International consensus guidelines on anticardiolipin and anti-β2-glycoprotein I testing: report from the 13th International Congress on Antiphospholipid Antibodies

Non-criteria autoantibodies in antiphospholipid syndrome may be associated with underlying disease activity

BACKGROUND

Antiphospholipid syndrome (APS) is a systemic autoimmune disorder characterized by persistent antiphospholipid antibodies (aPLs) with arterial and venous thrombosis and/or pregnancy morbidity. In recent years, several studies have highlighted the potential role of non-criteria aPL in diagnosing APS patients.

AIM

This study aimed to determine the association of the presence of non-criteria aPL antibodies to the clinical and laboratory features of patients with a diagnosis of APS.

METHODS

Eighty patients diagnosed with APS and under observation in the rheumatology clinic of Ankara City Hospital were assessed. Patient demographic and clinical features were meticulously recorded. Non-criteria antibodies tested in our center included antiphosphatidylserine IgA, antiphosphatidylserine IgM, beta 2 glycoprotein IgA, anti-cardiolipin IgA, antiphospholipid antibody IgG, and antiphospholipid antibody IgM. Antibodies from patients who were tested for at least one non-criteria antibody were documented.

RESULTS

Out of 80 patients, 55 (68.8%) were tested for at least one non-criteria antibody, and 29 of those patients (52.7%) tested positive for at least one non-criteria antibody. The antiphospholipid antibody IgM and the beta 2 glycoprotein IgA were the most commonly tested non-criteria antibodies. Patients with non-criteria antibody positivity had a higher frequency of Ds DNA positivity and low complement (62.0% vs. 35.0%, p = 0.042; 69.0% vs. 38.0%, p = 0.023), respectively. In addition, positivity for anti-cardiolipin IgG and b2 glycoprotein IgG was significantly higher in the group positive for non-criteria antibodies (79% vs. 31%, p ≤ 0.001; 72.0% vs. 19%, p ≤ 0.001). There was no significant difference between the clinical features of patients with at least one positivity for non-criteria antibodies and those without.

CONCLUSION

Systemic lupus erythematosus (SLE) is the most commonly associated disease with APS, being present in approximately 35% of cases [1]. Since the majority of the patient group in our study had APS that was secondary to SLE, non-criteria antibody positivity may be linked to the immunological activity of SLE. Large multicenter studies are necessary to investigate the clinical significance of isolated/combined positivity for criterion/non-criteria aPLs.

Pneumoconiosis combined with connective tissue disease in China: a cross-sectional study

OBJECTIVE

To describe the prevalence, clinical features and potential risk factors of pneumoconiosis in combination with connective tissue disease (CTD) or positive autoantibodies.

DESIGN

Cross-sectional study.

SETTING

A retrospective study of adults recruited in China between December 2016 and November 2021.

PARTICIPANTS

A total of 931 patients with pneumoconiosis at Beijing Chao-Yang Hospital were enrolled in this study; of these, 580 patients were included in the final analysis.

MAIN OUTCOME MEASURES

Pneumoconiosis combined with CTD or positive autoantibodies was a major adverse outcome.

RESULTS

In total, 13.8% (80/580) of the patients had combined pneumoconiosis with CTD, among whom the prevalence of CTD was 18.3% (46/251) in asbestosis and 11.4% (34/298) in silicosis/coal mine workers' pneumoconiosis. In comparison to the general Chinese adult population, the relative risk of various CTD in pneumoconiosis, including rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis, primary Sjögren's syndrome, idiopathic inflammatory myopathy and antineutrophil cytoplasmic antibodies-associated vasculitis, were 11.85, 12.12, 127.40, 4.23, 9.94 and 644.66, respectively. Multivariate analysis revealed that female sex (OR 2.55, 95% CI 1.56 to 4.17) and a later stage of pneumoconiosis (OR 2.04, 95% CI 1.24 to 3.34) were the independent risk factors for CTD in patients with pneumoconiosis (all p<0.050).

CONCLUSION

CTD is highly prevalent in patients with pneumoconiosis, especially in patients of asbestosis, and silicosis/coal mine workers' pneumoconiosis. Female sex and later stages of pneumoconiosis are associated with an increased risk of combined with CTD.

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).

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.

Detection of IgA Antiphospholipid Antibodies Does not Improve Thrombotic Antiphospholipid Syndrome Classification: A two-Center Study

Background

Thrombotic antiphospholipid syndrome (APS) is a systemic autoimmune disease; its diagnosis requires meeting both clinical and laboratory criteria. Prevalence rates of immunoglobulin (Ig) A anticardiolipin antibodies (aCL) and IgA anti-β₂ glycoprotein I antibodies (aβ₂GPI) remain unknown, and the clinical value of these antibodies to APS classification remains controversial. Therefore, we aimed to examine both items in the Chinese population.

Methods

Using chemiluminescence immunoassay, antiphospholipid antibodies (aPL) were quantified in 12,582 hospital-based general population, 278 thrombotic APS patients, and 233 healthy controls.

Results

In the general population, the positive rates of IgA aCL and IgA aβ₂GPI antibodies were 2.87% and 1.99%, respectively. Furthermore, isolated IgA aPL-positivity rate was 0.72% in patients with APS, which was comparable to those in the general population (0.68%, p = 1) and in healthy controls (0.43%, p = 1). Among the IgA aPL-positive individuals in the general population, isolated IgA-positive individuals had lower serum levels of IgA antibodies (p = 0.007 for IgA aCL and p = 0.059 for IgA aβ₂GPI). Regarding to APS classification, adding IgA aPL into conventional aPL assays may not improve and may even deteriorate the net reclassification index for APS; besides, no association between thrombosis and IgA aPL was observed.

Conclusions

this study assessed the prevalence of various aPL in Chinese population. IgA aPL may not enhance the classification ability of established laboratory criteria for thrombotic APS. Our data do not support the addition of IgA aPL to conventional aPL assays.

A systematic review of the association between anti-β-2 glycoprotein I antibodies and APS manifestations

Anti-β-2 glycoprotein I antibodies (anti-B2GPI) are often cited as the major pathogenically relevant antibody in antiphospholipid syndrome (APS), but it is unclear if there is clinical evidence to support this theory. We performed a systematic review to determine if immunoglobulin G anti-B2GPI positivity was independently associated with thrombotic and/or obstetric manifestations of APS. We searched MEDLINE, EMBASE, The Cochrane Library, and clinicaltrials.gov electronic databases through April 2020 for prospective studies that met prespecified design criteria. Of 4758 articles identified through computer-assisted search, 4 studies examining obstetric outcomes and 2 studies examining thrombotic outcomes were included for qualitative assessment. The presence of anti-B2GPI had only a weak independent association with thrombosis and was, at best, inconsistently associated with obstetric complications. A quantitative assessment could not be performed because of study heterogeneity. The overall quality of the evidence was very low. Although anti-B2GPI are commonly thought to mediate APS manifestations, clinical evidence is lacking with very low-quality data to support a weak association with thrombosis.

Evaluation of the Diagnostic Value of Non-criteria Antibodies for Antiphospholipid Syndrome Patients in a Chinese Cohort

Objective

Although specific anti-phospholipid antibodies (aPLs) have been used in the diagnosis of the antiphospholipid syndrome (APS) for years, new biomarkers are required to increase its diagnostic and risk-predictive power. This study aimed to explore the value of several non-criteria aPLs in a Chinese cohort.

Methods

A total of 312 subjects, namely, 100 patients diagnosed with primary APS, 51 with APS secondary to SLE, 71 with SLE, and 90 healthy controls, were recruited. Serum anticardiolipin (aCL) IgG/IgM/IgA, anti-β2-glycoprotein I (aβ2GPI) IgG/IgM/IgA, anti-phosphatidylserine/prothrombin antibodies (aPS/PT) IgG/IgM, and anti-annexin A5 antibodies (aAnxV) IgG/IgM were tested using ELISA kits.

Results

Of the total number of patients, 30.46% and 6.62% with APS were positive for aCL or aβ2GPI IgA, respectively, while 39.07% and 24.50% were positive for aAnxV or aPS/PT for at least one antibody (IgG or IgM). The addition test of aCL IgA and aAnxV IgM assists in identifying seronegative APS patients, and IgG aPS/PT was linked to stroke.

Conclusion

Detection of aCL IgA, aβ2GPI IgA, aAnxV IgG/M, and aPS/PT IgG/M as a biomarker provides additive value in APS diagnosis and would help in risk prediction for APS patients in medical practice.

Anti-Phospholipid Antibodies and COVID-19 Thrombosis: A Co-Star, Not a Supporting Actor

Background: COVID-19 clinical features include a hypercoagulable state that resembles the antiphospholipid syndrome (APS), a disease characterized by thrombosis and presence of antiphospholipid antibodies (aPL). The relationship between aPL-presence and the appearance of thrombi as well as the transience or permanence of aPL in COVID-19 patients is not sufficiently clear. Methods: A group of 360 COVID-19 patients were followed-up for 6 months. Classic aPL, anti-B2GPI IgA, anti-phosphatidylserine/prothrombin IgG/M and anti-SARS-CoV-2 antibodies were determined at acute phase and >12 weeks later. The reference group included 143 healthy volunteers of the same age-range distribution. Results: aPL prevalence was similar in COVID-19 patients and the reference population. aPL presence in both determinations was significantly associated with thrombosis (OR: 2.33 and 3.71), strong agreement being found for classic aPL and anti-B2GPI IgA (Weighted kappa: 0.85–0.91). Thrombosis-associated aPL occurred a median of 17 days after hospital admission (IQR: 6–28) vs. 4 days for the rest (IQR: 3–7). Although anti-SARS-CoV-2 antibodies levels increased during convalescence, aPL hardly changed. Conclusions: Most COVID-19 patients would carry these aPL before the infection. At least two mechanisms could be behind thrombosis, early immune-dysregulation-mediated thrombosis after infection and belated-aPL-mediated thrombosis, with SARS-CoV-2 behaving as a second hit.

Anti-vimentin/cardiolipin IgA in the anti-phospholipid syndrome: A new tool for 'seronegative' diagnosis

Anti-phospholipid syndrome (APS) is a systemic autoimmune disorder defined by the simultaneous presence of vascular clinical events, pregnancy morbidity and anti-phospholipid antibodies (aPL). In clinical practice, it is possible to find patients with APS who are persistently negative for the routine aPL tests (seronegative APS; SN-APS). Recently, the identification of aPL immunoglobulin (Ig)A and/or anti-β2-glycoprotein-I (β2-GPI) IgA was shown to represent a further test in SN-APS patients. In this study we analyzed the presence of anti-vimentin/cardiolipin (aVim/CL) IgA in a large cohort of patients with SN-APS, evaluating their possible association with clinical manifestations of the syndrome. This study includes 60 consecutive SN-APS patients, 30 patients with APS and 40 healthy donors. aVim/CL IgA were detected by enzyme-linked immunosorbent assay (ELISA). Results show that 12 of 30 APS patients (40%) and 16 of 60 SN-APS patients (26.7%) resulted positive for aVim/CL IgA. Interestingly, SN-APS patients who tested positive for aVim/CL IgA showed a higher prevalence of arterial thrombosis (p = 0.017, likelihood positive ratio = 5.7). This study demonstrates for the first time, to our knowledge, the presence of aVim/CL IgA in sera of patients with APS. In particular, they revealed a potential usefulness in identification of a significant proportion of SN-APS patients. Moreover, as patients tested positive for aVim/CL IgA reported a high likelihood ratio to have the clinical features of APS, this test may be considered a suitable approach in the clinical evaluation of SN-APS.

COVID-19 and Antiphospholipid Antibodies: Time for a Reality Check?

Antiphospholipid antibodies (aPL) comprise a panel of autoantibodies that reflect a potential prothrombotic risk in several autoimmune conditions, most notably antiphospholipid (antibody) syndrome (APS). aPL can be divided into those that form part of the laboratory criteria for APS, namely, lupus anticoagulant (LA), as well as anticardiolipin antibodies (aCL) and anti-β2-glycoprotein I antibodies (aβ2GPI) of the immunoglobulin G and M classes, and those that form a group considered as "noncriteria antibodies." The noncriteria antibodies include, for example, antiphosphatidylserine antibodies (aPS), antiprothrombin antibodies (aPT), and antiphosphatidylserine/prothrombin complex antibodies (aPS/PT). COVID-19 (coronavirus disease 2019) represents a prothrombotic disorder, and there have been several reports of various aPL being present in COVID-19 patients. There have also been similarities drawn between some of the pathophysiological features of COVID-19 and APS, in particular, the most severe form, catastrophic APS (CAPS). In this review, we critically appraise the literature on aPL and COVID-19. This is a companion piece to a separate review focused on LA. In the current review, we primarily concentrate on the so-called solid phase identifiable aPL, such as aCL and aβ2GPI, but also reflect on noncriteria aPL. We conclude that aPL positivity may be a feature of COVID-19, at least in some patients, but in general, identified "solid-phase" aPL are of low titer and not able to be well-linked to the thrombotic aspects of COVID-19. Also, most publications did not assess for aPL persistence, and where persistence was checked, the findings appeared to represent transient aPL. Importantly, high-titer aPL or multiple aPL positivity (including double, triple) were in the minority of COVID-19 presentations, and thus discount any widespread presence of APS, including the most severe form CAPS, in COVID-19 patients.

Presence of Extra-Criteria Antiphospholipid Antibodies Is an Independent Risk Factor for Ischemic Stroke

Background: Ischemic stroke is the most common and severe arterial thrombotic event in Antiphospholipid syndrome (APS). APS is an autoimmune disease characterized by the presence of thrombosis and antiphospholipid antibodies (aPL), which provide a pro-coagulant state. The aPL included in the classification criteria are lupus anticoagulant, anti-cardiolipin (aCL) and anti-β2-glycoprotein-I antibodies (aB2GPI) of IgG and IgM isotypes. Extra-criteria aPL, especially IgA aB2GPI and IgG/IgM anti-phosphatidylserine/prothrombin antibodies (aPS/PT), have been strongly associated with thrombosis. However, their role in the general population suffering from stroke is unknown. We aim (1) to evaluate the aPL prevalence in ischemic stroke patients, (2) to determine the role of aPL as a risk factor for stroke, and (3) to create an easy-to-use tool to stratify the risk of ischemic stroke occurrence considering the presence of aPL and other risk factors.

Materials and Methods: A cohort of 245 consecutive ischemic stroke patients was evaluated in the first 24 h after the acute event for the presence of classic aPL, extra-criteria aPL (IgA aB2GPI, IgG, and IgM aPS/PT) and conventional cardiovascular risk factors. These patients were followed-up for 2-years. A group of 121 healthy volunteers of the same age range and representative of the general population was used as reference population. The study was approved by the Ethics Committee for Clinical Research (Reference numbers CEIC-14/354 and CEIC-18/182).

Results: The overall aPL prevalence in stroke patients was 28% and IgA aB2GPI were the most prevalent (20%). In the multivariant analysis, the presence of IgA aB2GPI (OR 2.40, 95% CI: 1.03–5.53), dyslipidemia (OR 1.70, 95% CI: 1.01–2.84), arterial hypertension (OR 1.82, 95% CI: 1.03–3.22), atrial fibrillation (OR 4.31, 95% CI: 1.90–9.78), and active smoking (OR 3.47, 95% CI: 1.72–6.99) were identified as independent risk factors for ischemic stroke. A risk stratification tool for stroke was created based on these factors (AUC: 0.75).

Conclusions: IgA aB2GPI are an important independent risk factor for ischemic stroke. Evaluation of aPL (including extra-criteria) in cardiovascular risk factor assessment for stroke can potentially increase the identification of patients at risk of thrombotic event, facilitating a decision on preventive treatments.

In vitro diagnostics for the medical dermatologist. Part II: Hypercoagulability tests

The skin often provides initial clues of hypercoagulability with features such as livedo reticularis, livedo racemosa, retiform purpura, necrosis, and ulcerations. Because these cutaneous manifestations are nonspecific, laboratory testing is often needed to evaluate for underlying causes of hypercoagulability. Importantly, these disorders are reported to be the most common mimicker, resulting in an erroneous diagnosis of pyoderma gangrenosum. Understanding inherent properties of, and indications for, available tests is necessary for appropriate ordering and interpretation of results. Additionally, ordering of these tests in an indiscriminate manner may lead to inaccurate results, complicating the interpretation and approach to management. This second article in this continuing medical education series summarizes information on methodology, test characteristics, and limitations of several in vitro laboratory tests used for the work up of hypercoagulability and vasculopathic disease as it pertains to dermatologic disease.

How I treat unexplained arterial thrombosis

Most arterial thrombotic events have a clear atherosclerotic or cardioembolic etiology, but hematologists are frequently asked to assist in the diagnosis and management of a patient with a nonatherosclerotic and noncardioembolic arterial event, referred to here as an unexplained arterial thrombosis. Because there is an assorted list of factors that can precipitate an arterial event, we present a systematic diagnostic approach to ensure consideration of not only primary hypercoagulable disorders, but also pro-thrombotic medications or substances, vascular and anatomic abnormalities, and undiagnosed systemic disorders, such as malignancy and autoimmune diseases. We also review existing literature of the role of hypercoagulable disorders in arterial thrombosis and discuss our approach to thrombophilia workup in patients after an unexplained arterial event. We conclude with 3 representative cases to both illustrate the application of the outlined diagnostic schema and discuss common management considerations, specifically the selection of anticoagulation vs antiplatelet therapy for secondary prevention.

The Weight of IgA Anti-β2glycoprotein I in the Antiphospholipid Syndrome Pathogenesis: Closing the Gap of Seronegative Antiphospholipid Syndrome

The specific value of IgA Anti-β2glycoprotein I antibodies (aB2GP1) in the diagnosis and management of antiphospholipid syndrome (APS) is still controversial and a matter of active debate. The relevance of the IgA aB2GP1 isotype in the pathophysiology of APS has been increasingly studied in the last years. There is well know that subjects with multiple positive APS tests are at increased risk of thrombosis and/or miscarriage. However, these antibodies are not included in the 2006 APS classification criteria. Since 2010 the task force of the Galveston International Congress on APS recommends testing IgA aB2GP1 isotype in patients with APS clinical criteria in the absence of criteria antibodies. In this review, we summarize the molecular and clinical “state of the art” of the IgA aB2GP in the context of APS. We also discuss some of the characteristics that may help to evaluate the real value of the IgA aB2GP1 determination in basic research and clinical practice. The scientific community should be aware of the importance of clarifying the role of IgA aB2GP1 in the APS diagnosis.

Prothrombotic autoantibodies in serum from patients hospitalized with COVID-19

Patients with COVID-19 are at high risk for thrombotic arterial and venous occlusions. Lung histopathology often reveals fibrin-based blockages in the small blood vessels of patients who succumb to the disease. Antiphospholipid syndrome is an acquired and potentially life-threatening thrombophilia in which patients develop pathogenic autoantibodies targeting phospholipids and phospholipid-binding proteins (aPL antibodies). Case series have recently detected aPL antibodies in patients with COVID-19. Here, we measured eight types of aPL antibodies in serum samples from 172 patients hospitalized with COVID-19. These aPL antibodies included anticardiolipin IgG, IgM, and IgA; anti-β2 glycoprotein I IgG, IgM, and IgA; and anti-phosphatidylserine/prothrombin (aPS/PT) IgG and IgM. We detected aPS/PT IgG in 24% of serum samples, anticardiolipin IgM in 23% of samples, and aPS/PT IgM in 18% of samples. Antiphospholipid autoantibodies were present in 52% of serum samples using the manufacturer's threshold and in 30% using a more stringent cutoff (≥40 ELISA-specific units). Higher titers of aPL antibodies were associated with neutrophil hyperactivity, including the release of neutrophil extracellular traps (NETs), higher platelet counts, more severe respiratory disease, and lower clinical estimated glomerular filtration rate. Similar to IgG from patients with antiphospholipid syndrome, IgG fractions isolated from patients with COVID-19 promoted NET release from neutrophils isolated from healthy individuals. Furthermore, injection of IgG purified from COVID-19 patient serum into mice accelerated venous thrombosis in two mouse models. These findings suggest that half of patients hospitalized with COVID-19 become at least transiently positive for aPL antibodies and that these autoantibodies are potentially pathogenic.

Coagulation/Complement Activation and Cerebral Hypoperfusion in Relapsing-Remitting Multiple Sclerosis

Introduction

Multiple sclerosis (MS) is a demyelinating disease of the central nervous system with an underlying immune-mediated and inflammatory pathogenesis. Innate immunity, in addition to the adaptive immune system, plays a relevant role in MS pathogenesis. It represents the immediate non-specific defense against infections through the intrinsic effector mechanism “immunothrombosis” linking inflammation and coagulation. Moreover, decreased cerebral blood volume (CBV), cerebral blood flow (CBF), and prolonged mean transit time (MTT) have been widely demonstrated by MRI in MS patients. We hypothesized that coagulation/complement and platelet activation during MS relapse, likely during viral infections, could be related to CBF decrease. Our specific aims are to evaluate whether there are differences in serum/plasma levels of coagulation/complement factors between relapsing-remitting (RR) MS patients (RRMS) in relapse and those in remission and healthy controls as well as to assess whether brain hemodynamic changes detected by MRI occur in relapse compared with remission. This will allow us to correlate coagulation status with perfusion and demographic/clinical features in MS patients.

Materials and Methods

This is a multi-center, prospective, controlled study. RRMS patients (1° group: 30 patients in relapse; 2° group: 30 patients in remission) and age/sex-matched controls (3° group: 30 subjects) will be enrolled in the study. Patients and controls will be tested for either coagulation/complement (C3, C4, C4a, C9, PT, aPTT, fibrinogen, factor II, VIII, and X, D-dimer, antithrombin, protein C, protein S, von-Willebrand factor), soluble markers of endothelial damage (thrombomodulin, Endothelial Protein C Receptor), antiphospholipid antibodies, lupus anticoagulant, complete blood count, viral serological assays, or microRNA microarray. Patients will undergo dynamic susceptibility contrast-enhanced MRI using a 3.0-T scanner to evaluate CBF, CBV, MTT, lesion number, and volume.

Statistical Analysis

ANOVA and unpaired t-tests will be used. The level of significance was set at p ≤ 0.05.

Discussion

Identifying a link between activation of coagulation/complement system and cerebral hypoperfusion could improve the identification of novel molecular and/or imaging biomarkers and targets, leading to the development of new effective therapeutic strategies in MS.

Clinical Trial Registration

Clinicaltrials.gov, identifier NCT04380220.

"Non-criteria" antiphospholipid syndrome: A nomenclature proposal

The classification criteria for antiphospholipid syndrome (APS) generate discussion, with a growing impression that certain patients not fulfilling these criteria might be inadequately excluded from the classification. Nonetheless, these "non-criteria" patients are heterogeneously defined across different publications. We reviewed the "non-criteria" APS subgroups depicted in the literature and attempted to organize these subsets in a nomenclature proposal that could be used for research purposes. We established four potential patient profiles, grouped under the broad term "non-criteria APS": (A) "Seronegative APS": patients fulfilling clinical criteria, plus "non-criteria" manifestations, with persistently negative antiphospholipid antibodies (aPL); (B) "Clinical non-criteria APS": patients with "non-criteria" manifestations, plus aPL positivity fulfilling the classification criteria; (C) "Incomplete laboratory APS": patients fulfilling clinical criteria, plus positive aPL, but not fulfilling the classification criteria (low titer aPL); and (D) "Laboratory non-criteria APS": patients fulfilling clinical criteria, with negative or low titer criteria aPL, plus positive "non-criteria" aPL. This categorization could allow for a more homogeneous research approach to APS, enabling more sustained and universal conclusions.

Intensity of immune/clotting assays relate to multiple antiphospholipid antibody positivity in thrombotic primary antiphospholipid syndrome

The dual positivity (DP) and triple positivity (TP) concepts bypass the poor comparability of immune/clotting assay for the laboratory classification of antiphospholipid syndrome (APS). To evaluate intensity of immune/clotting assays and DP/TP through different clinical severity groups (CSG) as follows: (1) non-thrombotic asymptomatic carriers of aPL (N-THR), thrombotic primary APS (THR), deceased (D) for recurrent and fatal thrombosis. Activated partial thromboplastin time ratio (aPTTr), dilute Russell viper venom time ratio (DRVVTr), IgG/IgM anticardiolipin (aCL) and anti β-2-glycoprotein-I (aβ2GPI). Participants: 33 N-THR, 64 THR and 11 D. The frequency of DP and TP (DRVVTr or aPTTr partnered with respective IgG aCL or aβ2GPI) increased across CSG (p = 0.006 and p = 0.003); mean DRVVTr and IgG aCL/aβ2GPI were always greater in TP versus non-TP within each CSG and progressively increased across the CSG. The intensity of individual lupus anticoagulants partnered with their corresponding IgG aPL related to the frequency of multiple positivity throughout CSG suggesting that of intensity of immune/clotting assays and multiple positivity are the different faces of the same diagnostic coin in our thrombotic PAPS cohort.

Prothrombotic antiphospholipid antibodies in COVID-19

Patients with coronavirus disease 19 (COVID-19) are at high risk for thrombotic arterial and venous occlusions. At the same time, lung histopathology often reveals fibrin-based occlusion in the small vessels of patients who succumb to the disease. Antiphospholipid syndrome (APS) is an acquired and potentially life-threatening thrombophilia in which patients develop pathogenic autoantibodies (aPL) targeting phospholipids and phospholipid-binding proteins. Case series have recently detected aPL in patients with COVID-19. Here, we measured eight types of aPL [anticardiolipin IgG/IgM/IgA, anti-beta-2 glycoprotein I IgG/IgM/IgA, and anti- phosphatidylserine/prothrombin (aPS/PT) IgG/IgM] in the sera of 172 patients hospitalized with COVID-19. We detected aPS/PT IgG in 24%, anticardiolipin IgM in 23%, and aPS/PT IgM in 18%. Any aPL was present in 52% of patients using the manufacturer's threshold and in 30% using a more stringent cutoff (≥40 units). Higher levels of aPL were associated with neutrophil hyperactivity (including the release of neutrophil extracellular traps/NETs), higher platelet count, more severe respiratory disease, and lower glomerular filtration rate. Similar to patients with longstanding APS, IgG fractions isolated from patients with COVID-19 promoted NET release from control neutrophils. Furthermore, injection of these COVID-19 IgG fractions into mice accelerated venous thrombosis. Taken together, these studies suggest that a significant percentage of patients with COVID-19 become at least transiently positive for aPL and that these aPL are potentially pathogenic.

Nine-test panel has superior sensitivity to detect antiphospholipid antibody syndrome in patients with or without SLE

Anti-phospholipid antibodies (aPL) and lupus anticoagulant (LAC) represent diagnostic criteria for systemic lupus erythematosus (SLE) and underlie anti-phospholipid syndrome (APS) in patients with and without SLE. 526 healthy controls and 1633 SLE and 1835 primary APS (PAPS) patients were evaluated. LAC was assessed by hexagonal phase phospholipid neutralization assay (HPPNA), diluted Russell viper venom test (dRVVT), and platelet neutralization procedure (PNP). β2-glycoprotein-I and cardiolipin IgG, IgM, and IgA antibodies (aCL-IgG, aCL-IgM, aCL-IgA) were measured. 222/1633 SLE patients had APS based on the nine-test panel, which afforded the highest sensitivity (74%) and negative predictive value (90%) but lowest specificity (52%). HPPNA was the most sensitive individual test at 52%. The nine-test panel yielded the greatest sensitivity for aPL detection (70%) relative to HPPNA, the most sensitive individual test (36%) in PAPS. Superior sensitivity of a nine-test aPL panel has major implications for preventing potentially fatal thrombotic events in SLE and PAPS.

"Non-criteria" antiphospholipid antibodies add value to antiphospholipid syndrome diagnoses in a large Chinese cohort

BACKGROUND

Despite expansion in the 2006 Sydney antiphospholipid syndrome (APS) classification criteria to include IgG/IgM anti-β2-glycoprotein (aβ2GPI) antibodies in addition to IgG/IgM anti-cardiolipin antibodies (aCL) and lupus anticoagulant (LAC), some individuals with clinical features of APS remain seronegative (seronegative APS or SNAPS) and are at risk of recurrent thrombosis and pregnancy morbidities. Our aim was to assess the value of "non-criteria" aPL antibodies to detect these SNAPS patients.

METHODS

One hundred ninety-two APS patients, 90 SNAPS patients, 193 autoimmune disease controls, and 120 healthy controls were evaluated. Ten antiphospholipid antibodies (aPLs) were tested using commercial kits, including 5 non-criteria aPLs: anti-phosphatidylserine/prothrombin antibodies (aPS/PT) IgG/IgM, aCL IgA, aβ2GPI IgA, and anti-β2GPI Domain 1 (aβ2GPI-D1) IgG.

RESULTS

Up to 60.9% of the SNAPS and 93.5% of APS patients were detected by at least one non-criteria aPL. aPS/PT IgG had the highest Youden index in classifying APS and SNAPS from controls. aPS/PT IgG and aβ2GPI Domain 1 IgG seem to be the most significant risk factors for thrombotic events and pregnancy morbidity, respectively. aPS/PT IgG/IgM and aβ2GPI-D1 IgG were detected in some SNAPS patients, while IgA isotypes of aCL/aβ2GPI tended to appear together with other biomarkers. The combined analysis showed enhanced diagnostic performance with the inclusion of non-criteria aPLs.

CONCLUSIONS

Recognition of SNAPS patients is critical for clinical management and prevention of potential thrombotic and obstetric adverse events. The non-criteria antiphospholipid antibodies help to identify a considerable portion (60.9%) of these patients who otherwise may remain untreated and at clinical risk.

Seronegative antiphospholipid syndrome: refining the value of "non-criteria" antibodies for diagnosis and clinical management

Antiphospholipid syndrome (APS) is a systemic autoimmune disease characterized by arterial and venous thrombotic manifestations and/or pregnancy-related complications in patients with persistently high antiphospholipid antibodies (aPL), the most common being represented by anticardiolipin antibodies (aCL), anti-beta 2 glycoprotein-I (aβ2GPI), and lupus anticoagulant (LAC). A growing number of studies have showed that, in some cases, patients may present with clinical features of APS but with temporary positive or persistently negative titers of aPL. For these patients, the definition of seronegative APS (SN-APS) has been proposed. Nevertheless, the negativity to classic aPL criteria does not imply that other antibodies may be present or involved in the onset of thrombosis. The diagnosis of SN-APS is usually made by exclusion, but its recognition is important to adopt the most appropriate anti-thrombotic strategy to reduce the rate of recurrences. This research is in continuous development as the clinical relevance of these antibodies is far from being completely clarified. The most studied antibodies are those against phosphatidylethanolamine, phosphatidic acid, phosphatidylserine, phosphatidylinositol, vimentin/cardiolipin complex, and annexin A5. Moreover, the assays to measure the levels of these antibodies have not yet been standardized. In this review, we will summarize the evidence on the most studied non-criteria aPL, their potential clinical relevance, and the antithrombotic therapeutic strategies available in the setting of APS and SN-APS.

Clinical performance of automated chemiluminescent methods for anticardiolipin and anti-β2-glycoprotein I antibodies detection in a large cohort of Chinese patients with antiphospholipid syndrome

INTRODUCTION

To assess the clinical performance and correlations of automated chemiluminescence assay (CIA) and enzyme-linked immunosorbent assay (ELISA) for detecting antiphospholipid (aPL) antibodies in the diagnosis of antiphospholipid syndrome (APS).

METHODS

The study recruited 505 subjects, including 192 with APS, 193 with connective tissue diseases other than APS, and 120 healthy donors. We measured anticardiolipin (aCL) and anti-β2-glycoprotein I (anti-β2GPI) antibodies IgG, IgM, and IgA in all the samples using both CIA and ELISA.

RESULTS

Total agreement between the two methods ranged from 83.50% for anti-β2GPI IgG antibodies to 92.76% for anti-β2GPI IgM antibodies in all the groups. Anti-β2GPI and aCL IgG assays showed the highest Spearman's rho coefficients (anti-β2GPI IgG = 0.742, aCL IgG = 0.715). Anti-β2GPI IgG CIA showed the highest sensitivity for diagnosis of APS at 80.21%, which was significantly higher than the sensitivity of anti-β2GPI IgG ELISA (52.08%). For diagnosis of APS, anti-β2GPI IgG CIA had the best discrimination power with the area under the curves (AUC) of 0.922, followed by aCL IgG CIA (AUC of 0.905). While the CIA AUC was slightly higher in all cases, the difference was not statistically significant.

CONCLUSION

CIA measurements had a good agreement and correlation with comparative ELISA assays. The CIA anti-β2GPI IgG however was significantly more sensitive for APS diagnosis. The two assay methodologies showed comparable predictive powers and support the value of the CIA method for improved diagnosis and management of patients with APS.

The role of beta-2-glycoprotein I in health and disease associating structure with function: More than just APS

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.

Immune Complexes of Beta-2-Glycoprotein I and IgA Antiphospholipid Antibodies Identify Patients With Elevated Risk of Thrombosis and Early Mortality After Heart Transplantation

Background: The presence of anti-Beta 2 glycoprotein antibodies (aB2GP1) of IgA isotype is common in patients with functional impairment of the organs in which B2GP1 is elaborated. Pretransplant IgA aB2GP1 has been associated with increased risk of thrombosis in kidney and heart transplanted patients and has also been related with early mortality after heart transplantation. Circulating immune complexes between IgA and B2GP1 (B2A-CIC) have been described in the blood of patients positive for IgA aB2GP1 with thrombotic clinical symptoms. In kidney transplanted patients, B2A-CIC is a biomarker that predicts which patients IgA aB2GP1 positive are at risk of thrombosis events following kidney transplantation and may lead to early prophylactic treatment. The prevalence of B2A-CIC and its relation with outcomes after heart transplantation is not known.

Methods: Follow-up study based on 151 consecutive patients who received a heart transplant. Autoantibodies and B2A-CIC were quantified in pre-transplant serum samples. Three groups of patients were followed-up for 2 years: Group-1, positive for IgA aB2GP1 and B2A-CIC (N = 19). Group-2, only positive for IgA aB2GP1 (N = 28). Group-0 (control group): IgA aB2GP1 negative (N = 104).

Results: Kaplan-Meir survival analysis showed that mortality in B2A-CIC positive was higher than group-0 at 3 months (HR:5.08; 95%CI: 1.36–19.01) and at 2 years (HR:3.82; 95%CI: 1.54–12.66). No significant differences were observed between group-2 and group-0. Multivariate analysis identified B2A-CIC as the most important independent risk factor for early mortality (OR = 6.12; 95% CI: 1.93–19.4). Post-transplant incidence of thrombosis was significantly higher in B2A-CIC positive patients than in the control group (OR: 6.42; 95%CI: 2.1–19.63). Multivariate analysis identified the presence of B2A-CIC (OR: 6.13; 95%CI: 2.1–19.63) and the pre-transplant habit of smoking actively (OR: 4.18; 95%CI: 1.35–12.94) as independent risk factor for thrombosis. The proportion of patients who had thrombotic events or died in the first trimester was significantly higher in group-1 (73.7%) than in group-0 (16.3%; p < 0.001) and in group-2 (39.3%; p = 0.02). Multivariate analysis identified B2A-CIC as the main independent risk factor for early outcomes (mortality or thrombosis) in the first 3 months after heart transplant (OR = 11.42, 95% CI: 1.69–9.68).

Conclusion: B2A-CIC are a predictor of early mortality and thrombosis after heart transplant.

Anti-phospholipid antibody prevalence and association with subclinical atherosclerosis and atherothrombosis in the general population

BACKGROUND

There is no agreement on the prevalence of anti-phospholipid antibodies (aPLs) and the correlation with atherosclerosis and cardiovascular (CV) events in the general population.

METHODS

We performed a cross-sectional study on 1712 randomly enrolled subjects from a Northern Italian city to investigate the presence of aPLs and the association with subclinical atherosclerosis (using the carotid artery intima media thickness measured as inter-adventitia common carotid artery diameters - ICCAD) and retrospectively collected CV factors and events (i.e. acute myocardial infarction, stroke, and peripheral obliterans arterial vasculopathy) using physician-assisted questionnaires. We tested serum IgG, IgM, and IgA anti-cardiolipin, anti-beta2glycoprotein I (aGPI), and anti-phosphatidylserine-prothrombin antibodies.

RESULTS

Positive aPLs were found in 15.1% of the subjects, with no differences between sex but with higher rates in older subjects. Carotid subclinical atherosclerosis was more frequent in aPL positive subjects; more specifically, aGPI IgA were associated with higher ICCAD average (adjusted beta 0.51, 95% confidence interval (CI)0.17-0.84; p = 0.003). A positive history of CV events was also more frequent in aPL positive subjects (odds ratio (OR) 1.67, 95%CI 1.08-2.54; p = 0.012), particularly peripheral obliterans arterial vasculopathy (OR 2.02; 95%CI 1.14-3.57; p = 0.015). Among subjects with a Framingham risk score >20, and/or diabetes, and/or body mass index >35 kg/m², aPL positivity was associated to the highest risk of CV events (OR 2.52, 95%CI 1.24-5.11; p = 0.011).

CONCLUSIONS

APL prevalence in the general population is higher than previously reported. CV events and subclinical atherosclerosis are more frequent in the presence of aPL, particularly when a high CV risk coexists.

Laboratory Evaluation of Antiphospholipid Syndrome

OBJECTIVES

Anti-β2 glycoprotein I domain I (anti-domain I) and anti-phosphatidylserine/prothrombin (aPS/PT) antibodies are present in patients with antiphospholipid syndrome (APS); however, their use in evaluation remains unclear.

METHODS

Diagnostic attributes of lupus anticoagulant (LAC), anti-domain I IgG, anti-cardiolipin, anti-β2 glycoprotein I (anti-β2GPI), and aPS/PT IgG and IgM antibodies were assessed in 216 patients evaluated for APS.

RESULTS

LAC had the best odds ratio (OR, 14.2) while that for anti-domain 1 IgG was comparable to anti-β2GPI IgG (OR, 8.3 vs 9.4) but higher than all others. Significant correlations were observed for thrombosis (P = .03) and pregnancy-related morbidity (P = .001) with anti-domain IgG and for any thrombosis with aPS/PT IgG (P = .006). Use of noncriteria antiphospholipid with or without criteria markers did not significantly increase the probability to diagnose APS.

CONCLUSIONS

Noncriteria tests can contribute to diagnosis and stratification of APS but do not improve diagnostic yield. Optimal strategies for implementation require prospective investigation.

A cross-reactive monoclonal antibody as universal detection antibody in autoantibody diagnostic assays

Diagnostics of Autoimmune Diseases involve screening of patient samples for containing autoantibodies against various antigens. To ensure quality of diagnostic assays a calibrator is needed in each assay system. Different calibrators as recombinant human monoclonal antibodies as well as chimeric antibodies against the autoantigens of interest are described. A less cost-intensive and also more representative possibility covering different targets on the antigens is the utilization of polyclonal sera from other species. Nevertheless, the detection of human autoantibodies as well as the calibration reagent containing antibodies from other species in one assay constitutes a challenge in terms of assay calibration. We therefore developed a cross-reactive monoclonal antibody which binds human as well as rabbit sera with similar affinities in the nanomolar range. We tested our monoclonal antibody S38CD11B12 successfully in the commercial Serazym® Anti-Cardiolipin-ß2-GPI IgG/IgM assay and could thereby prove the eligibility of S38CD11B12 as detection antibody in autoimmune diagnostic assays using rabbit derived sera as reference material.

Evaluation of the sensitivity and specificity of a novel line immunoassay for the detection of criteria and non-criteria antiphospholipid antibodies in comparison to established ELISAs

Background

Persistent antiphospholipid antibodies (aPL) constitute the serological hallmark of the antiphospholipid syndrome (APS). Recently, various new assay technologies for the detection of aPL better suited to multiplex reaction environments than ELISAs emerged. We evaluated the diagnostic performance of such a novel line immunoassay (LIA) for the simultaneous detection of 10 different aPL.

Methods

Fifty-three APS patients and 34 healthy controls were investigated for criteria (antibodies against cardiolipin [aCL], β2-glycoprotein I [aβ2-GPI]) and non-criteria aPL (antibodies against phosphatidic acid [aPA], phosphatidyl-choline [aPC], -ethanolamine [aPE], -glycerol [aPG], -inositol [aPI], -serine [aPS], annexin V [aAnnV], prothrombin [aPT]) IgG and IgM by LIA. Criteria aPL were additionally determined with the established Alegria (ALE), AcuStar (ACU), UniCap (UNI), and AESKULISA (AES) systems and non-criteria aPL with the AES system. Diagnostic performance was evaluated with a gold standard for criteria aPL derived from the results of the four established assays via latent class analysis and with the clinical diagnosis as gold standard for non-criteria aPL.

Results

Assay performance of the LIA for criteria aPL was comparable to that of ALE, ACU, UNI, and AES. For non-criteria aPL, sensitivities of the LIA for aPA-, aPI-, aPS-IgG and aPA-IgM were significantly higher and for aPC-, aPE-, aAnnV-IgG and aPC- and aPE-IgM significantly lower than AES. Specificities did not differ significantly.

Conclusions

The LIA constitutes a valuable diagnostic tool for aPL profiling. It offers increased sensitivity for the detection of aPL against anionic phospholipids. In contrast, ELISAs exhibit strengths for the sensitive detection of aPL against neutral phospholipids.

Antı-β2 Glycoprotein I Antibodies in Children with Rheumatologic Disorders

Anti-beta-2-glycoprotein I antibodies (anti-β2GPI) which are the main antiphospholipid antibodies that characterize the autoimmune "antiphospholipid syndrome" are pathogenic and are contributing to thrombosis. We aimed to evaluate the presence and the diagnostic importance of these antibodies in children with different rheumatologic diseases with or without thrombosis risk. A total of 100 children with different rheumatologic diseases evaluated retrospectively. The mean anti-β2GPI IgG (p = 0.108), IgA (p = 0.547), and IgM (p = 0.807) levels showed no statistically significant difference between different diagnosis groups. But anti-β2GPI IgA and IgM levels were higher in SLE patient group. The mean anti-β2GPI IgG (p = 0.375), IgA (p = 0.811), and IgM (p = 0.276) levels were not also showed difference between disease groups with/without predisposition to thrombosis even though concentrations were higher in thrombosis group. In children with rheumatological complaints, anti-β2GPI antibody measurements should not be the first diagnostic criteria if vasculitis is not thought as the primary defect underlying the clinical symptoms.

Antiphospholipid syndrome: state of the art on clinical practice guidelines

Antiphospholipid syndrome (APS) is a rare disease characterised by venous and/or arterial thrombosis, pregnancy complications and the presence of specific autoantibodies called antiphospholipid antibodies. This review aims to identify existing clinical practice guidelines (CPG) as part of the ERN ReCONNET project, aimed at evaluating existing CPGs or recommendations in rare and complex diseases. Seventeen papers providing important data were identified; however, the literature search highlighted the scarceness of reliable clinical data to develop CPGs. With no formal clinical guidelines in place, diagnosis and treatment of APS is largely based on consensus and expert opinion. Patients' unmet need refers to the understanding of the disease and its clinical picture and implications, the need of education for patients, family members and healthcare providers, as well as to the development of monitoring pathways involving multiple healthcare providers.

The Clinical Performance of a New Chemiluminescent Immunoassay in Measuring Anti-β2 Glycoprotein 1 and Anti-Cardiolipin Antibodies

BACKGROUND Laboratory criterion is needed for the classification of antiphospholipid syndrome (APS), which contain anticardiolipin antibodies (aCL) and anti-β2-glycoprotein 1 antibodies (aβ2GP1). They are commonly identified by enzyme-linked immunosorbent assay (ELISA), but lack standardized kits, resulting in substantial variations in the antibody positivity between different laboratories. The emergence of chemiluminescence automated -BIO-FLASH may improve the situation. MATERIAL AND METHODS We selected 185 patients with APS, systemic lupus erythematosus (SLE), infertility, connective tissue disease (CTD), and other conditions in Peking University Third Hospital. We tested the aCL and aβ2GP1 levels by EUROIMMUN ELISA and 105 patients had at least one positive result for aCL and aβ2GP1, while the others had negative results. We retested them by chemiluminescence assay (CIA) and analyzed the result and compared the coincidence rate. The IgM levels were retested by AESKU ELISA. Data were analyzed using SPSS. RESULTS Our result suggested that CIA had good performance for IgG isotype of aCL and aβ2GP1 in the coincidence rate. The positive coincidence rate of aCL IgM between CIA and EUROIMMUN ELISA was only 41.67%, but two ELISA kits showed good coincidence, CIA and AESKU ELISA had an obviously higher positive rate. CIA and AESKU had a higher coincidence than that of AESKU and EUROIMMUN in aβ2GP1-IgM. CONCLUSIONS The new automated CIA BIO-FLASH is suitable for detecting aCL and aβ2GP1 antibodies, especially IgG isotype, which may provide an alternative to time-consuming conventional ELISA method.

Immunoglobulin A anti-phospholipid antibodies in Swedish cases of systemic lupus erythematosus: associations with disease phenotypes, vascular events and damage accrual

Immunoglobulin (Ig) G- and IgM-class anti-cardiolipin antibodies (aCL) and lupus anti-coagulant (LA) are included in the 1997 update of the American College of Rheumatology (ACR-97) systemic lupus erythematosus (SLE) criteria. Despite limited evidence, IgA-aCL and IgA anti-β₂ -glycoprotein-I (anti-β₂ GPI) were included in the 2012 Systemic Lupus International Collaborating Clinics criteria. The present study aimed to evaluate IgG-/IgA-/IgM-aCL and anti-β₂ GPI occurrence in relation to disease phenotype, smoking habits, pharmacotherapy, anti-phospholipid syndrome (APS) and organ damage among 526 Swedish SLE patients meeting ACR-97. Patients with rheumatoid arthritis (n = 100), primary Sjögren's syndrome (n = 50) and blood donors (n = 507) served as controls. Anti-phospholipid antibodies (aPL) were analysed by fluoroenzyme-immunoassays detecting aCL/anti-β₂ GPI. Seventy-six (14%) SLE cases fulfilled the Sydney APS-criteria, and ≥ 1 aCL/anti-β₂ GPI isotype (IgG/IgA/IgM) occurred in 138 SLE patients (26%). Forty-five (9%) of the SLE cases had IgA-aCL, 20 of whom (4%) lacked IgG-/IgM-aCL. Seventy-four (14%) tested positive for IgA anti-β₂ GPI, 34 (6%) being seronegative regarding IgG/IgM anti-β₂ GPI. Six (1%) had APS manifestations but were seropositive regarding IgA-aCL and/or IgA anti-β₂ GPI in the absence of IgG/IgM-aPL and LA. Positive LA and IgG-aPL tests were associated with most APS-related events and organ damage. Exclusive IgA anti-β₂ GPI occurrence associated inversely with Caucasian ethnicity [odds ratio (OR) = 0·21, 95% confidence interval (CI) = 0·06-0·72) and photosensitivity (OR = 0·19, 95% CI = 0·05-0·72). Nephritis, smoking, LA-positivity and statin/corticosteroid-medication associated strongly with organ damage, whereas hydroxychloroquine-medication was protective. In conclusion, IgA-aPL is not rare in SLE (16%) and IgA-aPL analysis may have additional value among SLE cases with suspected APS testing negative for other isotypes of aPL and LA.

McMaster RARE-Bestpractices clinical practice guideline on diagnosis and management of the catastrophic antiphospholipid syndrome

Background The McMaster RARE-Bestpractices project group selected the catastrophic antiphospholipid syndrome (CAPS) for a pilot exercise in guideline development for a rare disease. Objectives The objectives of this exercise were to provide a proof of principle that guidelines can be developed for rare diseases and assist in clinical decision making for CAPS. Patients/Methods The GIN-McMaster Guideline Development checklist and GRADE methodology were followed throughout the guideline process. The CAPS guideline was coordinated by a steering committee, and the guideline panel was formed with representation from all relevant stakeholder groups. Systematic reviews were performed for the key questions. To supplement the published evidence, we piloted novel methods, including use of an expert-based evidence elicitation process and ad hoc analysis of registry data. Results This paper describes the CAPS guideline recommendations, including evidence appraisal and discussion of special circumstances and implementation barriers identified by the panel. Many of these recommendations are conditional, because of subgroup considerations in this heterogeneous disease, as well as variability in patient values and preferences. Conclusions The CAPS clinical practice guideline initiative met the objective of the successful development of a clinical practice guideline in a rare disease using GRADE methodology. We expect that clinicians caring for patients with suspected CAPS will find the guideline useful in assisting with diagnosis and management of this rare disease.

Thrombotic risk assessment and analytical performance of the chemiluminescent analyzer IDS-iSYS for the detection of anti-cardiolipin and anti-beta 2 glycoprotein I autoantibodies

Patients with antiphospholipid antibodies (APLA) are predisposed to develop thrombosis, however the standardization of anti-cardiolipin (aCL) and anti-beta 2 glycoprotein I (β2-GPI) Ab assays are challenging. Therefore we decided to test the performance of a new chemiluminescent assay (CLIA), and assayed aCL and aβ2-GPI IgG/M in serum from 120 healthy individuals, 108 patients with idiopathic venous thrombosis, 78 patients with antiphospholipid syndrome (APS), and 64 non-thrombotic APLA-carriers using CLIA IDS-iSYS. Very good (aCL/aβ2-GPI IgG) to moderate (aCL/aβ2-GPI IgM) agreement with a commercial and an in house ELISA assay were observed and, in particular, CLIA demonstrated the highest sensitivity in aβ2-GPI IgG detection. Finally, aCL/aβ2-GPI Ab capacity to predict the thrombotic risk was tested showing for CLIA a significant odds ratio (OR) when considering double positivity for aCL/aβ2-GPI IgG, aCL IgG at high levels, and aβ2-GPI IgG at high levels. In conclusion, CLIA improves aβ2-GPI IgG detection and thrombotic risk assessment.

Assessment of diagnostic methods for the detection of anticardiolipin and anti-βeta2 glycoprotein I antibodies in patients under routine evaluation for antiphospholipid syndrome

BACKGROUND

We assessed the performance characteristics and correlations of the traditional enzyme-linked immunosorbent assay (ELISA) and chemiluminescence immunoassay (CIA) for detecting IgG and IgM antibodies to cardiolipin (aCL) and beta₂ glycoprotein (anti-β₂GPI) antibodies in patients under routine evaluation for APS.

METHODS

Patients (n = 216) referred to ARUP Laboratories for lupus anticoagulant (LAC) and/or aCL or anti-β₂GPI IgG/IgM antibodies evaluation were assessed by ELISA and CIA methods. Diagnostic accuracies, correlations between methods and specific clinical manifestations in APS were investigated.

RESULTS

The areas under the curve (%) for APS using LAC with CIA (74, 95% CI: 65-82) or ELISA (70, 95% CI: 61-79) aPLs were comparable. The overall agreements and linear regression correlations between methods for aPL antibody of the same specificity were variable: aCL IgG 87.3%; R² = 0.7491, aCL IgM 71.6%; R² = 0.2656, anti-β₂GPI IgG 77.2%; R² = 0.7688 and anti-β₂GPI IgM 81.7%; R² = 0.3305.

CONCLUSIONS

With inclusion of LAC, the ELISA and CIA show comparable performance for the diagnosis of APS. However, correlations of APS-specific manifestations were dependent on method of detecting the aPL antibodies suggesting platforms may not be used interchangeable.

Revisiting the Phadia/EliA cut-off values for anticardiolipin and anti-β2-glycoprotein I antibodies: a systematic evaluation according to the guidelines

Background Phadia/EliA fluorescence enzyme immunoassays are widely used automated assays for anticardiolipin (aCL) and anti-β2-glycoprotein I (aβ2GPI) antibodies. To date, cut-off values for these assays have not been evaluated systematically and the evidence behind manufacturer's recommended cut-off values is not clear. Objective To determine Phadia/EliA cut-off values for antiphospholipid antibodies (aPL) according to the procedures suggested by guidelines. Methods A total of 266 blood donors (135 females and 131 males) were included. The pre-handling and analysis of the samples were performed according to the International Society on Thrombosis and Hemostasis (ISTH) guideline for solid phase aPL assays. Cut-off values and corresponding 90% confidence intervals (CI) for each antibody were established and outliers were handled according to the Clinical and Laboratory Standards Institute (CLSI) guideline for reference intervals. Samples from 377 consecutive patients, referred to our thrombophilia center with evidence of thrombosis or pregnancy morbidity were included for aPL testing. Results The in-house 99th (97.5th) percentile cut-off values were 11 (8.7), 12 (6.9) 8.5 (5.0) AU/mL for aβ2GPI IgG, IgM and IgA, and 21 (13) GPL-U/mL and 41 (25) MPL-U/mL for aCL IgG and IgM, respectively. The prevalence of positive results (%) defined by these cut-off values in patients with evidence of thrombosis or pregnancy morbidity was 9.5 (12.2), 1.6 (2.9), and 7.0 (9.9), and 0.8 (3.8) for aβ2GPI IgG, IgM, and aCL IgG and IgM respectively. The use of in-house 99th percentile cut-off values compared to the manufacturer suggested cut-off values resulted in 1 and 39 fewer samples for aβ2GPI and aCL to be classified as positive for aPL, respectively. Conclusions We present Phadia/EliA cut-off values with 90% CI for aPL determined systematically according to the ISTH and CLSI guidelines. These values are different from values previously determined, suggesting variation of aPLs in different populations. Our findings indicate the need for each laboratory to determine/validate assay specific cut-off values for aPL.

Recent initiatives in harmonization of hemostasis practice

Accepting that standardizing and harmonizing laboratory practice has considerable value within laboratory medicine, including within the field of hemostasis, this paper concentrates on some recent and important initiatives in harmonizing hemostasis practice. Harmonization of hemostasis practice to improve clinical diagnosis and management is best driven by evidence and, in the absence of evidence, by consensus and expert opinion. To such end, there are various groups involved in such initiatives, and recent initiatives by these groups are highlighted in this review.

Towards harmonization of external quality assessment/proficiency testing in hemostasis

Quality in diagnostic testing represents a key target of laboratory medicine, for which an assurance around the quality of testing is expected from all involved in the process. Laboratories attempt to assure the quality of their testing by various processes, but especially by performance of internal quality control and external quality assessment (EQA). This is especially true for tests of hemostasis and coagulation. EQA in general provides information on test accuracy and on evaluation of long-term laboratory performance. EQA providers support laboratory performance by various means, including distribution of material for testing of analytes (“proficiency testing”), educational support through expert advice, distribution of publications or case series. Participation in EQA is often a laboratory accreditation requirement. This review aims to identify some of the strengths and weaknesses of EQA, and targets attempts towards harmonization of EQA practice, in order to achieve the best outcome for participant laboratories and, thus, for patients and their clinical care providers.

Diagnosis and management of non-criteria obstetric antiphospholipid syndrome

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 preeclampsia, 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.

Antiphospholipid syndrome and IgA anti-beta2-glycoprotein I antibodies: when Cinderella becomes a princess

IgA anti-beta2-glycoprotein I (IgA-aB2GPI) antibodies are currently not included as a laboratory criterion of antiphospholipid syndrome (APS). In the 13th International Congress on Antiphospholipid Antibodies, Galveston, TX, (USA) in 2010, these antibodies were accepted as an APS laboratory criterion in patients who had clinical manifestations of APS but were negative for "consensus" antiphospholipid antibodies (aPL) (IgG and IgM isotypes). Consequently, individuals with thrombotic events who are negative for consensus aPL may be undiagnosed for APS. The most recent publications have confirmed that IgA-aB2GPI antibodies are a risk factor for thrombotic events. In this viewpoint, we propose that IgA-aB2GPI antibodies should be included as an APS consensus criterion and that we have to help Cinderella become a princess.