The effect of unfractionated heparin, enoxaparin, and danaparoid on lupus anticoagulant testing: Can activated carbon eliminate false‐positive results?

Abstract Background Heparins and heparinoids interfere with functional clotting assays used for lupus anticoagulant (LAC) detection. However, current guidelines for LAC testing do not provide clear guidance on this matter. Objectives We aimed to assess to effect of unfractionated heparin (UFH), enoxaparin, and danaparoid on LAC assays over broad anti‐Xa activity ranges and to evaluate whether activated carbon (AC) is able to neutralize these effects. Methods UFH (0.1‐3.0 IU/mL), enoxaparin (0.2‐2.9 IU/mL), and danaparoid (0.6‐2.2 IU/mL) were spiked to normal pooled plasma. AC was added at multiple activity levels. Anti‐Xa assays and LAC tests were performed on all samples using Stago analyzers and reagents. Results Abnormal activated partial thromboplastin time (APTT) screening and mixing tests were obtained at the lowest levels for all compounds. Abnormal APTT confirmation tests were seen from 2.5 and 1.9 anti‐Xa IU/mL for enoxaparin and danaparoid, respectively. Abnormal dilute Russell’s viper venom test (dRVVT) screening tests were obtained from 1.6, 1.4, and 1.1 anti‐Xa IU/mL for UFH, enoxaparin, and danaparoid, respectively. Mixing tests were abnormal from 2.5 and 1.3 anti‐Xa IU/mL for enoxaparin and danaparoid, respectively. Abnormal dRVVT confirmation results were seen for danaparoid only from 1.9 anti‐Xa IU/mL. AC was unable to neutralize anti‐Xa activity in plasma and overcome the effect of the tested anticoagulants on LAC assays but may cause prolongation of APTT clotting times. Conclusions UFH, enoxaparin, and danaparoid clearly affected LA tests; however, false‐positive LAC conclusions were obtained at supratherapeutic enoxaparin and danaparoid levels only. AC may prolong APTT screen clotting times, requiring 3‐step testing to avoid potential misdiagnosis of LAC

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-beta 2- glycoprotein I (a beta 2GPI) IgG/IgM antibodies. Objectives: To evaluate the role of aPS/PT IgG and IgM in OAPS. Methods: aPS/PT IgG/IgM, aCL IgG/IgM, a beta 2GPI 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 a beta 2GPI. 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

Detection of anti-domain I antibodies by chemiluminescence enables the identification of high-risk antiphospholipid syndrome patients : a multicenter multiplatform study

Background Classification of the antiphospholipid syndrome (APS) relies predominantly on detecting antiphospholipid antibodies (aPLs). Antibodies against a domain I (DI) epitope of anti-beta 2glycoprotein I (beta 2GPI) proved to be pathogenic, but are not included in the current classification criteria. Objectives Investigate the clinical value of detecting anti-DI IgG in APS. Patients/Methods From eight European centers 1005 patients were enrolled. Anti-cardiolipin (CL) and anti-beta 2GPI were detected by four commercially available solid phase assays; anti-DI IgG by the QUANTA Flash (R) beta 2GPI domain I assay. Results Odds ratios (ORs) of anti-DI IgG for thrombosis and pregnancy morbidity proved to be higher than those of the conventional assays. Upon restriction to patients positive for anti-beta 2GPI IgG, anti-DI IgG positivity still resulted in significant ORs. When anti-DI IgG was added to the criteria aPLs or used as a substitute for anti-beta 2GPI IgG/anti-CL IgG, ORs for clinical symptoms hardly improved. Upon removing anti-DI positive patients, lupus anticoagulant remained significantly correlated with clinical complications. Anti-DI IgG are mainly present in high-risk triple positive patients, showing higher levels. Combined anti-DI and triple positivity confers a higher risk for clinical symptoms compared to only triple positivity. Conclusions Detection of anti-DI IgG resulted in higher ORs for clinical manifestations than the current APS classification criteria. Regardless of the platform used to detect anti-beta 2GPI/anti-CL, addition of anti-DI IgG measured by QUANTA Flash (R) did not improve the clinical associations, possibly due to reduced exposure of the pathogenic epitope of DI. Our results demonstrate that anti-DI IgG potentially helps in identifying high-risk patients