Testing For Antiphospholipid Antibodies Research Articles

Challenges in Diagnosis and Management of SLE in Africa: An Online Survey.

We surveyed African physicians about challenges in diagnosis and management of systemic lupus erythematosus (SLE). We used a cross-sectional, online questionnaire-based survey of African specialist physicians on availability of laboratory tests, medications, and specialized services for the diagnosis of SLE. Our 226 respondents from 31 countries were dermatologists (38%), rheumatologists (28%), and nephrologists (23%), the majority practicing at university/state-funded hospitals (80.8%), but over half of patients (59.6%) were self-funded for laboratory tests and medications. Antinuclear antibody (ANA), antiphospholipid antibody, and complement tests were available to 79.4%, 67.6%, and 62.3% of respondents, respectively, but fewer in the East and West African regions. Median turnaround time for the ANA test was within two weeks but more than four weeks for 5.6% of respondents, and longer in West Africa compared with other regions (P = 0.0002). Availability of urine protein-to-creatinine test, skin and renal histopathology was 82%, 82.5%, and 76.2%, respectively. Median turnaround times were within one to two weeks, but more than four weeks for 13.8% of respondents for skin histology results and usually within four weeks but more than four weeks for 24.5% of respondents for renal histology. Glucocorticoids and antimalarials were readily available across all regions, with variable availability of immunosuppressants from 93.7% for methotrexate to 65% for calcineurin inhibitors and only 58.4% for the biologic rituximab. Intensive care units/high care facilities, hemodialysis, and renal transplantation were available to 69.8%, 91.9%, and 56.5% of respondents, respectively. Variable availability of laboratory tests, medications, and supportive services coupled with cost constraints are major impediments to early diagnosis and optimal management of SLE in most of Africa and are likely factors contributing to underreporting and poor prognosis of SLE in Africa.

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.

Antiphospholipid Antibody Testing in a Maximum Care Hospital: Method-Dependent Differences.

Background: Antiphospholipid antibody (aPL) testing is critical for the classification of antiphospholipid syndrome. The 2023 ACR/EULAR classification criteria recommend the use of enzyme-linked immunosorbent assays (ELISAs) and specific thresholds for aPL positivity. Since non-ELISA methods are increasingly used, we compared and evaluated ELISA and non-ELISA aPL assays in a real-world maximum care hospital setting. Methods: Between January 2021 and June 2024, anticardiolipin (aCL; IgG and IgM) and anti-beta2 glycoprotein I (aß2GPI; IgG and IgM) antibodies were measured using ELISA (n = 5115) and a chemiluminescence-based automated immunoassay (CLIA) (n = 3820). Results of parallel testing were compared, and associations with clinical and laboratory characteristics were evaluated. Results: A total of 946 samples were tested using ELISA and CLIA in parallel. A total of 136 (14%) specimens were positive for at least one aPL, and 55 (6%) specimens were from patients diagnosed with APS. Among the latter, 47 (85%) and 41 (75%) patients were positive when ELISA- or CLIA-based aPL assays were used, respectively. After applying the >40 units threshold of the new classification criteria, the number of aPL-positive specimens was significantly lower. In the entire cohort, the agreement between ELISA and CLIA aPL assays was acceptable only for aß2GPI IgG; the results from the two methods did not agree for aCL IgG/IgM and aß2GPI IgM. In APS patients, the agreement between ELISA and CLIA aPL assays was acceptable for aß2GPI IgG and IgM but poor for aCL IgG and IgM. Antibody levels in APS patients were significantly higher using CLIA compared to ELISA. Conclusions: The method-dependent discrepancies between ELISA- and CLIA-based aPL assays regarding the quantitative and qualitative results are substantial. Both methods are suitable for APS classification, but the choice of aPL assay may influence the classification, and therefore, aPL results should be interpreted carefully in the clinical context.

Immunological testing for female infertility: a modern view on the problem

Introduction. According to various estimates, in Russia 10 to 20 % of people of reproductive age are infertile. Changes in the immune system play a key role in the etiology and treatment of various infertility forms. The active introduction of immunological testing into clinical practice can potentially improve the results of infertility diagnostics and treatment.Aim: to analyze the current literature data on immunological testing in female infertility, as well as to assess its potential role in infertility diagnostics and treatment.Materials and Methods. There was conducted a search for publications in the electronic databases PubMed and eLibrary by using the following keywords and their combinations: "infertility", "immunology", "immune system", "immunological testing", "diagnostics", "treatment". The articles were evaluated in accordance with the PRISMA recommendations. Ultimately, 88 publications were included in the review.Results. Testing for antiphospholipid antibodies (APA) may be useful for women undergoing assisted reproductive technology (ART) therapy, as these antibodies increase the risk of pregnancy complications and thrombotic risks associated with ovarian stimulation, but studies assessing AFA effect on in vitro fertilization (IVF) outcomes have ambiguous results. The presence of antithyroid antibodies (ATA) may be associated with infertility, so their assessment is indeed important to determine treatment tactics. It has been suggested that antinuclear antibodies (ANA) may affect reproductive function by disrupting trophoblast cell development and interfering with RNA transcription, which may lead to lowered reproductive success. Studies have shown that patients with a positive ANA data have a lower incidence of pregnancy and a higher rate of miscarriages after IVF procedure. The human herpes virus type 6 (HHV-6) affects female fertility and is often the cause of spontaneous termination of pregnancy. B-cell lymphoma protein 6 (BCL-6) can serve as an important prognostic biomarker to identify individuals with endometriosis and related reproductive disorders, including idiopathic infertility. Evaluation of endometrial decidualization can be a useful tool to assess readiness for endometrial implantation and provide opportunities for targeted therapeutic interventions. The issue of testing for NK-cells in patients undergoing infertility screening remains controversial due to the difficulties of standardizing testing recommendations.Conclusion. To date, there is a limited number of reliable data on the role of various immunological tests in infertility diagnostics and treatment. With the exception of testing for AFA in patients with RPL, as well as for thyroid-stimulating hormone (TSH) and anti-thyroperoxidase antibodies (TPOAb) in patients undergoing therapy using various types of assisted reproductive technologies, the remaining immunological tests provide scant data to justify their routine use in clinical practice. The major limitations of existing studies are coupled to a small patient sample, as well as heterogeneity of inclusion criteria, patient groups and research methods.

Characteristics and prognosis of elderly-onset antiphospholipid syndrome: An observational cohort study.

Antiphospholipid syndrome (APS) is an autoimmune disease mainly affecting young individuals. Testing for antiphospholipid antibodies is recommended for young patients who are suspected to have APS. Yet, it is hard to differentiate APS from other acquired thrombophilia disorders in elderly-onset APS patients. This study aim to investigate the characteristics and prognosis of elderly-onset APS. This is an observational cohort study. Thrombotic APS patients who underwent follow-ups between 2009 and 2022 were included. Elderly-onset APS patients (onset age ≥60years) were compared to non-elderly-onset APS patients (onset age <60years) and matched cases of elderly non-APS patients (age ≥60years with thrombosis). A total of 161 APS patients were included in this study, 45 (28.0%) were elderly-onset APS. Stroke (35.6% vs. 18.1%, p = .018) was more common at disease onset in elderly-onset APS patients. Compared to non-elderly-onset patients, elderly-onset APS patients were associated with a higher number of cardiovascular risk factors. Elderly-onset APS patients showed significantly lower positive rate (51.1% vs. 71.6%, p = .014) and ratios [1.24 (1.01-1.38) vs. 1.37 (1.16-1.77), p = .004] of lupus anticoagulant. Elderly-onset APS patients had a significantly higher 10-years cumulative all-cause mortality (p < .001) and APS-related mortality than non-elderly-onset patients (p = .002) and elderly non-APS patients (p = .040). Elderly-onset APS patients have unique disease characteristics with higher 10-years cumulative all-cause mortality and APS-related mortality. Early recognition and control of comorbidities may reduce the recurrence of thrombosis and mortality in elderly-onset APS patients.

Current status of testing intervals for antiphospholipid syndrome testing: a 13-year retrospective national data analysis in South Korea.

To assess the appropriateness of laboratory testing intervals and antiphospholipid syndrome (APS) incidence. Between January 2010 and August 2022, insurance claims data of patients with disease codes for other thrombophilia (D68.6) and APS (V253) were retrieved in South Korea. Patients who received antiphospholipid antibody tests more than twice were classified as having suspected APS. The interval between the first 2 antiphospholipid antibody tests was evaluated in the patients with suspected APS. Patients with suspected APS who received anticoagulants for >180 days were classified as having APS. Overall, 8656 patients were classified as having suspected APS. The testing interval for the first 2 tests in patients with suspected APS was <6 and <12 weeks in 11.1% and 20.6% of cases, respectively, in 2010, gradually increasing to 21.0% and 35.4%, respectively, in 2021. Subsequently, 4344 patients were classified as having APS, with 65.0% being female. Only 330 patients were diagnosed with APS in 2021, down from 436 in 2020. This study showed a gradual increase in patients receiving antiphospholipid antibody testing with an inappropriate short-term interval, underscoring the need for laboratory stewardship to ensure an appropriate interval for APS testing.

Laboratory assessment of antiphospholipid syndrome: Laboratory data.

Thorough assessment of the antiphospholipid syndrome (APS) includes retesting of positive antiphospholipid antibody (aPL) tests after at least 12 weeks, and a full antiphospholipid antibody profile. To what extent this work-up is done in clinical practice is unknown. Data on 25 116 in- and out-hospital patients tested for the presence of lupus anticoagulant (LA), the aPL which most strongly correlates with thrombosis, was extracted from the laboratory information system of the only laboratory that performs LA tests in the Capital Region, Denmark. We estimated fraction of repeated tests, tests repeated within the recommended time span, and fraction with a full aPL profile. Out of 25 116 patients, 843 were positive for LA (3.3%), and 3948 results were inconclusive (16%). Only 51% (95% CI of the proportion: 48%-54%) (n = 431) of positive tests were repeated. The proportion of inconclusive LA test results increased from 13% (12%-15%) in 2009 to 20% (19%-22%) in 2020. Out of the positive tests repeated within the first year, only 60/353 (17%; 13%-21%) were repeated within 12-16 weeks; 177/353 (50%; 45%-55%) were re-tested within the first 12 weeks of first positive test result. The proportion of patients with a full antiphospholipid antibody profile increased from 161/1978 (8%) in 2010 to 1041/1978 (43%) in 2020. We found several issues with the laboratory workup of APS. This indicates a need for increased awareness of comprehensive laboratory assessment of possible APS as well as a closer collaboration between the laboratory and clinicians.

Low recurrent thrombosis rates in single positive antiphospholipid syndrome regardless of type of anticoagulation

Thrombotic antiphospholipid syndrome (TAPS) is characterized by thrombosis and persistently positive tests for antiphospholipid antibodies or lupus anticoagulant (LAC). Triple-positive APS has the highest risk of recurrent thrombosis, but no studies have focused on recurrent thrombosis in patients with single-positive TAPS. We conducted a retrospective cohort study of patients with single-positive TAPS diagnosed at Lifespan Health System, Rhode Island, to determine the rates and risk factors for recurrent thrombosis. Between January 2001 and April 2022, 128 patients were assessed who had single-positive APS (LAC = 98, aCL = 21, aβ2GPI = 9) and who had been followed for a total of 1453.8 patient-years (median follow-up 3.04 years). The initial antithrombotic regimen was warfarin in 44 %, a direct oral anticoagulant (DOAC) in 34 %, enoxaparin in 2 %, and no antithrombotic therapy or antiplatelet therapy only in 20 %. Recurrent thrombosis occurred in 16 (12.5 %) with a recurrent thrombosis rate of 3.08 per 100 patient-years. Systemic lupus erythematosus was the only variable significantly associated with recurrent thrombosis in a model adjusted for age, sex, body mass index, and type of positive APS test. All 16 patients with recurrent thrombosis were initially treated with warfarin, and, at the time of recurrent thrombosis, 13 patients remained on warfarin and three were off anticoagulation. In conclusion, the recurrent thrombosis rate in single-positive APS is low, and not all patients with a single-positive test may need indefinite anticoagulation with warfarin. Larger prospective studies are required to confirm this finding and establish optimal anticoagulation regimens for low-risk TAPS.

Antiphospholipid Antibody Testing: An Audit on Testing Practices in a Public Tertiary Care Center.

Antiphospholipid antibodies (aPLs) are antibodies directed against cell membrane components and can be associated with clinical features or be asymptomatic. Testing and interpreting these antibodies is associated with many challenges and pitfalls in clinical practice. To review all antiphospholipid antibody testing and describe the testing practices, indications for testing and interpretation of results to infer local challenges with aPL testing and subsequently address ways to overcome those challenges. This is a retrospective analysis of all aPL testing done in a tertiary center between 2014 and 2018. Characteristics of study patients collected through chart review were described using the mean and standard deviation for continuous variables and proportion for categorical variables. Group differences were compared between patients with any aPL-positive result and those with no positive result using chi-square or Fisher's exact test as appropriate for categorical variables and a simple regression model for numerical variables. Among 414 patients undergoing aPL testing, mainly adult females, 62 (14.9%) patients had at least one positive antibody, of those, 26 (42%) had repeat testing done. Testing was mostly done for obstetric indication (107, 25.8%), with 36 patients having one or two early pregnancy losses <10 weeks as their testing indication. A total of 27 (6.5%) patients were labeled with APS/possible APS based on chart review, but on review of the testing of those patients according to classification criteria, only nine patients satisfied the criteria for APS. This study highlights the clinical challenges associated with aPL testing, including the controversies around indication for testing, the low rates of repeat testing to confirm persistence, and the common misinterpretation of results. Having an aPL testing profile, explicit reference ranges, results commentary, and close interaction between ordering physicians and laboratory staff might be starting points to overcome these challenges.

A Syngeneic Murine Model of Antiphospholipid Syndrome (APS) Recapitulates Aspects of Human APS

Background Antiphospholipid syndrome (APS) is characterized by arterial or venous thrombosis, or recurrent pregnancy loss, in the presence of persistently positive tests for antiphospholipid antibodies (aPL). aPL include lupus anticoagulants (LAC), anti-β2-glycoprotein 1 (β2GPI) and anti-cardiolipin antibodies (aCL). Among them, antibodies directed toward β2GPI have been best characterized and shown in most studies to have a significant association with thrombosis. Most murine models of APS are generated by infusion of either polyclonal IgG isolated from APS patients, or monoclonal IgG directed against human or murine β2GPI. However, one or more of the following limitations may limit their clinical relevance: 1) Unlike chronically elevated autologous aPL in APS patients, cross-species IgG infused into mice circulate for only limited periods of time and may provoke allogeneic responses; 2) Monoclonal human or murine anti-β2GPI IgG, unlike polyclonal aPL from patients, tend to be high affinity, monospecific, and may recognize epitopes different than those recognized by clinical aPL. Hence, we sought to develop a relevant syngeneic murine model of APS that employed polyclonal murine anti-β2GPI IgG that would circulate in mice for extended periods, and not induce allogeneic inflammatory responses. Methods β2GPI-deficient ( apoh -/-) mice were previously developed in our lab on a C57/BL6 background using CRISPR/cas9. IgG isolated from apoh -/- mice immunized with human plasma β2GPI was used as a source of polyclonal murine aPL IgG, while IgG isolated from apoh -/- mice treated with adjuvant alone served as control IgG in all experiments. Wild-type (WT) C57/BL6 mice (two groups of 8 mice each) were injected intravenously with 20 µg of either murine polyclonal aPL or control IgG, and after 72 hours were evaluated for venous thrombosis using the IVC stasis model, with thrombi harvested and measured 48 h after IVC ligation. In parallel studies, we injected mice with aPL or control IgG and evaluated 1) activation of washed platelets, 2) aortic wall gene expression, and 3) levels of circulating neutrophil extracellular traps (NETs) using blood and tissue samples isolated at identical time points as IVC ligation studies (mice in these studies did not undergo IVC ligation). Platelet activation was assessed by measuring the binding of JON/A and expression of platelet P-selectin by flow-cytometry. Total RNA isolated from aortic walls of 3 mice each treated with murine aPL or control IgG was analyzed by RNA sequencing. Results WT C57/BL6 mice that received 20 µg of polyclonal murine aPL sustained plasma anti-β2GPI IgG levels &amp;gt;500 ng/mL for more than 120 h after IgG injection. In the IVC stasis model, six out of eight mice receiving aPL IgG and four out of eight mice receiving control IgG developed thrombi (lack of thrombi in all mice was likely due to bleeding of extensive IVC back branches in C57/BL6 mice). Thrombi weight in aPL-treated mice were significantly larger than those from mice that received control IgG (19.7 ± 1.7 mg vs 13.5 ± 1.0 mg, P = 0.015). Thrombin (0.1 U/ml)-induced platelet activation was significantly greater for platelets isolated from aPL-administered mice compared to those from control mice 72h after IgG injection as determined by binding of JON/A (1246.7 ± 55.3 MFI vs 879 ± 37.9 MFI, P = 0.005) and expression of P-selectin (5729.7 ± 553.9 MFI vs 3777.3 ± 402.5 MFI, P=0.046). Gene enrichment analysis of mRNA from aortas demonstrated significant upregulation of gene pathways related to complement and coagulation cascades, blood coagulation, and oxidoreductase activity in the aPL-treated mice. Individually upregulated genes included C8, C9 fga and fgb. Elevated levels of circulating nucleosomes were also observed in aPL treated mice but did not reach significance due to small numbers. Conclusion These results demonstrate that anti-β2GPI polyclonal aPL raised in apoh-/- mice circulate for extended periods when reinfused into WT mice, enhance thrombosis, induce platelet hyperreactivity, and cause changes in mRNA expression in the vascular wall. Further characterization of anti-β2GPI IgG for LAC activity, anti-PS/PT reactivity and β2GPI domain 1 reactivity is in progress. While all animal models of APS have weaknesses, this syngeneic model provides an additional approach that recapitulates many aspects of vascular inflammation seen in human APS.

Current status and value of testing antiphospholipid antibody in patients with acute ischemic stroke: a retrospective single-center study in China.

Testing for antiphospholipid antibodies (aPL) is useful to determine the cause of ischemic stroke in young and female patients. However, the clinical relevance of aPL in older patients with ischemic stroke remains unclear. We aimed to explore the status and diagnostic value of initial aPL testing in all patients with acute ischemic stroke. We retrospectively analyzed patients with acute ischemic stroke who were consecutively hospitalized in our hospital between June 2012 and January 2022 and investigated the factors associated with performing aPL screening in real-world clinical practice. Furthermore, factors associated with initial aPL positivity were evaluated by comparing the demographic, etiological, and therapeutic characteristics. Of 1209 patients, 287 (23.7%) were tested for aPL and 58 (20.2%) tested positive. Physicians tended to conduct aPL testing on female patients (P<0.001), younger patients (P<0.001), patients with fewer vascular risk factors (P<0.001), and multiple infarctions in the multivascular blood supply area (P<0.001). Multivariate logistic regression analysis showed that only stroke of other determined etiology type was a significant influencing factor for positive aPL results (OR 2.97, 95% CI 1.137, 7.774, P=0.026), adjusting for sex, age, and causes of stroke, etc. CONCLUSION: Approximately one-quarter of the patients with acute ischemic stroke were tested for aPL. Age, sex, number of vascular risk factors, and neuroimaging features affected the discretion in performing aPL testing. aPL testing may be appropriate in older patients with no identified cause of ischemic stroke and may provide additional diagnostic opportunities for acute ischemic stroke.

The 2023 ACR/EULAR Antiphospholipid Syndrome Classification Criteria.

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. 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. 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-β2 -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%. 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.

Abstract 8: Outcomes And Recurrence Rates Among Patients With Provoked And Cryptogenic Cerebral Venous Thrombosis: Analysis Of The ACTION CVT Study

Introduction: Cerebral venous thrombosis (CVT) is a rare cause of stroke. While the standard treatment is anticoagulation, the type and duration of anticoagulation depend on the underlying etiology. This study aims to identify the characteristics and risk of recurrent venous thromboembolism (VTE) in patients with unprovoked CVT (cryptogenic), transient provoked CVT (peripartum, contraception, infection, trauma) and persistent provoked CVT (cancer, hereditary thrombophilias). Methods: We used the ACTION CVT retrospective database which included consecutive CVT patients in 27 stroke centers in the United States, Europe, and New Zealand from January 2015 to December 2020. Baseline characteristics were compared between the groups using Chi square test, T test or Mann-Whitney-U test, followed by multivariable logistic regression. We used interaction analysis to assess the risk of recurrent venous thromboembolism (VTE). Results: A total of 1025 CVT patients were included in this study; 363 (35.4%) had transient provoking factors, 152 (14.8%) had persistent provoking factors, and 510 (49.8%) had cryptogenic CVT. Patients with transiently provoked CVT were younger (P=0.003) and more likely to be women (P&lt;0.001), and patients with cryptogenic CVT were less likely to have a prior VTE (P&lt;0.001). Compared to patients with transient provoked, there was higher risk of recurrent VTE in patients with persistent provoking factors (HR 2.59, 95% CI 1.29-5.22, P=0.008) and numerically higher recurrent VTE risk in cryptogenic CVT (HR 1.85, 95% CI 0.98-3.51, P=0.059). These associations did not vary by age, sex, or history of VTE status (p-interaction &gt; 0.1 for all). Results were similar in sensitivity analyses excluding those with positive Factor V Leiden or Prothrombin gene mutation as well as in analyses excluding patients with positive antiphospholipid antibody test. Conclusions: In this multicenter study, we found that the risk of recurrent VTE after CVT may vary depending on the underlying etiology with higher rates in patients with cryptogenic CVT and those with persistent provoking factors. Longer anticoagulation duration may be needed in such groups compared to CVT with transient provoking factors.

Hematological workup in cases of recurrent early miscarriages: what evidences?

Recurrent miscarriages have a major psychological and somatic impact, as well as a significant economic burden. An etiological work-up should be offered after two or three miscarriages, the threshold varying from one scientific society to another. However, the proposed biological work-up must be justified by scientific evidence. A simple blood count, basic coagulation tests including fibrinogen assay and anti-phospholipid antibodies testing should be performed initially. Hereditary thrombophilia testing should only be carried out if there is a history of maternal thrombosis. In the event of an abnormality, management should be multidisciplinary, and the prescription of medication should follow recommended guidelines. Prophylactic treatment is not justified in the absence of a known etiology.

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.

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).

Thrombophilia Testing Patterns, Result Interpretation, and Clinical Outcomes in a Retrospective Cohort of Patients with Retinal Vascular Occlusion

Background Low quality evidence exists to support an association between retinal vascular occlusion and thrombophilia. However, testing may be complicated by the impact of anticoagulants, hormone use and other factors on the results. Even when test results are interpretable, the implications for clinical decision-making are not established. We performed a retrospective chart review to assess patterns of test selection, result interpretation, and clinical outcomes in a cohort of patients who received thrombophilia testing after presenting to a tertiary care center for retinal vascular occlusion. Methods Eligible patients were >18 years with retinal vein occlusion (RVO) or retinal artery occlusion (RAO) and referred for thrombophilia testing by an ophthalmologist between 3/16/2011 and 3/22/2021 at the University of Washington. Electronic medical records were extracted for relevant clinical characteristics, test results, use of antithrombotic therapy, and recurrent arterial or venous events. Continuous variables are summarized by means and standard deviations or medians and range, as applicable. Categorical variables are described by proportions. Differences between groups were assessed using Student's t-tests and Fisher's exact tests for continuous and categorical variables, respectively. Analyses were conducted in R. Results A cohort of 57 patients were identified, with median age of 44 years at diagnosis (Table 1). 38 (66.7%) presented with RVO and 23 (40.4%) presented with RAO, including 4 patients with concurrent RVO and RAO at diagnosis. Baseline characteristics were not significantly different between patients presenting RAO versus RVO, apart from a trend toward higher prevalence of stroke history in the RAO group (4/23 vs 1/38, p = 0.06). Thrombophilia test selection varied: protein C activity was most commonly tested (80.7%) while activated protein C resistance (40.4%) was least commonly ordered (Figure 1). Among the 50 patients who received some combination of antiphospholipid antibody (aPL) testing, only 44% had all Sydney criteria aPL assays performed. The underlying prevalence of thrombophilia was 3.5% (2/57). One patient was found to be homozygous for the factor V Leiden mutation (FVL) after presenting with a central RVO and 1 was diagnosed with antiphospholipid syndrome (APS) in the context of a branch RAO plus persistent positivity of anti-beta-2 glycoprotein I (IgM) and anticardiolipin (IgM) antibodies. Another 5 patients had abnormal test results that were not diagnostic of an underlying thrombophilia (1 heterozygous FVL, 1 heterozygous prothrombin gene mutation, and 3 positive aPL). In total, 15 patients were initiated on low-dose aspirin following diagnosis, including the patient diagnosed with APS. Four patients were treated with anticoagulation, including the heterozygous FVL and heterozygous prothrombin gene mutation patients, who were placed on indefinite anticoagulation. The patient found to be homozygous for FVL briefly received prophylactic dosing of rivaroxaban before switching to low-dose aspirin due to side effects. After a median follow-up of 3.1 years, 3 patients had recurrent events (1 RVO, 2 strokes). One developed recurrent stroke while taking rivaroxaban for atrial fibrillation, while the other 2 were not receiving antithrombotic therapy at the time of thrombosis recurrence. Conclusion A low prevalence of thrombophilia was observed in a young cohort of patients presenting with retinal vascular occlusion. Incomplete testing was common, including for antiphospholipid syndrome, which is associated with 2-fold increased risk of retinal vascular occlusion. Thrombophilia testing did not clearly aid in clinical decision making; the tests ordered and the actions taken based on the test result were inconsistent. Both patients identified to have underlying thrombophilia lacked other history of venous or arterial thromboembolism and ultimately opted against long-term anticoagulation. An additional 14 patients opted for antithrombotic therapy with low-dose aspirin after an entirely negative thrombophilia workup. Misinterpretation of test results likely led to inappropriate recommendations for indefinite anticoagulation in at least 2 patients. The utility of thrombophilia testing in retinal vascular occlusion is poorly studied. In this cohort, we found no evidence that such testing should influence clinical decision-making. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Anticoagulation and/or Antiplatelet in Thrombotic Antiphospholipid Syndrome with Previous Arterial Thromboembolism: A Retrospective Cohort

Introduction: Thrombotic antiphospholipid syndrome (TAPS) is a prothrombotic autoimmune disease associated with a high risk of arterial thromboembolism (ATE). While direct oral anticoagulants (DOAC) are inferior treatment in TAPS with ATE, the optimal antithrombotic regimen of vitamin K antagonists (VKA) and/or antiplatelet therapy (AP) remains unclear. Objectives: To assess the effectiveness and safety of VKA (target (t) international normalized ratio (INR) 2-3), VKA (t INR 2-3) with AP (including dual AP therapy), VKA (t INR >3), VKA (t INR >3) with AP, and AP alone at preventing recurrent thrombotic events in TAPS patients with previous ATE. Methods: This retrospective cohort study included adult TAPS patients with previous ATE assessed at two academic tertiary care centers in Toronto, Canada between April 1, 2011 to April 1, 2021. Included patients met Sydney criteria for TAPS and had a history of ATE (ischemic stroke (IS), transient ischemic attack (TIA), myocardial infarction (MI), or systemic embolism (SE)). At participating centers, patients with a thrombotic history suspicious for TAPS were screened for lupus anticoagulant, anti-cardiolipin antibodies, and/or anti-beta-2-glycoprotein 1 antibodies (anti-B2GP1) at the discretion of the treating physician. Testing for anti-B2GP1 was only available as a send away test. We excluded patients with a known cardioembolic source for their ATE including atrial fibrillation, patent foramen ovale, mechanical heart valves, Libman-Sacks endocarditis, those with initial ATE associated with catastrophic antiphospholipid syndrome (CAPS), and those treated with DOAC. Outcomes included both thrombotic and bleeding events. Recurrent thrombosis included both ATE and VTE. ATE included IS, TIA, MI, or SE. Bleeding events were categorized as major bleeding (MB) or clinically relevant non-major bleeding (CRNMB) as defined by International Society on Thrombosis and Haemostasis criteria. Outcomes were assessed during the time the particular antithrombotic regimen was used. If a single patient had multiple antithrombotic regimens, they were included in multiple groups for the time they used that particular antithrombotic regimen, defined as antithrombotic trials. Outcomes were calculated as the number of events per 100 patient years by antithrombotic regimen with 95% confidence intervals (CI) using Poisson's exact test. Statistical calculations were performed using SPSS. Results: From an initial 891 patients with at least one positive antiphospholipid antibody test, 120 patients met criteria for TAPS and had a previous ATE. 62 patients were excluded for the following reasons: 47 for a cardio-embolic source of ATE, 5 for absence of any follow up, 7 for use of DOAC, and 3 for CAPS in the absence of any other ATE. After exclusions, 58 patients with a total of 89 antithrombotic trials were included in the analysis with a cumulative follow up of 248.4 years. The study population comprised of thirty-one (53.4%) women with a mean age of 51 (Standard Deviation (SD) 12.9) years at the start of their initial antithrombotic trial. Twenty-three (39.7%) patients were known to have systemic lupus erythematosus (SLE) whereas seven (12.1%) patients had non-SLE autoimmune disorders. Thirty-four (58.6%) patients had baseline hypertension. The baseline characteristics are summarized in table 1. Overall, there were a total of 7 ATE and 1 VTE recurrences with a thrombotic rate of 3.2 per 100 patient-years (95% CI 1.4 to 6.3). The recurrence rates in the VKA (t INR 2-3), VKA (t INR 2-3) with AP, VKA (t INR >3) with AP, and AP alone were 3.3 (95% CI 0.9 to 8.4), 2.6 (95% CI 0.3 to 9.3), 0 (95% CI 0 to 18.8), and 6.8 (0.8 to 24.4) per 100 patient-years respectively. There were a total of 10 MB events including 4 intracranial bleeding (ICB), 1 gastrointestinal bleeding, and 5 other types of MB. ICB occurred in 3 patients on VKA (t INR 2-3) and 1 on VKA (t INR 2-3) with AP. Outcomes are summarized in table 2. Conclusions: This retrospective cohort of 58 patients with TAPS and a previous ATE demonstrated a numerically higher risk of recurrent thrombosis with AP alone and a numerically higher risk of MB with the combination VKA and AP. Study limitations include the small sample size, risk of selection bias, and retrospective design. Larger, prospective studies are needed to confirm our observations. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Neurologic Manifestations of Catastrophic Antiphospholipid Syndrome.

Understanding of antiphospholipid antibody syndrome (APS), associated neurological manifestations, and disease-directed treatment has grown considerably over the last decade. Herein, we critically review the current and high-yield literature related to the pathophysiology, neurological presentations, and management of APS with particular emphasis on the rare and more fatal subset of APS, catastrophic antiphospholipid syndrome (CAPS). APS may manifest with a variety of neurologic syndromes, with cerebrovascular disease representing the most commonly encountered presentation. Diagnostic evaluation and treatment are often tailored to the specific presentation, with suspicion and testing for antiphospholipid antibodies recommended when neurologic presentations occur atypically or in younger individuals. In CAPS, which is more rapidly progressive with multiorgan involvement, potential alternative microangiopathic syndromes should be carefully considered in the differential diagnosis. To date, anticoagulation with vitamin K antagonists remains the mainstay of therapy in APS while triple therapy with anticoagulation, corticosteroids, and plasma exchange is standard of care in CAPS. Immunotherapy has shown early promise in refractory cases. APS is an autoimmune clinical syndrome with neurologic presentations classically characterized by vascular thrombosis, though recent understandings suggest additional direct immune-mediated phenomena. Our understanding of the underlying pathogenic mechanisms of APS continues to grow and will continue to influence our therapeutic approaches.

Prevalence and Clinical Significance of Antiphospholipid Antibodies in Hospitalized Patients With COVID-19 Infection.

Background: Coronavirus disease 2019 (COVID-19) infection is associated with an increased risk of arterial thromboembolic events (ATE) and venous thromboembolic events (VTE). Hypercoagulability associated with COVID-19 infection is multifactorial, and underlying pathogenic mechanisms potentially responsible for thrombosis include inflammation resulting in endothelial damage, platelet activation and the presence of antiphospholipid antibodies (APAs). Antiphospholipid antibody syndrome is one of the very few causes which is associated with venous and arterial thromboembolic events. COVID-19 patients have a high prevalence of APAs as well as both ATE and VTE, but their clinical significance in COVID-19 patients is not fully understood yet.Objectives: In this study, we intend to find the prevalence of APAs in hospitalized COVID-19 patients at the time of diagnosis and determine whether their presence has any clinical significance.Methods: This is a retrospective single-institution study involving patients hospitalized for the management of COVID-19 infection at The University of Toledo Medical Center. After obtaining approval from the biomedical institutional review board at The University of Toledo, antiphospholipid antibody (APA) testing was done on pre-stored blood samples of these patients and hospital charts were reviewed till six months from the positive COVID-19 test result. Two groups were created based on the patients' APA testing results (APA positive and APA negative) and used for statistical comparison. Any patients with positive lupus anticoagulant (LA) or abnormal titers APA antibodies were labeled as positive. Demographic data, prognostic outcomes and laboratory values were compared either using Mann-Whitney U-test for continuous variables or Fisher’s exact test for categorical variables.Results: The prevalence of APAs in hospitalized COVID-19 patients at the time of diagnosis was 39.3% in this study. There was no difference in demographic variables between the APA-positive and APA-negative groups. The prevalence of APAs was higher in smokers, where 91% of the APA-positive patients were smokers. There was no statistically significant difference in prognostic outcomes including six-month mortality between APA-positive and APA-negative patients. The comorbidity profile was the same in the two groups. APA-positive patients were found to have lower nadir of absolute lymphocyte count and higher nadir levels of C-reactive protein during hospitalization.Conclusions: The prevalence of APA positivity in hospitalized COVID-19 patients is higher in our study than in historical studies involving non-COVID-19 hospitalized patients, particularly in smokers. However, there is no correlation between APA positivity and prognostic outcomes including six-month mortality. At this point, it is unclear whether APAs are just bystanders or have a pathogenic role. Routine testing of APA in COVID-19 patients is not indicated. Further prospective studies to elucidate the persistence and clinical implications of APAs are needed.