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Objective: To assess the impact of concomitant systemic lupus erythematosus (SLE) on the clinicopathological manifestations of thrombotic antiphospholipid syndrome (APS)., Methods: This single-centre, retrospective study compared clinical and antiphospholipid antibody (aPL) data from 118 patients, 58 with SLE-associated APS (SLE-APS), and 60 with primary APS., Results: Median follow-up was 13.9 (IQR 7.7-19.3) and 8.6 years (3.5-10.6) for the SLE-APS cohort and PAPS cohort, respectively. Age at diagnosis of APS was lower in the SLE-APS cohort (mean 35.9 vs PAPS: 46.7 years; p < 0.05). Distribution of aPL subtypes was similar across cohorts. 198 thrombotic events were identified overall (index plus recurrent), with venous thromboembolism (VTE) and arterial thrombosis each occurring in just over half of patients in both cohorts. Microvascular thrombosis (12.1% vs 0%), and a mixed (any combination of venous, arterial and microvascular) thrombotic phenotype (19.0% vs 6.7%, p = 0.05) were more prevalent in SLE-APS patients. Recurrent thrombosis incidence rates (∼0.5 events/10-patient years), and Kaplan-Meier recurrence-free survival after index thrombosis, were similar. In the PAPS cohort, only: (i) triple-aPL-positivity was associated with a significantly higher recurrent thrombosis event rate (incidence rate ratio 2.22, p = 0.03) and lower recurrence-free survival after first thrombosis (log-rank test p = 0.01); (ii) lupus anticoagulant (LA)-positivity was associated with higher prevalance of arterial thrombosis (RR 2.69, p = 0.01), and lower prevlance of VTE (RR 0.48, p < 0.001), versus LA-negativity., Conclusion: Concomitant SLE does not appear to modify long-term recurrent thrombosis risk, or aPL phenotypes, in patients with APS. Triple-aPL-positivity and LA-positive status may have less influence on thrombotic outcomes in patients with SLE-APS compared to PAPS., Competing Interests: Declaration of conflicting interestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: HC reports, outside the submitted work, institutional research support and support to attend scientific meetings from Bayer Healthcare; Roche Advisory Board; Consultancy fees from UCB Biopharma and Speaker fees from Technoclone paid to University College London Hospitals Charity. ME reports consultancy fees from Alexion Pharmaceutical. PM, MP, LT, JR, IT and DI have nothing to disclose.

Background: Long-term anticoagulant therapy is generally recommended for thrombotic antiphospholipid syndrome (TAPS) patients, however it may be withdrawn or not introduced in routine practice., Objectives: To prospectively evaluate the risk of thrombosis recurrence and major bleeding in non-anticoagulated TAPS patients, compared to anticoagulated TAPS, and secondly, to identify different features between those two groups., Patients/methods: Using an international registry, we identified non-anticoagulated TAPS patients at baseline, and matched them with anticoagulated TAPS patients based on gender, age, type of previous thrombosis, and associated autoimmune disease. Thrombosis recurrence and major bleeding were prospectively analyzed using Kaplan-Meier method and compared using a marginal Cox's regression model., Results: As of June 2022, 94 (14 %) of the 662 TAPS patients were not anticoagulated; and 93 of them were matched with 181 anticoagulated TAPS patients (median follow-up 5 years [interquartile range 3 to 8]). The 5-year thrombosis recurrence and major bleeding rates were 12 % versus 10 %, and 6 % versus 7 %, respectively (hazard ratio [HR] 1.38, 95 % confidence interval [CI] 0.53 to 3.56, p = 0.50 and HR 0.53; 95 % CI 0.15 to 1.86; p = 0.32, respectively). Non-anticoagulated patients were more likely to receive antiplatelet therapy (p < 0.001), and less likely to have more than one previous thrombosis (p < 0.001) and lupus anticoagulant positivity (p = 0.01)., Conclusion: Fourteen percent of the TAPS patients were not anticoagulated at recruitment. Their recurrent thrombosis risk did not differ compared to matched anticoagulated TAPS patients, supporting the pressing need for risk-stratified secondary thrombosis prevention trials in APS investigating strategies other than anticoagulation., Competing Interests: Declaration of competing interest Authors had no conflict of interest to declare., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Objectives: Our primary objective was to quantify damage burden measured by Damage Index for Antiphospholipid Syndrome (DIAPS) in aPL-positive patients with or without a history of thrombosis in an international cohort (the APS ACTION cohort). Secondly, we aimed to identify clinical and laboratory characteristics associated with damage in aPL-positive patients., Methods: In this cross-sectional study, we analysed the baseline damage in aPL-positive patients with or without APS classification. We excluded patients with other autoimmune diseases. We analysed the demographic, clinical and laboratory characteristics based on two subgroups: (i) thrombotic APS patients with high vs low damage; and (ii) non-thrombotic aPL-positive patients with vs without damage., Results: Of the 826 aPL-positive patients included in the registry as of April 2020, 586 with no other systemic autoimmune diseases were included in the analysis (412 thrombotic and 174 non-thrombotic). In the thrombotic group, hyperlipidaemia (odds ratio [OR] 1.82; 95% CI 1.05, 3.15; adjusted P = 0.032), obesity (OR 2.14; 95% CI 1.23, 3.71; adjusted P = 0.007), aβ2GPI high titres (OR 2.33; 95% CI 1.36, 4.02; adjusted P = 0.002) and corticosteroid use (ever) (OR 3.73; 95% CI 1.80, 7.75; adjusted P < 0.001) were independently associated with high damage at baseline. In the non-thrombotic group, hypertension (OR 4.55; 95% CI 1.82, 11.35; adjusted P = 0.001) and hyperlipidaemia (OR 4.32; 95% CI 1.37, 13.65; adjusted P = 0.013) were independent predictors of damage at baseline; conversely, single aPL positivity was inversely correlated with damage (OR 0.24; 95% CI 0.075, 0.77; adjusted P = 0.016)., Conclusions: DIAPS indicates substantial damage in aPL-positive patients in the APS ACTION cohort. Selected traditional cardiovascular risk factors, steroids use and specific aPL profiles may help to identify patients more prone to present with a higher damage burden., (© The Author(s) 2023. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

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., (© The Author(s) 2024. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Objective: To develop new antiphospholipid syndrome (APS) classification criteria with high specificity for use in observational studies and trials, jointly supported by the American College of Rheumatology (ACR) and EULAR., Methods: This international multidisciplinary initiative included 4 phases: 1) Phase I, criteria generation by surveys and literature review; 2) Phase II, criteria reduction by modified Delphi and nominal group technique exercises; 3) Phase III, criteria definition, further reduction with the guidance of real-world patient scenarios, and weighting via consensus-based multicriteria decision analysis, and threshold identification; and 4) Phase IV, validation using independent adjudicators' consensus as the gold standard., Results: The 2023 ACR/EULAR APS classification criteria include an entry criterion of at least one positive antiphospholipid antibody (aPL) test within 3 years of identification of an aPL-associated clinical criterion, followed by additive weighted criteria (score range 1-7 points each) clustered into 6 clinical domains (macrovascular venous thromboembolism, macrovascular arterial thrombosis, microvascular, obstetric, cardiac valve, and hematologic) and 2 laboratory domains (lupus anticoagulant functional coagulation assays, and solid-phase enzyme-linked immunosorbent assays for IgG/IgM anticardiolipin and/or IgG/IgM anti-β 2 -glycoprotein I antibodies). Patients accumulating at least 3 points each from the clinical and laboratory domains are classified as having APS. In the validation cohort, the new APS criteria versus the 2006 revised Sapporo classification criteria had a specificity of 99% versus 86%, and a sensitivity of 84% versus 99%., Conclusion: These new ACR/EULAR APS classification criteria were developed using rigorous methodology with multidisciplinary international input. Hierarchically clustered, weighted, and risk-stratified criteria reflect the current thinking about APS, providing high specificity and a strong foundation for future APS research., (© 2023 American College of Rheumatology.)

Objective: To develop new antiphospholipid syndrome (APS) classification criteria with high specificity for use in observational studies and trials, jointly supported by the American College of Rheumatology (ACR) and EULAR., Methods: This international multidisciplinary initiative included four phases: (1) Phase I, criteria generation by surveys and literature review; (2) Phase II, criteria reduction by modified Delphi and nominal group technique exercises; (3) Phase III, criteria definition, further reduction with the guidance of real-world patient scenarios, and weighting via consensus-based multicriteria decision analysis, and threshold identification; and (4) Phase IV, validation using independent adjudicators' consensus as the gold standard., Results: The 2023 ACR/EULAR APS classification criteria include an entry criterion of at least one positive antiphospholipid antibody (aPL) test within 3 years of identification of an aPL-associated clinical criterion, followed by additive weighted criteria (score range 1-7 points each) clustered into six clinical domains (macrovascular venous thromboembolism, macrovascular arterial thrombosis, microvascular, obstetric, cardiac valve, and hematologic) and two laboratory domains (lupus anticoagulant functional coagulation assays, and solid-phase enzyme-linked immunosorbent assays for IgG/IgM anticardiolipin and/or IgG/IgM anti-β 2 -glycoprotein I antibodies). Patients accumulating at least three points each from the clinical and laboratory domains are classified as having APS. In the validation cohort, the new APS criteria vs the 2006 revised Sapporo classification criteria had a specificity of 99% vs 86%, and a sensitivity of 84% vs 99%., Conclusion: These new ACR/EULAR APS classification criteria were developed using rigorous methodology with multidisciplinary international input. Hierarchically clustered, weighted, and risk-stratified criteria reflect the current thinking about APS, providing high specificity and a strong foundation for future APS research., Competing Interests: Competing interests: RAL is an employee of GlaxoSmithKline., (© Author(s) (or their employer(s)) 2023. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: The optimal strategy for diagnosis and antithrombotic treatment of patients with antiphospholipid syndrome (APS)-associated acute ischemic stroke (AIS), transient ischemic attack (TIA), or other brain ischemic injury is poorly defined., Objectives: The survey goal was to capture variations in diagnosis and antithrombotic treatment of APS-associated ischemic stroke and related disorders to inform guidance and clinical trials to define optimal management., Methods: Professional colleagues, including key opinion leaders, were invited to complete a REDCap survey questionnaire initiated by the International Society on Thrombosis and Haemostasis Scientific and Standardisation Committee Subcommittee on Lupus Anticoagulant/Antiphospholipid Antibodies. The survey data were tallied using simple descriptive statistics., Results: There was generally good agreement on several aspects, including which patients to test for antiphospholipid antibodies (aPL), use of a lifelong vitamin K antagonist for AIS or recurrent TIA, and formal cognitive assessment for suspected cognitive impairment. There was less agreement on other aspects, including aPL testing for brain ischemic injury other than AIS/TIA or if an alternative cause for AIS or TIA exists; choice of aPL tests, their timing, and age cutoff; the aPL phenotype to trigger antithrombotic treatment; management for patent foramen ovale; antithrombotic treatment for first TIA or white matter hyperintensities; head magnetic resonance imaging specifications; and low-molecular-weight heparin dosing/anti-Xa monitoring in pregnancy. The survey highlighted that approximately 25% practice at dedicated APS clinics and <50% have a multidisciplinary team structure for patients with APS., Conclusion: Much of the variation in practice reflects the lack of evidence-based recommendations. The survey results should inform the development of a more uniform multidisciplinary consensus approach to diagnosis and antithrombotic treatment., Competing Interests: Declaration of competing interests H.C. reports lecture fees from Technoclone, paid to University College London Hospitals Charity. M.C. reports consulting for Bayer for products other than rivaroxaban. M.K. reports being GSK Global Medical Expert (Lupus), Dubai, United Arab Emirates. The other authors and remaining study group members have no competing interests to disclose., (Copyright © 2023 International Society on Thrombosis and Haemostasis. Published by Elsevier Inc. All rights reserved.)

Objective: This study aimed to elucidate the presence, antigen specificities, and potential clinical associations of anti-neutrophil extracellular trap (anti-NET) antibodies in a multinational cohort of antiphospholipid (aPL) antibody-positive patients who did not have lupus., Methods: Anti-NET IgG/IgM levels were measured in serum samples from 389 aPL-positive patients; 308 patients met the classification criteria for antiphospholipid syndrome. Multivariate logistic regression with best variable model selection was used to determine clinical associations. For a subset of the patients (n = 214), we profiled autoantibodies using an autoantigen microarray platform., Results: We found elevated levels of anti-NET IgG and/or IgM in 45% of the aPL-positive patients. High anti-NET antibody levels are associated with more circulating myeloperoxidase (MPO)-DNA complexes, which are a biomarker of NETs. When considering clinical manifestations, positive anti-NET IgG was associated with lesions affecting the white matter of the brain, even after adjusting for demographic variables and aPL profiles. Anti-NET IgM tracked with complement consumption after controlling for aPL profiles; furthermore, patient serum samples containing high levels of anti-NET IgM efficiently deposited complement C3d on NETs. As determined by autoantigen microarray, positive testing for anti-NET IgG was significantly associated with several autoantibodies, including those recognizing citrullinated histones, heparan sulfate proteoglycan, laminin, MPO-DNA complexes, and nucleosomes. Anti-NET IgM positivity was associated with autoantibodies targeting single-stranded DNA, double-stranded DNA, and proliferating cell nuclear antigen., Conclusion: These data reveal high levels of anti-NET antibodies in 45% of aPL-positive patients, where they potentially activate the complement cascade. While anti-NET IgM may especially recognize DNA in NETs, anti-NET IgG species appear to be more likely to target NET-associated protein antigens., (© 2023 The Authors. Arthritis & Rheumatology published by Wiley Periodicals LLC on behalf of American College of Rheumatology.)

Several antiphospholipid antibody (aPL) profiles ("triple" and lupus anticoagulant [LA] positivity) are associated with a higher risk for clinical manifestations of antiphospholipid syndrome (APS). Further risk is correlated with higher levels of anticardiolipin antibody (aCL) and anti-β 2 glycoprotein-I antibody (aβ 2 GPI), and with aPL persistence. Given that the 3 aPL tests detect partially overlapping sets of antibodies, the primary goal of this study was to characterize the associations among aPL tests using AntiPhospholipid Syndrome Alliance for Clinical Trials and InternatiOnal Networking (APS ACTION) core laboratory data. The APS ACTION Registry includes annually followed adult patients with positive aPL based on the Revised Sapporo Classification Criteria. We analyzed baseline and prospective core laboratory data of the registry for associations among aPL tests using the Spearman rank correlation with Bonferroni-adjusted significance level for multiple comparisons. An aPL Load was calculated based on 6 tests (aCL IgG/IgM/IgA and aβ 2 GPI IgG/IgM/IgA); a receiver operating characteristic curve was used to evaluate the diagnostic performance of the aPL Load in predicting LA positivity. In 351 patients simultaneously tested for LA, aCL, and aβ 2 GPI, the frequency of moderate-to-high (≥40 U) titers of aCL and aβ 2 GPI IgG/IgM/IgA was higher in patients who were positive for LA vs those who were negative. An aPL Load was calculated for each patient to assess the overall aPL burden. For every 1-point increase in the aPL Load, the possibility of a positive LA test increased by 32% (odds ratio, 1.32; 95% CI, 1.2-1.5; P < .001). Based on core laboratory data from a large international registry, most aPL enzyme-linked immunosorbent assay ≥40 U and a high calculated aPL Load combining 6 aPL enzyme-linked immunosorbent assays were predictive of a positive LA. These data suggest that the combined quantitative burden of aPL may provide a mechanistic explanation of a positive LA., (Copyright © 2023 United States & Canadian Academy of Pathology. Published by Elsevier Inc. All rights reserved.)

Objective: The present study was undertaken to longitudinally evaluate titers of antibodies against β 2 -glycoprotein I (anti-β 2 GPI) and domain 1 (anti-D1), to identify predictors of variations in anti-β 2 GPI and anti-D1 titers, and to clarify whether antibody titer fluctuations predict thrombosis in a large international cohort of patients who were persistently positive for antiphospholipid antibodies (aPL) in the APS ACTION Registry., Methods: Patients with available blood samples from at least 4 time points (at baseline [year 1] and at years 2-4 of follow-up) were included. Detection of anti-β 2 GPI and anti-D1 IgG antibodies was performed using chemiluminescence (BIO-FLASH; INOVA Diagnostics)., Results: Among 230 patients in the study cohort, anti-D1 and anti-β 2 GPI titers decreased significantly over time (P < 0.0001 and P = 0.010, respectively). After adjustment for age, sex, and number of positive aPL tests, we found that the fluctuations in anti-D1 and anti-β 2 GPI titer levels were associated with treatment with hydroxychloroquine (HCQ) at each time point. Treatment with HCQ, but not immunosuppressive agents, was associated with 1.3-fold and 1.4-fold decreases in anti-D1 and anti-β 2 GPI titers, respectively. Incident vascular events were associated with 1.9-fold and 2.1-fold increases in anti-D1 and anti-β 2 GPI titers, respectively. Anti-D1 and anti-β 2 GPI titers at the time of thrombosis were lower compared to titers at other time points. A 1.6-fold decrease in anti-D1 titers and a 2-fold decrease in anti-β 2 GPI titers conferred odds ratios for incident thrombosis of 6.0 (95% confidence interval [95% CI] 0.62-59.3) and 9.4 (95% CI 1.1-80.2), respectively., Conclusion: Treatment with HCQ and incident vascular events in aPL-positive patients predicted significant anti-D1 and anti-β 2 GPI titer fluctuations over time. Both anti-D1 and anti-β 2 GPI titers decreased around the time of thrombosis, with potential clinical relevance., (© 2023 The Authors. Arthritis & Rheumatology published by Wiley Periodicals LLC on behalf of American College of Rheumatology.)

Antiphospholipid syndrome (APS) is a prothrombotic autoimmune disease with heterogeneous clinicopathological manifestations and is a well-established cause of acute ischemic stroke (AIS) and transient ischemic attack (TIA), particularly in younger patients. There is growing recognition of a wider spectrum of APS-associated cerebrovascular lesions, including white matter hyperintensities, cortical atrophy, and infarcts, which may have clinically important neurocognitive sequalae. Diagnosis of APS-associated AIS/TIA requires expert review of clinical and laboratory information. Management poses challenges, given the potential for substantial morbidity and recurrent thrombosis, additional risk conferred by conventional cardiovascular risk factors, and limited evidence base regarding optimal antithrombotic therapy for secondary prevention. In this review, we summarize key features of APS-associated cerebrovascular disorders, with focus on clinical and laboratory aspects of diagnostic evaluation. The current status of prognostic markers is considered. We review the evidence base for antithrombotic treatment in APS-associated stroke and discuss uncertainties, including the optimal intensity of anticoagulation and efficacy of direct oral anticoagulants. Clinical practice recommendations are provided, covering antithrombotic treatment, supportive management, and options for anticoagulant-refractory cases, and we highlight the benefits of adopting a considered, multidisciplinary team approach.

Objectives: To determine whether early damage and its kinetics measured by the Damage Index for Antiphospholipid Syndrome (DIAPS) predicts mortality., Methods: We carried out a single-centre retrospective analysis of thrombotic APS patients (2006 Sydney criteria), using the DIAPS for damage assessment. Early damage was considered to be at six months after disease onset; early damage increase (delta-DIAPS) was deemed to be at least a one-point rise in DIAPS within the first five years of illness. Groups were compared using appropriate statistical tests. Survival was analysed by the Kaplan-Meier method. Cox regression analysis was performed to investigate predictors of mortality., Results: A total of 197 patients (71.1% female; 65.9% primary APS; 72.4% Caucasian) were followed for up to 43 years (median 10). Damage developed in 143 (73.6%) patients. Twenty-three patients (12%) died. Secondary APS (HR 3.07, 95%CI 1.32-7.12, p=0.009), male sex (HR 3.14, 95%CI 1.35-7.33, p=0.008) and age at APS onset ≥40 years (HR 5.34, 95%CI 1.96-14.53, p=0.001) were risk factors for death. Early damage (n=69, 35.0%) was not associated with death (p=0.231). Having a first arterial event was associated with early damage (p<0.001), but not with delta-DIAPS (p=0.539) nor with the risk of death (p=0.151). Delta-DIAPS (n=53/181, 29.3%) predicted mortality (HR 5.40, 95%CI 2.33-12.52, p<0.001), even after adjusting individually for APS category (secondary), sex (male), early damage and age at APS onset (≥40 years) (all p<0.005)., Conclusions: Evolving damage in the first five years of illness, but not early damage, predicted mortality regardless of the nature of the first thrombotic event, sex, APS category and age.

Background/purpose: APS ACTION Registry was created to study the outcomes of patients with persistently positive antiphospholipid antibodies (aPL) with or without other systemic autoimmune disease (SAIDx). Given that immunosuppression (IS) is used for certain aPL manifestations, for example, thrombocytopenia (TP), our primary objective was to describe the indications for IS in aPL-positive patients without other SAIDx. Secondly, we report the type of IS used in patients with selected microvascular or non-thrombotic aPL manifestations., Methods: An online database is used to collect clinical data. The inclusion criteria are positive aPL based on the laboratory section of the APS Classification Criteria, tested at least twice within one year prior to enrollment. Patients are followed every 12 ± 3 months. For this descriptive retrospective and prospective analysis, we included aPL-positive patients without other SAIDx and excluded those with new SAIDx classification during follow-up. For each patient, we retrieved clinical data at baseline and follow-up including selected aPL manifestations (diffuse alveolar hemorrhage [DAH], antiphospholipid-nephropathy [aPL-N], livedoid vasculopathy [LV]-related skin ulcers, TP, autoimmune hemolytic anemia [AIHA], cardiac valve disease [VD]), and IS medications., Results: Of 899 patients enrolled, 537 were included in this analysis (mean age 45 ± 13 years, female 377 [70%], APS Classification in 438 [82%], and at least one selected microvascular or non-thrombotic aPL manifestation in 141 (26%)). Of 537 patients, 76 (14%) were reported to use IS (ever), and 41/76 (54%) received IS primarily for selected aPL manifestation. In six of 8 (75%) DAH patients, 6/19 (32%) aPL-N, 4/28 (14%) LV, 25/88 (28%) TP, 6/11 (55%) AIHA, and 1/43 (2%) VD, the IS (excluding corticosteroids/hydroxychloroquine) indication was specific for selected aPL manifestation., Conclusion: In our international cohort, 14% of aPL-positive patients without other SAIDx were reported to receive IS; the indication was at least one of the selected microvascular and/or non-thrombotic aPL-related manifestations in half. Thrombocytopenia was the most frequent among those selected aPL-related manifestations; however, approximately one-third received IS specifically for that indication. Diffuse alveolar hemorrhage was frequently treated with IS followed by AIHA and aPL-N. Systematic controlled studies are urgently needed to better define the role of IS in APS.

Limited evidence exists to guide the management of recurrent thrombosis occurring despite therapeutic anticoagulation in patients with thrombotic antiphospholipid syndrome (APS). In this case series, fondaparinux, with or without an antiplatelet agent, provided an effective and safe option in three patients with thrombotic APS, all two triple and one single positive for antiphospholipid antibodies, who had recurrent venous and/or arterial thromboembolism. Rituximab was also used in all patients. Recurrent events occurred despite therapeutic anticoagulation, including at high-intensity, with warfarin and subsequent low-molecular-weight heparin. There were no major bleeding events. Adjunctive therapies used for thrombosis included catheter-directed thrombolysis and rituximab.

Background: Not all patients fulfil criteria for specific autoimmune rheumatic diseases (ARDs) and are then defined as having non-criteria (nc)ARD. It is uncertain whether well-recognised associations with adverse pregnancy outcomes in patients with criteria ARD also exist in patients with ncARD or undifferentiated connective tissue disease (UCTD). Therefore, we undertook a systematic review of the prevalence of adverse pregnancy outcomes in various ncARD and UCTD compared with criteria ARD to identify whether there are increased risks and to examine for any benefits of treatment., Methods: This study was conducted in accordance with the guidance of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) standard. A systematic literature review was performed using online databases including Medline and PubMed from inception to the beginning of April 2021 using appropriate keywords for various ARD and pregnancy outcomes., Results: After screening 665 articles, 36 articles were chosen for full text review and 15 selected for final analysis. There were eight studies of nc antiphospholipid syndrome (APS) of more than 7000 pregnancies and seven studies of UCTD of more than 1000 pregnancies. No studies of any other ncARD in pregnancy were identified. We found that patients with either ncAPS or UCTD seem to have an increased burden of poor pregnancy outcomes compared with the general population. Despite the heterogeneity and poor quality of the studies, we also noted that ncAPS and criteria APS patients may have similar rates of obstetric complications with standard and/or non-standard APS treatment regimens., Conclusion: Our findings of increased risks of poor pregnancy outcomes in patients with ncAPS or UCTD will be helpful for pre-pregnancy counselling and management of these patients in pregnancy and support their referral to specialist obstetric-rheumatology and obstetric-haematology clinics.

Objectives: Cognitive dysfunction is common in patients with aPL (including primary APS or APS associated with SLE). Neuroimaging biomarkers may contribute to our understanding of mechanisms of cognitive dysfunction in these cohorts. This review aimed to investigate: (i) the prevalence of cognitive dysfunction in studies including neuroimaging biomarkers; and (ii) associations between cognition and neuroimaging biomarkers in patients with APS/aPL., Methods: We conducted a systematic search of electronic databases PubMed, Science Direct, Scopus and PsycINFO, and included studies with descriptions of neuroimaging findings, cognitive dysfunction or both, in patients with aPL positivity (LA, IgG and IgM aCL and anti-β2 glycoprotein-I antibodies)., Results: Of 120 search results we included 20 eligible studies (6 APS, 4 SLE with APS/aPL and 10 NPSLE). We identified a medium risk of bias in 6/11 (54%) of cohort studies and 44% of case-control studies, as well as marked heterogeneity in cognitive assessment batteries, APS and aPL definitions, and neuroimaging modalities and protocols. The prevalence of cognitive dysfunction ranged between 11 and 60.5%. Structural MRI was the most common imaging modality, reporting cognitive dysfunction to be associated with white matter hyperintensities, ischaemic lesions and cortical atrophy (four with cerebral atrophy, two with white matter hyperintensities and two with cerebral infarcts)., Conclusion: Our findings confirm that cognitive impairment is commonly found in patients with aPL (including APS, SLE and NPSLE). The risk of bias, and heterogeneity in the cognitive and neuroimaging biomarkers reported does not allow for definitive conclusions., (© The Author(s) 2021. Published by Oxford University Press on behalf of the British Society for Rheumatology.)

Coronavirus disease 2019 (COVID-19) is associated with a high rate of thrombosis. Prolonged activated partial thromboplastin times (aPTT) and antiphospholipid antibodies (aPL) are reported in COVID-19 patients. The majority of publications have not reported whether patients develop clinically relevant persistent aPL, and the clinical significance of new aPL-positivity in COVID-19 is currently unknown. However, the reports of aPL-positivity in COVID-19 raised the question whether common mechanisms exist in the pathogenesis of COVID-19 and antiphospholipid syndrome (APS). In both conditions, thrombotic microangiopathy resulting in microvascular injury and thrombosis is hypothesized to occur through multiple pathways, including endothelial damage, complement activation, and release of neutrophil extracellular traps (NETosis). APS-ACTION, an international APS research network, created a COVID-19 working group that reviewed common mechanisms, positive aPL tests in COVID-19 patients, and implications of COVID-19 infection for patients with known aPL positivity or APS, with the goals of proposing guidance for clinical management and monitoring of aPL-positive COVID-19 patients. This guidance also serves as a call and focus for clinical and basic scientific research.

Background: Antiphospholipid syndrome (APS) is characterized by episodes of thrombosis, obstetric morbidity or both, associated with persistently positive antiphospholipid antibodies (aPL). Studying the profile of a rare disease in an admixed population is important as it can provide new insights for understanding an autoimmune disease. In this sense of miscegenation, Brazil is characterized by one of the most heterogeneous populations in the world, which is the result of five centuries of interethnic crosses of people from three continents. The objective of this study was to compare the clinical and laboratory characteristics of Brazilian vs. non-Brazilian primary antiphospholipid syndrome (PAPS) patients., Methods: We classified PAPS patients into 2 groups: Brazilian PAPS patients (BPAPS) and PAPS patients from other countries (non-BPAPS). They were compared regarding demographic characteristics, criteria and non-criteria APS manifestations, antiphospholipid antibody (aPL) profile, and the adjusted Global Antiphospholipid Syndrome Score (aGAPSS)., Results: We included 415 PAPS patients (88 [21%] BPAPS and 327 [79%] non-BPAPS). Brazilian patients were significantly younger, more frequently female, sedentary, obese, non-white, and had a higher frequency of livedo (25% vs. 10%, p < 0.001), cognitive dysfunction (21% vs. 8%, p = 0.001) and seizures (16% vs. 7%, p = 0.007), and a lower frequency of thrombocytopenia (9% vs. 18%, p = 0.037). Additionally, they were more frequently positive for lupus anticoagulant (87.5% vs. 74.6%, p = 0.01), and less frequently positive to anticardiolipin (46.6% vs. 73.7%, p < 0.001) and anti-ß2-glycoprotein-I (13.6% vs. 62.7%, p < 0.001) antibodies. Triple aPL positivity was also less frequent (8% vs. 41.6%, p < 0.001) in Brazilian patients. Median aGAPSS was lower in the Brazilian group (8 vs. 10, p < 0.0001). In the multivariate analysis, BPAPS patients still presented more frequently with livedo, cognitive dysfunction and sedentary lifestyle, and less frequently with thrombocytopenia and triple positivity to aPL. They were also less often white., Conclusions: Our study suggests a specific profile of PAPS in Brazil with higher frequency of selected non-criteria manifestations and lupus anticoagulant positivity. Lupus anticoagulant (not triple positivity) was the major aPL predictor of a classification criteria event., (© 2021. The Author(s).)

Antiphospholipid syndrome (APS) and myeloproliferative neoplasms (MPN) are associated with an increased risk of thrombosis. The optimal management of patients with coexistent APS and MPN has not been defined. A single centre and systematic literature review of patients with coexistent APS and MPN was performed. Cases were divided into two groups based on whether they met international consensus criteria for APS. Of the 12 studies identified, eight were excluded (leaving five of a total 54 patients), as although antiphospholipid antibodies (aPL) were documented, the diagnosis of APS was not conclusively demonstrated. Another ten patients with definite APS were identified at our centre. Fifteen patients (ten females, five males) were therefore included in this analysis (eleven definite APS and four highly likely), median age 44 (range: 13-71) years. Nine had polycythaemia vera and six, essential thrombocythaemia. Thirteen of the 15 patients (86.7%) had thrombotic APS (seven with initial venous events and six arterial) and two (13.3%) had obstetric APS. Nine patients were single-positive, and six double-positive for aPL. None were triple aPL-positive. Four patients at our centre had recurrent thrombotic/obstetric events, including while on anticoagulation/antiplatelet treatment.

Purpose of Review: APS ACTION is an international research network created to design and conduct large-scale, multicenter research in persistently antiphospholipid antibody (aPL)-positive patients. Given the expanding research activities of the network in the last decade since its creation, the purpose of this article is to review the scientific contributions of APS ACTION as well as future directions., Recent Findings: APS ACTION has achieved increased international collaboration with internal and external investigators for outcome, interventional, and mechanistic antiphospholipid syndrome (APS) studies. This has been linked to substantial progress in Core laboratory work, which has demonstrated that laboratories can achieve good agreement in performance of aPL assays by use of the same reagents, analyzer type, and protocols. APS ACTION will continue to identify gaps in the existing aPL/APS literature, design mechanistic studies to elucidate underlying mechanisms, and conduct prospective, large-scale clinical studies, all for the ultimate goal of early diagnosis and improved management of aPL-positive patients.

Objective: The APS ACTION Registry studies long-term outcomes in persistently antiphospholipid antibody (aPL)-positive patients. Our primary objective was to determine whether clinically meaningful aPL profiles at baseline remain stable over time. Our secondary objectives were to determine (1) whether baseline characteristics differ between patients with stable and unstable aPL profiles, and (2) predictors of unstable aPL profiles over time., Methods: A clinically meaningful aPL profile was defined as positive lupus anticoagulant (LAC) test and/or anticardiolipin (aCL)/anti-β 2 glycoprotein-I (anti-β 2 -GPI) IgG/M ≥ 40 U. Stable aPL profile was defined as a clinically meaningful aPL profile in at least two-thirds of follow-up measurements. Generalized linear mixed models with logit link were used for primary objective analysis., Results: Of 472 patients with clinically meaningful aPL profile at baseline (median follow-up 5.1 yrs), 366/472 (78%) patients had stable aPL profiles over time, 54 (11%) unstable, and 52 (11%) inconclusive. Time did not significantly affect odds of maintaining a clinically meaningful aPL profile at follow-up in univariate ( P = 0.906) and multivariable analysis ( P = 0.790). Baseline triple aPL positivity decreased (OR 0.25, 95% CI 0.10-0.64, P = 0.004) and isolated LAC test positivity increased (OR 3.3, 95% CI 1.53-7.13, P = 0.002) the odds of an unstable aPL profile over time., Conclusion: Approximately 80% of our international cohort patients with clinically meaningful aPL profiles at baseline remain stable at a median follow-up of 5 years; triple aPL-positivity increase the odds of a stable aPL profile. These results will guide future validation studies of stored blood samples through APS ACTION Core Laboratories., (Copyright © 2021 by the Journal of Rheumatology.)

Anticoagulation is central to the management of thrombotic antiphospholipid syndrome (APS). The standard anticoagulant treatment for thrombotic APS is life-long warfarin or an alternative vitamin K antagonist. The role of direct oral anticoagulants for thrombotic APS is not established due to the lack of definitive evidence and has recently been addressed in international guidance. Other anticoagulant options include low molecular weight heparin, unfractionated heparin, and fondaparinux. In APS patients, lupus anticoagulant can affect phospholipid-dependent coagulation monitoring tests, so that they may not reflect true anticoagulation intensity. Accurate assessment of anticoagulation intensity is essential, to optimize anticoagulant dosing and facilitate thrombus resolution; minimize the risk of recurrent thrombosis or bleeding; inform assessment of whether recurrent thrombosis is related to breakthrough thrombosis while on therapeutic anticoagulation, subtherapeutic anticoagulation, non-adherence, or spurious results; and guide the management of bleeding. Knowledge of anticoagulant intensity also informs assessment and comparison of anticoagulation regimens in clinical studies. Considerations regarding anticoagulation dosing and/or monitoring of thrombotic APS patients underpin appropriate management in special situations, notably APS-related severe renal impairment, which can occur in APS or APS/systemic lupus erythematosus-related nephropathy or catastrophic APS; and APS-related thrombocytopenia. Anticoagulant dosing and monitoring in thrombotic APS patients also require consideration in anticoagulant-refractory APS and during pregnancy. In this review, we summarize the tests generally used in monitoring anticoagulant therapy, use of the main anticoagulants considered for thrombotic APS, lupus anticoagulant effects on anticoagulation monitoring tests, and strategies for appropriate anticoagulant monitoring in thrombotic APS., (© 2020 The Authors. Journal of Thrombosis and Haemostasis published by Wiley Periodicals LLC on behalf of InternationalSociety on Thrombosis and Haemostasis.)

Thrombotic antiphospholipid syndrome (APS) is characterised by venous, arterial and/or small vessel thrombosis in the context of persistently positive antiphospholipid antibodies (aPL). The diagnosis and management of thrombotic APS continues to prove challenging for clinicians. We provide a practical guide to the diagnosis of APS including who to test for aPL and which tests to do. We also consider clinical practice points on the management of venous, arterial and small vessel thrombosis, in the context of first and recurrent thrombotic events. Non-criteria manifestations of APS are reviewed. An approach to recurrent thrombosis and anticoagulant-refractory APS is discussed, with options including increasing the anticoagulation intensity of vitamin K antagonists, switching to low-molecular-weight-heparin, the use of fondaparinux and/or the addition of antiplatelet treatment. Adjunctive options such as vitamin D, hydroxychloroquine and statins are also addressed., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The standard treatment of thrombotic antiphospholipid syndrome (APS) is lifelong oral anticoagulation with a vitamin K antagonist (VKA), generally warfarin. A minority of patients with APS rethrombose despite seemingly adequate anticoagulation. These patients are deemed anticoagulant refractory. The management of anticoagulant-refractory APS is largely empirical and extrapolated from other clinically similar situations. Further options include increased VKA anticoagulation intensity or alternative antithrombotic strategies, including low-molecular-weight heparin, fondaparinux, the addition of antiplatelet therapy, and consideration of vascular options. Patients with anticoagulant-refractory thrombotic APS may have APS-associated thrombocytopenia, which necessitates balancing the risk of recurrent thrombosis vs bleeding to achieve adequate anticoagulation. The multiple mechanisms involved in the generation of the thrombotic phenotype in APS suggest that anticoagulation alone may not control thrombosis. Thus, other modalities, including adjunctive treatment (hydroxychloroquine, statins, and vitamin D) for APS-related thrombosis, merit consideration, as do immunomodulatory therapy and complement inhibition. Patients with APS may have coexistent systemic lupus erythematosus, which adds to the complexity of managing their thromboembolic disease. However, with attention to detail and judicious application of the limited data, it is possible to minimize the morbidity resulting from anticoagulant-refractory thrombotic APS. Multicenter studies are required to guide the sequence of interventions and their comparative efficacy in patients with anticoagulant-refractory thrombotic APS., (© 2021 by The American Society of Hematology.)

This guidance focuses on methodological aspects of lupus anticoagulant (LA) testing, as well as interpretation of results for clinicians. The main changes in how to test for LA compared with the International Society on Thrombosis and Haemostasis Scientific and Standardization Committee 2009 guidelines, in the preanalytical phase are more detailed recommendations on how to handle testing in anticoagulated patients, and the timing of testing. Also, routine coagulation tests are advised to obtain more information on the coagulation background of the patient, and when necessary, anti-Xa activity measurement for heparins or specific assays for direct oral anticoagulants should be performed. The three-step procedure with two test systems (diluted Russell's viper venom time and activated partial thromboplastin time [aPTT]) is essentially not changed. Silica remains the preferable activator in the aPTT assays, but ellagic acid is not excluded. We advise simultaneous performance of the mixing and confirmatory step, in each sample with a prolonged screening test. The confirmatory step can also be performed on a mixture of patient plasma and normal pooled plasma. Cutoff values should be established in-house on at least 120 normals, with transference of the manufacturer's cutoffs as an alternative. Reporting of results has not been changed, although more attention is focused on what clinicians should know. Patient selection for LA testing has been expanded., (© 2020 International Society on Thrombosis and Haemostasis.)

Antiphospholipid syndrome (APS), an acquired autoimmune thrombophilia, is characterised by thrombosis and/or pregnancy morbidity in association with persistent antiphospholipid antibodies. The 16th International Congress on Antiphospholipid Antibodies Task Force on APS Treatment Trends reviewed the current status with regard to existing and novel treatment trends for APS, which is the focus of this Task Force report. The report addresses current treatments and developments since the last report, on the use of direct oral anticoagulants in patients with APS, antiplatelet agents, adjunctive therapies (hydroxychloroquine, statins and vitamin D), targeted treatment including rituximab, belimumab, and anti-TNF agents, complement inhibition and drugs based on peptides of beta-2-glycoprotein I. In addition, the report summarises potential new players, including coenzyme Q10, adenosine receptor agonists and adenosine potentiation. In each case, the report provides recommendations for clinicians, based on the current state of the art, and suggests a clinical research agenda. The initiation and development of appropriate clinical studies requires a focus on devising suitable outcome measures, including a disease activity index, an optimal damage index, and a specific quality of life index.

Clarity and guidance is required with regard to the use of direct oral anticoagulants in antiphospholipid syndrome (APS) patients, within the confines of the recent European Medicines Agency recommendations, discrepant recommendations in other international guidelines and the limited evidence base. To address this, the Lupus Anticoagulant/Antiphospholipid Antibodies Scientific and Standardization Committee (SSC) chair and co-chairs together with SSC Control of Anticoagulation members propose guidance for healthcare professionals to help them manage APS patients. Uncertainty in this field will be addressed. This guidance will also serve as a call and focus for research., (© 2020 International Society on Thrombosis and Haemostasis.)

Lifelong anticoagulation with warfarin or alternative vitamin K antagonist is the standard anticoagulant treatment for thrombotic antiphospholipid syndrome. Anticoagulant-refractory thrombotic antiphospholipid syndrome can be broadly defined as breakthrough thrombosis while on standard oral anticoagulation treatment and its management is a major challenge given the serious nature of the thrombotic disease observed, which has become refractory to oral anticoagulation. The factors (genetic and cellular) that cause anticoagulant-refractory thrombotic antiphospholipid syndrome are now better understood. However, efforts to use this greater understanding have not yet transformed the capacity to treat it successfully in many patients. In this Viewpoint, we review the factors that are likely to be contributing to the cause of this syndrome and consider how they might be modified or inhibited. We also discuss management, including general strategies to minimise thrombotic risk, intensification of anticoagulation, addition of an antiplatelet agent, adjunctive treatment for thrombosis, immunomodulatory therapy, complement inhibition, vascular options, and future potential therapeutic targets., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The antiphospholipid antibody syndrome (APS), a chronic autoimmune thrombophilia with an increased mortality and morbidity, has been recognized for more than three decades. Unlike other autoimmune rheumatic conditions such as systemic lupus erythematosus, myositis and Sjögren's syndrome, relatively few attempts have been made to develop activity, damage or disease-specific quality of life indices for APS. In this review of the literature, we consider those attempts that have been made to develop assessment tools for patients with APS, but also reflect upon the nature of the condition, to discuss, in particular, whether an activity index is appropriate for this disease., (© The Author(s) 2020. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Background: The laboratory detection of lupus anticoagulants (LA) in anticoagulated patients represents a challenge and there is no consensus on the types of assays/procedures to be adopted., Objectives: This communication of the International Society on Thrombosis and Haemostasis (ISTH), Scientific and Standardization Committee (SSC) aims to give guidance on the procedures to be adopted., Methods: Members of the ISTH-SSC on Lupus Anticoagulant/Antiphospholipid Antibodies reviewed the literature to search for evidence on the most appropriate assays/procedures to be adopted., Results: Anticoagulants are able to interfere with the tests used for LA detection, giving rise to occasional false-positive or false-negative LA. Some commercial tests include in their composition heparin-neutralizers able to quench unfractionated or low molecular weight heparin up to 1.0 U/mL. LA tests are less affected by low molecular weight heparin, but caution is needed in the interpretation of results. Vitamin K antagonists (VKAs) may affect LA detection. Dilution of test plasma into pooled normal plasma is not a reliable solution as false-negative or false-positive LA may occur. Direct oral anticoagulants (DOACs) affect LA detection. Hence, it is not recommended to attempt LA detection in those patients. The use of DOAC adsorbents is a promising solution and should be further investigated on LA-positive and LA-negative patient populations. Taipan/Ecarin tests may be a solution for VKAs and anti-FXa DOACs, but independent evidence on their value and standardized kits is needed., Conclusions: LA detection during anticoagulation remains a challenge, especially for VKAs. DOAC removal by in vitro addition to plasma of appropriate absorbents is promising., (© 2020 International Society on Thrombosis and Haemostasis.)

Beta-2-Glycoprotein I (β2GPI) plays a number of essential roles throughout the body. β2GPI, C-reactive protein and thrombomodulin are the only three proteins that possess the dual capability to up and down regulate the complement and coagulation systems depending upon external stimulus. Clinically, β2GPI is the primary antigen in the autoimmune condition antiphospholipid syndrome (APS), which is typically characterised by pregnancy morbidity and vascular thrombosis. This protein is also capable of adopting at least two distinct structural forms, but it has been argued that several other intermediate forms may exist. Thus, β2GPI is a unique protein with a key role in haemostasis, homeostasis and immunity. In this review, we examine the genetics, structure and function of β2GPI in the body and how these factors may influence its contribution to disease pathogenesis. We also consider the clinical implications of β2GPI in the diagnosis of APS and as a potentially novel therapeutic target., Competing Interests: Declaration of Competing Interest TM, CP, IG and AR are inventors on the patent for Domain I., (Copyright © 2019 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: Variability remains a challenge in lupus anticoagulant (LA) testing., Objective: To validate LA test performance between Antiphospholipid Syndrome Alliance for Clinical Trials and International Networking (APS ACTION) Core laboratories and examine agreement in LA status between Core and local/hospital laboratories contributing patients to this prospective registry., Methods: Five Core laboratories used the same reagents, analyzer type, protocols, and characterized samples for LA validation. Non-anticoagulated registry samples were retested at the corresponding regional Core laboratories and anticoagulated samples at a single Core laboratory. Categorical agreement and discrepancies in LA status between Core and local/hospital laboratories were analyzed., Results: Clotting times for the reference/characterized plasmas used for normalized ratios were similar between Core laboratories (CV <4%); precision and agreement for LA positive/negative plasma were similar (all CV ≤5%) in the four laboratories that completed both parts of the validation exercise; 418 registry samples underwent LA testing. Agreement for LA positive/negative status between Core and local/hospital laboratories was observed in 87% (115/132) non-anticoagulated and 77% (183/237) anticoagulated samples. However, 28.7% (120/418) of samples showed discordance between the Core and local/hospital laboratories or equivocal LA results. Some of the results of the local/hospital laboratories might have been unreliable in 24.7% (41/166) and 23% (58/252) of the total non-anticoagulated and anticoagulated samples, respectively. Equivocal results by the Core laboratory might have also contributed to discordance., Conclusions: Laboratories can achieve good agreement in LA performance by use of the same reagents, analyzer type, and protocols. The standardized Core laboratory results underpin accurate interpretation of APS ACTION clinical data., (© 2019 International Society on Thrombosis and Haemostasis.)

Objectives: To assess whether patients with antiphospholipid syndrome (APS) and history of recurrent thrombosis have higher levels of adjusted Global AntiphosPholipid Syndrome Score (aGAPSS) when compared to patients without recurrent thrombosis., Methods: In this cross-sectional study of antiphospholipid antibody (aPL)-positive patients, we identified APS patients with a history of documented thrombosis from the AntiPhospholipid Syndrome Alliance For Clinical Trials and InternatiOnal Networking (APS ACTION) Clinical Database and Repository ("Registry"). Data on aPL-related medical history and cardiovascular risk factors were retrospectively collected. The aGAPSS was calculated at Registry entry by adding the points corresponding to the risk factors: three for hyperlipidemia, one for arterial hypertension, five for positive anticardiolipin antibodies, four for positive anti-β 2 glycoprotein-I antibodies and four for positive lupus anticoagulant test., Results: The analysis included 379 APS patients who presented with arterial and/or venous thrombosis. Overall, significantly higher aGAPSS were seen in patients with recurrent thrombosis (arterial or venous) compared to those without recurrence (7.8 ± 3.3 vs. 6 ± 3.9, p<0.05). When analyzed based on the site of the recurrence, patients with recurrent arterial, but not venous, thrombosis had higher aGAPSS (8.1 ± SD 2.9 vs. 6 ± 3.9; p<0.05)., Conclusions: Based on analysis of our international large-scale Registry of aPL-positive patients, the aGAPSS might help risk stratifying patients based on the likelihood of developing recurrent thrombosis in APS., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Objective: To evaluate the subsequent rate of thrombosis among women with obstetric antiphospholipid syndrome (Ob-APS) in a multicentre database of antiphospholipid antibody (aPL)-positive patients, and the clinical utility of the adjusted Global Antiphospholipid Syndrome Score (aGAPSS), a validated tool to assess the likelihood of developing new thrombosis, in this group of patients., Design: Retrospective study., Setting: The Antiphospholipid Syndrome Alliance for Clinical Trials and International Networking Clinical Database and Repository., Population: Women with Ob-APS., Methods: Comparison of clinical and laboratory characteristics and measurement of aGAPSS in women with Ob-APS, with or without thrombosis, after initial pregnancy morbidity (PM)., Main Outcome Measures: Risk factors for thrombosis and aGAPSS., Results: Of 550 patients, 126 had Ob-APS; 74/126 (59%) presented with thrombosis, and 47 (63%) of these women developed thrombosis after initial PM, in a mean time of 7.6 ± 8.2 years (4.9/100 patient years). Younger age at diagnosis of Ob-APS, additional cardiovascular risk factors, superficial vein thrombosis, heart valve disease, and multiple aPL positivity increased the risk of first thrombosis after PM. Women with thrombosis after PM had a higher aGAPSS compared with women with Ob-APS alone [median 11.5 (4-16) versus 9 (4-13); P = 0.0089]., Conclusion: Based on a retrospective analysis of our multicentre aPL database, 63% of women with Ob-APS developed thrombosis after initial obstetric morbidity; additional thrombosis risk factors, selected clinical manifestations, and high-risk aPL profile increased the risk. Women with subsequent thrombosis after Ob-APS had a higher aGAPSS at entry to the registry. We believe that aGAPSS is a valid tool to improve risk stratification in aPL-positive women., Tweetable Abstract: More than 60% of women with obstetric antiphospholipid syndrome had thrombosis after initial pregnancy morbidity., (© 2018 Royal College of Obstetricians and Gynaecologists.)

Background: The APS ACTION International Clinical Database and Repository includes a secure web-based data capture system storing patient information including demographics, antiphospholipid antibodies (aPL)-related medical history, and aPL tests. Despite efforts at harmonization, inter-assay variability remains a problem in aPL testing. As a clinical repository open to researchers, ensuring comparability between assays and consistency in results between APS ACTION laboratories is essential to the validity of studies emerging from this network., Objective: To assess the level of agreement between an aPL-registry inclusion and core laboratory (core lab) anticardiolipin antibody (aCL) and anti-β 2 -glycoprotein-I antibody (aβ 2 GPI) ELISA testing results., Methods: Patients are recruited from 25 international centers based on positive aPL tests at inclusion. All samples are retested at the corresponding national APS ACTION core lab to confirm aPL positivity based on standard validated protocols. We analysed the categorical agreement, degree of linear association, and correlation between inclusion (local laboratory) and core lab aPL tests. Samples were included in this study only if results of aPL testing with ELISA at baseline were available., Results: 497 registry samples underwent confirmatory aPL tests. Categorical agreement between the inclusion and core lab values, as expressed by Cohen's kappa coefficients, ranged between 0.61 and 0.80 (as substantial agreement). The correlation between quantitative results in the aCL and aβ 2 GPI was better for IgM and IgA compared to IgG (Spearman rho 0.789 and 0.666 vs. 0.600 for aCL and rho 0.892 and 0.744 vs. 0.432 for aβ 2 GPI)., Conclusions: The results of inclusion for aCL and aβ 2 GPI tests used for recruitment into the registry were in agreement to the results obtained by the APS ACTION core laboratories; aCL and aβ 2 GPI results showed very good categorical agreement. This agreement increased when considering high titer (>40 units) samples. APS ACTION is a reliable and useful research resource for APS., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Background: Tissue factor pathway inhibitor (TFPI) antibodies, which have been reported in patients with antiphospholipid syndrome (APS), may impair TFPI activity and contribute to hypercoagulability, but their role in APS and in thrombosis remains undefined., Objective/methods: We assessed the presence and avidity of TFPI IgG antibodies, associations with protein C IgG antibodies and associations with clinical disease severity, in 50 patients with thrombotic APS and 50 thrombotic control patients, on long term anticoagulation with warfarin., Results: Thrombotic APS patients had a significantly higher prevalence of TFPI IgG antibodies (40%; 20/50) compared to thrombotic controls (18%; 9/50). TFPI antibodies were predominantly high avidity in APS (50%, 10/20 of positive patients) and strongly associated with a severe thrombotic phenotype (venous and arterial thromboembolism or recurrent thromboembolic episodes despite therapeutic anticoagulation) (odds ratio (OR): 12.0, 95%CI: 2.2-66.1, p = 0.004), while thrombotic control patients mainly showed low avidity antibodies (78%, 7/9 of positive patients). Coexistence of TFPI and protein C IgG antibodies, regardless of their avidity, was strongly associated with a more severe thrombotic phenotype in APS patients (OR: 20.2, 95%CI: 2.0-47.0, p < 0.0001) and also in thrombotic controls (OR: 75.0, 95%CI 1.2-195, p = 0.02)., Conclusions: Coexistent TFPI and protein C IgG antibodies, irrespective of their avidity, may be a useful marker for a severe thrombotic phenotype in thrombotic patients. This suggests a possibly pathophysiological relationship between the two antibodies, predisposing to thrombosis with a possibly more general role in the development of thrombotic complications., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

The current mainstay of the treatment and secondary thromboprophylaxis of thrombotic antiphospholipid syndrome (APS) is anticoagulation with warfarin or other vitamin K antagonists (VKAs). In addition to their well-known limitations, VKAs are often problematic in APS patients because of the variable sensitivity of thromboplastins to lupus anticoagulant. As a result, the international normalized ratio may not accurately reflect the intensity of anticoagulation. Direct oral anticoagulants (DOACs) are established as therapeutic alternatives to VKAs for a wide range of indications, including the treatment and secondary prevention of venous thromboembolism. Definition of the role of DOACs in the treatment of thrombotic APS is emerging with the results of recent and ongoing clinical studies. This review focuses on the current situation with regard to DOACs for secondary thromboprophylaxis in APS and issues pertinent to DOAC use in APS patients, as well as potential future directions., Competing Interests: Hannah Cohen reports receiving institutional research support and honoraria (diverted to local Charity) for lectures and Advisory Board from Bayer. Maria Efthymiou, Carolyn Gates, and David Isenberg had no conflicts of interest to disclose., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

The direct oral anticoagulants (DOACs) are therapeutic alternatives to warfarin and other vitamin K antagonists (VKAs), and constitute the standard of care for many indications. VKAs constitute the conventional therapy for the treatment and secondary thromboprophylaxis of thrombotic antiphospholipid syndrome (APS), but are often problematic, owing to the variable sensitivity of thromboplastins to lupus anticoagulant. Thus, the International Normalized Ratio may not accurately reflect anticoagulation intensity, or be clinically effective. Definition of the current role of DOACs in the treatment of APS is based on limited clinical trial data and information from other sources, including manufacturers' data, case series or cohort studies, and expert consensus. The Rivaroxaban in Antiphospholipid Syndrome (RAPS) randomized controlled trial (RCT), which had a laboratory surrogate primary outcome measure, suggests that rivaroxaban has the potential to be an effective and convenient alternative to warfarin in thrombotic APS patients with a single venous thromboembolism event requiring standard-intensity anticoagulation. However, further studies, in particular to provide better long-term efficacy and safety data, are needed before it can be widely recommended. APS patients are clinically heterogeneous, with the risk of recurrent thrombosis and the intensity of anticoagulation being influenced by their clinical phenotype and risk profile. DOAC trials involving homogeneous thrombotic APS populations, with the antiphospholipid antibody status well defined, will help to optimize the appropriate treatment in APS patient subgroups. Ongoing and emerging DOAC RCTs should provide further information to guide the use of DOACs in APS patients. Optimal identification of APS patients is a key step in working towards improved therapeutic strategies in these individuals., (© 2018 International Society on Thrombosis and Haemostasis.)

Competing Interests: Disclosure The authors report no conflicts of interest in this work.

We respond to comments by Dufrost et al. about the RAPS trial, in particular, showing that the trial did achieve its target sample size; pointing out that thrombin potential is not synonymous with overall thrombin generation; confirming that overall, no increased thrombotic risk was evident comparing rivaroxaban with warfarin; and that high-risk patients (28% were triple positive, representative of patients with venous thromboembolism requiring standard-intensity anticoagulation) were included; and clarifying our rationale for using a laboratory surrogate primary outcome measure instead of a clinical one.

Essentials Complement activation has a pathogenic role in thrombotic antiphospholipid syndrome (APS). Coagulation proteases such as factor Xa can activate complement proteins. Complement activation markers were elevated in anticoagulated thrombotic APS patients. Complement activation decreased in APS patients switching from warfarin to rivaroxaban., Summary: Background Complement activation may play a major role in the pathogenesis of thrombotic antiphospholipid syndrome (APS). Coagulation proteases such as factor Xa can activate complement proteins. Aims To establish whether rivaroxaban, a direct factor Xa inhibitor, limits complement activation compared with warfarin in APS patients with previous venous thromboembolism (VTE). Methods A total of 111 APS patients with previous VTE, on warfarin target INR 2.5, had blood samples taken at baseline and at day 42 after randomization in the RAPS (Rivaroxaban in Antiphospholipid Syndrome) trial. Fifty-six patients remained on warfarin and 55 switched to rivaroxaban. Fifty-five normal controls (NC) were also studied. Markers of complement activation (C3a, C5a, terminal complement complex [SC5b-9] and Bb fragment) were assessed. Results APS patients had significantly higher complement activation markers compared with NC at both time-points irrespective of the anticoagulant. There were no differences between the two patient groups at baseline, or patients remaining on warfarin at day 42. In 55 patients randomized to rivaroxaban, C3a, C5a and SC5b-9 were lower at day 42 (median (ng mL -1 ) [confidence interval] 64 [29-125] vs. 83 [35-147], 9 [2-15] vs. 12 [4-18] and 171 [56-245] vs. 201 [66-350], respectively) but levels of Bb fragment were unchanged. There were no correlations between rivaroxaban levels and complement activation markers. Conclusions APS patients with previous VTE on warfarin exhibit increased complement activation, which is likely to occur via the classical pathway and is decreased by rivaroxaban administration. Rivaroxaban may therefore potentially provide an additional benefit to its anticoagulant effect in this patient group by limiting complement activation., (© 2016 International Society on Thrombosis and Haemostasis.)

Background: Rivaroxaban is established for the treatment and secondary prevention of venous thromboembolism, but whether it is useful in patients with antiphospholipid syndrome is uncertain., Methods: This randomised, controlled, open-label, phase 2/3, non-inferiority trial, done in two UK hospitals, included patients with antiphospholipid syndrome who were taking warfarin for previous venous thromboembolism, with a target international normalised ratio of 2·5. Patients were randomly assigned 1:1 to continue with warfarin or receive 20 mg oral rivaroxaban daily. Randomisation was done centrally, stratified by centre and patient type (with vs without systemic lupus erythematosus). The primary outcome was percentage change in endogenous thrombin potential (ETP) from randomisation to day 42, with non-inferiority set at less than 20% difference from warfarin in mean percentage change. Analysis was by modified intention to treat. Other thrombin generation parameters, thrombosis, and bleeding were also assessed. Treatment effect was measured as the ratio of rivaroxaban to warfarin for thrombin generation. This trial is registered with the ISRCTN registry, number ISRCTN68222801., Findings: Of 116 patients randomised between June 5, 2013, and Nov 11, 2014, 54 who received rivaroxaban and 56 who received warfarin were assessed. At day 42, ETP was higher in the rivaroxaban than in the warfarin group (geometric mean 1086 nmol/L per min, 95% CI 957-1233 vs 548, 484-621, treatment effect 2·0, 95% CI 1·7-2·4, p<0·0001). Peak thrombin generation was lower in the rivaroxaban group (56 nmol/L, 95% CI 47-66 vs 86 nmol/L, 72-102, treatment effect 0·6, 95% CI 0·5-0·8, p=0·0006). No thrombosis or major bleeding were seen. Serious adverse events occurred in four patients in each group., Interpretation: ETP for rivaroxaban did not reach the non-inferiority threshold, but as there was no increase in thrombotic risk compared with standard-intensity warfarin, this drug could be an effective and safe alternative in patients with antiphospholipid syndrome and previous venous thromboembolism., Funding: Arthritis Research UK, Comprehensive Clinical Trials Unit at UCL, LUPUS UK, Bayer, National Institute for Health Research Biomedical Research Centre., (Copyright © 2016 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY license. Published by Elsevier Ltd.. All rights reserved.)

Introduction: The current mainstay of the treatment of thrombotic antiphospholipid syndrome (APS) is long-term anticoagulation with vitamin K antagonists (VKAs) such as warfarin. Non-VKA oral anticoagulants (NOACs), which include rivaroxaban, have been shown to be effective and safe compared with warfarin for the treatment of venous thromboembolism (VTE) in major phase III prospective, randomized controlled trials (RCTs), but the results may not be directly generalizable to patients with APS., Aims: The primary aim is to demonstrate, in patients with APS and previous VTE, with or without systemic lupus erythematosus (SLE), that the intensity of anticoagulation achieved with rivaroxaban is not inferior to that of warfarin. Secondary aims are to compare rates of recurrent thrombosis, bleeding and the quality of life in patients on rivaroxaban with those on warfarin., Methods: Rivaroxaban in antiphospholipid syndrome (RAPS) is a phase II/III prospective non-inferiority RCT in which eligible patients with APS, with or without SLE, who are on warfarin, target international normalized ratio (INR) 2.5 for previous VTE, will be randomized either to continue warfarin (standard of care) or to switch to rivaroxaban. Intensity of anticoagulation will be assessed using thrombin generation (TG) testing, with the primary outcome the percentage change in endogenous thrombin potential (ETP) from randomization to day 42. Other TG parameters, markers of in vivo coagulation activation, prothrombin fragment 1.2, thrombin antithrombin complex and D-dimer, will also be assessed., Discussion: If RAPS demonstrates i) that the anticoagulant effect of rivaroxaban is not inferior to that of warfarin and ii) the absence of any adverse effects that cause concern with regard to the use of rivaroxaban, this would provide sufficient supporting evidence to make rivaroxaban a standard of care for the treatment of APS patients with previous VTE, requiring a target INR of 2.5., (© The Author(s) 2015.)

Introduction: Rivaroxaban can affect lupus anticoagulant (LA) testing and antiphospholipid antibodies (aPL) may interfere with the anticoagulant action of rivaroxaban., Aims: To establish the influence of rivaroxaban on LA detection and of aPL on the anticoagulant action of rivaroxaban., Methods: Rivaroxaban and 52 IgG preparations (20 LA+ve, 12 LA-ve thrombotic antiphospholipid syndrome [APS] patients, and 20 normal controls [NC]) were spiked into pooled normal plasma (PNP) for relevant studies. LA detection was also studied in APS patients receiving rivaroxaban 20 mg once daily., Results: In vitro spiking of samples with rivaroxaban showed no false positive LA with Textarin time, Taipan venom time/Ecarin clotting time (TVT/ECT), dilute prothrombin time (dPT) and in-house dilute Russell's viper venom time (DRVVT), but false positives in the majority of NC and LA negative IgG with two commercial DRVVT reagents at 250 ng/mL but not 50 ng/mL rivaroxaban. Ex vivo studies: six LA+ve patients on rivaroxaban remained LA positive with TVT/ECT and DRVVT at peak (162-278 ng/mL) and trough (30-85 ng/mL) rivaroxaban levels. Six LA-ve patients became (apparently) LA+ve with two DRVVT reagents (test/confirm ratio median [confidence interval], 1.6 [1.3-1.8], 1.6 [1.4-1.9]) but not with TVT/ECT at peak rivaroxaban levels, and remained LA-ve with both DRVVT reagents and TVT/ECT at trough levels. aPL positive IgG spiking of PNP had no effect on rivaroxaban's anticoagulant action on thrombin generation or rivaroxaban anti-Xa levels., Conclusions: The TVT/ECT ratio and Textarin time were not affected even at peak rivaroxaban levels, enabling detection of LA ex vivo. aPL had no effects on rivaroxaban's anticoagulant action in vitro., (© 2015 International Society on Thrombosis and Haemostasis.)

Monitoring warfarin anticoagulation in patients with thrombotic antiphospholipid syndrome (APS) may be complicated by the sensitivity of different thromboplastins to lupus anticoagulant. The aim of this study was to compare the degree of anticoagulation intensity in thrombotic APS and non-APS patients (50 in each group) on long-term warfarin, by measurement of the INR with two widely available thromboplastins with instrument-specific ISI values, and to investigate the potential role of amidolytic FX levels and thrombin generation (TG) testing in the assessment of anticoagulant intensity in thrombotic APS patients. There were no overall differences in INR between reagents or patient groups, but 20% (10/50) of APS patients showed ≥0.5 INR unit difference between reagents, which would have resulted in altered clinical management in some patients. FX levels were useful in assessing anticoagulation intensity for INR 2.0-3.0, but showed poor utility at INR ≥3.5 where the lowest measured FX level was 12IU/dL. In contrast, ETP and peak thrombin showed significant inverse correlations with the INR, suggesting that TG testing may be helpful in the determination of true anticoagulant intensity in APS patients, including those with ≥3.5 INR. TG testing also highlighted a subgroup of APS patients with increased peak thrombin relative to the intensity of anticoagulation as assessed by INR and FX, suggesting that TG testing may be useful in identifying an ongoing prothrombotic state in patients with apparently adequate anticoagulation intensity as assessed by INR., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Accurate diagnosis of obstetric antiphospholipid syndrome (APS) is a prerequisite for optimal clinical management. The international consensus (revised Sapporo) criteria for obstetric APS do not include low positive anticardiolipin (aCL) and anti β2 glycoprotein I (aβ2GPI) antibodies (< 99th centile) and/or certain clinical criteria such as two unexplained miscarriages, three non-consecutive miscarriages, late pre-eclampsia, placental abruption, late premature birth, or two or more unexplained in vitro fertilisation failures. In this review we examine the available evidence to address the question of whether patients who exhibit non-criteria clinical and/or laboratory manifestations should be included within the spectrum of obstetric APS. Prospective and retrospective cohort studies of women with pregnancy morbidity, particularly recurrent pregnancy loss, suggest that elimination of aCL and/or IgM aβ2GPI, or low positive positive aCL or aβ2GPI from APS laboratory diagnostic criteria may result in missing the diagnosis in a sizeable number of women who could be regarded to have obstetric APS. Such prospective and retrospective studies also suggest that women with non-criteria obstetric APS may benefit from standard treatment for obstetric APS with low-molecular-weight heparin plus low-dose aspirin, with good pregnancy outcomes. Thus, non-criteria manifestations of obstetric APS may be clinically relevant, and merit investigation of therapeutic approaches. Women with obstetric APS appear to be at a higher risk than other women of pre-eclampsia, placenta-mediated complications and neonatal mortality, and also at increased long-term risk of thrombotic events. The applicability of these observations to outcomes in women with non-criteria obstetric APS remains to be determined.

Background: Antiphospholipid antibodies may interfere with the anticoagulant activity of activated protein C (APC) to induce acquired APC resistance (APCr)., Aims: To investigate the frequency and characteristics of APCr by using recombinant human APC (rhAPC) and endogenous protein C activation in antiphospholipid syndrome (APS)., Methods: APCr was assessed in APS and non-APS venous thromboembolism (VTE) patients on warfarin and normal controls with rhAPC or Protac by thrombin generation. IgG anti-protein C and anti-protein S antibodies and avidity were assessed by ELISA., Results: APS patients showed greater resistance to both rhAPC and Protac than non-APS patients and normal controls (median normalized endogenous thrombin potential inhibition): APS patients with rhAPC, 81.3% (95% confidence interval [CI] 75.2-88.3%; non-APS patients with rhAPC, 97.7% (95% CI 93.6-101.8%; APS patients with Protac, 66.0% (95% CI 59.5-72.6%); and non-APS patients with Protac, 80.7 (95% CI 74.2-87.2%). APS patients also had a higher frequency and higher levels of anti-protein C antibodies, with 60% (15/25) high-avidity antibodies. High-avidity anti-protein C antibodies were associated with greater APCr and with a severe thrombotic phenotype (defined as the development of recurrent VTE while patients were receiving therapeutic anticoagulation or both venous and arterial thrombosis). Twelve of 15 (80%) patients with high-avidity anti-protein C antibodies were classified as APS category I., Conclusion: Thrombotic APS patients showed greater APCr to both rhAPC and activation of endogenous protein C by Protac. High-avidity anti-protein C antibodies, associated with greater APCr, may provide a marker for a severe thrombotic phenotype in APS. However, in patients with category I APS, it remains to be established whether anti-protein C or anti-β2 -glycoprotein I antibodies are responsible for APCr., (© 2014 International Society on Thrombosis and Haemostasis.)

Antiphospholipid Syndrome (APS) is characterized by vascular thrombosis and/or pregnancy morbidity occurring in patients with persistent antiphospholipid antibodies (aPL). The primary objective of the APS Treatment Trends Task Force, created as part of the 14th International Congress on aPL, was to systematically review the potential future treatment strategies for aPL-positive patients. The task force chose as future clinical research directions: a) determining the necessity for controlled clinical trials in venous thromboembolism with the new oral direct thrombin or anti-factor Xa inhibitors pending the results of the ongoing rivaroxaban in APS (RAPS) trial, and designing controlled clinical trials in other forms of thrombotic APS; b) systematically analyzing the literature as well as aPL/APS registries, and creating specific registries for non-warfarin/heparin anticoagulants; c) increasing recruitment for an ongoing primary thrombosis prevention trial, and designing secondary thrombosis and pregnancy morbidity prevention trials with hydroxychloroquine; d) determining surrogate markers to select patients for statin trials; e) designing controlled studies with rituximab and other anti-B-cell agents; f) designing mechanistic and clinical studies with eculizumab and other complement inhibitors; and g) chemically modifying peptide therapy to improve the half-life and minimize immunogenicity. The report also includes recommendations for clinicians who consider using these agents in difficult-to-manage aPL-positive patients., (Copyright © 2014 Elsevier B.V. All rights reserved.)