Antiphospholipid antibodies and the risk of thrombocytopenia in patients with systemic lupus erythematosus: A systematic review and meta-analysis

Immune thrombocytopenia in systemic lupus erythematosus: Prevalence, risk factors, and a novel predictive model for risk assessment

INTRODUCTION

Immune thrombocytopenia (ITP) is a potentially severe manifestation of systemic lupus erythematosus (SLE) reported in 7-40% of SLE patients. ITP has been associated with a higher risk of organ damage and mortality.

OBJECTIVES

To describe which factors are associated with the presence of ITP in SLE patients.

METHODS

Retrospective case-control study. Cases were defined as SLE patients who had ever developed ITP and were sex- and age-matched with two controls. A predictive model was constructed to identify SLE patients who were at risk of developing ITP.

RESULTS

ITP prevalence in our SLE cohort was 8.35%. Cases had a higher frequency of hemolytic anemia, while controls had a higher prevalence of arthritis at SLE diagnosis. During SLE progression, cases tested positive for anticardiolipin, anti-β2-glycoprotein 1, and lupus anticoagulant antibodies more frequently. Cases received mycophenolic acid and azathioprine more often than controls and had a higher SLICC/ACR score. The model demonstrated a sensitivity of 87.53%, a positive predictive value of 81.92%, a specificity of 80.50%, area under the curve of 83.92%, a F1 of 83% and an overall accuracy of 83.68%. The variables that best explain the model were hemolytic anemia, arthritis, oral ulcers, Raynaud's phenomenon, low C4, low CH50, anticardiolipin and anti-β2GP1 antibodies.

CONCLUSION

SLE patients who develop ITP have a distinct phenotype characterized by more hemolytic anemia and less arthritis at SLE onset, and higher prevalence of antiphospholipid syndrome antibodies during SLE progression. This phenotype is associated with heightened organ damage and the need for more intensive therapies and stricter follow-up. Our predictive model has demonstrated an impressive ability to identify SLE patients at risk of developing ITP.

Systemic Lupus Erythematosus: A Review

Importance

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by inflammation and immune-mediated injury to multiple organ systems, including the mucocutaneous, musculoskeletal, hematologic, and kidney systems. Approximately 3.4 million people worldwide have received a diagnosis of SLE.

Observations

Approximately 90% of people with SLE are female. Although there are no uniformly accepted diagnostic criteria for SLE, the 2019 European Alliance of Associations for Rheumatology (formerly the European League Against Rheumatism)/American College of Rheumatology classification criteria developed for scientific study are an estimated 96.1% sensitive and 93.4% specific for SLE. These classification criteria include both clinical factors, such as fever, cytopenia, rash, arthritis, and proteinuria, which may be indicative of lupus nephritis; and immunologic measures, such as SLE-specific autoantibodies and low complement levels. Approximately 40% of people with SLE develop lupus nephritis, and an estimated 10% of people with lupus nephritis develop end-stage kidney disease after 10 years. The primary goal of treatment is to achieve disease remission or quiescence, defined by minimal symptoms, low levels of autoimmune inflammatory markers, and minimal systemic glucocorticoid requirement while the patient is treated with maintenance doses of immunomodulatory or immunosuppressive medications. Treatment goals include reducing disease exacerbations, hospitalizations, and organ damage due to the disease or treatment toxicity. Hydroxychloroquine is standard of care for SLE and has been associated with a significant reduction in mortality. Treatments in addition to hydroxychloroquine are individualized, with immunosuppressive agents, such as azathioprine, mycophenolate mofetil, and cyclophosphamide, typically used for treating moderate to severe disease. Three SLE medications were recently approved by the Food and Drug Administration: belimumab (for active SLE in 2011 and for lupus nephritis in 2020), voclosporin (for lupus nephritis), and anifrolumab (for active SLE).

Conclusions and Relevance

Systemic lupus erythematosus is associated with immune-mediated damage to multiple organs and increased mortality. Hydroxychloroquine is first-line therapy and reduces disease activity, morbidity, and mortality. When needed, additional immunosuppressive and biologic therapies include azathioprine, mycophenolate mofetil, cyclophosphamide, belimumab, voclosporin, and anifrolumab.

Clinical presentation and outcomes in patients with antiphospholipid syndrome-associated adrenal hemorrhage. A multicenter cohort study and systematic literature review

BACKGROUND

Adrenal hemorrhage (AH) can occur in patients with antiphospholipid Syndrome (APS). We aimed to characterize the clinical manifestations, treatments, and outcomes of patients presenting with APS-associated AH (APS-AH) through a retrospective cohort and a systematic literature review (SLR).

METHODS

We performed a mixed-source approach combining a multicenter cohort with an SLR of patients with incident APS-AH. We included patients from Mayo Clinic and published cases with persistent positivity for antiphospholipid antibodies and presenting with AH, demonstrated by imaging or biopsy. We extracted demographics, clinical characteristics, laboratory findings, treatment strategies, and outcomes (primary adrenal insufficiency and mortality). We used Kaplan-Meier and Cox models for survival analysis.

RESULTS

We included 256 patients in total, 61 (24%) from Mayo Clinic and 195 (76%) from the SLR. The mean age was 46.8 (SD 15.2) years, and 45% were female. 69% of patients had bilateral adrenal involvement and 64% presented adrenal insufficiency. The most common symptoms at presentation were abdominal pain in 79%, and nausea and vomiting 46%. Hyponatremia (77%) was the most common electrolyte abnormality. Factors associated with primary adrenal insufficiency were bilateral adrenal involvement at initial imaging (OR 3.73, CI; 95%, 1.47-9.46) and anticardiolipin IgG positivity (OR 3.80, CI; 95%, 1.30-11.09). The survival rate at five years was 82%. History of stroke was associated with 3.6-fold increase in mortality (HR 3.62, 95% CI; 1.33-9.85).

CONCLUSION

AH is a severe manifestation of APS with increased mortality. Most patients developed permanent primary adrenal insufficiency, particularly those positive for anticardiolipin IgG and bilateral adrenal involvement.

The impact of antiphospholipid antibodies/antiphospholipid syndrome on systemic lupus erythematosus

aPLs are a major determinant of the increased cardiovascular risk in patients with SLE. They adversely affect clinical manifestations, damage accrual and prognosis. Apart from the antibodies included in the 2006 revised classification criteria for APS, other non-classical aPLs might help in identifying SLE patients at increased risk of thrombotic events. The best studied are IgA anti-β2-glycoprotein I, anti-domain I β2-glycoprotein I and aPS-PT. Major organ involvement includes kidney and neuropsychiatric systems. aPL/APS severely impacts pregnancy outcomes. Due to increased thrombotic risk, these patients require aggressive cardiovascular risk factor control. Primary prophylaxis is based on low-dose aspirin in high-risk patients. Warfarin is the gold-standard drug for secondary prophylaxis.

Belimumab therapy for refractory immune thrombocytopenia in systemic lupus erythematosus patients with anti-phospholipid antibodies

OBJECTIVE

To observe the effect of belimumab treatment in refractory anti-phospholipid antibody-associated immune thrombocytopenia with systemic lupus erythematosus (SLE).

METHOD

Four SLE patients with refractory anti-phospholipid antibody-associated immune thrombocytopenia were included in this one-arm observational study. Inclusion criteria were a diagnosis of SLE according to 1997 American College of Rheumatology criteria, severe immune thrombocytopenia (platelets <30 × 109/L), no bleeding symptoms, lack of satisfactory response to traditional treatment, and high-titre anti-phospholipid antibodies. All patients received belimumab (Benlysta®) for 6 months.

RESULTS

The mean platelet count was 21.8 × 109 cells/L, ranging between 16 and 29 × 109/L at baseline, 123.3 × 109/L at 1 month, and 172.5 × 109/L at the end of 6 months after belimumab treatment. No bleeding complications occurred during the entire follow-up period.

CONCLUSION

In this study, belimumab reduced the anti-phospholipid antibodies while increasing the platelet count in SLE patients with anti-phospholipid antibody-associated immune thrombocytopenia.

Thrombocytopenia in antiphospholipid syndrome: Is anticoagulation and/or antiaggregation always required?

The antiphospholipid syndrome (APS) is an autoimmune and prothrombotic condition defined by the association of thrombotic events and/or obstetrical complications and the persistence of antiphospholipid antibodies (aPL) over time. Among the new criteria recently included in the 2023 ACR/EULAR classification criteria for APS, thrombocytopenia is one of the most frequent. The occurrence of thrombocytopenia in aPL/APS patients is important to consider because it could predict APS-related clinical events with a 3-fold increased risk for thrombotic events or obstetrical morbidity or all-cause deaths. A debate on the need or not of anticoagulation and/or antiaggregation in APS patients and aPL carriers with thrombocytopenia took place on the 7th edition of the International Congress on Controversies in Rheumatology and Autoimmunity (CORA), that was organized in Turin, Italy, on March 18th, 2023, and this review summarizes the main arguments that were discussed in this session.

Anti-phospholipid autoantibodies in human diseases

Anti-phospholipid autoantibodies are a group of antibodies that can specifically bind to anionic phospholipids and phospholipid protein complexes. Recent studies have reported elevated serum anti-phospholipid autoantibody levels in patients with antiphospholipid syndrome, systemic lupus erythematosus, rheumatoid arthritis, metabolic disorders, malaria, SARS-CoV-2 infection, obstetric diseases and cardiovascular diseases. However, the underlying mechanisms of anti-phospholipid autoantibodies in disease pathogenesis remain largely unclear. Emerging evidence indicate that anti-phospholipid autoantibodies modulate NETs formation, monocyte activation, blockade of apoptotic cell phagocytosis in macrophages, complement activation, dendritic cell activation and vascular endothelial cell activation. Herein, we provide an update on recent advances in elucidating the effector mechanisms of anti-phospholipid autoantibodies in the pathogenesis of various diseases, which may facilitate the development of potential therapeutic targets for the treatment of anti-phospholipid autoantibody-related disorders.

2023 ACR/EULAR antiphospholipid syndrome classification criteria

OBJECTIVE

To develop new antiphospholipid syndrome (APS) classification criteria with high specificity for use in observational studies and trials, jointly supported by the American College of Rheumatology (ACR) and EULAR.

METHODS

This international multidisciplinary initiative included four phases: (1) Phase I, criteria generation by surveys and literature review; (2) Phase II, criteria reduction by modified Delphi and nominal group technique exercises; (3) Phase III, criteria definition, further reduction with the guidance of real-world patient scenarios, and weighting via consensus-based multicriteria decision analysis, and threshold identification; and (4) Phase IV, validation using independent adjudicators' consensus as the gold standard.

RESULTS

The 2023 ACR/EULAR APS classification criteria include an entry criterion of at least one positive antiphospholipid antibody (aPL) test within 3 years of identification of an aPL-associated clinical criterion, followed by additive weighted criteria (score range 1-7 points each) clustered into six clinical domains (macrovascular venous thromboembolism, macrovascular arterial thrombosis, microvascular, obstetric, cardiac valve, and hematologic) and two laboratory domains (lupus anticoagulant functional coagulation assays, and solid-phase enzyme-linked immunosorbent assays for IgG/IgM anticardiolipin and/or IgG/IgM anti-β2-glycoprotein I antibodies). Patients accumulating at least three points each from the clinical and laboratory domains are classified as having APS. In the validation cohort, the new APS criteria vs the 2006 revised Sapporo classification criteria had a specificity of 99% vs 86%, and a sensitivity of 84% vs 99%.

CONCLUSION

These new ACR/EULAR APS classification criteria were developed using rigorous methodology with multidisciplinary international input. Hierarchically clustered, weighted, and risk-stratified criteria reflect the current thinking about APS, providing high specificity and a strong foundation for future APS research.

The 2023 ACR/EULAR Antiphospholipid Syndrome Classification Criteria

OBJECTIVE

To develop new antiphospholipid syndrome (APS) classification criteria with high specificity for use in observational studies and trials, jointly supported by the American College of Rheumatology (ACR) and EULAR.

METHODS

This international multidisciplinary initiative included 4 phases: 1) Phase I, criteria generation by surveys and literature review; 2) Phase II, criteria reduction by modified Delphi and nominal group technique exercises; 3) Phase III, criteria definition, further reduction with the guidance of real-world patient scenarios, and weighting via consensus-based multicriteria decision analysis, and threshold identification; and 4) Phase IV, validation using independent adjudicators' consensus as the gold standard.

RESULTS

The 2023 ACR/EULAR APS classification criteria include an entry criterion of at least one positive antiphospholipid antibody (aPL) test within 3 years of identification of an aPL-associated clinical criterion, followed by additive weighted criteria (score range 1-7 points each) clustered into 6 clinical domains (macrovascular venous thromboembolism, macrovascular arterial thrombosis, microvascular, obstetric, cardiac valve, and hematologic) and 2 laboratory domains (lupus anticoagulant functional coagulation assays, and solid-phase enzyme-linked immunosorbent assays for IgG/IgM anticardiolipin and/or IgG/IgM anti-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%.

CONCLUSION

These new ACR/EULAR APS classification criteria were developed using rigorous methodology with multidisciplinary international input. Hierarchically clustered, weighted, and risk-stratified criteria reflect the current thinking about APS, providing high specificity and a strong foundation for future APS research.

2022 Chinese guideline for the management of pregnancy and reproduction in systemic lupus erythematosus

Systemic lupus erythematosus (SLE), a prevalent autoimmune disease predominantly affecting women of childbearing age, presents ongoing challenges despite notable advances in diagnosis and treatment. Although survival rates for SLE patients have significantly improved, pregnancy continues to pose a considerable obstacle. Addressing this critical need for enhanced reproductive and prenatal care, there is a pressing imperative to establish standardized protocols for peri-gestational monitoring and treatment in SLE patients. This guideline is jointly sponsored by the National Clinical Research Center for Dermatologic and Immunologic Diseases (NCRC-DID), the Chinese Systemic Lupus Erythematosus Treatment and Research Group (CSTAR), and the Chinese Research Committee of Pregnancy and Reproduction in Autoimmune Rheumatic Diseases (CHOPARD). Thirteen pertinent clinical questions have been generated through several rounds of rigorous clinical and methodological expert discussions and selections for a comprehensive understanding of key aspects in this domain. Guided by thorough examination of research evidence and expert perspectives, the formulated recommendations aim to optimize pregnancy success rates, reduce maternal and infant mortality rates, and ultimately enhance the overall well-being of SLE patients.

Severe thrombocytopenia is associated with high mortality in systemic lupus erythematosus-analysis from Indian SLE Inception cohort for Research (INSPIRE)

Thrombocytopenia in patients with systemic lupus erythematosus (SLE) is associated with higher morbidity and mortality. We report frequency, associations and short-term outcome of moderate-severe thrombocytopenia in a prospective inception cohort from India (INSPIRE). We evaluated consecutive SLE patients classified per SLICC2012 for the occurrence of thrombocytopenia and its associations. The outcomes assessed included bleeding manifestations, kinetics of thrombocytopenia recovery, mortality and recurrence of thrombocytopenia. Among a total of 2210 patients in the cohort, 230 (10.4%) had incident thrombocytopenia, of whom moderate (platelet count [PC] 20-50 × 109/L) and severe thrombocytopenia (PC < 20 × 109/L) were noted in 61 (26.5%) and 22 (9.5%), respectively. Bleeding manifestations were generally limited to the skin. Compared to controls, cases had a higher proportion of autoimmune haemolytic anaemia (p < 0.001), leukopenia (p < 0.001), lymphopenia (p < 0.001), low complement (p < 0.05), lupus anticoagulant (p < 0.001), higher median SLEDAI 2 K (p < 0.001) and lower proportion of anti-RNP antibody (p < 0.05). There was no significant difference in these variables between moderate and severe thrombocytopenia. There was a sharp rise in PC by 1 week that was sustained in the majority through the period of observation. There was three times higher mortality in the severe thrombocytopenia group as compared to moderate thrombocytopenia and controls. The thrombocytopenia relapse and lupus flare rates were similar across categories. We report a low occurrence of major bleeds and higher mortality in those with severe thrombocytopenia as compared to moderate thrombocytopenia and controls. Key Points • Severe thrombocytopenia occurs in 1% of patients with SLE; however, major bleeds are uncommon. • Thrombocytopenia has a strong association with other lineage cytopenias and lupus anticoagulants. • Response to initial glucocorticoids therapy is quick and is well sustained with additional immunosuppressants. • Severe thrombocytopenia increases mortality threefold in SLE.

French National Diagnostic and Care Protocol for antiphospholipid syndrome in adults and children

Antiphospholipid syndrome (APS) is a chronic autoimmune disease involving vascular thrombosis and/or obstetric morbidity and persistent antibodies to phospholipids or certain phospholipid-associated proteins. It is a rare condition in adults and even rarer in children. The diagnosis of APS can be facilitated by the use of classification criteria based on a combination of clinical and biological features. APS may be rapidly progressive with multiple, often synchronous thromboses, resulting in life-threatening multiple organ failure. This form is known as "catastrophic antiphospholipid syndrome" (CAPS). It may be primary or associated with systemic lupus erythematosus (associated APS) and in very rare cases with other systemic autoimmune diseases. General practitioners and paediatricians may encounter APS in patients with one or more vascular thromboses. Because APS is so rare and difficult to diagnosis (risk of overdiagnosis) any suspected case should be confirmed rapidly and sometimes urgently by an APS specialist. First-line treatment of thrombotic events in APS includes heparin followed by long-term anticoagulation with a VKA, usually warfarin. Except in the specific case of stroke, anticoagulants should be started as early as possible. Any temporary discontinuation of anticoagulants is associated with a high risk of thrombosis in APS. A reference/competence centre specialised in autoimmune diseases must be urgently consulted for the therapeutic management of CAPS.

Persistence of antiphospholipid antibodies over time and its association with recurrence of clinical manifestations: A longitudinal study from a single centre

PURPOSE

To analyze the antiphospholipid antibody (aPL) persistence over time in patients with antiphospholipid syndrome (APS) and its association with clinical recurrence and to identify predictors of aPL persistence over time.

PATIENTS AND METHODS

200 patients with a diagnosis of APS and at least three follow-up aPL determinations were included. Persistent aPL profile was defined as the presence of lupus anticoagulant (LAC) and/or IgG/IgM anticardiolipin (aCL) and/or IgG/IgM anti-β2 glycoprotein-I (aβ2GPI) (> 99th percentile) antibodies in at least 66% of follow-up measurements. Multilevel mixed-effect generalized linear models with logit link were used.

RESULTS

112 (56%) patients maintained persistent aPL profiles over time, while 88 (44%) were transient. Median follow-up time was 172.5 months. Follow-up time did not affect the odds of aPL persistence in multivariate analysis (p = 1.00). Baseline triple aPL positivity [OR 78 (95%CI 16.9-359.7, p < 0.001)] and double aPL positivity [OR = 7.6 (95%CI 3.7-15.7, p < 0.001)] correlated with persistent aPLs over time, while isolated LAC [OR = 0.26 (95% CI 0.08-0.49, p = 0.002)] or isolated IgG/IgM aCL [OR = 0.20 (95% CI 0.11-0.59, p = 0.004)] positivity, were predictors of transient aPL profile. Patients with persistent aPLs had higher rate of clinical recurrence in comparison to patients with transient aPLs [OR = 2.48 (95%CI 1.34-4.58, p = 0.003)].

CONCLUSIONS

More than half of patients with baseline medium-high titer aPL positivity had persistent positive aPLs over time. Patients with persistent aPLs were more prone to present recurrence of clinical manifestations. Multiple aPL positivity increased the odds of a persistent aPL profile over time, while isolated LAC and aCL positivity decreased it.

Risk of livedo with antiphospholipid antibodies in patients with systemic lupus erythematosus: A systematic review and meta-analysis

Background

Livedo is a well-known skin condition in patients with systemic lupus erythematosus (SLE) which correspond to small vessels involvement. The influence of antiphospholipid antibodies (aPL) on the occurrence of livedo is controversial. The aim of our study was to estimate the risk of livedo associated with aPL in patients with SLE.

Methods

We conducted a systematic review and meta-analysis of the literature from 1977 to 2021 to estimate the risk of livedo in SLE patients according to different aPL profiles. Data sources were PubMed, Embase, Cochrane Library, hand search, and reference lists of studies. Studies were selected if they included SLE patients with descriptions of the exposure to aPL and the outcome ( livedo). Two independent investigators assessed study eligibility, quality, and extracted patient characteristics from each study as well as exposure (aPL) and outcome ( livedo). Risk estimates were pooled using random effects models and sensitivity analyses. For all stages of the meta-analysis, we followed the PRISMA guidelines. PROSPERO registration number: CRD42015027377.

Results

Of the 2,355 articles identified, 27 were included with a total of 4,810 SLE patients. The frequency of livedo was 25.5% in aPL-positive patients and 13.3% in aPL-negative patients. The overall Odds Ratio (OR) for livedo in aPL-positive patients compared to aPL-negative patients was 2.91 (95% CI; 2.17–3.90). The risk of livedo was significantly increased for most of aPL subtypes, including lupus anticoagulant (LA) (OR = 4.45 [95% CI; 2.21–8.94]), IgG anticardiolipin (OR = 3.95 [95% CI; 2.34–6.65]), and IgG anti-β2-glycoprotein 1 (OR = 3.49 [95% CI; 1.68–7.27]).

Conclusions

We demonstrated in this meta-analysis an excess risk of livedo in aPL-positive SLE patients compared to aPL-negative patients. For daily practice, in patients with SLE, livedo associated with aPL could correspond to a peculiar group of patients with small vessel disease. Livedo could be a good candidate for inclusion in future classification criteria for antiphospholipid syndrome.

Solid Phase Assays for Antiphospholipid Antibodies

The diagnosis of antiphospholipid syndrome (APS) relies on the detection of circulating antiphospholipid antibodies (aPL). Currently, lupus anticoagulant (LA), anticardiolipin (aCL), and anti-β2-glycoprotein I antibodies (aβ2GPI) IgG or IgM are the laboratory criteria if persistently present over time. As aCL and aβ2GPI are two out of the three laboratory criteria, the detection of aPL by solid phase assays is an essential step in the diagnosis of APS. Advancement has been made to resolve some of the methodological challenges of aCL and aβ2GPI assays by providing guidelines how to measure aPL, as well as to gain a better understanding of their diagnostic role. However, solid phase assays for aCL and aβ2GPI still show substantive inter-assay differences, resulting in disagreement concerning positive/negative results, but also differences in titer of antibodies. This hampers the semiquantitative classification into low-medium-high positivity. The non-criteria aPL, such as antibodies against the domain one of β2GPI and anti-phosphatidylserine/prothrombin antibodies (aPS/PT) have roles in confirming the risk in APS, and can be useful, especially in patients with incomplete antibody profiles.

Predictors of refractory risk in systemic lupus erythematosus-related thrombocytopenia: a dual-centre retrospective study

Objectives

Based on clinical and laboratory indicators, this study aimed to establish a multiparametric nomogram to assess the risk of refractory cases of SLE-related thrombocytopenia (SLE-related TP) before systematic treatment.

Methods

From June 2012 to July 2021, a dual-centre retrospective cohort study of prospectively collected data of patients with SLE-related TP was conducted. The cohort data were divided into a developing set, internal validation set and external validation set. Refractory thrombocytopenia (RTP) was defined as failed to prednisone at 1 mg/kg per day with a platelet count cannot achieve or maintain higher than 50×10⁹/L. In the developing set, a nomogram were established to predict RTP risk based on clinical characteristics and laboratory indicators by multivariable logistic regression, and its performance was assessed by receiver operating characteristic (ROC) curves, calibration curves, decision curve analysis (DCA) and clinical impact curve (CIC).

Results

A total of 1778 patients with SLE were included, and 413 eligible patients were involved in the final analysis with 121 RTPs. The RTP risk assessment (RRA) model was composed of five significant risk variables: pregnancy, severity of TP, complement 3, anticardiolipin antibody-immunoglobulin G and autoimmune haemolytic anaemia. In three datasets, the AUCs were 0.887 (95% CI 0.830 to 0.945), 0.880 (95% CI 0.785 to 0.975) and 0.871 (95% CI 0.793 to 0.949), respectively. The calibration curve, DCA and CIC all showed good performance of the RRA model.

Conclusion

The RRA model demonstrated good capability for assessing the refractory risk in SLE-related TP, which may be helpful for early identification and intervention.

Laboratory Diagnosis of Antiphospholipid Syndrome: Insights and Hindrances

Diagnosis of antiphospholipid syndrome (APS) requires the presence of a clinical criterion (thrombosis and/or pregnancy morbidity), combined with persistently circulating antiphospholipid antibodies (aPL). Currently, laboratory criteria aPL consist of lupus anticoagulant (LAC), anticardiolipin antibodies (aCL) IgG/IgM, and anti-β2 glycoprotein I antibodies (aβ2GPI) IgG/IgM. Diagnosis and risk stratification of APS are complex and efforts to standardize and optimize laboratory tests have been ongoing since the initial description of the syndrome. LAC detection is based on functional coagulation assays, while aCL and aβ2GPI are measured with immunological solid-phase assays. LAC assays are especially prone to interference by anticoagulation therapy, but strategies to circumvent this interference are promising. Alternative techniques such as thrombin generation for LAC detection and to estimate LAC pathogenicity have been suggested, but are not applicable yet in routine setting. For aCL and aβ2GPI, a lot of different assays and detection techniques such as enzyme-linked immunosorbent and chemiluminescent assays are available. Furthermore, a lack of universal calibrators or standards results in high variability between the different solid-phase assays. Other non-criteria aPL such as anti-domain I β2 glycoprotein I and antiphosphatidylserine/prothrombin antibodies have been suggested for risk stratification purposes in APS, while their added value to diagnostic criteria seems limited. In this review, we will describe laboratory assays for diagnostic and risk evaluation in APS, integrating applicable guidelines and classification criteria. Current insights and hindrances are addressed with respect to both laboratory and clinical implications.

Role of antiphospholipid antibodies in the diagnosis of antiphospholipid syndrome

The diagnosis of antiphospholipid syndrome (APS) relies on the detection of antiphospholipid antibodies (aPL). Currently, lupus anticoagulant (LA), anticardiolipin (aCL), and antibeta2-glycoprotein I antibodies (aβ2GPI) IgG or IgM are included as laboratory criteria, if persistently present. LAC measurement remains a complicated procedure with many pitfalls and interfered by anticoagulant therapy. Solid-phase assays for aCL and aβ2GPI show interassay differences. These methodological issues make the laboratory diagnosis of APS challenging. In the interpretation of aPL results, antibody profiles help in identifying patients at risk. Other aPL, such as antibodies against the domain I of beta2-glycoprotein (aDI) and antiphosphatidylserine-prothrombin (aPS/PT) antibodies have been studied in the last years and may be useful in risk stratification of APS patients. Because of the methodological shortcomings of immunological and clotting assays, these non-criteria aPL may be useful in patients with incomplete antibody profiles to confirm or exclude the increased risk profile. This manuscript will focus on the laboratory aspects, the clinical relevance of assays and interpretation of aPL results in the diagnosis of APS.

•

The presence of antiphospholipid antibodies (aPL) define the diagnosis of the antiphospholipid syndrome (APS).

•

Laboratory criteria are lupus anticoagulant, anticardiolipin (aCL), and antibeta2-glycoprotein I antibodies (aβ2GPI) IgG/IgM.

•

Lupus anticoagulant measurement, as well as solid phase assays for aCL and aβ2GPI, show methodological challenges.

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Antibodies against domain I of β2GPI (aDI) and antiphosphatidylserine-prothrombin (aPS/PT) antibodies are non-criteria aPL.

•

aDI and aPS/PT may be useful in risk stratification of APS patients.

Antiphospholipid antibodies and the risk of autoimmune hemolytic anemia in patients with systemic lupus erythematosus: A systematic review and meta-analysis

BACKGROUND

According to criteria for the classification of Systemic Lupus Erythematosus (SLE), autoimmune hemolytic anemia is one of the disease-defining hematologic disorders together with thrombocytopenia. Since the recognition of Antiphospholipid Syndrome (APS), hemolytic anemia was frequently reported but several studies yielded contradictory results on the association between antiphospholipid antibodies (aPL) and hemolytic anemia. Therefore, we evaluated the association of aPL and autoimmune hemolytic anemia in SLE patients by conducting a systematic review and meta-analysis of available literature.

METHODS

MEDLINE, EMBASE, Cochrane Library, congress abstracts, and reference lists of eligible studies were searched from 1987 to 2020. Studies were selected if they included SLE patients with descriptions of exposure to aPL and occurrence of hemolytic anemia. Three reviewers extracted study characteristics and association data from published reports. Risk estimates were pooled using random effects models and sensitivity analyses. We followed the PRISMA guidelines for all stages of the meta-analysis (Supplemental Table). PROSPERO registration number: CRD42015027376.

RESULTS

From 3555 articles identified, 38 studies met inclusion criteria and included 8286 SLE patients. 20.5% of aPL-positive SLE patients had hemolytic anemia compared to 8.7% in aPL-negative SLE patients. The overall pooled Odds Ratio (OR) for hemolytic anemia in aPL positive patients was 2.83 (95% CI; 2.12-3.79). Among aPL subtypes, the risk of hemolytic anemia was highest for lupus anticoagulant (OR = 3.37 [95% CI; 2.26-5.04]) and, antiβ₂Glycoprotein I antibodies (OR = 3.21 [95% CI; 1.54-6.72]), especially IgM antiβ₂Glycoprotein I (OR = 3.01 [95% CI; 1.26, 7.24]).

CONCLUSIONS

The occurrence of hemolytic anemia was strongly associated with presence of aPL in SLE patients. Interestingly, IgM isotypes indicate an increased risk of hemolytic anemia in SLE.

Altered Expression of TSPAN32 during B Cell Activation and Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a chronic inflammatory disease with various clinical features. Autoreactive B cells play a role in disease pathogenesis, through the production of multiple autoantibodies, which form immune complexes and induce the inflammatory response and tissue damage associated with SLE. Recently, tetraspanins, and in particular, TSPAN32, have been recognized to play a central role in immunity, as they are involved in various biological processes, such as the antigen presentation and the activation of lymphocytes. Evidence suggests that tetraspanins could represent in the future a target for therapeutic purposes in patients suffering from autoimmune/immunoinflammatory disorders. In the present study, by performing in silico analyses of high-throughput data, we evaluated the expression levels of TSPAN32 in B cell activation and investigated its modulation in circulating B cells from SLE patients. Our data show that B cell activation is associated with a significant downregulation of TSPAN32. Additionally, significantly lower levels of TSPAN32 were observed in circulating plasmablasts from SLE patients as compared to healthy donor plasmablasts. In addition, type I interferons (IFNs)-related genes were enriched among the genes negatively correlated to TSPAN32, in SLE plasmablasts. Accordingly, IFN-α is able to induce a dose-dependent downregulation of TSPAN32 in B cells. Overall, the data here presented suggest the potential use of TSPAN32 as a diagnostic marker and therapeutic target for the evaluation and management of humoral immune responses in chronic diseases, such as SLE.

Development of a New International Antiphospholipid Syndrome Classification Criteria Phase I/II Report: Generation and Reduction of Candidate Criteria

OBJECTIVE

An international multidisciplinary initiative, jointly supported by the American College of Rheumatology and European Alliance of Associations for Rheumatology, is underway to develop new rigorous classification criteria to identify patients with high likelihood of antiphospholipid syndrome (APS) for research purposes. The present study was undertaken to apply an evidence- and consensus-based approach to identify candidate criteria and develop a hierarchical organization of criteria within domains.

METHODS

During phase I, the APS classification criteria steering committee used systematic literature reviews and surveys of international APS physician scientists to generate a comprehensive list of items related to APS. In phase II, we reviewed the literature, administered surveys, formed domain subcommittees, and used Delphi exercises and nominal group technique to reduce potential APS candidate criteria. Candidate criteria were hierarchically organized into clinical and laboratory domains.

RESULTS

Phase I generated 152 candidate criteria, expanded to 261 items with the addition of subgroups and candidate criteria with potential negative weights. Using iterative item reduction techniques in phase II, we initially reduced these items to 64 potential candidate criteria organized into 10 clinical and laboratory domains. Subsequent item reduction methods resulted in 27 candidate criteria, hierarchically organized into 6 additive domains (laboratory, macrovascular, microvascular, obstetric, cardiac, and hematologic) for APS classification.

CONCLUSION

Using data- and consensus-driven methodology, we identified 27 APS candidate criteria in 6 clinical or laboratory domains. In the next phase, the proposed candidate criteria will be used for real-world case collection and further refined, organized, and weighted to determine an aggregate score and threshold for APS classification.

Direct oral anticoagulants in antiphospholipid syndrome: Meta-analysis of randomized controlled trials

BACKGROUND

The gold standard for secondary thromboprophylaxis in APS is long term anticoagulation with vitamin K antagonists (VKAs). Because of their widespread use and potential advantages of directs oral anticoagulants (DOACs) over VKAs, they have been prescribed in APS without definitive evidence of their safety and efficacy in this context. Recent specific randomized controlled trials (RCT) in APS and results from pivotal RCTs comparing DOACs vs VKAs are now available. Their results are conflicting but these studies have been conducted in different APS populations.

PURPOSE OF REVIEW

To summarize available data from RCT and determine risks of recurrent thrombosis and bleeding.

RESULTS

Four studies were included and 23 and 10 thrombotic events were recorded among 282 and 294 APS patients treated with DOACs and warfarin respectively. Overall recurrent thrombotic events were not significantly increased during DOACs treatment (OR = 2.22 [95% CI, 0.58-8.43]) compared to VKAs. However, when different types of thrombosis were analyzed separately, there was an increased risk of recurrent arterial thrombosis (5.17 [95% CI, 1.57-17.04]) with DOACs compared to warfarin but no significant higher risk of venous thrombosis (OR 0.69 [95% CI, 0.23-2.06). No increased risk of bleeding was found.

IN CONCLUSION

In APS patients treated with DOACs compared to those treated with warfarin, no evidence of a higher risk of recurrent venous thromboembolism was found however there was a significantly increased risk of recurrent arterial thrombosis. Moreover risk of recurrent arterial thrombosis tended to be more frequent in patients with a history of arterial thrombosis. These results are in line with international guidelines which recommend not to use DOACs in APS patients with a history of arterial thrombosis but raise the question of the efficacy of DOACs to prevent venous thrombosis in a subset of APS patients without a history of arterial thrombosis.

[Secondary ITP in adults]

Secondary forms of immune thrombocytopenia (ITP) represent approximately 20% of all ITP cases in adulthood and this rate increases with age. Since some causes may influence both the prognosis and outcome but also the management of ITP, a minimal workup must be performed at ITP diagnosis to look for an associated or underlying cause. Among adults, B-cell lymphomas and mainly chronic lymphocytic leukemia, systemic auto-immune diseases such as systemic lupus or primary immunodeficiencies mainly represented by common variable immunodeficiency are the most frequent causes of secondary ITP. Whereas first-line therapy used for secondary ITP is usually similar to the one commonly used in primary ITP and relies mostly on corticosteroids±intravenous immunoglobulin according to the severity of bleeding, second and third-line treatments must take into account the type and degree of activity of the underlying disease.

Why thromboembolism occurs in some patients with thrombocytopenia and treatment strategies

Platelets play such an important role in the process of thrombosis that patients with thrombocytopenia generally have an increased risk of bleeding. However, abnormal thrombotic events can sometimes occur in patients with thrombocytopenia, which is unusual and inexplicable. The treatments for thrombocytopenia and thromboembolism are usually contradictory. This review introduces the mechanisms of thromboembolism in patients with different types of thrombocytopenia and outlines treatment recommendations for the prevention and treatment of thrombosis. According to the cause of thrombocytopenia, this article addresses four etiologies, including inherited thrombocytopenia (Myh9-related disease, ANKRD26-associated thrombocytopenia, Glanzmann thrombasthenia, Bernard-Soulier syndrome), thrombotic microangiopathy (thrombotic thrombocytopenic purpura, atypical hemolytic uremic syndrome, hemolytic uremic syndrome, Hemolysis Elevated Liver enzymes and Low Platelets syndrome, disseminated intravascular coagulation), autoimmune-related thrombocytopenia (immune thrombocytopenic purpura, antiphospholipid syndrome, systemic lupus erythematosus), and acquired thrombocytopenia (Infection-induced thrombocytopenia and drug-induced thrombocytopenia, heparin-induced thrombocytopenia). We hope to provide more evidence for clinical applications and future research.

"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.

Childhood-onset systemic lupus erythematosus-related antiphospholipid syndrome: A multicenter study with 1519 patients

OBJECTIVE

To assess childhood-onset systemic lupus erythematosus-related antiphospholipid syndrome(cSLE-APS) in a large Brazilian population.

METHODS

A retrospective observational cohort study was carried-out in 27 Pediatric Rheumatology university centers, including 1519 cSLE patients.

RESULTS

cSLE-APS was observed in 67/1519 (4%) and was diagnosed at disease onset in 39/67 (58%). The median disease duration was 4.9 (0-17) years. Thrombosis recurrences were evidenced in 18/67 (27%) cSLE-APS patients. The most frequent thrombosis sites in cSLE-APS patients were: venous thrombosis in 40/67 (60%), especially deep vein thrombosis in 29/40 (72%); arterial thrombosis in 35/67 (52%), particularly stroke; small vessels thrombosis in 9/67 (13%) and mixed thrombosis in 3/67 (4%). Pregnancy morbidity was observed in 1/67 (1%). Non-thrombotic manifestation associated to cSLE-APS occurred in 21/67 (31%), mainly livedo reticularis in 14/67 (21%), valvar thickening in 4/67 (6%) and valvar vegetations not related to infections in 2/67 (3%). None of them had catastrophic APS. Further analysis demonstrated that the median of SLICC/ACR-DI [1(0-5) vs. 0(0-7),p < 0.0001] was significantly higher in cSLE-APS patients compared to cSLE without APS. The frequencies of cerebrovascular disease (40% vs. 1%,p < 0.0001), polyneuropathy (9% vs. 1%,p < 0.0001), SLICC/ACR-DI ≥1 (57% vs. 27%, p < 0.0001) and intravenous cyclophosphamide use (59% vs. 37%, p < 0.0001) were significantly higher in the former group.

CONCLUSIONS

Our large multicenter study demonstrated that cSLE-APS was a rare condition, occurring during disease course with a high accrual damage. Central and peripheral neuropsychiatric involvements were distinctive features of this autoimmune thrombosis.

Systemic lupus erythematosus: year in review 2019

Systemic lupus erythematosus (SLE) is an autoimmune disease with extreme heterogeneity and potentially involvement of any organ or system. Numerous unanswered questions and challenges in SLE always prompt further exploration. In 2019, great progress in various aspects of SLE emerged. Both the classification criteria and management recommendation for SLE were updated. New promising medications have been widely developed and tested, although subsequent clinical studies are warranted. As an emerging number of most notable studies in SLE were published in both clinical area and basic research in 2019, we aim to summarize the highest quality data on SLE regarding novel insights of pathogenesis, updated recommendations, hot-spot issues on clinical manifestations, new understanding of disease prognosis, and most importantly, the therapeutic advances in SLE in this review.

Clinical characteristics of systemic lupus erythematosus patients in long-term remission without treatment

OBJECTIVE

To describe the clinical and serological characteristics of patients with SLE who reached a state of sustained remission for more than 10 years in the absence of treatment.

METHODS

From a retrospective cohort of 2121 patients, 44 cases with sustained remission (PtRem) were identified and compared with 88 patients whose course has been chronically active (PtAct).The clinical and serological characteristics were analyzed, as well as the treatment of each group at the beginning of the disease and during its evolution.

RESULTS

Older age at disease onset was associated with a tendency to reach a state of prolonged remission. These patients also had a higher frequency of thrombocytopenia at the beginning of the disease 34.1% vs 10.2% (p < 0.001). PtAct had a significantly higher initial SLEDAI compared with cases (10.4 ± 5.6 vs 14.1 ± 5.8; p < 0.001). PtRem had a higher initial frequency of anti-β2 GP1 IgG antibodies. Also, 25% of these patients were serologically active. We did not find differences in the initial treatment between both groups. The accumulated damage measured by SLICC/ACR damage index at the end of the study was significantly less in the patients who remained in prolonged remission.

CONCLUSIONS

Although patients with SLE who achieve prolonged remission have some different characteristics at baseline compared with PtAct, it is not possible to identify a characteristic phenotype for the former. Achieving a state of prolonged remission should always be the goal in patients with SLE. Key Points • SLE patients can reach a very prolonged state of remission, free of treatment, including antimalarials, for at least 10 years. • Venous thromboembolism and thrombocytopenia are commonly present in patients that achieved remission. • The presence of serological markers of activity, even after 10 years in remission, is a risk factor for relapse.

Evaluation of novel assays for the detection of autoantibodies in antiphospholipid syndrome

Patients with antiphospholipid syndrome (APS) present with clinical features of recurrent thrombosis and pregnancy morbidity and persistently test positive for the presence of antiphospholipid antibodies (aPL). At least one clinical (vascular thrombosis or pregnancy morbidity) and one lab-based (positive test result for lupus anticoagulant, anticardiolipin antibodies and/or anti-β2-glycoprotein 1 antibodies) criterion have to be met for a patient to be classified as having APS. Nevertheless, the clinical variety of APS encompasses additional signs and symptoms, potentially affecting any organ, that cannot be explained exclusively by a prothrombotic state. Those manifestations, also known as extra-criteria manifestations, include haematologic (thrombocytopenia and haemolytic anaemia), neurologic (chorea, myelitis and migraine) manifestations as well as the presence of livedo reticularis, nephropathy and valvular heart disease. The growing body of evidence describing the clinical aspect of the syndrome has been paralleled over the years by emerging research interest focusing on the development of novel biomarkers that might improve the diagnostic accuracy for APS when compared to the current aPL tests. This review will focus on the clinical utility of extra-criteria aPL specificities. Besides, the promising role of a new technology using particle based multi-analyte testing that supports aPL panel algorithm testing will be discussed. Diagnostic approaches to difficult cases, including real-world case studies investigating the diagnostic added value of extra criteria aPL, particularly anti-phosphatidylserine/prothrombin, will also be examined.

Management of Non-criteria Manifestations in Antiphospholipid Syndrome

PURPOSE OF THE REVIEW

To review the available evidence on the management of a variety of non-criteria manifestations in antiphospholipid syndrome (APS), including valvular disease, alveolar hemorrhage, thrombocytopenia, hemolytic anemia, APS nephropathy, skin ulcers, livedo reticularis, cognitive dysfunction, and epilepsy.

RECENT FINDINGS

Current treatment relies on low-level evidence and mainly on expert consensus due to the rarity and the heterogeneity of non-criteria APS manifestations and the diversity in management approaches. Conventional anticoagulation and/or antiplatelet APS treatment do not adequately control most of non-criteria manifestations. Increasing knowledge about the contribution of inflammatory in addition to, or independently of, thrombotic mechanisms in non-criteria APS manifestations provides insight into the potential effect of novel therapies targeting B-cells, mammalian target of rapamycin, neutrophil, and complement or interferon pathways. Existing evidence is limited by lack of high-quality studies. Better understanding of the pathophysiology and clinical phenotypes of APS and well-designed prospective studies of homogenous populations are needed to provide evidence-based recommendations for the management of non-criteria APS manifestations.

T cells expressing the lupus susceptibility allele Pbx1d enhance autoimmunity and atherosclerosis in dyslipidemic mice

Patients with systemic lupus erythematosus (SLE) present a high incidence of atherosclerosis, which contributes significantly to morbidity and mortality in this autoimmune disease. An impaired balance between regulatory (Treg) and follicular helper (Tfh) CD4+ T cells is shared by both diseases. However, whether there are common mechanisms of CD4+ T cell dysregulation between SLE and atherosclerosis remains unclear. Pre-B cell leukemia transcription factor 1 isoform d (Pbx1d) is a lupus susceptibility gene that regulates Tfh cell expansion and Treg cell homeostasis. Here, we investigated the role of T cells overexpressing Pbx1d in low-density lipoprotein receptor-deficient (Ldlr-/-) mice fed with a high-fat diet, an experimental model for atherosclerosis. Pbx1d-transgenic T cells exacerbated some phenotypes of atherosclerosis, which were associated with higher autoantibody production, increased Tfh cell frequency, and impaired Treg cell regulation, in Ldlr-/- mice as compared with control T cells. In addition, we showed that dyslipidemia and Pbx1d-transgenic expression independently impaired the differentiation and function of Treg cells in vitro, suggesting a gene/environment additive effect. Thus, our results suggest that the combination of Pbx1d expression in T cells and dyslipidemia exacerbates both atherosclerosis and autoimmunity, at least in part through a dysregulation of Treg cell homeostasis.