The predictive value of antinuclear antibodies in patients with suspected connective tissue disease for the development of connective tissue diseases.

OBJECTIVES: Early confirmation of the diagnosis of connective tissue diseases (CTD) is important, as prolonged disease activity can result in irreversible organ damage. Although antinuclear antibodies (ANAs) have been shown to precede the diagnosis of SLE, this has not been investigated in large cohorts for other CTDs. In this study, we investigated whether the presence of antinuclear autoantibodies in undiagnosed patients suspected of having CTDs is predictive of development of a future CTD. METHODS: We screened the Electronic Health Records of a cohort of 1030 patients, who were tested for ANAs and their specificity in 2013/2014, to evaluate whether new CTD diagnoses had been recorded by a clinician between the original blood draw date and 2020. We compared the prevalence of ANAs in patients who developed a new CTD diagnosis during follow-up with patients with similar symptoms at baseline who did not receive a subsequent CTD diagnosis and with patients with an established CTD at baseline. RESULTS: Sixteen out of 1030 patients had developed a new CTD in the studied time period. The mean time period between baseline blood draw and subsequent CTD diagnosis of these patients was approximately 2.3 years. Eleven out of 16 (69%) newly diagnosed patients had positive ANA screening tests, compared to 54% of patients with a CTD diagnosis at baseline (p=ns) and 30% of symptomatic undiagnosed patients (p<0.001). This resulted in a positive predictive value (PPV) of 7% and a negative predictive value (NPV) of 98% for the development of a new CTD in undiagnosed symptomatic patients. For specific ANAs associated with the suspected CTD, the PPV was 12%, with a NPV of 98%. CONCLUSIONS: Progression to a CTD diagnosis is rare in undiagnosed patients. Undiagnosed patients with symptoms associated with a CTD who progress to a CTD more often have ANAs than patients with similar symptoms who do not progress to a CTD. ANA testing can be used to more stringently select patients who should remain in follow-up.

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-ß2-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.

ERN ReCONNET points to consider for treating patients living with autoimmune rheumatic diseases with antiviral therapies and anti-SARS-CoV-2 antibody products.

Recent studies have shown that people who are immunocompromised may inadvertently play a role in spurring the mutations of the virus that create new variants. This is because some immunocompromised individuals remain at risk of getting COVID-19 despite vaccination, experience more severe disease, are susceptible to being chronically infected and remain contagious for longer if they become infected and considering that immunocompromised individuals represent approximately 2% of the overall population, this aspect should be carefully considered. So far, some autoimmune rheumatic disease (ARD) patients with COVID-19 have been treated with antiviral therapies or anti-SARS-CoV-2 antibody products. However, there is no homogeneous approach to these treatment strategies. This issue was addressed within the European Reference Network (ERN) on Rare and Complex Connective Tissue and Musculoskeletal Diseases (ReCONNET) in a discussion among experts and patient's representatives in the context of the rare and complex connective tissue diseases (rCTDs) covered by the Network. ERN ReCONNET is one of the 24 ERNs launched by the European Commission in 2017 with the aim of tackling low prevalence and rare diseases that require highly specialised treatment and promoting concentration of knowledge and resources through virtual networks involving healthcare providers (HCPs) across the European Union (EU). Considering the urgent need to provide guidance not only to the rCTDs community, but also to the whole ARDs community, a multidisciplinary Task Force, including expert clinicians and European Patient Advocacy Group (ePAG) Advocates, was created in the framework of ERN ReCONNET with the aim of developing overarching principles (OP) and points-to-consider (PtC) on a homogenous approach to treat immunocompromised patients with ARDs (with a particular focus on CTDs) affected by COVID-19 using antiviral therapies and anti-SARS-CoV-2 antibody products. The present work reports the final OP and PtC agreed by the Task Force.

Clinical features and immune-related protein patterns of anti-MDA5 positive clinically amyopathic dermatomyositis Dutch patients.

OBJECTIVES: The presence of melanoma differentiation-associated protein 5 (MDA5) antibodies in patients with DM is associated with the development of a rapidly progressive interstitial lung disease (RPILD), unresponsive to conventional treatment. We characterize patients and provide more insight into potential biomarkers to identify patients with RPILD. METHODS: Patients diagnosed with anti-MDA5 positive DM between December 2015 and November 2017 were included in this study. Clinical data were retrospectively retrieved from medical records. A total of 180 immune-related markers were measured in sera of 16 patients and 15 healthy controls using proximity extension assay-based technology. RESULTS: Twenty patients were included, with a median time from symptoms till diagnosis of 4 months. All patients had clinically amyopathic DM. Interstitial lung disease (ILD) was present at diagnosis in 94% of the patients, 45% presented with RPILD. The mortality rate was 35% within 4 months after diagnosis and respiratory failure was the main cause of death in these patients. Furthermore, unsupervised analysis revealed that patients with RPILD show clearly different inflammatory serum profiles than healthy controls. In addition, in comparison to healthy controls, the IFN, IL1, IL10 and IL18 signalling pathways are different regulated in anti-MDA5 positive patients. CONCLUSION: In this Dutch anti-MDA5 positive clinically amyopathic DM (CADM) cohort, one-third of the patients died due to RPILD soon after diagnosis, which underlines the severity of this disease. In addition, we have found several possible pathways that are differentially regulated in RPILD vs no RPILD DM and healthy controls. These markers await further validation before clinical use.

Rare clinical manifestations in systemic lupus erythematosus: a review on frequency and clinical presentation.

OBJECTIVES: The purpose of this study was to review the frequency and clinical presentation of the rarest clinical manifestations of systemic lupus erythematosus (SLE). METHODS: A list of 6 rare SLE manifestations were defined: gastrointestinal, liver, pulmonary, cardiac, ocular and neurological manifestations. Each topic was assigned to a pair of authors to perform a literature search and article review. RESULTS: In total, 149 articles were included in the literature review: 37 for gastrointestinal manifestations, 6 for liver manifestations, 27 for pulmonary manifestations, 50 for cardiac manifestations, 16 for ocular manifestations, 13 for neurological manifestations. Gastrointestinal disorders included several clinical presentations with variable frequency (from 0.5% to 10.7% of the cases); liver involvement included lupus-related hepatitis (9.3%) and autoimmune hepatitis (2.3%). The rarest pulmonary manifestations identified were shrinking lung syndrome, described in 1.5% of patients, while interstitial lung disease and lupus pneumonia were reported in 4% and 3% of patients respectively. Myocarditis and pulmonary hypertension were also rarely described in SLE patients although ranging from 0.4-16% and 1-14% respectively, depending on the methodology used for its identification. Ocular manifestations in SLE included some rare manifestations (reported in less than 5% of patients) and lupus retinopathy that is described in 1.2-28.8% of patients depending on methods of ascertainment. Aseptic meningitis and chorea were also confirmed as very rare manifestations being reported in less than 1% and in 0.3-2.4% of cases respectively. CONCLUSIONS: The results of this literature review provide the basis for a better understanding of some less-known manifestations of SLE and for stressing the need for a higher awareness in diagnostic and therapeutic protocols regarding these rare disease aspects.

The added value of a European Reference Network on rare and complex connective tissue and musculoskeletal diseases: insights after the first 5 years of the ERN ReCONNET.

In order to address the main challenges related to the rare diseases (RDs) the European Commission launched the European Reference Networks (ERNs), virtual networks involving healthcare providers (HCPs) across Europe. The mission of the ERNs is to tackle low prevalence and RDs that require highly specialised treatment and a concentration of knowledge and resources. In fact, ERNs offer the potential to give patients and healthcare professionals across the EU access to the best expertise and timely exchange of lifesaving knowledge, trying to make the knowledge travelling more than patients. For this reason, ERNs were established as concrete European infrastructures, and this is particularly crucial in the framework of rare and complex diseases in which no country alone has the whole knowledge and capacity to treat all types of patients.It has been five years since their kick-off launch in Vilnius in 2017. The 24 ERNs have been intensively working on different transversal areas, including patient management, education, clinical practice guidelines, patients' care pathways and many other fundamental topics. The present work is therefore aimed not only at reporting a summary of the main activities and milestones reached so far, but also at celebrating the first 5 years of the ERN on Rare and Complex Connective Tissue and Musculo-skeletal Diseases (ReCONNET), in which the members of the network built together one of the 24 infrastructures that are hopefully going to change the scenario of rare diseases across the EU.

The early identification of disease progression in patients with suspected infection presenting to the emergency department: a multi-centre derivation and validation study.

BACKGROUND: There is a lack of validated tools to assess potential disease progression and hospitalisation decisions in patients presenting to the emergency department (ED) with a suspected infection. This study aimed to identify suitable blood biomarkers (MR-proADM, PCT, lactate and CRP) or clinical scores (SIRS, SOFA, qSOFA, NEWS and CRB-65) to fulfil this unmet clinical need. METHODS: An observational derivation patient cohort validated by an independent secondary analysis across nine EDs. Logistic and Cox regression, area under the receiver operating characteristic (AUROC) and Kaplan-Meier curves were used to assess performance. Disease progression was identified using a composite endpoint of 28-day mortality, ICU admission and hospitalisation > 10 days. RESULTS: One thousand one hundred seventy-five derivation and 896 validation patients were analysed with respective 28-day mortality rates of 7.1% and 5.0%, and hospitalisation rates of 77.9% and 76.2%. MR-proADM showed greatest accuracy in predicting 28-day mortality and hospitalisation requirement across both cohorts. Patient subgroups with high MR-proADM concentrations (≥ 1.54 nmol/L) and low biomarker (PCT < 0.25 ng/mL, lactate < 2.0 mmol/L or CRP < 67 mg/L) or clinical score (SOFA < 2 points, qSOFA < 2 points, NEWS < 4 points or CRB-65 < 2 points) values were characterised by a significantly longer length of hospitalisation (p < 0.001), rate of ICU admission (p < 0.001), elevated mortality risk (e.g. SOFA, qSOFA and NEWS HR [95%CI], 45.5 [10.0-207.6], 23.4 [11.1-49.3] and 32.6 [9.4-113.6], respectively) and a greater number of disease progression events (p < 0.001), compared to similar subgroups with low MR-proADM concentrations (< 1.54 nmol/L). Increased out-patient treatment across both cohorts could be facilitated using a derivation-derived MR-proADM cut-off of < 0.87 nmol/L (15.0% and 16.6%), with decreased readmission rates and no mortalities. CONCLUSIONS: In patients presenting to the ED with a suspected infection, the blood biomarker MR-proADM could most accurately identify the likelihood of further disease progression. Incorporation into an early sepsis management protocol may therefore aid rapid decision-making in order to either initiate, escalate or intensify early treatment strategies, or identify patients suitable for safe out-patient treatment.

Correction to: The early identification of disease progression in patients with suspected infection presenting to the emergency department: a multi-centre derivation and validation study.

In the publication of this article [1], there are two errors in contributing author affiliations. This has now been included in this correction article.

An evidence-based approach to pre-pregnancy counselling for patients with systemic lupus erythematosus.

Patients with SLE are often young females of childbearing age and a pregnancy wish in this patient group is common. However, SLE patients are at high risk for adverse pregnancy outcomes that require adequate guidance. It is widely acknowledged that pre-pregnancy counselling is the pivotal first step in the management of SLE patients with a wish to become pregnant. Next, management of these patients is usually multidisciplinary and often requires specific expertise from the different physicians involved. Very recently a EULAR recommendation was published emphasizing the need for adequate preconception counselling and risk stratification. Therefore the present review specifically addresses the issue of pre-pregnancy counselling for SLE patients with an evidence-based approach. The review summarizes data retrieved from recently published, high-quality cohort studies that have contributed to a better understanding and estimation of pregnancy-related risks for SLE patients. The present review categorizes risks from a patient-oriented point of view, that is, the influence of pregnancy on SLE, of SLE on pregnancy, of SLE on the foetus/neonate and of SLE-related medication. Lastly, pre-pregnancy counselling of SLE patients with additional secondary APS is reviewed. Collectively these data can guide clinicians to formulate appropriate preventive strategies and patient-tailored monitoring plans during pre-pregnancy counselling of SLE patients.

Procalcitonin-guided therapy for the initiation of antibiotics in the ED: a systematic review.

BACKGROUND: Procalcitonin (PCT) is a new biomarker with a higher accuracy in the diagnosis of bacterial infections. Utilization of PCT may reduce the number of unnecessary antibiotics prescribed to patients and consequently may decrease the rise in antibiotic resistance. The aim of this systematic review is to determine if a PCT-guided algorithm can safely reduce the number of antibiotics prescribed to all patients with a suspected of infection in the emergency department (ED). METHODS: MEDLINE, EMBASE, Web of Science, COCHRANE central, PubMed publisher, and Google scholar were searched. Two reviewers performed the screening independently. The QUADAS 2 tool was used to assess quality. RESULTS: In total, 1621 articles were screened. Nine articles were included in the analysis. In the 6 studies on adult patients, only patients with respiratory tract infections were investigated. In these studies, a cutoff value of 0.25 µg/L was used, and PCT-guided therapy reduced the number of prescribed antibiotics significantly. Three studies were on pediatric patients, 2 on fever without source and 1 on respiratory complaints. Procalcitonin-guided therapy did not reduce antibiotic prescription in children. Procalcitonin-guided therapy did not result in an increase in adverse events in any of the studies. DISCUSSION: Procalcitonin-guided therapy in the ED is only studied in subpopulations, where it was effective and safe in adult patients with respiratory tract infections and not effective but safe nonetheless in specific pediatric populations. Nonadherence is a significant problem in prospective PCT-guided therapy studies. There is not enough evidence to use PCT-guided therapy in a general ED population.

Higher diagnostic accuracy and cost-effectiveness using procalcitonin in the treatment of emergency medicine patients with fever (The HiTEMP study): a multicenter randomized study.

BACKGROUND: Fever is a common symptom in the emergency department(ED). Fever can be caused by bacterial infections, which are treated with antibiotics. Often, bacterial infections cannot be ruled out in the ED using standard diagnostics, and empiric antibiotic treatment is started. Procalcitonin(PCT) is a biomarker for bacterial infections, but its role in an undifferentiated ED population remains unclear. We hypothesize that PCT-guided therapy may reduce antibiotics prescription in undifferentiated febrile ED patients. The primary objectives of this study are to determine a) the efficacy, b) the safety of PCT-guided therapy, and c) the accuracy of the biomarker PCT for bacterial infections. The secondary objective is to study the cost-effectiveness of PCT-guided therapy. METHODS/DESIGN: This is a multicenter noninferiority randomized controlled trial. All adult ED patients with fever(≥38.2 °C) are randomized between standard care with and without the addition of a PCT level, after written informed consent. a) For efficacy, the reduction of patients receiving antibiotics is calculated, using a superiority analysis: differences between the PCT-guided group and control group are assessed using a Fisher's exact test, and a multivariable logistic regression analysis to account for the effects of demographic and medical variables on the percentage of febrile patients receiving antibiotics. b) Safety consists of a composite endpoint, defined as mortality, intensive care admission and ED return visit within 14 days. Noninferiority of PCT will be tested using a one-sided 95 % confidence interval for the difference in the composite safety endpoint between the PCT-guided and control groups using a noninferiority margin of 7.5 %. c) Accuracy of PCT and CRP for the diagnosis of bacterial infections will be reported, using the sensitivity, specificity, and the area under the receiver-operating-characteristic curve in the definitive diagnosis of bacterial infections. The sample size is 550 patients, which was calculated using a power analysis for all primary objectives. Enrollment of patients started in August 2014 and will last 2 years. DISCUSSION: PCT may offer a more tailor-made treatment to the individual ED patient with fever. Prospective costs analyses will reveal the economic consequences of implementing PCT-guided therapy in the ED. THIS TRIAL IS REGISTERED IN THE DUTCH TRIAL REGISTER: NTR4949.

Adult patient diagnosed with Muckle-Wells syndrome, antiphospholipid syndrome and glomerular haematuria.

Muckle-Wells syndrome (MWS) is a genetic periodic fever syndrome characterised by urticaria, fever and malaise starting in childhood with the development of perceptive hearing loss and risk of amyloidosis later in life.Patient A, in his 60s, was referred to a nephrologist because of glomerular haematuria and elevated erythrocyte sedimentation rate. He appeared to have periodic fevers since childhood, skin changes in cold circumstances and progressive deafness since he was 30 years of age. Genetic analysis revealed a pathogenic variant in the NLRP3 gene compatible with MWS. Treatment with anakinra (interleukin 1 antagonist) improved his symptoms, but only mild episodic arthralgia remained. Glomerular erythrocyturia diminished during treatment, supposing a relation between MWS and haematuria.This case report shows that rare genetic fever syndromes starting from early childhood can still be diagnosed in adult patients, with important therapeutic consequences. Symptoms can be relieved and amyloidosis with potential renal failure may be prevented.

Pregnancy outcome predictors in systemic lupus erythematosus: a systematic review and meta-analysis.

BACKGROUND: To enhance patient-tailored preconception risk assessment for women with systemic lupus erythematosus (SLE), knowledge on risk factors associated with adverse pregnancy outcomes is required. Therefore, we did a systematic review and meta-analysis to identify and provide unambiguous effect sizes of preconception predictors of pregnancy outcomes in women with SLE. METHODS: In this systematic review and meta-analysis, we searched PubMed and Embase for studies reporting preconception predictors of pregnancy outcomes in women with SLE, from database inception to Aug 22, 2023. Studies were included if they presented original, quantitative data on pregnant women with SLE and reported on preconception risk factors on at least one of the outcomes as defined in the protocol. Studies were excluded if they had a sample size of less than 20 patients, were restricted to multiple pregnancies, had unclear timing of prognostication, or exclusively reported a composite outcome. Literature screening, data extraction, and risk-of-bias assessment (quality in prognostic studies tool) were done by two reviewers independently, in a blinded, standardised manner. The reported outcomes included livebirth, pre-eclampsia, small for gestational age, preterm birth, pregnancy loss before and after 20 weeks of gestation, and SLE flares. We computed pooled univariate odds ratios (ORs) and 95% CIs using a random effects model. We assessed heterogeneity using the I2 statistic and prediction intervals. This study is registered with PROSPERO, CRD42022344732. FINDINGS: Of the 6705 unique articles identified, 72 (1·1%) were included in the meta-analysis, comprising 10 355 pregnancies in 8065 women with SLE. One potentially eligible study was retracted and therefore removed from our analysis. Previous lupus nephritis was associated with decreased livebirth probability (OR 0·62 [95% CI 0·47-0·81]; I2=0%), increased risk of preterm birth (2·00 [1·55-2·57]; I2=17%), and increased risk of pre-eclampsia (3·11 [2·35-4·12]; I2=0%). Chronic hypertension was associated with increased risk of disease flare (2·50 [1·74-3·58]; I2=0%), preterm birth (2·65 [1·87-3·77]; I2=0%), and pre-eclampsia (5·86 [3·41-10·06]; I2=33%). SLE disease activity at conception or preconception was associated with increased risk of preterm birth (2·91 [1·96-4·33]; I2=21%) and pre-eclampsia (2·32 [1·40-3·83]; I2=0%). Secondary antiphospholipid syndrome was associated with decreased livebirth probability (0·40 [0·27-0·58]; I2=0%), increased risk of pregnancy loss after 20 weeks of gestation (2·77 [1·44-5·31]; I2=0%), and increased risk of preterm birth (1·65 [1·29-2·11]; I2=0%). Across studies, risk-of-bias assessment suggested considerable bias in study attrition and confounding. INTERPRETATION: We identified previous lupus nephritis, chronic hypertension, SLE disease activity before and at conception, and secondary antiphospholipid syndrome as predictors of adverse pregnancy outcomes in women with SLE. These findings contribute to an optimal patient-tailored risk assessment in preconception counselling. FUNDING: None.

An Intestinal Microbiome Intervention Affects Biochemical Disease Activity in Patients with Antiphospholipid Syndrome.

Background The origin of autoantibodies in patients with antiphospholipid syndrome (APS) is unknown. The gut microbiome contributes to autoimmunity and contains peptide homologues to the main APS autoantigen, which affect disease activity in animal models. Alteration of the gut microbiota with vancomycin diminishes disease activity in mice but no data on the effect of gut microbiota alteration in APS patients are available to date. Objective To evaluate whether the gut microbiome affects disease activity in human APS. Methods This was a pre-post design intervention study in APS patients with stable disease and no gastrointestinal comorbidity. Subjects received oral vancomycin, 500 mg four times daily for 7 days, previously shown to alter gut microbiota composition without systemic effects. Disease activity was assessed at four time points by measuring a panel of clinical phenotype-related biomarkers: antiphospholipid antibodies (APLAs), complement and inflammation markers, and hemostatic parameters. The primary outcome was the composite of the biomarker panel determined by multilevel principal component analysis. Results A total of 15 subjects completed the study. The primary outcome, the first principal component of the biomarker panel data, was significantly different after 7 days of vancomycin treatment ( p = 0.03), but not at day 42. APLA titers were unaffected. Unexpectedly, 4 out of 15 patients were negative for APLAs at baseline. In a post-hoc analysis, there was a prolonged effect for subjects with positive antibodies at baseline ( p = 0.03). In subjects with negative APLAs at baseline, the intervention showed no effect. Conclusion The intestinal microbiome affects the biochemical disease activity in APS patients. The mechanism is yet unknown but appears to be APS-specific.

Association of autoantibodies with the IFN signature and NETosis in patients with systemic lupus erythematosus.

Objective: Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by a variety of disease symptoms and an unpredictable clinical course. To improve treatment outcome, stratification based on immunological manifestations commonly seen in patients with SLE such as autoantibodies, type I interferon (IFN) signature and neutrophil extracellular trap (NET) release may help. It is assumed that there is an association between these immunological phenomena, since NET release induces IFN production and IFN induces autoantibody formation via B-cell activation. Here we studied the association between autoantibodies, the IFN signature, NET release, and clinical manifestations in patients with SLE. Methods: We performed principal component analysis (PCA) and hierarchical clustering of 57 SLE-related autoantibodies in 25 patients with SLE. We correlated each autoantibody to the IFN signature and NET inducing capacity. Results: We observed two distinct clusters: one cluster contained mostly patients with a high IFN signature. Patients in this cluster often present with cutaneous lupus, and have higher anti-dsDNA concentrations. Another cluster contained a mix of patients with a high and low IFN signature. Patients with high and low NET inducing capacity were equally distributed between the clusters. Variance between the clusters is mainly driven by antibodies against histones, RibP2, RibP0, EphB2, RibP1, PCNA, dsDNA, and nucleosome. In addition, we found a trend towards increased concentrations of autoantibodies against EphB2, RibP1, and RNP70 in patients with an IFN signature. We found a negative correlation of NET inducing capacity with anti-FcER (r = -0.530; p = 0.007) and anti-PmScl100 (r = -0.445; p = 0.03). Conclusion: We identified a subgroup of patients with an IFN signature that express increased concentrations of antibodies against DNA and RNA-binding proteins, which can be useful for further patient stratification and a more targeted therapy. We did not find positive associations between autoantibodies and NET inducing capacity. Our study further strengthens the evidence of a correlation between RNA-binding autoantibodies and the IFN signature.

Routine Lupus Anticoagulant Sensitive aPTT Testing Can Prevent Unnecessary LA Testing.

Even though routine screening of the general hospital population is discouraged, medical laboratories may use a "lupus sensitive" activated partial thromboplastin time test (aPTT) with phospholipid concentrations that are susceptible to inhibition by lupus anticoagulant (LA), to screen for the presence of LA. If deemed necessary, follow-up testing according to ISTH guidelines may be performed. However, LA testing is a laborious and time-consuming effort that is often not readily available due to a lack of automation and/or temporary unavailability of experienced staff. In contrast, the aPTT is a fully automated test that is available 24/7 in almost all medical laboratories and is easily interpreted with the use of reference ranges. In addition to clinical signs, the result of an LA sensitive aPTT may thus be used to lower the suspicion of the presence of LA and reduce costly follow-up testing. In this study, we show that a normal LA sensitive aPTT result may be safely used to refrain from LA testing in the absence of strong clinical suspicion.

Interference in point-of-care international normalized ratio monitoring in patients with lupus anticoagulant is correlated with anti-ß2-glycoprotein I antibody titers.

Background: Patients with antiphospholipid syndrome (APS) receive anticoagulant therapy with vitamin K antagonists (VKAs) to prevent recurrent thrombosis. VKA treatment requires strict monitoring with an international normalized ratio (INR). It is known that lupus anticoagulants (LAs) can lead to elevated INR results with point-of-care-testing (POCT) devices, which could result in inadequate adaptation of anticoagulant therapy. Objective: To determine discrepancies between POCT-INR and laboratory-INR in patients who are LA-positive on VKA therapy. Methods: Paired INR testing was performed with 1 POCT device (CoaguChek XS) and 2 laboratory assays (Owren and Quick method) in 33 patients with LA-positive APS on VKA in a single-center cross-sectional study. Patients were tested for anti-ß2-glycoprotein I, anticardiolipin, and antiphosphatidylserine/prothrombin immunoglobulin (Ig) G and IgM antibodies. Agreement between assays was evaluated with Spearman's correlation, Lin's correlation coefficient, and Bland-Altman plots. Agreement limits were considered satisfactory if differences were ≤20% as determined by the Clinical and Laboratory Standards Institute. Results: We found poor agreement between POCT-INR and laboratory-INR based on Lin's concordance correlation coefficient (ρc) of 0.42 (95% CI, 0.26-0.55) between POCT-INR and Owren-INR, a ρc of 0.64 (95% CI, 0.47-0.76) between POCT-INR and Quick-INR, and a ρc of 0.77 (95% CI, 0.64-0.85) between Quick-INR and Owren-INR. High anti-ß2-glycoprotein I IgG antibody titers correlated with INR disagreement between POCT-INR and laboratory-INR. Conclusion: There is a disagreement between INR values measured with the CoaguChek XS and laboratory-INR in a proportion of patients with LA. Consequently, laboratory-INR monitoring should be preferred over POCT-INR monitoring in patients with LA-positive APS, especially in patients with high anti-ß2-glycoprotein IgG antibody titers.

Anti-ß2-glycoprotein I and anti-phosphatidylserine/prothrombin antibodies interfere with cleavage of factor V(a) by activated protein C.

BACKGROUND: The acquired thrombotic risk factor known as lupus anticoagulant (LA) interferes with laboratory clotting assays and can be caused by autoantibodies against ß2-glycoprotein I (ß2GPI) and prothrombin. LA is associated with activated protein C (APC) resistance, which might contribute to thrombotic risk in patients with antiphospholipid syndrome. How antibodies against ß2GPI and prothrombin cause APC resistance is currently unclear. OBJECTIVES: To investigate how anti-ß2GPI and antiphosphatidylserine/prothrombin (PS/PT) antibodies induce APC resistance. METHODS: The effects of anti-ß2GPI and anti-PS/PT antibodies on APC resistance were studied in plasma (of patients with antiphospholipid syndrome) and with purified coagulation factors and antibodies. RESULTS: APC resistance was observed in LA-positive patients with anti-ß2GPI or anti-PS/PT antibodies and in normal plasma spiked with monoclonal anti-ß2GPI or anti-PS/PT antibodies with LA activity. Analysis of factor (F)V cleavage patterns after APC incubation indicated that anti-ß2GPI antibodies attenuated APC-mediated FV cleavage at R506 and R306. APC-mediated cleavage at R506 is required for FV cofactor activity during inactivation of FVIIIa. Assays with purified coagulation factors confirmed that anti-ß2GPI antibodies interfered with the cofactor function of FV during FVIIIa inactivation but not with FVa inactivation. Anti-PS/PT antibodies attenuated APC-mediated FVa and FVIIIa inactivation. Analysis of FV(a) cleavage patterns after APC incubation indicated that anti-PS/PT antibodies interfere with APC-mediated cleavage of FV at positions R506 and R306. CONCLUSION: Anti-ß2GPI antibodies with LA activity contribute to a procoagulant state by causing APC resistance via interference with the cofactor function of FV during FVIIIa inactivation. LA-causing anti-PS/PT antibodies interfere with the anticoagulant function of APC by preventing FV(a) cleavage.

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-ß2 -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.