On the other hand, LA detection is based on functional coagulation procedures that are characterized by poor standardization, difficulties in interpreting the results, and interference by several drugs commonly used in the clinical settings in which LA search is appropriate. This article aims to review the current state of the art and the challenges that clinicians and laboratories incur in the detection of LA.

Removing direct oral factor Xa inhibitor interferences from routine and specialised coagulation assays using a raw activated charcoal product

BACKGROUND

Direct oral anticoagulants (DOACs) are increasingly prescribed for the prevention and treatment of thrombosis. However, DOACs are associated with extensive interference in coagulation assays. Herein, we evaluate raw activated charcoal (AC) as an adsorbent material, to minimise DOAC-associated interferences in routine and specialised coagulation parameters on CS-series analysers (Sysmex, Kobe, Japan).

METHODS

Commercial human-derived non-anticoagulated plasma materials, with or without increasing concentrations of anticoagulant, were assayed for routine and specialised coagulation parameters before and after treatment with AC.

RESULTS

Treatment of non-anticoagulated plasma with raw AC had minimal impact on routine and specialised coagulation parameters available on the CS-series; however, clinically relevant prolongations of certain activated partial thromboplastin time (APTT)-based assays were observed after treatment. Furthermore, in apixaban- and rivaroxaban-containing plasma material, AC efficiently adsorbed therapeutic and supratherapeutic DOAC concentrations; and, treatment with raw AC resolved DOAC-associated interferences on all affected routine and specialised coagulation parameters.

CONCLUSIONS

Overall, raw AC efficiently adsorbed apixaban and rivaroxaban from human-derived plasma, without significantly affecting the majority of underlying routine and specialised coagulation parameters available on CS-series analysers.

Thrombotic Antiphospholipid Syndrome and Direct Oral Anticoagulants: Unmet Needs and Review of the Literature

Patients with thrombotic antiphospholipid syndrome (APS) require long-term anticoagulation due to the high-thrombotic recurrence risk. Vitamin K antagonists (VKA) have been traditionally considered the standard of care in thrombotic APS. Nevertheless, the risk of recurrence persists with VKA. There are publications considering different intensities of anticoagulation with VKA; however, the standard-intensity anticoagulation (international normalized ratio between 2.0 and 3.0) is the most recommended. Furthermore, there is no consensus on the role of antiplatelet treatment in thrombotic APS. Nonvitamin K antagonist oral anticoagulants (NOACs) have emerged as an alternative to VKA for many indications. There are, however, discrepancies regarding the management with NOACs in thrombotic APS. In this review, we update the different clinical trials with NOACs in venous, arterial, and microvascular thrombosis and suggest how these patients should be managed in agreement with the expert panels. Although scarce data are published regarding the current role of NOACs in thrombotic APS, the clinical trials failed to demonstrate noninferiority of NOACs compared with VKA, especially in patients with triple antiphospholipid antibodies positivity and/or arterial thrombosis. Single or double antiphospholipid positivity should be analyzed on a case-by-case basis. In addition, we focus on different areas of uncertainty that still remain in thrombotic APS and NOACs. To summarize, emerging clinical trials are needed to provide robust data on the management of thrombotic APS.

Anti-Phospholipid Antibodies in Women with Placenta-Mediated Complications Delivered at >34 Weeks of Gestation

OBJECTIVE

To determine the prevalence of positive antiphospholipid (aPL) antibodies among pregnant women with placenta-mediated complications delivered at >34^0/7 weeks of gestation.

METHODS

This was a single-center retrospective observational study conducted between 2017 and 2022. Inclusion criteria included pregnant or post-partum women, >18 years, diagnosed with any of the following placenta-mediated complications and delivered at >34^0/7 weeks of gestation: small-for-gestational-age neonate (SGA ≤ 5th percentile according to local birthweight charts), preeclampsia with severe features, and placental abruption. The primary outcome was the prevalence of positive aPL antibodies: Lupus anticoagulant, Anticardiolipin, or Anti-ß2glycoprotein1.

RESULTS

Overall, 431 women met the inclusion criteria. Of them, 378(87.7%) had an SGA neonate, 30 had preeclampsia with severe features (7%), 23 had placental abruption (5.3%), and 21 patients had multiple diagnoses(4.9%). The prevalence of aPL antibodies in the cohort was 4.9% and was comparable between the three subgroups (SGA-3.9%; PET with severe features-3.3%; and placental abruption-13% (p = 0.17)).

CONCLUSION

aPL antibodies prevalence in women with placenta-mediated complications > 34 weeks of gestation was 4.9%, with comparable prevalence rates among the three subgroups. Future prospective studies are needed to delineate the need for treatment in those who tested positive for aPL antibodies and do not meet Anti-Phospholipid Antibody Syndrome clinical criteria.

Added value of antiphosphatidylserine/prothrombin antibodies in the workup of obstetric antiphospholipid syndrome: communication from the ISTH SSC Subcommittee on Lupus Anticoagulant/Antiphospholipid Antibodies

BACKGROUND

The added value of antiphosphatidylserine/prothrombin antibodies (aPS/PT) in the diagnostic workup of antiphospholipid syndrome (APS) is unclear. Currently, diagnosis of thrombotic APS (TAPS) and obstetric APS (OAPS) requires persistent presence of lupus anticoagulant (LAC), anticardiolipin (aCL) immunoglobulin (Ig) G/IgM, or anti-β2-glycoprotein I (aβ2GPI) IgG/IgM antibodies.

OBJECTIVES

To evaluate the role of aPS/PT IgG and IgM in OAPS.

METHODS

aPS/PT IgG/IgM, aCL IgG/IgM, aβ2GPI IgG/IgM, and LAC were determined in 653 patients (OAPS, TAPS, and controls). In-house aPS/PT cut-off values were calculated, titers and prevalence were compared between OAPS, TAPS, and controls and type of pregnancy morbidity. Sensitivity, specificity, likelihood ratios, and odds ratios (OR) with 95% CI were calculated.

RESULTS

In OAPS, aPS/PT IgG and IgM showed an OR of 4.32 (95% CI, 2.54-7.36) and 3.37 (95% CI, 1.93-5.89), respectively, but the association was not independent of LAC. Prevalence and titers of aPS/PT IgG and IgM were lower in OAPS than in patients with TAPS. aPS/PT were more prevalent and showed higher titers in patients with late pregnancy loss than in patients with early pregnancy loss with a positivity of 86.4% and 39.3%, respectively. Higher aPS/PT titers did not increase the likelihood of having OAPS.

CONCLUSION

The added value of aPS/PT testing in the current diagnostic workup of OAPS seems limited compared with LAC, aCL, and aβ2GPI. aPS/PT might be useful in specific subsets of patients with OAPS. However, future multicentric studies are needed to elucidate the risk of less frequent and most severe obstetrical manifestations.

Antiphospholipid Antibody Testing for Anti-cardiolipin and Anti-β2 Glycoprotein I Antibodies Using Chemiluminescence-Based Panels

Antiphospholipid (antibody) syndrome (APS) is a prothrombotic condition with increased risk for thrombosis and pregnancy-related morbidity. In addition to clinical criteria related to these risks, APS is characterized by the persistent presence of antiphospholipid antibodies (aPL), as detected in the laboratory using a potentially wide variety of assays. The three APS criteria-related assays are lupus anticoagulant (LA), as detected using clot-based assays, and the solid-phase assays of anti-cardiolipin antibodies (aCL) and anti-β2 glycoprotein I antibodies (aβ2GPI), with immunoglobulin subclasses of IgG and/or IgM. These tests may also be used for the diagnosis of systemic lupus erythematosus (SLE). In particular, APS diagnosis/exclusion remains challenging for clinicians and laboratories because of the heterogeneity of clinical presentations in those being evaluated and the technical application and variety of the associated tests used in laboratories. Although LA testing is affected by a wide variety of anticoagulants, which are often given to APS patients to prevent any associated clinical morbidity, detection of solid-phase aPL is not influenced by these anticoagulants, and this thus represents a potential advantage to their application. On the other hand, various technical issues challenge accurate laboratory detection or exclusion of aPL. This report describes protocols for the assessment of solid-phase aPL, specifically aCL and aβ2GPI of IgG and IgM class by means of a chemiluminescence-based assay panel. These protocols reflect tests able to be performed on the AcuStar instrument (Werfen/Instrumentation Laboratory). Certain regional approvals may also allow this testing to be performed on a BIO-FLASH instrument (Werfen/Instrumentation Laboratory).

Hemostasis and Thrombosis: An Overview Focusing on Associated Laboratory Testing to Diagnose and Help Manage Related Disorders

Hemostasis is a complex but balanced process that permit normal blood flow, without adverse events. Disruption of the balance may lead to bleeding or thrombotic events, and clinical interventions may be required. Hemostasis laboratories typically offer an array of tests, including routine coagulation and specialized hemostasis assays used to guide clinicians for diagnosing and managing patients. Routine assays may be used to screen patients for hemostasis-related disturbances but may also be used for drug monitoring, measuring efficacy of replacement or adjunctive therapy, and other indications, which may then be used to guide further patient management. Similarly, "specialized" assays are used for diagnostic purposes or may be used to monitor or measure efficacy of a given therapy. This chapter provides an overview of hemostasis and thrombosis, with a focus on laboratory testing that may be used to diagnose and help manage patients suspected of hemostasis- and thrombosis-related disorders.

Post-analytical Issues in Hemostasis and Thrombosis Testing: An Update

There are typically three phases identified as contributing to the total testing process. The preanalytical phase starts with the clinician and the patient, when laboratory testing is being considered. This phase also includes decisions about which tests to order (or not), patient identification, blood collection, blood transport, sample processing, and storage to name a few. There are many potential failures that may occur in this preanalytical phase, and these are the topic of another chapter in this book. The second phase, the analytical phase, represents the performance of the test, which is essentially covered in various protocols in this book and the previous edition. The third is the post-analytical phase, which is what occurs after sample testing, and is the topic of the current chapter. Post-analytical issues are generally related to reporting and interpretation of test results. This chapter provides a brief description of these events, as well as guidance for preventing or minimizing post-analytical issues. In particular, there are several strategies for improved post-analytical reporting of hemostasis assays, with this providing the final opportunity to prevent serious clinical errors in patient diagnosis or management.

An Overview of Laboratory Testing for Antiphospholipid Antibodies

Antiphospholipid antibodies (aPL) represent a group of autoantibodies directed against phospholipids. These antibodies may arise in a number of autoimmune conditions, of which the antiphospholipid (antibody) syndrome (APS) is best recognized. aPL can be detected by various laboratory assays, essentially comprising both solid-phase (immunological) assays and "liquid-phase" clotting assays identifying so-called lupus anticoagulants (LA). aPL are associated with various adverse pathologies, including thrombosis and placental/fetal morbidity and mortality. The type of aPL present, as well as the pattern of reactivity, is variously associated with the severity of the pathology. Thus, laboratory testing for aPL is indicated to help assess the future risk of such events, as well as representing certain "classification" criteria for APS, also used as surrogates for diagnostic criteria. The current chapter overviews the laboratory tests available to measure aPL and their potential clinical utility.

Autoimmune Diseases Affecting Hemostasis: A Narrative Review

Hemostasis reflects a homeostatic mechanism that aims to balance out pro-coagulant and anti-coagulant forces to maintain blood flow within the circulation. Simplistically, a relative excess of procoagulant forces can lead to thrombosis, and a relative excess of anticoagulant forces can lead to bleeding. There are a wide variety of congenital disorders associated with bleeding or thrombosis. In addition, there exist a vast array of autoimmune diseases that can also lead to either bleeding or thrombosis. For example, autoantibodies generated against clotting factors can lead to bleeding, of which acquired hemophilia A is the most common. As another example, autoimmune-mediated antibodies against phospholipids can generate a prothrombotic milieu in a condition known as antiphospholipid (antibody) syndrome (APS). Moreover, there exist various autoimmunity promoting environments that can lead to a variety of antibodies that affect hemostasis. Coronavirus disease 2019 (COVID-19) represents perhaps the contemporary example of such a state, with potential development of a kaleidoscope of such antibodies that primarily drive thrombosis, but may also lead to bleeding on rarer occasions. We provide here a narrative review to discuss the interaction between various autoimmune diseases and hemostasis.

The myths behind DOAC measurement: Analyses of prescribing information from different regulatory bodies and a call for harmonization

For more than a decade, US laboratories have failed to implement solutions to help their clinicians in managing complex situations or patients on direct oral anticoagulants (DOACs). The problem may find different origins, among which is the position of the Food and Drug Administration, which categorized these drugs as monitoring- and measurement-free, whereas other regulatory bodies like the European Medicines Agency or the Therapeutic Goods Administration in Australia were more conservative on the principle that the absence of proof (of monitoring/measurement benefits) is not proof of an absence (of monitoring/measurement needs). Pivotal clinical studies that led to the approval of DOACs were presented as devoid of such testing, although some companies considered monitoring as a solution to improve their benefit/risk ratio. In this JTH In Clinics issue, we report more than a decade of development that has permitted the activation of smart laboratory solutions to qualify or quantify DOACs and discuss myths and misconceptions around technical and regulatory requirements that support the current reluctance of implementing these technologies in most US laboratories. Use of DOACs is ever expanding, with DOAC prescriptions now exceeding those of other anticoagulants, including vitamin K antagonists, in some geographies. As this use increases, the likely need to measure DOAC exposure will also increase. Measurement of DOACs does not represent any technical difficulty. That these laboratory tests are not available in some locations suggests disparities in patient care, and we suggest it is time to address such inequalities.