Developing and Refining New Candidate Criteria for Systemic Lupus Erythematosus Classification: An International Collaboration

SLE criteria are by necessity still based on clinical (and immunological) criteria items

INTRODUCTION

The 2019 European League Against Rheumatism/American College of Rheumatology (EULAR/ACR) classification criteria for systemic lupus erythematosus (SLE) rely on clinical and routine immunological items. The criteria have anti-nuclear antibodies (ANA) as an obligatory entry criterion; items are weighted and ordered in domains. While demonstrating good sensitivity and specificity, the lack of a more molecular approach to some came as a disappointment.

AREAS COVERED

Based on a non-systematic literature search, this review covers items investigated in the EULAR/ACR classification criteria project, but not included in the set of criteria. It demonstrates data on the importance of the criteria and analyses implications of multiomics studies started around the same time as the criteria project. We also discuss data on the type-I interferon signature and on other cytokines, as well as on complement proteins and their split products. The final part deals with the variability in disease and the apparently random pattern of autoantibodies and organ manifestations in individual patients.

EXPERT OPINION

We believe that the EULAR/ACR criteria are a relevant step toward the right direction. A more uniform molecular approach will not be feasible as long as the molecular mechanisms underlying the tendency toward producing multiple autoantibodies are not better understood.

Severe adult hemophagocytic lymphohistiocytosis (HLHa) correlates with HLH-related gene variants

BACKGROUND

The contribution of genetic factors to the severity of adult hemophagocytic lymphohistiocytosis (HLHa) remains unclear.

OBJECTIVE

We sought to assess a potential link between HLHa outcomes and HLH-related gene variants.

METHODS

Clinical characteristics of 130 HLHa patients (age ≥ 18 years and HScore ≥ 169) and genotype of 8 HLH-related genes (LYST, PRF1, UNC13-D, STX11, STXBP2, RAB27A, XIAP, and SAP) were collected. A total of 34 variants found in only 6 genes were selected on the basis of their frequency and criteria predicted to impair protein function. Severity was defined by refractory disease to HLH treatment, death, or transfer to an intensive care unit.

RESULTS

HLHa-associated diseases (ADs) were neoplasia (n = 49 [37.7%]), autoimmune/inflammatory disease (n = 33 [25.4%]), or idiopathic when no AD was identified (n = 48 [36.9%]). Infectious events occurred in 76 (58.5%) patients and were equally distributed in all ADs. Severe and refractory HLHa were observed in 80 (61.5%) and 64 (49.2%) patients, respectively. HScore, age, sex ratio, AD, and infectious events showed no significant association with HLHa severity. Variants were identified in 71 alleles and were present in 56 (43.1%) patients. They were distributed as follows: 44 (34.4%), 9 (6.9%), and 3 (2.3%) patients carrying 1, 2, and 3 variant alleles, respectively. In a logistic regression model, only the number of variants was significantly associated with HLHa severity (1 vs 0: 3.86 [1.73-9.14], P = .0008; 2-3 vs 0: 29.4 [3.62-3810], P = .0002) and refractoriness (1 vs 0: 2.47 [1.17-5.34], P = .018; 2-3 vs 0: 13.2 [2.91-126.8], P = .0003).

CONCLUSIONS

HLH-related gene variants may be key components to the severity and refractoriness of HLHa.

Classification of systemic lupus erythematosus: From the development of classification criteria to a new taxonomy?

SLE is a highly variable systemic autoimmune disease. Its immunopathological effector phase is partly understood. However, the background of its variability is not. SLE classification criteria have been relying on the clinical manifestations and standard autoimmune serology. This still holds true for the 2019 EULAR/ACR classification criteria. On one hand, this has led to significant precision in defining patients with SLE. On the other hand, the information in the criteria neither helps understanding the individual patient's pathophysiology, nor does it predict the efficacy of the available immunomodulatory therapies. Chances of further improvement of clinical criteria are most likely limited. This is where new multi-omic approaches have started to make an impact. While not yet able to differentiate diseases with the same precision as the classification criteria, the results of these studies go far beyond the scope of the criteria with regard to immune dysregulation. Looking at both sides in detail, we here try to synthesize the available data, aiming at a better understanding of SLE and its immune pathophysiology.

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.

[Assessment tools for systemic lupus erythematosus]

A systematic assessment is critical for taking advantage of the current options for optimizing systemic lupus erythematosus (SLE) management. Without regular SLE activity measurements, treat to target and remission are empty words, and the EULAR recommendations therefore insist on these assessments. They rely on activity scores, such as SLEDAI, ECLAM and BILAG or more recently, EasyBILAG and SLE-DAS. Assessment is completed by organ-specific measurement methods and the evaluation of damage. In the study setting the classification criteria and combined endpoints for clinical testing are crucial, as is measurement of the quality of life. This review article provides an overview of the current state of SLE assessments.

IL-4-Induced Quiescence of Resting Naive B Cells Is Disrupted in Systemic Lupus Erythematosus

Activated naive (aNAV) B cells have been shown to be the precursor of the CD11c+T-bet+ IgD-CD27- double-negative (DN)2 or atypical memory (aMEM) B cells in systemic lupus erythematosus (SLE). To determine factors that maintain resting naive (rNAV) B cells, the transcriptomic program in naive (IGHD+IGHM +) B cells in human healthy control subjects (HC) and subjects with SLE was analyzed by single-cell RNA-sequencing analysis. In HC, naive B cells expressed IL-4 pathway genes, whereas in SLE, naive B cells expressed type I IFN-stimulated genes (ISGs). In HC, aNAV B cells exhibited upregulation of the gene signature of germinal center and classical memory (cMEM) B cells. In contrast, in SLE, aNAV B cells expressed signature genes of aMEM. In vitro exposure of SLE B cells to IL-4 promoted B cell development into CD27+CD38+ plasmablasts/plasma and IgD-CD27+ cMEM B cells. The same treatment blocked the development of CD11c+Tbet+ aNAV and DN2 B cells and preserved DN B cells as CD11c-Tbet- DN1 B cells. Lower expression of IL-4R and increased intracellular IFN-β in naive B cells was correlated with the accumulation of CD21-IgD- B cells and the development of anti-Smith and anti-DNA autoantibodies in patients with SLE (n = 47). Our results show that IL-4R and type I IFN signaling in naive B cells induce the development of distinct lineages of cMEM versus aMEM B cells, respectively. Furthermore, diminished IL-4R signaling shifted activated B cell development from the DN1 to the DN2 trajectory in patients with SLE. Therapies that enhance IL-4R signaling may be beneficial for ISGhi SLE patients.

Advances in SLE classification criteria

This year, the American College of Rheumatology (ACR) 1982 classification criteria for systemic lupus erythematosus (SLE) celebrate their 40th anniversary. From this start, the quest for optimal SLE criteria has led to the 1997 ACR update, the 2012 publication of the Systemic Lupus International Collaborating Clinics (SLICC) criteria, and, in 2019, the European League Against Rheumatism (EULAR)/ACR classification criteria. The latter have since been externally validated in more than two dozen studies and have become the gold standard inclusion criterion of SLE clinical trials. This comprehensive review attempts to follow the evolving success story of SLE classification, highlighting relevant decisions and their rationale, and discussing consequences for the way SLE is defined and managed.

Evaluation of the European League Against Rheumatism/American College of Rheumatology-2019 classification criteria in patients with childhood-onset systemic lupus erythematosus: a single-center retrospective study

This study aimed to compare the sensitivity and specificity of the European League Against Rheumatism/American College of Rheumatology-2019 (EULAR/ACR-2019) classification criteria with prior classification schemes for patients with childhood-onset systemic lupus erythematosus (cSLE). This single-center retrospective study examined 53 patients with cSLE and 53 patients having antinuclear antibody (ANA) titers ≥ 1:80 but not cSLE as controls. Sensitivity and specificity were calculated for the EULAR/ACR-2019 criteria, original criteria reported earlier in 2019, the ACR-1997 criteria, and the Systemic Lupus International Collaborating Clinics-2012 (SLICC-2012) criteria. The frequency of positivity in the cSLE group for each item of the EULAR/ACR-2019, ACR-1997, and SLICC-2012 criteria was determined. Characteristics of the misclassified patients were also investigated. All patients with cSLE had ANA titers ≥ 1:80. The non-SLE diagnoses included juvenile idiopathic inflammatory myopathies, primary Sjögren's syndrome (pSS), juvenile idiopathic arthritis, systemic sclerosis, mixed connective tissue disease (MCTD), and others. Sensitivities of the EULAR/ACR-2019 criteria, the original criteria, the ACR-1997 criteria, and the SLICC-2012 criteria were 100%, 100%, 86.8%, and 100%, respectively; the specificities were 84.9%, 92.5%, 98.1%, and 88.7%, respectively. In the cSLE group, the items of the SLE-specific antibody (100%), complement (98.1%), hematological (94.3%), and renal (84.9%) domains were frequently observed in the EULAR/ACR-2019 criteria. The EULAR/ACR-2019 criteria misclassified patient controls more frequently, especially those with MCTD or pSS, as having SLE than the previous criteria. The EULAR/ACR-2019 criteria for cSLE had high sensitivity but low specificity; the weighted scoring of the original criteria reported earlier in 2019 may confer higher specificity and be more appropriate for the classification of SLE in a pediatric population. Key Points • The EULAR/ACR-2019 criteria for cSLE had high sensitivity but low specificity. • The EULAR/ACR-2019 criteria more frequently misclassified non-SLE patients who did not have SLE, especially those with MCTD or pSS, as having SLE than the previous criteria in patients with childhood onset. • The weighted scoring of the original criteria reported earlier in 2019 may confer higher specificity and be a more appropriate classification of SLE for a pediatric population.

Anti-dsDNA antibodies in the classification criteria of systemic lupus erythematosus

Anti-double stranded DNA (dsDNA) antibodies play an important role in the diagnosis, classification and management of systemic lupus erythematosus (SLE), an autoimmune disease characterized by heterogeneous clinical manifestations and a wide range of autoantibodies, which makes the diagnosis quite challenging. In the absence of diagnostic criteria, classification criteria have been used for many decades. The first classification criteria for SLE were formulated in 1971 by the American College of Rheumatology (ACR), followed by two revisions in 1982 and 1997. In order to improve their clinical performance and to reflect new knowledge on autoantibodies, new classification criteria for SLE were issued in 2012 by the Systemic Lupus International Collaborating Clinics (SLICC). These criteria proposed to classify only patients that have at least one immunologic criterion, overcoming SLE classification based solely on clinical manifestations. In 2019, the European League Against Rheumatism (EULAR)/ACR proposed new criteria that aimed to maintain the high specificity of the ACR criteria with a sensitivity close to the SLICC 2012 criteria. These 2019 criteria reinforced the importance of autoantibodies in SLE diagnosis, assigning the highest score (6 points) to anti-dsDNA antibodies in the fully weighted scoring of the disease. The current criteria require the use of an anti-dsDNA assay with at least 90% specificity, such as the Crithidia luciliae immunofluorescence test (CLIFT) or FARR assay. However, the criteria do not comment on all the tests currently widely used in clinical laboratories. Neither do they consider the technological evolutions, nor standardization issues. Since strict adherence to any of the classification criteria, including the serological items, could lead to possible misclassification of SLE and/or delayed diagnosis, test characteristics of the distinct immunoassays should be taken into consideration.

Retinal thickness and microvascular alterations in the diagnosis of systemic lupus erythematosus: a new approach

BACKGROUND

To investigate the differences of retinal thickness (RT) and superficial vascular density (SVD) between patients with systemic lupus erythematosus (SLE) and healthy controls using optical coherence tomography angiography (OCTA).

METHODS

Individuals with SLE (n=12; 24 eyes) and healthy controls (n=12; 24 eyes) were recruited to this study. The study protocol was in accordance with the tenets of the Declaration of Helsinki (as revised in 2013). The monocular best-corrected visual acuity (BCVA) was determined using a Snellen eye chart. Each image was segmented into 9 early treatment diabetic retinopathy study subregions, within which the macular RT and SVD were measured by OCTA. The vascular perfusion area as a percentage of the measured area was considered to be the vascular density.

RESULTS

The mean age of the SLE group was 33.80±9.49 years, and the mean age of the control group was 33.20±9.41 years. The mean duration of SLE was 4.33±2.67 years. The BCVA was significantly different between the SLE and control groups (0.17±0.20 vs. 0.05±0.07, respectively; P=0.021). In the SLE group, inner RT was reduced in the outer superior and temporal regions and full RT was reduced in the outer temporal region, compared with the control group (P<0.05). In the outer temporal region, the area under the receiver operating characteristic curve (AUC) for the inner RT was 0.805 [95% confidence interval (CI): 0.674 to 0.935], and the full RT was 0.828 (95% CI: 0.701 to 0.955). Thinning of RT was negatively correlated with erythrocyte sedimentation rate (ESR) in the inner retina at the outer temporal and outer superior regions and the full retina at the outer temporal region (P<0.05). The SVD was significantly lower in SLE participants than in controls in the central region, all 4 inner quadrants, and 4 outer quadrants (P<0.05). In the SLE group, SVD was positively correlated with inner RT in the outer superior region, inner RT, and full RT in the outer temporal region (P<0.05).

CONCLUSIONS

Variations in RT within the macular area may affect visual acuity. The OCTA measurement of RT may be a potential marker for diagnosis of SLE and an indicator of its inflammatory activity.

ANA positivity and complement level in pleural fluid are potential diagnostic markers in discriminating lupus pleuritis from pleural effusion of other aetiologies

OBJECTIVE

Lupus pleuritis is the most common pulmonary manifestation of systemic lupus erythematosus (SLE). We aimed to compare various biomarkers in discriminating between pleural effusions due to lupus pleuritis and other aetiologies.

METHODS

We determined in 59 patients (16 patients with SLE and 43 patients without SLE) pleural fluid levels of high-mobility group box 1, soluble receptor for advanced glycation end products (sRAGE), adenosine deaminase (ADA), interleukin (IL) 17A, tumour necrosis factor-α, antinuclear antibodies (ANA), and complements C3 and C4.

RESULTS

We found significant differences in the pleural fluid level of sRAGE, ADA, IL-17A, C3 and C4, and in the proportion of ANA positivity, among lupus pleuritis and other groups with pleural effusion. Specifically, ANA positivity (titre ≥1: 80) achieved a high sensitivity of 91%, specificity of 83% and negative predictive value (NPV) of 97% in discriminating lupus pleuritis from non-lupus pleural effusion. A parallel combination of the level of C3 (<24 mg/dL) and C4 (<3 mg/dL) achieved a sensitivity of 82%, specificity of 89% and NPV of 93% in discriminating lupus pleuritis from non-lupus exudative pleural effusion.

CONCLUSIONS

In conclusion, ANA, C3 and C4 in pleural fluid are useful in discriminating lupus pleuritis from pleural effusion due to other aetiologies with high NPV.

Systematic review of anti-dsDNA testing for systemic lupus erythematosus: A meta-analysis of the diagnostic test specificity of an anti-dsDNA fluorescence enzyme immunoassay

BACKGROUND AND AIMS

The objective of this meta-analysis was to review the diagnostic performance of anti-dsDNA testing, to determine whether test specificity meets the revised 2019 EULAR/ACR classification criteria for systemic lupus erythematosus (SLE). The new criteria state that anti-dsDNA testing should be conducted using "an immunoassay with demonstrated ≥ 90% specificity for SLE against relevant disease controls".

MATERIALS AND METHODS

A systematic review (MEDLINE, Embase, CENTRAL and DARE) identified cross-sectional or case-control studies published January 2004 to August 2019, reporting anti-dsDNA test accuracy data. Studies included cases of SLE (confirmed using one or more of three validated SLE classification criteria sets) and a disease control group. Data were adjusted to exclude healthy controls. A hierarchical, bivariate mixed-effect meta-analysis of eligible quantitative studies was conducted in STATA MP v16.1 to produce a pooled estimate of sensitivity and specificity.

RESULTS

The review identified six fluorescence immunoassay (FEIA) dsDNA studies (1977 total patients, of whom 47% had SLE) eligible to be included in quantitative meta-analysis and all reported a point estimate >90% for specificity. The meta-analysis estimated a pooled specificity of 94.7% (95% CI 91.67%-96.67%).

CONCLUSION

The meta-analysis has demonstrated that the specificity of FEIA dsDNA is ≥90% for SLE, against relevant disease controls, and therefore performs in accordance with the 2019 classification criteria.

Evaluating the performance of ACR, SLICC and EULAR/ACR classification criteria in childhood onset systemic lupus erythematosus

BACKGROUND

The ACR 1997, SLICC 2012 and EULAR/ACR 2019 classification criteria were validated based on adult patients. To date, there are no classification criteria specific for children with SLE. The aim of the study is to compare the performance characteristics among the three SLE classification criteria (ACR-1997, SLICC-2012 and EULAR/ACR-2019) in childhood onset SLE (cSLE) cohort of Arab ethnicity from Oman.

METHODS

We conducted a retrospective multicenter study in Oman of cSLE patients as cases and patients with other rheumatic disease with a positive ANA titer as controls. The cSLE cases recruited were children diagnosed with SLE before 13 years of age. Data was retrospectively collected to establish the ACR-1997, SLICC-2012 and EULAR/ACR-2019 criteria fulfilled at first visit, first year follow up and last follow up.

RESULTS

Study population included 113 cSLE cases (mean age at diagnosis of 7.3 ± 3.4 years with disease duration of 6.1 ± 4.6 years) and 51 controls (mean age at diagnosis 5.0 ± 3.4 with disease duration 5.7 ± 3.9). The cSLE cases had higher frequency of familial SLE than controls (38% vs 7.8%; p < 0.001). The performance measures demonstrated that EULAR/ACR-2019 criteria had the highest sensitivity (81, 88, 89%) compared to ACR 1997 (49, 57, 66%) and SLICC 2012 (76, 84,86%); while the ACR 1997 had the highest specificity (96%) compared to SLICC 2012 (94%) and EULAR/ACR 2019 (90%) at first visit, first year and last assessment. When we increased the threshold score to ≥13 rather than the traditional score ≥ 10 for ACR/EULAR 2019, there was increased specificity (96%) at the expense of lower sensitivity (76, 83, and 84%) at first visit, first year and last assessment.

CONCLUSION

In this cSLE population, EULAR/ACR 2019 scored better at initial presentation, first year and last assessment follow up. Further multinational studies are needed to validate the appropriate cut off score for the newly proposed ACR/EULAR 2019 classification criteria in cSLE to increase early sensitivity and specificity for cSLE classification.

Update and clinical management of anti-DNA auto-antibodies

Anti-deoxyribonucleic acid (DNA) antibodies in the clinical laboratory are intimately linked to the diagnosis and monitoring of systemic lupus erythematosus (SLE); however, the characteristics of the analytical methods and the properties of the antibodies themselves are heterogeneous. To review the definition and properties of anti-double-stranded anti-DNA (anti-dsDNA) antibodies, the adequacy of analytical methods, and the clinical requirements for this biomarker. Through PubMed we searched the existing literature with the terms anti-dsDNA, editorial, review, guideline, meta-analysis and SLE. The last search, anti-dsDNA and SLE restricted to the last two years. Information was expanded through related articles and those published in official state bodies related to anti-dsDNA and SLE. Clinical laboratory methods for anti-dsDNA analysis and their characteristics are analyze. The clinical utility of anti-dsDNA in its diagnostic, clinical association and follow-up aspects of SLE is reviewed. There is wide variability in analytical methods and deficits in standardization persist. They are part of the current SLE classification criteria and are used as markers in the follow-up of the disease. Their diagnostic usefulness improves when they are determined in antinuclear antibody (ANA)-positive patients. In follow-up, quantification is of interest, preferably with the same analytical method (given the deficits in standardization).

Lupus Nephritis: The Significant Contribution of Electron Microscopy

Background

Systemic lupus erythematosus (SLE) represents a principal prototype of a multisystemic autoimmune disease with the participation of both cell- and antibody-mediated mechanisms causing significant renal impairment. A renal biopsy diagnosis is the gold standard for clinical renal disease in SLE, which includes a broad range of indications.

Summary

Renal disease in SLE can involve glomerular, tubulointerstitial, and/or vascular compartments, none of which are mutually exclusive. In most instances, the basic pathogenetic mechanism involves tissue deposition of immune complexes and/or cell-mediated mechanisms, identified by light microscopy, immunohistochemical methods, and electron microscopy (EM), evoking intraglomerular proliferative, inflammatory, and other tissue responses. These produce a spectrum of histologic lesions, depending on the participation of a wide range of clinical triggers, namely, genetic, serological, and immunological factors, correlating with their underlying pathogenetic potential. In addition to light and immunofluorescence microscopy, EM in this setting facilitates an accurate diagnosis, assesses disease activity, delineates subclasses, differentiates from primary forms of non-lupus renal lesions, identifies organized deposits, and rarely, identifies other forms of nonimmune complex lesions such as podocytopathies, amyloidosis, and thrombotic microangiopathy.

Key Messages

EM findings that are distinctive for most of the renal lesions in SLE include immune complex and nonimmune complex diseases as well as overlapping entities. Routine ultrastructural examination not only provides significant diagnostic and prognostic information from both initial and repeat renal biopsies from lupus patients but also contributes toward the understanding of the underlying pathophysiology of the disease process.

Systemic Lupus Erythematosus Classification and Diagnosis

Since the European League Against Rheumatism/American College of Rheumatology 2019 classification criteria for systemic lupus erythematosus (SLE) were published, they were externally validated by groups worldwide. In particular, the new criteria worked well also in East Asian and pediatric cohorts. Antinuclear antibodies (ANA) as an entry criterion were critically discussed, but the group of ANA-negative patients is small (<5%) worldwide. Specificity of the criteria is dependent on correct attribution only of those criteria that are not better explained by other causes. Although the classification criteria should not be used for diagnosis, many novel aspects inform diagnostic considerations.

Performance of the New 2019 European League Against Rheumatism/American College of Rheumatology Classification Criteria for Systemic Lupus Erythematosus in Children and Young Adults

OBJECTIVE

To compare the diagnostic usefulness of the 2019 European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR) classification criteria for systemic lupus erythematosus (SLE) to that of the 1997 ACR classification criteria for SLE when applied to youths (age ≤21 years) with SLE.

METHODS

Data were extracted from electronic health records of patients followed at a large academic pediatric hospital. The treating rheumatologist's diagnosis of SLE served as the standard criterion for identifying SLE patients (cases). Controls were patients with juvenile dermatomyositis (DM), juvenile scleroderma, or juvenile systemic sclerosis (SSc). The 2019 EULAR/ACR criteria and the 1997 ACR criteria were tested against the standard criterion.

RESULTS

A total of 112 SLE patients ages 2-21 years and 105 controls ages 1-19 years (66% juvenile DM, 34% juvenile scleroderma or juvenile SSc) were available for analysis. The 2019 EULAR/ACR criteria had significantly higher sensitivity (85% versus 72%; P = 0.023) and similar specificity (83% versus 87%; P = 0.456) than the 1997 ACR criteria. The mean ± SD 2019 EULAR/ACR classification summary scores were significantly higher among non-White than White patients (22.41 ± 10.04 versus 17.59 ± 9.19; P < 0.01). The sensitivity of the 2019 EULAR/ACR criteria in non-White/White patients was 92%/80% (P = 0.08) versus 83%/64% (P < 0.02) for the 1997 ACR criteria. The sensitivity of the 2019 EULAR/ACR criteria was not affected by age or sex.

CONCLUSION

The 2019 EULAR/ACR criteria efficiently classify youths with SLE, irrespective of age, sex, and race. Compared to the 1997 ACR criteria, the new criteria are significantly more sensitive and similarly specific in youths with SLE.

Elevated Urinary and Blood Vascular Cell Adhesion Molecule-1 as Potential Biomarkers for Active Systemic Lupus Erythematosus: A Meta-analysis

OBJECTIVE

Due to the inconsistent results of current studies on the association between urinary and blood vascular cell adhesion molecule-1 (VCAM-1) and systemic lupus erythematosus (SLE) disease activity, we conducted this study and analyzed its influencing factors.

METHODS

A literature search was conducted in PubMed, EMBASE, Web of Science, and Cochrane Library. Data were extracted from eligible studies to calculate standardized mean differences (SMD) with 95% confidence intervals (CI). Cochrane Q test and I2 statistics were used to examine heterogeneity. The sources of heterogeneity were assessed through sensitivity analysis and subgroup analysis. Publication bias was evaluated by funnel plots and Egger's test.

RESULTS

A total of 15 studies met the inclusion criteria, including 473 active SLE patients and 674 inactive SLE patients. The random effects model was used for data analysis. In both urine and blood samples, VCAM- 1 level in active SLE patients was significantly higher than those in inactive SLE patients (urine: SMD: 0.769; 95% CI: 0.260-1.278; blood: SMD=0.655, 95% CI: 0.084-1.226). No publication bias was found in this study.

CONCLUSION

Compared with inactive SLE patients, patients with active SLE have higher levels of VCAM-1 in both urine and blood. VCAM-1 may be a potential indicator of SLE disease activity.

Evaluation of structured data from electronic health records to identify clinical classification criteria attributes for systemic lupus erythematosus

Objective

Our objective was to develop algorithms to identify lupus clinical classification criteria attributes using structured data found in the electronic health record (EHR) and determine whether they could be used to describe a cohort of people with lupus and discriminate them from a defined healthy control cohort.

Methods

We created gold standard lupus and healthy patient cohorts that were fully adjudicated for the American College of Rheumatology (ACR), Systemic Lupus International Collaborating Clinics (SLICC) and European League Against Rheumatism/ACR (EULAR/ACR) classification criteria and had matched EHR data. We implemented rule-based algorithms using structured data within the EHR system for each attribute of the three classification criteria. Individual criteria attribute and classification criteria algorithms as a whole were assessed over our combined cohorts and the overall performance of the algorithms was measured through sensitivity and specificity.

Results

Individual classification criteria attributes had a wide range of sensitivities, 7% (oral ulcers) to 97% (haematological disorders) and specificities, 56% (haematological disorders) to 98% (photosensitivity), but all could be identified in EHR data. In general, algorithms based on laboratory results performed better than those primarily based on diagnosis codes. All three classification criteria systems effectively distinguished members of our case and control cohorts, but the SLICC criteria-based algorithm had the highest overall performance (76% sensitivity, 99% specificity).

Conclusions

It is possible to characterise disease manifestations in people with lupus using classification criteria-based algorithms that assess structured EHR data. These algorithms may reduce chart review burden and are a foundation for identifying subpopulations of patients with lupus based on disease presentation to support precision medicine applications.

Applying the 2019 EULAR/ACR lupus criteria to patients from an established cohort: a Latin American perspective

Objective

To evaluate the performance of the 2019 European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR) systemic lupus erythematosus (SLE) criteria in terms of earlier patients’ classification in comparison to the 1982/1997 ACR or the 2012 Systemic Lupus International Collaborating Clinics (SLICC) criteria.

Materials and methods

Patients from a Latin America, multiethnic, multicentre cohort, where SLE was defined using the physicians’ diagnosis, were included. To calculate the sensitivity of the 2019 EULAR/ACR criteria, the 1982/1997 ACR criteria were considered the gold standard. Additionally, comparison of the 1982/1997 ACR criteria and the 2012 SLICC criteria with the 2019 EULAR/ACR criteria was performed.

Results

The sensitivity of the 2019 EULAR/ACR criteria when compared with the 1982/1997 ACR criteria as the gold standard was 91.3%. This new set of criteria allowed an earlier SLE patient classification in 7.4% (mean 0.67 years) and 0.6% (mean 1.47 years) than the 1982/1997 ACR and the 2012 SLICC criteria, respectively. Patients accruing the 2019 EULAR/ACR earlier than the 1982/1997 ACR criteria were more likely to have high anti-dsDNA titres; those accruing them later were less likely to have mucocutaneous and joint manifestations; this was not observed when comparing them with the 2012 SLICC criteria.

Conclusions

The 2019 EULAR/ACR criteria classified earlier only a small proportion of Latin America patients than with the two other criteria sets in real-life clinical practice scenarios. Further studies in different patient populations are needed before these new criteria are adopted worldwide.

New lupus criteria: a critical view

PURPOSE OF REVIEW

To review the validation of the European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR) 2019 classification criteria for systemic lupus erythematosus (SLE).

RECENT FINDINGS

Positive antinuclear antibodies, which constitute the obligatory entry criterion of the EULAR/ACR criteria, were found in the vast majority of SLE patients worldwide, with 97% (94-100%) of patients antinuclear antibodies positive in studies investigating EULAR/ACR criteria performance. Combined over the publications, EULAR/ACR criteria sensitivity was 92% (range 85-97%). Specificity varied more relevantly, with the publications published after the EULAR/ACR 2019 criteria showing 93% (83-98%) specificity. Of particular relevance is the good performance of the EULAR/ACR criteria seen in pediatric SLE as well as in early SLE.

SUMMARY

The new classification criteria have been investigated in an impressive number of cohorts worldwide, adding to the data from the EULAR/ACR criteria project cohort. It is critical to strictly keep to the attribution rule, that items are only counted if there is no more likely alternative explanation than SLE, the domain structure, where only the highest weighted item in a domain counts, and the limitation to highly specific tests for antibodies to double-stranded DNA.

European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR) SLE classification criteria item performance

BACKGROUND/OBJECTIVES

The European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR) 2019 classification criteria for systemic lupus erythematosus system showed high specificity, while attaining also high sensitivity. We hereby analysed the performance of the individual criteria items and their contribution to the overall performance of the criteria.

METHODS

We combined the EULAR/ACR derivation and validation cohorts for a total of 1197 systemic lupus erythematosus (SLE) and n=1074 non-SLE patients with a variety of conditions mimicking SLE, such as other autoimmune diseases, and calculated the sensitivity and specificity for antinuclear antibodies (ANA) and the 23 specific criteria items. We also tested performance omitting the EULAR/ACR criteria attribution rule, which defines that items are only counted if not more likely explained by a cause other than SLE.

RESULTS

Positive ANA, the new entry criterion, was 99.5% sensitive, but only 19.4% specific, against a non-SLE population that included other inflammatory rheumatic, infectious, malignant and metabolic diseases. The specific criteria items were highly variable in sensitivity (from 0.42% for delirium and 1.84% for psychosis to 75.6% for antibodies to double-stranded DNA), but their specificity was uniformly high, with low C3 or C4 (83.0%) and leucopenia <4.000/mm³ (83.8%) at the lowest end. Unexplained fever was 95.3% specific in this cohort. Applying the attribution rule improved specificity, particularly for joint involvement.

CONCLUSIONS

Changing the position of the highly sensitive, non-specific ANA to an entry criterion and the attribution rule resulted in a specificity of >80% for all items, explaining the higher overall specificity of the criteria set.

Splicing factor SRSF1 controls T cell homeostasis and its decreased levels are linked to lymphopenia in systemic lupus erythematosus

OBJECTIVE

Lymphopenia is a frequent clinical manifestation and risk factor for infections in SLE, but the underlying mechanisms are not fully understood. We previously identified novel roles for the RNA-binding protein serine arginine-rich splicing factor 1 (SRSF1) in the control of genes involved in signalling and cytokine production in human T cells. SRSF1 is decreased in T cells from patients with SLE and associates with severe disease. Because SRSF1 controls the expression of apoptosis-related genes, we hypothesized that SRSF1 controls T cell homeostasis and, when reduced, leads to lymphopenia.

METHODS

We evaluated SRSF1 expression in T cells from SLE patients by immunoblots and analysed its correlation with clinical parameters. T cell conditional Srsf1 knockout mice were used to evaluate lymphoid cells and apoptosis by flow cytometry. Quantitative PCR and immunoblots were used to assess Bcl-xL mRNA and protein expression. SRSF1 overexpression was performed by transient transfections by electroporation.

RESULTS

We found that low SRSF1 levels correlated with lymphopenia in SLE patients. Selective deletion of Srsf1 in T cells in mice led to T cell lymphopenia, with increased apoptosis and decreased expression of the anti-apoptotic Bcl-xL. Lower SRSF1 expression correlated with low Bcl-xL levels in T cells and lower Bcl-xL levels associated with lymphopenia in SLE patients. Importantly, overexpression of SRSF1 rescued survival of T cells from patients with SLE.

CONCLUSION

Our studies uncovered a previously unrecognized role for SRSF1 in the control of T cell homeostasis and its reduced expression as a molecular defect that contributes to lymphopenia in systemic autoimmunity.

New EULAR/ACR 2019 SLE Classification Criteria: defining ominosity in SLE

OBJECTIVE

To determine the ominosity of the European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR) Systemic Lupus Erythematosus Classification Criteria by determining its predictive role for disease severity in the first 5 years following diagnosis.

METHODS

867 patients with systemic lupus erythematosus (SLE) from the Toronto Lupus Clinic were included (all first 12 months after SLE diagnosis). The EULAR/ACR criteria score was calculated based on baseline information. To determine disease severity in the first 5 years after diagnosis, adjusted mean SLE Disease Activity Index 2000 (AMS), flares, remission and immunosuppressive treatment were used as outcomes. The Systemic Lupus International Collaborating Clinics (SLICC) registry comprised the validation cohort.

RESULTS

Based on receiver operating characteristic analysis, a EULAR/ACR score of 20 was used as a threshold to compare outcomes between groups. In the first 5 years of disease course, patients with a score of ≥20 had higher AMS scores (p<0.001) and were more likely to ever experience a flare (p<0.001). These patients had lower probabilities of achieving remission and higher requirements for immunosuppressives. Results were confirmed in the SLICC validation cohort. Patients with a score of ≥20 had higher AMS during the first 5 years of disease (5.4 vs 3.1% and ≥20 vs <20 respectively, p≤0.001). The score correlated with AMS (r=0.43, p≤0.001) in the same time frame.

CONCLUSION

A EULAR/ACR score of ≥20 is an indicator of ominosity in SLE. Patients with a score of ≥20 were characterised by a more active disease course throughout the first 5 years. These criteria provide prognostic information regarding disease severity in the first 5 years following diagnosis.

Validation of the 2019 European League Against Rheumatism/American College of Rheumatology Criteria Compared to the 1997 American College of Rheumatology Criteria and the 2012 Systemic Lupus International Collaborating Clinics Criteria in Pediatric Systemic Lupus Erythematosus

OBJECTIVE

Different classification criteria for systemic lupus erythematosus (SLE) have been proposed for many years. The most widely used and accepted criteria has been the 1997 American College of Rheumatology (ACR) criteria. In 2012, the Systemic Lupus International Collaborating Clinics (SLICC) criteria were published in an attempt to improve the clinical relevance of SLE criteria. In 2017, weighted criteria were proposed that included entry criteria, something the 1997 ACR and the 2012 SLICC criteria did not identify. The aim of the present study was to validate the 2017 weighted criteria, the 1997 ACR criteria, and the 2012 SLICC criteria and compare the sensitivities and specificities in pediatric SLE.

METHODS

For the past 15 years, retrospective chart review of patients diagnosed with SLE before age 19 years was conducted. The controls were patients referred for serologies positive for antinuclear antibodies but did not fulfill criteria for diagnosis of SLE at the initial visit or were diagnosed with another autoimmune disease. The 3 classification criteria sets were applied to these patients and compared against a gold standard of physician diagnosis.

RESULTS

A total of 156 patients were diagnosed with SLE. The sensitivity for the 2017 weighted criteria was 0.974 (95% confidence interval [95% CI] 0.936-0.993) and the specificity was 0.984 (95% CI 0.966-0.994). The sensitivity for the 1997 ACR criteria was 0.872 (95% CI 0.809-0.920) and the specificity was 1.00 (95% CI 0.990-1.000). The sensitivity for the 2012 SLICC criteria was 0.974 (95% CI 0.936-0.993) and the specificity was 0.997 (95% CI 0.985-1.000).

CONCLUSION

The 2017 weighted criteria and the 2012 SLICC criteria were more sensitive than the 1997 ACR criteria. There were no significant differences in sensitivity and specificity between the 2012 SLICC and the 2017 weighted criteria.

Classifying and diagnosing systemic lupus erythematosus in the 21st century

The EULAR/ACR 2019 classification criteria for SLE constitute a current and optimized clinical approach to SLE classification. Classification is still not based on molecular approaches and the results from large studies using polyomics may be interpreted as demonstrating the relevance of the genetic and environmental background rather than splitting SLE into several entities. In fact, an association study within the EULAR/ACR classification criteria project found associations between manifestations only within organ domains. This independency of various organ manifestations argues for SLE as one disease entity. The current review article will therefore concentrate on the clinical and immunological manifestations of SLE and on what we have already learned in this century. Moreover, the structure and essential rules of the EULAR/ACR 2019 classification criteria will be discussed. While classification and diagnosis are distinct concepts, which have to remain clearly separated, information derived from the process towards the classification criteria is also useful for diagnostic purposes. Therefore this article also tries to delineate what classification can teach us for diagnosis, covering a wide variety of SLE manifestations.

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.

Associations Between Classification Criteria Items in Systemic Lupus Erythematosus

OBJECTIVE

A project aimed at developing new classification criteria for systemic lupus erythematosus (SLE) is based on weighted criteria that include both laboratory and clinical items. Combinations of certain symptoms may occur commonly in SLE, which provides an argument against independently counting these items. The current study was undertaken to evaluate the interrelationship between candidate criteria items in the International Early SLE cohort and in the Euro-Lupus cohort.

METHODS

The International Early SLE cohort included 389 patients, who were diagnosed within 3 years prior to the study. Data on the ACR's 1997 update of the SLE revised criteria, the Systemic Lupus International Collaborating Clinics 2012 criteria, and on 30 additional items were collected. To evaluate the interrelationship of the criteria, a tetrachoric correlation was used to assess the degree of association between different manifestations in the same organ system. The correlations identified in the International Early SLE cohort were validated in the Euro-Lupus cohort.

RESULTS

A few relevant correlations were observed among specific clinical cutaneous manifestations (in particular, malar rash correlated with photosensitivity, alopecia, and oral ulcers) and serologic manifestations (anti-Sm and anti-double-stranded DNA and anti-RNA polymerase, anti-Ro and anti-La, and antiphospholipid antibodies), and these results were validated in the Euro-Lupus cohort. The associations within the mucocutaneous domain, hematologic and the specific autoantibodies suggest that within a single domain only the highest ranking item should be counted to avoid overrepresentation.

CONCLUSION

Some of the candidate SLE criteria cluster within domains. Given these interrelationships, multiple criteria within a domain should not be independently counted. These results are important to consider for the structure of new SLE classification criteria.

The association between antinuclear antibody and response to rituximab treatment in adult patients with primary immune thrombocytopenia

Background: Antinuclear antibodies (ANAs) can be detected in about 30% of patients with primary immune thrombocytopenia (ITP), yet their relationship with treatment response to rituximab remains elusive.Methods: we retrospectively reviewed the clinical records of hospitalized adult ITP patients who were treated with rituximab from three medical centers across China. Rituximab was given intravenously at 100 mg weekly for 4 weeks, or at a single dose of 375 mg/m². All included patients had their ANAs tested before rituximab treatment.Results: A total of 287 patients fulfilled the inclusion criteria and were eligible for analysis. ANAs were positive in 98 (34.1%) of the included patients. The incidence of overall response and complete response (CR) in ANA-positive patients was significantly higher than that in ANA-negative patients (overall response: 76.5% vs. 55.0%, P < 0.001; CR: 46.9% vs. 29.1%, P = 0.003). However, sustained response (SR) rates in ANA-positive patients at 6, 12 and 24 months were all lower compared with ANA-negative patients (all P < 0.05). The overall duration of response (DOR) estimated by Kaplan-Meier analysis in ANA-negative patients was greater than that in ANA-positive patients (P < 0.001).Conclusion: ITP patients with positive ANA test were likely to achieve a better initial response to rituximab treatment, while their long-term outcome was unfavorable. Therefore, ANA test could be useful for predicting rituximab response in ITP.

New classification criteria for systemic lupus erythematosus

PURPOSE OF REVIEW

To compare the recently published European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR) classification criteria for SLE with the Systemic Lupus International Collaborating Centers (SLICC) criteria and the earlier ACR criteria, focusing on their key concepts.

RECENT FINDINGS

Although the SLICC criteria introduced numbers of new criteria items, the new EULAR/ACR criteria added only noninfectious fever, based on an early SLE cohort study and an SLE patient survey, and condensed hematological, mucocutaneous and neurological items. Whereas the SLICC criteria maintained the overall structure familiar from the ACR criteria, the EULAR /ACR criteria use antinuclear antibodies (ANA) as an obligatory entry criterion, have weighted criteria and group these in domains. Where the SLICC criteria greatly increased sensitivity, losing some specificity, the EULAR/ACR criteria increased specificity again, for excellent classification criteria performance.

SUMMARY

Despite differences in structure and statistical performance, the EULAR/ACR and SLICC criteria agree on the importance of both immunological and clinical findings, on the high impact of lupus nephritis by histology, and on most clinical items.

Performance of the 2019 EULAR/ACR classification criteria for systemic lupus erythematosus in early disease, across sexes and ethnicities

OBJECTIVES

The European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR) 2019 Classification Criteria for systemic lupus erythematosus (SLE) have been validated with high sensitivity and specificity. We evaluated the performance of the new criteria with regard to disease duration, sex and race/ethnicity, and compared its performance against the Systemic Lupus International Collaborating Clinics (SLICC) 2012 and ACR 1982/1997 criteria.

METHODS

Twenty-one SLE centres from 16 countries submitted SLE cases and mimicking controls to form the validation cohort. The sensitivity and specificity of the EULAR/ACR 2019, SLICC 2012 and ACR 1982/1997 criteria were evaluated.

RESULTS

The cohort consisted of female (n=1098), male (n=172), Asian (n=118), black (n=68), Hispanic (n=124) and white (n=941) patients; with an SLE duration of 1 to <3 years (n=196) and ≥5 years (n=879). Among patients with 1 to <3 years disease duration, the EULAR/ACR criteria had better sensitivity than the ACR criteria (97% vs 81%). The EULAR/ACR criteria performed well in men (sensitivity 93%, specificity 96%) and women (sensitivity 97%, specificity 94%). Among women, the EULAR/ACR criteria had better sensitivity than the ACR criteria (97% vs 83%) and better specificity than the SLICC criteria (94% vs 82%). Among white patients, the EULAR/ACR criteria had better sensitivity than the ACR criteria (95% vs 83%) and better specificity than the SLICC criteria (94% vs 83%). The EULAR/ACR criteria performed well among black patients (sensitivity of 98%, specificity 100%), and had better sensitivity than the ACR criteria among Hispanic patients (100% vs 86%) and Asian patients (97% vs 77%).

CONCLUSIONS

The EULAR/ACR 2019 criteria perform well among patients with early disease, men, women, white, black, Hispanic and Asian patients. These criteria have superior sensitivity than the ACR criteria and/or superior specificity than the SLICC criteria across many subgroups.

Complement activation in human autoimmune diseases and mouse models; employing a sandwich immunoassay specific for C3dg

In human autoimmune diseases, low plasma levels of complement factors C3 and C4 are commonly used as a proxy for complement activation. The measurements of C3 and C4 concentrations (the result of synthesis and consumption) however, show low sensitivity in patient follow-up. We find that the estimation of the C3dg fragment released during complement activation is a better parameter for complement activation. Available techniques for measuring the activation fragment C3dg, e.g. immune-electrophoresis or involving PEG-precipitation, are time-consuming and difficult to standardize. Here we examine the specificity and use of an antibody with mono-specificity for a neoepitope at the N-terminus of C3dg, which is only exposed after cleavage of C3. We present a stable, reproducible, and easy-to-use, time-resolved immunoassay with specificity for C3dg that can be used to directly evaluate ongoing complement activation. We demonstrate that the assay can be applied to clinical samples with a high specificity (95%) and a positive likelihood ratio of 10. It can also differentiate the complement related disease Systemic Lupus Erythematosus from controls and other immune-mediatedimmune mediated diseases like Rheumatoid Arthritis (86% specificity) and Spondyloarthritis (91% specificity). Further, we establish how the assay may also be used for experimental research in in vivo mouse models.

Incomplete Systemic Lupus Erythematosus: What Remains After Application of American College of Rheumatology and Systemic Lupus International Collaborating Clinics criteria?

Incomplete systemic lupus (iSLE) is an acknowledged condition of patients with clinical signs of lupus who do not fulfill classification criteria for SLE. Some patients with iSLE have persistent mild disease, but others have serious organ involvement, and up to 55% progress to established SLE. Research on this subject could reveal predictive or diagnostic biomarkers for SLE. Ideally, it would become possible to discern those patients with critical organ involvement or a high risk for progression to SLE. This high‐risk group might benefit from early treatment, which would preferably be confirmed in randomized controlled trials. This process would, however, require agreement on a definition of iSLE. The Systemic Lupus International Collaborating Clinics (SLICC) classification criteria was composed in order to diagnose SLE earlier. The present review outlines the clinical characteristics of iSLE after introduction of SLICC criteria and furthermore proposes a definition of iSLE with the aim of discriminating the high‐risk group from those with a lower risk.

EULAR/ACR classification criteria for SLE

Supported by both the European League Against Rheumatism (EULAR) and the American College of Rheumatology (ACR) from the beginning, a large transatlantic, and in many phases worldwide, project has led to new classification criteria for systemic lupus erythematosus (SLE). The project had ambitious goals, particularly maintaining the high specificity of the ACR criteria, while reaching a sensitivity close to the Systemic Lupus International Collaborating Clinics (SLICC) 2012 criteria. The validation data suggest that the new criteria reached this goal, with a specificity of 93% (as for the ACR criteria) and a sensitivity of 96% (vs 97% for the SLICC criteria). The new EULAR/ACR classification criteria use positive antinuclear antibodies (ANA) as an entry criterion and have weighted items, ranging from 2 (for delirium, non-infectious fever and anti-phospholipid antibodies) to 10 (for class III or IV lupus nephritis). The cut-off for classification is 10, reached by class III/IV nephritis alone. Items are organized in domains, within which only the highest item is to be counted. Instead of many defined exclusions, one rule is used for all, namely that items are to be attributed to SLE and counted only if there is no more likely alternative diagnosis. These criteria are now expected to be externally validated in various other cohorts. The team spirit and collegiality characteristic for this EULAR/ACR criteria effort will hopefully facilitate future international projects on SLE.

Neue Klassifikationskriterien des SLE: was helfen sie für die klinische Diagnose des SLE?

Im September 2019 sind die gemeinsamen Klassifikationskriterien der European League Against Rheumatism (EULAR) und des American College of Rheumatology (ACR) für den systemischen Lupus erythematodes (SLE) erschienen. Die EULAR/ACR 2019 Klassifikationskriterien verwenden (jemals) positive antinukleäre Antikörper (ANA) als obligates Eingangskriterium und gewichtete Kriterien mit Werten von 2 bis 10 und einem Cut-off von 10. Die Kriterien sind in 10 Domänen geordnet, innerhalb derer Assoziationen zwischen verschiedenen Manifestationen bestehen, und nur der höchste Wert in einer Domäne wird verwendet. Kriterien werden nur gewertet, wenn es für sie keine andere Erklärung gibt, die wahrscheinlicher ist als der SLE. Die neuen Kriterien sind statistisch den älteren Kriteriensets überlegen. Sie gelten aber nur für die Klassifikation. Für die meisten Rheumatologinnen und Rheumatologen ist das Stellen der Diagnose eines SLE wesentlich relevanter als der Einschluss in SLE-Studien, für den die Klassifikationskriterien gedacht sind. Daher stellt sich die Frage, wie weit die Klassifikationskriterien für die Diagnose helfen können. Direkt dafür verwendet werden dürfen sie wirklich nicht. Erfahrene Ärztinnen und Ärzte sind besser und v. a. sensitiver als die besten Kriterien. Manche Detailinformationen helfen aber dennoch dabei, die individuelle Diagnose für konkret Patientinnen und Patienten zu stellen. Die vorliegende Arbeit erörtert die Neuigkeiten in den EULAR/ACR 2019-Kriterien, stellt den Unterschied zwischen Klassifikation und Diagnose dar und diskutiert, welche Informationen auch im klinischen Alltag Anwendung finden können.

New Criteria for Lupus

PURPOSE OF THE REVIEW

Classification criteria define the patient population for clinical trials and translational studies, but also influence current understanding of the disease. This review attempts to delineate the development from the American College of Rheumatology (ACR) 1982 to the European League Against Rheumatism (EULAR)/ACR 2019 classification criteria for systemic lupus erythematosus (SLE).

RECENT FINDINGS

The new EULAR/ACR classification criteria use antinuclear antibodies (ANA) as an entry criterion. (Non-infectious) fever is the one new criterion. All criteria items now have individual weights (from 2 to 10) and are structured in domains, within which only the highest item is counted. There is one common attribution rule, counting criteria only if there is no more likely alternative explanation. Ten points are sufficient for classification. The new criteria have reached a sensitivity of 96.1% and a specificity of 93.4%. The new EULAR/ACR 2019 classification criteria for SLE build on the previous criteria sets, adding fever only as a new criteria item. The new structure is reflective of the current diagnostic approach and has led to improved statistical performance.

A hierarchical bivariate meta-analysis of diagnostic test accuracy to provide direct comparisons of immunoassays vs. indirect immunofluorescence for initial screening of connective tissue diseases

OBJECTIVES

To compare indirect immunofluorescence (IIF) for antinuclear antibodies (ANA) against immunoassays (IAs) as an initial screening test for connective tissue diseases (CTDs).

METHODS

A systematic literature review identified cross-sectional or case-control studies reporting test accuracy data for IIF and enzyme-linked immunosorbent assays (ELISA), fluorescence enzyme immunoassay (FEIA), chemiluminescent immunoassay (CLIA) or multiplex immunoassay (MIA). The meta-analysis used hierarchical, bivariate, mixed-effect models with random-effects by test.

RESULTS

Direct comparisons of IIF with ELISA showed that both tests had good sensitivity (five studies, 2321 patients: ELISA: 90.3% [95% confidence interval (CI): 80.5%, 95.5%] vs. IIF at a cut-off of 1:80: 86.8% [95% CI: 81.8%, 90.6%]; p = 0.4) but low specificity, with considerable variance across assays (ELISA: 56.9% [95% CI: 40.9%, 71.5%] vs. IIF 1:80: 68.0% [95% CI: 39.5%, 87.4%]; p = 0.5). FEIA sensitivity was lower than IIF sensitivity (1:80: p = 0.005; 1:160: p = 0.051); however, FEIA specificity was higher (seven studies, n = 12,311, FEIA 93.6% [95% CI: 89.9%, 96.0%] vs. IIF 1:80 72.4% [95% CI: 62.2%, 80.7%]; p < 0.001; seven studies, n = 3251, FEIA 93.5% [95% CI: 91.1%, 95.3%] vs. IIF 1:160 81.1% [95% CI: 73.4%, 86.9%]; p < 0.0001). CLIA sensitivity was similar to IIF (1:80) with higher specificity (four studies, n = 1981: sensitivity 85.9% [95% CI: 64.7%, 95.3%]; p = 0.86; specificity 86.1% [95% CI: 78.3%, 91.4%]). More data are needed to make firm inferences for CLIA vs. IIF given the wide prediction region. There were too few studies for the meta-analysis of MIA vs. IIF (MIA sensitivity range 73.7%-86%; specificity 53%-91%).

CONCLUSIONS

FEIA and CLIA have good specificity compared to IIF. A positive FEIA or CLIA test is useful to support the diagnosis of a CTD. A negative IIF test is useful to exclude a CTD.

An Epigenetics-Based Hypothesis of Autoantigen Development in Systemic Lupus Erythematosus

Currently, we have a limited understanding of mechanisms leading to systemic lupus erythematosus, but we know that genetics, environmental factors, and epigenetics contribute to the disease. One common aspect of the various environmental triggers is that they can cause cellular stress. When extraordinary stress occurs, such as viral activation, a cell's response can include increased nucleolar volume and activity to produce more machinery (e.g., ribosomes) to help the cell recover. However, nucleolar expansion can disrupt the epigenetic control in neighboring heterochromatin that comprises the nucleolar shell. This disruption can open underlying vulnerabilities that provoke an autoimmune reaction. Here, we review the "X chromosome-nucleolus nexus" hypothesis, which explains how nucleolar stress can disrupt epigenetically silenced chromatin, especially the neighboring inactive X chromosome (aka the nucleolar satellite). Chromatin disruption can lead to the expression of sequestered DNA, such as Alu elements and fully functional LINE-1 reverse transcriptase genes. In addition, Alu transcripts can disrupt the nucleolar structural integrity, leading to nucleolar disintegration. Such disintegration can leave nucleolar components and products in autoantigenic forms, such as abnormal conformations or incomplete macromolecular assemblies. Recent research on DNA sensing pathways can now be incorporated into the hypothesis to provide further details explaining how autoantibodies to endogenous nucleic acids arise.

Validation of the new classification criteria for systemic lupus erythematosus on a patient cohort from a national referral center: a retrospective study

AIM

To validate Systemic Lupus International Collaborating Clinics (SLICC)-12 and American College of Rheumatology (ACR)-97 classification criteria on a patient cohort from the University Hospital Center Zagreb.

METHODS

This retrospective study, conducted from 2014 to 2016, involved 308 patients with systemic lupus erythematosus (SLE) (n=146) and SLE-allied conditions (n=162). Patients' medical charts were evaluated by an expert rheumatologist to confirm the clinical diagnosis, regardless of the number of the ACR-97 criteria met. Overall sensitivity and specificity, as well as the sensitivity and specificity according to disease duration, were compared between ACR-97 and SLICC-12 classifications. Predictive value for SLE for both classifications was assessed using logistic regression and receiver operating characteristic (ROC) curves.

RESULTS

The SLICC-12 criteria had significantly higher sensitivity in early disase, which increased with disease duration. The ACR-97 criteria had higher specificity. The specificity of the SLICC-12 criteria was low and decreased with disease duration. Regression analysis demonstrated the superiority of the SLICC-12 classification criteria over the ACR-97 criteria, with areas under the ROC curve of 0.801 and 0.780, respectively.

CONCLUSION

Although the SLICC-12 criteria were superior to the ACR-97 and were more sensitive for diagnosing early SLE, their specificity in our population was too low. The sensitivity of the SLICC-12 classification is increased by better defined clinical features within each criterion. Our results contribute to the current initiative for developing new criteria for SLE.

In an early SLE cohort the ACR-1997, SLICC-2012 and EULAR/ACR-2019 criteria classify non-overlapping groups of patients: use of all three criteria ensures optimal capture for clinical studies while their modification earlier classification and treatment

OBJECTIVES

Classification criteria are biased towards classifying long-standing disease. We compared the European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR)-2019, Systemic Lupus International Collaborating Clinics (SLICC)-2012 and ACR-1997 criteria in an early (median 48 months) systemic lupus erythematosus (SLE) cohort.

METHODS

Patients diagnosed with SLE (n=690) or control diseases (n=401). Sensitivity, specificity of the criteria and time-to-classification were calculated. Modified classification algorithms were derived from a random 80% and validated in the remaining 20% of the dataset running multiple iterations.

RESULTS

At last assessment, sensitivities of ACR-1997, SLICC-2012 and EULAR/ACR-2019 criteria were 85.7%, 91.3% and 88.6%, with specificities 93.0%, 93.8% and 97.3%, respectively. Both SLICC and EULAR/ACR enabled earlier classification. Only 76.7% of patients with SLE met all three criteria suggesting non-overlapping groups. Notably, unclassified patients had high prevalence of British Isles Lupus Assessment Group moderate/severe manifestations (43.3%-60%) and SLICC/ACR organ damage (30%-50%). At diagnosis, criteria missed 25.6%-30.5% of patients. Modification of EULAR/ACR and SLICC algorithms to include hypocomplementaemia and/or positive anti-phospholipid antibodies as alternative entry criterion, and/or allow classification with fewer clinical criteria from multiple organs, increased their sensitivity at diagnosis (median 82.0% and 86.2%) and overall (93.7% and 97.1%) with modest decreases in specificity. Importantly, patients who were still missed by the modified criteria had lower incidence of major organ involvement, use of immunosuppressive/biological therapies and organ damage.

CONCLUSIONS

The SLICC and EULAR/ACR are more sensitive than the ACR and the EULAR/ACR criteria have superior specificity in early SLE, although patients with significant disease can be missed. Combination and/or modification of the classification algorithms may enhance their sensitivity, allowing earlier classification and treatment of more patients with high disease burden.

ANA as an entry criterion for the classification of SLE

Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease with highly variable clinical and immunological manifestations. In the classification of patients with this condition, the presence of an antinuclear antibody (ANA) is an important element, with new criteria from the American College of Rheumatology and European League against Rheumatism positioning ANA positivity by an immunofluorescence assay on HEp2-cells (HEp2-IFA) or by an equivalent solid phase assay as the entry criterion. This positioning is based on assumptions about the frequency of ANA positivity in SLE as well as the reliability of the assays. Studies indicate that these assumptions are still a matter of uncertainty since both types of assay show considerable variability and patients with SLE may display negative results in ANA testing. These findings suggest caution in positioning ANA positivity as an entry criterion for classification and point to the value of alternative serological approaches for ANA determinations.

Does seronegative obstetric APS exist? "pro" and "cons"

Antiphospholipid Syndrome (APS) is the commonest treatable cause of recurrent miscarriage and pharmacological treatment of pregnant patients with antiphospholipid antibodies (aPL) should aim at preventing obstetric complications and maternal thrombotic events. Conventional treatment for patients with an established diagnosis of obstetric APS (OAPS), generally resulting in over 70-80% successful pregnancies. Since seropositive (SP)-APS and seronegative (SN)-APS patients had shown similar clinical profiles, patients with SN- OAPS, as well as SP-OAPS, should receive combined treatment in order to improve the pregnancy prognosis; indeed, current standard of care increased good pregnancy outcome in SN-APS, with similar effect to confirmed APS. The above data suggest that there are patients with the clinical manifestations of OAPS but persistently negative to conventional aPL that need to be identified to ensure adequate therapy and therefore a better prognosis. The clinical utility of non-criteria aPL in the diagnosis of SN-APS is still a matter of debate. In the last decade more and more studies have reported the presence of patients suffering from SN-APS in which non-conventional ("non-criteria") aPL might be present or antibodies may be detected using methodological approaches different from the traditional assays. To improve test standardization large prospective, multicenter, and multinational studies are needed. Therefore, when assessing a patient with clinical manifestations consistent with OAPS but aPL negative using the conventional available assays, the clinician should consider the possibility that the patient is affected with SN-APS.