Exploring the influence of baseline rheumatoid factor levels on TNF inhibitor retention rate in patients with rheumatoid arthritis: a multicentre and retrospective study.

OBJECTIVE: To assess whether the retention rate of certolizumab pegol (CZP) was longer than that of other tumour necrosis factor inhibitors (TNFi) based on baseline rheumatoid factor (RF) levels. METHODS: Longitudinal, retrospective and multicentre study including patients with RA who were treated with any TNFi (monoclonal antibodies (mAB), etanercept (ETA) or CZP). Log-rank test and Cox regressions were conducted to evaluate the retention rate in the three groups according to the level of RF, with the third quartile of the baseline levels used as cut-off: <200 (

Preclinical Characterization of Pharmacologic NAD+ Boosting as a Promising Therapeutic Approach in Rheumatoid Arthritis.

OBJECTIVE: We analyzed NAD+ metabolism in patients with rheumatoid arthritis (RA), its association with disease activity and clinical outcomes of RA, and the therapeutic potential of pharmacologic NAD+ boosting. METHODS: Our study included 253 participants. In the first cohort, comprising 153 RA patients and 56 healthy donors, we assessed NAD+ levels and NAD+ -related gene pathways. We analyzed 92 inflammatory molecules by proximity extension assay. In the second cohort, comprising 44 RA patients starting anti-tumor necrosis factor (anti-TNF) drugs, we evaluated changes in NAD+ levels and their association with clinical response after 3 months. Mechanistic studies were performed ex vivo on peripheral blood mononuclear cells (PBMCs) from patients with RA to test the beneficial effects of NAD+ boosters, such as nicotinamide and nicotinamide riboside. RESULTS: Reduced NAD+ levels were found in RA samples, in line with altered activity and expression of genes involved in NAD+ consumption (sirtuins, poly[ADP-ribose] polymerase, CD38), transport (connexin 43), and biosynthesis (NAMPT, NMNATs). Unsupervised clustering analysis identified a group of RA patients with the highest inflammatory profile, the lowest NAD+ levels, and the highest disease activity (as shown by the Disease Activity Score in 28 joints). NAD+ levels were modulated by anti-TNF therapy in parallel with the clinical response. In vitro studies using PBMCs from RA patients showed that nicotinamide riboside and nicotinamide increased NAD+ levels via NAMPT and NMNAT and reduced their prooxidative, proapoptotic, and proinflammatory status. CONCLUSION: RA patients display altered NAD+ metabolism, directly linked to their inflammatory and disease activity status, which was reverted by anti-TNF therapy. The preclinical beneficial effects of NAD+ boosters, as shown in leukocytes from RA patients, along with their proven clinical safety, might pave the way for the development of clinical trials using these compounds.

Smoking and alcohol consumption are associated with peripheral musculoskeletal involvement in patients with spondyloarthritis (including psoriatic arthritis). Results from the ASAS-PerSpA study.

BACKGROUND: An inverse association between alcohol consumption and disease activity and functional impairment has been observed in patients with spondyloarthritis (SpA). However, neither this association nor the influence of smoking has been investigated in peripheral manifestations of SpA. OBJECTIVES: The objective of this study was to analyze the association between smoking and alcohol consumption and the presence of peripheral musculoskeletal manifestations (arthritis, enthesitis or dactylitis) and to determine the specific location of these manifestations. METHODS: Patients from the worldwide cross-sectional ASAS-PerSpA study with a diagnosis of axial SpA (axSpA), peripheral SpA (pSpA) or psoriatic arthritis (PsA) according to their rheumatologist were included. Generalised linear mixed models used peripheral manifestation (or location) as a dependent variable, smoking status and alcohol consumption as fixed effects and country as a random effect. The interaction between smoking and alcohol was tested. Analyses were performed for each diagnosis (axSpA, pSpA and PsA). RESULTS: A total of 4181 patients were included. In axSpA patients, smoking was associated with a lower prevalence of any peripheral manifestation, and current alcohol consumption was associated with a lower prevalence of both current arthritis and current enthesitis. In pSpA patients, current alcohol consumption was associated with a lower prevalence of current arthritis or enthesitis. In PsA patients, a significant association was found for arthritis with smoking and for enthesitis with alcohol consumption, and current alcohol consumption was associated with a lower prevalence of current arthritis or enthesitis. CONCLUSION: Taking into account the country, smoking and alcohol are associated with a lower prevalence of peripheral manifestations.

Recommendations for prevention of infection in systemic autoimmune rheumatic diseases.

OBJECTIVES: To develop recommendations for the prevention of infection in adult patients with systemic autoimmune rheumatic diseases (SARD). METHODS: Clinical research questions relevant to the objective of the document were identified by a panel of experts selected based on their experience in the field. Systematic reviews of the available evidence were conducted, and evidence was graded according to the Scottish Intercollegiate Guidelines Network criteria. Specific recommendations were made. RESULTS: Five questions were selected, referring to prevention of infection by Pneumocystis jirovecii with trimethoprim/sulfamethoxazole, primary and secondary prophylactic measures against hepatitis B virus, vaccination against human papillomavirus, vaccination against Streptococcus pneumoniae and vaccination against influenza virus, making a total of 18 recommendations, structured by question, based on the evidence found for the different SARD and/or expert consensus. CONCLUSIONS: There is enough evidence on the safety and efficacy of vaccinations and other prophylactic measures against the microorganisms reviewed in this document to specifically recommend them for patients with SARD.

Splicing machinery is impaired in rheumatoid arthritis, associated with disease activity and modulated by anti-TNF therapy.

OBJECTIVES: To characterise splicing machinery (SM) alterations in leucocytes of patients with rheumatoid arthritis (RA), and to assess its influence on their clinical profile and therapeutic response. METHODS: Leucocyte subtypes from 129 patients with RA and 29 healthy donors (HD) were purified, and 45 selected SM elements (SME) were evaluated by quantitative PCR-array based on microfluidic technology (Fluidigm). Modulation by anti-tumour necrosis factor (TNF) therapy and underlying regulatory mechanisms were assessed. RESULTS: An altered expression of several SME was found in RA leucocytes. Eight elements (SNRNP70, SNRNP200, U2AF2, RNU4ATAC, RBM3, RBM17, KHDRBS1 and SRSF10) were equally altered in all leucocytes subtypes. Logistic regressions revealed that this signature might: discriminate RA and HD, and anti-citrullinated protein antibodies (ACPAs) positivity; classify high-disease activity (disease activity score-28 (DAS28) >5.1); recognise radiological involvement; and identify patients showing atheroma plaques. Furthermore, this signature was altered in RA synovial fluid and ankle joints of K/BxN-arthritic mice. An available RNA-seq data set enabled to validate data and identified distinctive splicing events and splicing variants among patients with RA expressing high and low SME levels. 3 and 6 months anti-TNF therapy reversed their expression in parallel to the reduction of the inflammatory profile. In vitro, ACPAs modulated SME, at least partially, by Fc Receptor (FcR)-dependent mechanisms. Key inflammatory cytokines further altered SME. Lastly, induced SNRNP70-overexpression and KHDRBS1-overexpression reversed inflammation in lymphocytes, NETosis in neutrophils and adhesion in RA monocytes and influenced activity of RA synovial fibroblasts. CONCLUSIONS: Overall, we have characterised for the first time a signature comprising eight dysregulated SME in RA leucocytes from both peripheral blood and synovial fluid, linked to disease pathophysiology, modulated by ACPAs and reversed by anti-TNF therapy.

Characteristics and Predictors of Progression Interstitial Lung Disease in Rheumatoid Arthritis Compared with Other Autoimmune Disease: A Retrospective Cohort Study.

OBJECTIVES: To describe the characteristics and progression of interstitial lung disease in patients with associated systemic autoimmune disease (ILD-SAI) and to identify factors associated with progression and mortality. PATIENTS AND METHODS: We performed a multicenter, retrospective, observational study of patients with ILD-SAI followed between 2015 and 2020. We collected clinical data and performed pulmonary function testing and high-resolution computed tomography at diagnosis and at the final visit. The main outcome measure at the end of follow-up was forced vital capacity (FVC) >10% or diffusing capacity of the lungs for carbon monoxide >15% and radiological progression or death. Cox regression analysis was performed to identify factors associated with worsening of ILD. RESULTS: We included 204 patients with ILD-SAI: 123 (60.3%) had rheumatoid arthritis (RA), 58 had (28.4%) systemic sclerosis, and 23 (11.3%) had inflammatory myopathy. After a median (IQR) period of 56 (29.8-93.3) months, lung disease had stabilized in 98 patients (48%), improved in 33 (16.1%), and worsened in 44 (21.5%). A total of 29 patients (14.2%) died. Progression and hospitalization were more frequent in patients with RA (p = 0.010). The multivariate analysis showed the independent predictors for worsening of ILD-SAI to be RA (HR, 1.9 [95% CI, 1.3-2.7]), usual interstitial pneumonia pattern (HR, 1.7 [95% CI, 1.0-2.9]), FVC (%) (HR, 2.3 [95% CI, 1.4-3.9]), and smoking (HR, 2.7 [95%CI, 1.6-4.7]). CONCLUSION: Disease stabilizes or improves after a median of 5 years in more than half of patients with ILD-SAI, although more than one-third die. Data on subgroups and risk factors could help us to predict poorer outcomes.

Potential relation of cardiovascular risk factors to disease activity in patients with axial spondyloarthritis.

BACKGROUND: Axial spondyloarthritis (axSpA) patients are known to have a higher prevalence of several comorbidities, including, among others, an increased risk of atherosclerosis, hypertension, dyslipidemia, and diabetes. The purpose of the present study was to determine whether the sum of traditional cardiovascular (CV) risk factors is related to disease characteristics, such as disease activity, in patients with axSpA. METHODS: A cross-sectional study that encompassed 804 patients with axSpA was conducted. Patients were assessed for the presence of five traditional CV risk factors (diabetes mellitus, dyslipidemia, hypertension, obesity, and smoking status), and disease activity measurements. A multivariable regression analysis was performed to evaluate whether the number of classic CV risk factors was independently associated with specific features of the disease, to include disease activity. RESULTS: A multivariable analysis showed that Ankylosing Spondylitis Disease Activity Score-C reactive protein (ASDAS-CRP) activity score was significantly higher in patients with 1 [beta coefficient 0.3 (95% confidence interval (CI) 0.1-0.5), p = 0.001] and ⩾2 [beta coefficient 0.5 (95% CI 0.3-0.7), p = 0.000] CV risk factors compared with those without CV risk factors. Similarly, patients with 1 [OR 2.00 (95%CI 0.99-4.02), p = 0.053] and ⩾2 [OR 3.39 (95%CI 1.82-6.31), p = 0.000] CV risk factors had a higher odds ratio for the presence of high disease activity compared with the zero CV category. The Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) activity score was significantly associated with the number of CV risk factors, being higher in patients with more CV risk factors. These relationships showed a CV risk factor-dependent effect being beta coefficients and ORs higher for the effect of ⩾2 over 1 CV risk factor. CONCLUSION: Among patients with axSpA, as the number of traditional CV risk factors increased, disease activity similarly increases in an independent manner.

Recommendations for prevention of infection in systemic autoimmune rheumatic diseases. / Recomendaciones SER sobre prevención de infección en enfermedades reumáticas autoinmunes sistémicas.

OBJECTIVES: To develop recommendations for the prevention of infection in adult patients with systemic autoimmune rheumatic diseases (SARD). METHODS: Clinical research questions relevant to the objective of the document were identified by a panel of experts selected based on their experience in the field. Systematic reviews of the available evidence were conducted, and evidence was graded according to the Scottish Intercollegiate Guidelines Network criteria. Specific recommendations were made. RESULTS: Five questions were selected, referring to prevention of infection by Pneumocystis jirovecii with trimethoprim/sulfamethoxazole, primary and secondary prophylactic measures against hepatitis B virus, vaccination against human papillomavirus, vaccination against Streptococcus pneumoniae and vaccination against influenza virus, making a total of 18 recommendations, structured by question, based on the evidence found for the different SARD and/or expert consensus. CONCLUSIONS: There is enough evidence on the safety and efficacy of vaccinations and other prophylactic measures against the microorganisms reviewed in this document to specifically recommend them for patients with SARD.

Integrative Clinical, Molecular, and Computational Analysis Identify Novel Biomarkers and Differential Profiles of Anti-TNF Response in Rheumatoid Arthritis.

Background: This prospective multicenter study developed an integrative clinical and molecular longitudinal study in Rheumatoid Arthritis (RA) patients to explore changes in serologic parameters following anti-TNF therapy (TNF inhibitors, TNFi) and built on machine-learning algorithms aimed at the prediction of TNFi response, based on clinical and molecular profiles of RA patients. Methods: A total of 104 RA patients from two independent cohorts undergoing TNFi and 29 healthy donors (HD) were enrolled for the discovery and validation of prediction biomarkers. Serum samples were obtained at baseline and 6 months after treatment, and therapeutic efficacy was evaluated. Serum inflammatory profile, oxidative stress markers and NETosis-derived bioproducts were quantified and miRNomes were recognized by next-generation sequencing. Then, clinical and molecular changes induced by TNFi were delineated. Clinical and molecular signatures predictors of clinical response were assessed with supervised machine learning methods, using regularized logistic regressions. Results: Altered inflammatory, oxidative and NETosis-derived biomolecules were found in RA patients vs. HD, closely interconnected and associated with specific miRNA profiles. This altered molecular profile allowed the unsupervised division of three clusters of RA patients, showing distinctive clinical phenotypes, further linked to the TNFi effectiveness. Moreover, TNFi treatment reversed the molecular alterations in parallel to the clinical outcome. Machine-learning algorithms in the discovery cohort identified both, clinical and molecular signatures as potential predictors of response to TNFi treatment with high accuracy, which was further increased when both features were integrated in a mixed model (AUC: 0.91). These results were confirmed in the validation cohort. Conclusions: Our overall data suggest that: 1. RA patients undergoing anti-TNF-therapy conform distinctive clusters based on altered molecular profiles, which are directly linked to their clinical status at baseline. 2. Clinical effectiveness of anti-TNF therapy was divergent among these molecular clusters and associated with a specific modulation of the inflammatory response, the reestablishment of the altered oxidative status, the reduction of NETosis, and the reversion of related altered miRNAs. 3. The integrative analysis of the clinical and molecular profiles using machine learning allows the identification of novel signatures as potential predictors of therapeutic response to TNFi therapy.

Predictors of Progression and Mortality in Patients with Prevalent Rheumatoid Arthritis and Interstitial Lung Disease: A Prospective Cohort Study.

OBJECTIVES: To describe a prospective cohort of patients with rheumatoid arthritis associated with interstitial lung disease (RA-ILD) and identify risk factors associated with disease progression and mortality in this cohort. PATIENTS AND METHODS: We performed a multicenter, prospective, observational study of patients with RA-ILD receiving disease-modifying antirheumatic drugs (DMARDs) between 2015 and 2020. The patients were assessed using high-resolution computed tomography and pulmonary function tests at baseline and at 60 months. The main endpoint was "Progression to ILD at the end of follow-up" in terms of the following outcomes: (1) improvement (i.e., improvement in forced vital capacity (FVC) ≥10% or diffusing capacity of the lungs for carbon monoxide (DLCO) ≥15% and absence of radiological progression); (2) nonprogression (stabilization or improvement in FVC ≤10% or diffusing capacity of the lungs for carbon monoxide (DLCO) <15% and absence of radiological progression); (3) progression (worsening of FVC >10% or DLCO >15% and radiological progression); or (4) death. We recorded demographic and clinical characteristics, lung function, and the incidence of adverse events. A Cox regression analysis was performed to identify factors associated with the worsening of ILD. RESULTS: After 60 months, lung disease had stabilized in 66 patients (56.9%), improved in 9 (7.8%), and worsened in 23 (19.8%). Eighteen patients (15.5%) died, with a mean survival of 71.8 (1.9) months after diagnosis of ILD. The Cox multivariate analysis revealed the independent predictors of worsening of RA-ILD to be usual interstitial pneumonia (hazard ratio (HR), 2.6 (95%CI, 1.0-6.7)), FVC <80% (HR, 3.8 (95%CI, 1.5-6.7)), anticitrullinated protein antibody titers (HR, 2.8 (95%CI, 1.1-6.8)), smoking (HR, 2.5 (95%CI, 1.1-6.2)), and treatment with abatacept, tocilizumab, or rituximab (HR, 0.4 (95%CI, 0.2-0.8)). During follow-up, 79 patients (68%) experienced an adverse event, mostly infection (61%). Infection was fatal in 10/18 patients (55.5%) during follow-up. CONCLUSIONS: Lung function is stable in most patients with RA-ILD receiving treatment with disease-modifying anti-rheumatic drugs (DMARDs), although one-third worsened or died. Identifying factors associated with worsening in RA-ILD is important for clinical management.

ASAS Health Index in patients with spondyloarthritis and its association with disease activity and disease burden including fibromyalgia.

OBJECTIVES: To evaluate the association of the Assessment of Spondyloarthritis international Society Health Index (ASAS-HI) with disease activity and disease burden in patients with spondyloarthritis (SpA). METHODS: Observational, cross-sectional and single-centre study from the Córdoba AxSpA Task force, Registry and Outcomes (CASTRO). Scores related to disease activity (BASDAI and ASDAS), functionality (BASFI), structural damage, mobility, health and the presence of concomitant fibromyalgia (FM) were obtained from all patients. ASAS-HI score was considered the main outcome. Pearson's r statistic, Student's t test, and univariate and multivariate linear regressions were performed to assess the association between the ASAS-HI score and the studied covariates. RESULTS: A total of 126 SpA patients were included. The mean ASAS-HI score was 4.6±3.9, showing a "strong" positive linear correlation (r>0.60) with the BASDAI and BASFI and a "moderate" positive linear correlation (r=0.40 to 0.60) with the global VAS and ASDAS. Patients with FM showed a significantly higher ASAS-HI score than patients without FM (9.5±3.2 vs. 3.7±3.4, respectively, p<0.01). Multiple linear regression showed that 57.4% of the ASAS-HI variability (R2=0.574) was explained by the presence of concomitant FM (ß=2.23, 95% CI 0.73 to 3.80, p=0.004), higher scores on the BASDAI (ß=0.62, 95% CI 0.25 to 0.97, p=0.001) and BASFI (ß=0.57, 95% CI 0.26 to 0.88, p=0.001). CONCLUSIONS: The impairment of health in patients with SpA was mainly associated with high disease activity, worsening functionality and with the presence of a possible concomitant FM. Therefore, in patients with high ASAS-HI scores we must evaluate the presence of concomitant FM.

Axial and peripheral spondyloarthritis: does psoriasis influence the clinical expression and disease burden? Data from REGISPONSER registry.

OBJECTIVE: To evaluate whether the presence of psoriasis influences the clinical expression, disease activity and disease burden in both axial and peripheral phenotypes of spondyloarthritis (SpA). METHODS: Patients from the Spanish REGISPONSER registry classified as having SpA according to the ESSG criteria were included. Patients were classified as psoriatic or non-psoriatic depending on the presence of cutaneous or nail psoriasis; thereafter, they were classified as having either axial [presence of radiographic sacroiliitis OR inflammatory back pain (IBP)] or peripheral phenotype (absence of radiographic sacroiliitis AND absence of IBP AND presence of peripheral involvement). Pair-wise univariate and multivariate analyses among the four groups (psoriatic/non-psoriatic axial phenotypes and psoriatic/non-psoriatic peripheral phenotypes) were performed with adjustment for treatment intake. RESULTS: A total of 2296 patients were included in the analysis. Among patients with axial phenotype, psoriasis was independently associated (P < 0.05) with HLA-B27+ [odds ratio (OR) 0.27], uveitis (OR 0.46), synovitis (ever) (OR 2.59), dactylitis (OR 2.78) and the use of conventional synthetic DMARDs (csDMARDs) (OR 1.47) in comparison with non-psoriatic patients. Among patients with peripheral phenotype and adjusting for csDMARD intake, psoriasis was independently associated with higher age at disease onset (OR 1.05), HLA-B27+ (OR 0.14) and heel enthesitis (OR 0.22). Higher scores for patient-reported outcomes and greater use of treatment at the time of the study visit were observed in psoriatic patients with either axial or peripheral phenotype. CONCLUSION: These findings suggest that, among all patients with SpA, psoriasis is associated with differences in clinical expression of SpA, a greater disease burden and increased use of drugs.

Genome-wide whole blood transcriptome profiling in a large European cohort of systemic sclerosis patients.

OBJECTIVES: The analysis of annotated transcripts from genome-wide expression studies may help to understand the pathogenesis of complex diseases, such as systemic sclerosis (SSc). We performed a whole blood (WB) transcriptome analysis on RNA collected in the context of the European PRECISESADS project, aiming at characterising the pathways that differentiate SSc from controls and that are reproducible in geographically diverse populations. METHODS: Samples from 162 patients and 252 controls were collected in RNA stabilisers. Cases and controls were divided into a discovery (n=79+163; Southern Europe) and validation cohort (n=83+89; Central-Western Europe). RNA sequencing was performed by an Illumina assay. Functional annotations of Reactome pathways were performed with the Functional Analysis of Individual Microarray Expression (FAIME) algorithm. In parallel, immunophenotyping of 28 circulating cell populations was performed. We tested the presence of differentially expressed genes/pathways and the correlation between absolute cell counts and RNA transcripts/FAIME scores in regression models. Results significant in both populations were considered as replicated. RESULTS: Overall, 15 224 genes and 1277 functional pathways were available; of these, 99 and 225 were significant in both sets. Among replicated pathways, we found a deregulation in type-I interferon, Toll-like receptor cascade, tumour suppressor p53 protein function, platelet degranulation and activation. RNA transcripts or FAIME scores were jointly correlated with cell subtypes with strong geographical differences; neutrophils were the major determinant of gene expression in SSc-WB samples. CONCLUSIONS: We discovered a set of differentially expressed genes/pathways validated in two independent sets of patients with SSc, highlighting a number of deregulated processes that have relevance for the pathogenesis of autoimmunity and SSc.

Assessment of the relationship between estimated cardiovascular risk and structural damage in patients with axial spondyloarthritis.

AIMS: To evaluate the association of estimated cardiovascular (CV) risk and subclinical atherosclerosis with radiographic structural damage in patients with axial spondyloarthritis (axSpA). METHODS: Cross-sectional study including 114 patients axSpA from the SpA registry of Córdoba (CASTRO) and 132 age- and sex-matched healthy controls (HCs). Disease activity and the presence of traditional CV risk factors were recorded. The presence of atherosclerotic plaques and carotid intima media thickness (cIMT) were evaluated through carotid ultrasound and the SCORE index was calculated. Radiographic damage was measured though modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS). The association between mSASSS and SCORE was tested using generalized linear models (GLM), and an age-adjusted cluster analysis was performed to identify different phenotypes dependent on the subclinical CV risk. RESULTS: Increased traditional CV risk factors, SCORE, and the presence of carotid plaques were found in axSpA patients compared with HCs. The presence of atherosclerotic plaques and SCORE were associated with radiographic structural damage. The GLM showed that the total mSASSS was associated independently with the SCORE [ß coefficient 0.24; 95% confidence interval (CI) 0.10-0.38] adjusted for disease duration, age, tobacco, C-reactive protein, and non-steroidal anti-inflammatory drugs (NSAID) intake. Hard cluster analysis identified two phenotypes of patients. Patients from cluster 1, characterized by the presence of plaques and increased cIMT, had a higher prevalence of CV risk factors and SCORE, and more structural damage than cluster two patients. CONCLUSION: Radiographic structural damage is associated closely with increased estimated CV risk: higher SCORE levels in axSpA patients were found to be associated independently with mSASSS after adjusting for age, disease duration, CRP, tobacco and NSAID intake.

Complement component 3 as biomarker of disease activity and cardiometabolic risk factor in rheumatoid arthritis and spondyloarthritis.

OBJECTIVE: To analyze the relationship between complement component 3 (C3) and the prevalence of cardiometabolic risk factors and disease activity in the rheumatic diseases having the highest rates of cardiovascular morbidity and mortality: rheumatoid arthritis (RA), psoriatic arthritis (PsA) and axial spondyloarthritis (axSpA). METHODS: This is a cross-sectional study including 200 RA, 80 PsA, 150 axSpA patients and 100 healthy donors. The prevalence of cardiometabolic risk factors [obesity, insulin resistance, type 2 diabetes mellitus, hyperlipidemia, apolipoprotein B/apolipoprotein A (apoB/apoA) and atherogenic risks and hypertension] was analyzed. Serum complement C3 levels, inflammatory markers and disease activity were evaluated. Cluster analysis was performed to identify different phenotypes. Receiver operating characteristic (ROC) curve analysis to assess the accuracy of complement C3 as biomarker of insulin resistance and disease activity was carried out. RESULTS: Levels of complement C3, significantly elevated in RA, axSpA and PsA patients, were associated with the prevalence of cardiometabolic risk factors. Hard clustering analysis identified two distinctive phenotypes of patients depending on the complement C3 levels and insulin sensitivity state. Patients from cluster 1, characterized by high levels of complement C3 displayed increased prevalence of cardiometabolic risk factors and high disease activity. ROC curve analysis showed that non-obesity related complement C3 levels allowed to identify insulin resistant patients. CONCLUSIONS: Complement C3 is associated with the concomitant increased prevalence of cardiometabolic risk factors in rheumatoid arthritis and spondyloarthritis. Thus, complement C3 should be considered a useful marker of insulin resistance and disease activity in these rheumatic disorders.