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Early intervention has been the cornerstone of improving outcomes in patients with rheumatoid arthritis. Over the past decade, the boundaries have been pushed in an attempt to achieve effective prevention strategies in those who are at high risk of developing rheumatoid arthritis. Core risk factors including the presence of serum anti-citrullinated protein antibodies, arthralgia and subclinical inflammation on imaging are highly predictive of arthritis development. The influence of air pollution, diet and the role of microbiome on disease progression are less clear. In turn, therapeutic focus has shifted to an earlier pre-arthritis phase of the disease continuum where the clinically apparent arthritis may potentially be intercepted. Seven proof-of-concept interventional trials in at-risk individuals have been conducted so far. Whether true prevention of rheumatoid arthritis is possible remains elusive. Promising signals towards permanent disease modulation and improvement in symptom burden were seen with some immunomodulatory therapies, whilst others were unsuccessful. Long-term follow-up is required to ascertain a true effect. Looking forward, a better understanding of the natural history and underlying biological mechanisms of arthritis development and more accurate, validated risk stratification is needed., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Objective: To investigate the prevalence of poly-refractory rheumatoid arthritis (RA) defined as failure of all biological (b)/targeted synthetic (ts)-disease-modifying drugs (DMARDs). To further investigate whether patients with persistent inflammatory refractory RA (PIRRA) and noninflammatory refractory RA (NIRRA), determined by objective ultrasound (US) synovitis, have distinct clinical phenotypes in both EULAR difficult-to-treat RA (D2T-RA) and poly-refractory RA groups., Methods: A cross-sectional study of 1,591 patients with RA on b/tsDMARDs that evaluated D2T-RA criteria and subclassified as poly-refractory if inefficacy/toxicity to at least one drug of all classes. PIRRA was defined if US synovitis in one or more swollen joint and NIRRA if absent. Univariate tests and multivariate logistic regression were conducted to investigate factors associated with poly-refractory, PIRRA, and NIRRA phenotypes., Results: 122 of 1,591 were excluded due to missing data. 247 of 1,469 (16.8%) had D2T-RA and only 40 of 1,469 (2.7%) poly-refractory RA. This latter group had higher disease activity score 28 C-reactive protein (CRP) (median 5.4 vs 5.02, P < 0.05), CRP levels (median 13 vs 5 mg/l, P < 0.01), and smoking (ever) rates (20% vs 4%, P < 0.01) compared with other D2T patients. Smoking was associated with poly-refractory RA (odds ratio 5.067, 95% CI 1.774-14.472, P = 0.002). Of 107 patients with D2T-RA with recent US, 61 (57%) were PIRRA and 46 (43%), NIRRA. Patients with NIRRA had elevated body mass index (median 30 vs 26, P < 0.001) and higher fibromyalgia prevalence (15% vs 3%, P < 0.05), lower swollen joint count (median: 2 vs 5, P < 0.001), and lower CRP levels (5 vs 10, P < 0.01)., Conclusion: Only 2.7% of D2T-RA failed all classes of b/tsDMARDs. Among D2T-RA, less than 60% had objective signs of inflammation, representing a target for innovative strategies., (© 2023 The Authors. Arthritis & Rheumatology published by Wiley Periodicals LLC on behalf of American College of Rheumatology.)

Background: Subclinical synovitis occurs in a third of individuals at risk of rheumatoid arthritis. The objective of this study was to assess the reversibility of subclinical synovitis in individuals at risk of rheumatoid arthritis who are positive for anti-cyclic citrullinated peptide (CCP) antibody with musculoskeletal symptoms and investigate factors associated with its resolution within 12 months., Methods: We conducted a single-centre, prospective, cohort study in the UK, recruiting individuals aged 18 years or older who were anti-CCP-positive with a new non-specific musculoskeletal symptom but no clinical synovitis. Referrals were made through primary or secondary care. Participants attended a baseline visit, which included a clinical assessment, blood tests, patient questionnaires, and a musculoskeletal ultrasound scan (ie, of wrists and metacarpophalangeal, proximal interphalangeal, and metatarsophalangeal joints), and then follow-up visits every 3 months for the first year, with a repeat ultrasound scan every 12 months. Participants with subclinical synovitis (ie, grey scale ≥1 and power Doppler ≥1) in at least one joint at baseline were selected for this analysis. Investigation of good prognostic factors by 12 months was done first using univariable analysis to identify significant factors in participants with no missing data. Then receiver operating characteristic (ROC) curves were used to establish the optimal cutoffs for significant continuous variables. Finally, a modified Poisson regression approach was performed to identify the best prediction model and was adjusted for confounders, using data from all participants, with missing values imputed. This study is registered with ClinicalTrials.gov, NCT02012764., Findings: Between June 30, 2008, and Feb 24, 2020, 451 participants consented to participate in the CCP study and 122 (27%) individuals had subclinical synovitis at baseline, of whom 90 (74%) had data available at 12 months. Mean age was 54·1 years (SD 12·5), and 63 (70%) of 90 participants were women and 27 (30%) were men. Subclinical synovitis resolved in 43 (48%) of 90 participants, whereas subclinical synovitis persisted in 47 (52%) participants, 27 (57%) of whom developed clinical synovitis within 12 months. In the multivariable analysis, low anti-CCP titre (relative risk [RR] 1·52, 95% CI 1·04-2·22), negative rheumatoid factor (1·54, 0·92-2·58), subclinical synovitis in only one joint (1·62, 1·04-2·50), and an erythrocyte sedimentation rate of 15 mm/h or lower (1·82, 1·15-2·87) were predictors of subclinical synovitis resolution within 12 months (ie, good prognostic factors). ROC curve showed an area under the curve of 0·84 (95% CI 0·76-0·92; p<0·0001). Resolution occurred in seven (100%) of seven participants with all four factors present, and in only one (7%) of 14 participants with none of the factors present., Interpretation: In individuals who were anti-CCP-positive, subclinical synovitis disappeared in approximately half of the participants by 12 months and was associated with the presence of good prognostic factors. Subclinical synovitis should be interpreted in the context of these additional factors., Funding: National Institute for Health Research Leeds Biomedical Research Centre., Competing Interests: Declaration of interests KM has received grants from Lilly, Gilead, and Serac Life Sciences; consulting fees from Serac Life Sciences; and honoraria from AbbVie, Lilly, and Galapagos. PE has received grants from Lilly and Samsung; received consulting fees from AbbVie, AnaptysBio, BMS, Gilead, Lilly, and Novartis; received honoraria from AbbVie, BMS, Gilead, Lilly, Novartis, and Sandoz; received support for attending meetings from Lilly; and reports participation on data safety monitoring or advisory board by AstraZeneca. LG-M, JK, LD, ADM, JLN, KH, and RC declare no competing interests., (Copyright © 2024 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license. Published by Elsevier Ltd.. All rights reserved.)

Objective: Recent advances imply that early events triggering rheumatoid arthritis (RA) occur at mucosal surfaces. We aimed to evaluate whether intestinal permeability is altered in patients at increased risk of RA, and/or predicts the development of clinical arthritis, by measuring serum zonulin family peptides (ZFP) levels, which are shown to reflect intestinal barrier integrity., Methods: Two independent prospective observational cohorts were studied, including subjects with musculoskeletal symptoms and anticitrullinated protein antibodies (ACPA), but without clinical arthritis at baseline. In Sweden, 82 such at-risk patients were compared to 100 age-matched healthy blood donors. In the UK, 307 at-risk patients were compared to 100 ACPA-negative symptomatic controls. ZFP was measured in baseline sera by enzyme-linked immunoassays., Results: In the Swedish at-risk cohort, ZFP levels were significantly increased in patients compared to controls (mean 41.4 vs 33.6 ng/mL, P < 0.001) and Cox regression analysis showed prognostic value of ZFP for arthritis development (hazard ratio [HZ] 1.04 per ng/mL ZFP increase, 95% CI 1.01-1.07, P = 0.02). Elevated ZFP levels among ACPA-positive at-risk patients compared to symptomatic ACPA-negative controls were confirmed in the UK at-risk cohort (mean 69.7 vs 36.0 ng/mL, P < 0.001), but baseline ZFP were not associated with arthritis development (HR 1.00 per ng/mL ZFP increase, 95% CI 1.00-1.01, P = 0.30)., Conclusion: Serum ZFP levels are elevated in ACPA-positive at-risk patients when compared to both healthy blood donors and symptomatic ACPA-negative controls. Thus, gut barrier function may be of importance in RA-associated autoimmunity. A possible prognostic value of serum ZFP merits further investigation, preferably in larger prospective cohorts., (Copyright © 2024 by the Journal of Rheumatology.)

Background: Inflammatory arthritis (IA) is an immune-related condition defined by the presence of clinical synovitis. Its most common form is rheumatoid arthritis., Objective: To develop scores for predicting IA in at-risk persons using multidimensional biomarkers., Design: Prospective observational cohort study., Setting: Single-center, Leeds, United Kingdom., Participants: Persons with new musculoskeletal symptoms, a positive test result for anticitrullinated protein antibodies, and no clinical synovitis and followed for 48 weeks or more or until IA occurred., Measurements: A simple score was developed using logistic regression, and a comprehensive score was developed using the least absolute shrinkage and selection operator Cox proportional hazards regression. Internal validation with bootstrapping was estimated, and a decision curve analysis was done., Results: Of 455 participants, 32.5% (148 of 455) developed IA, and 15.4% (70 of 455) developed it within 1 year. The simple score identified 249 low-risk participants with a false negative rate of 5% (and 206 high-risk participants with a false-positive rate of 72%). The comprehensive score identified 119 high-risk participants with a false-positive rate of 29% (and 336 low-risk participants with a false-negative rate of 19%); 40% of high-risk participants developed IA within 1 year and 71% within 5 years., Limitations: External validation is required. Recruitment occurred over 13 years, with lower rates of IA in later years. There was geographic variation in laboratory testing and recruitment availability., Conclusion: The simple score identified persons at low risk for IA who were less likely to need secondary care. The comprehensive score identified high-risk persons who could benefit from risk stratification and preventive measures. Both scores may be useful in clinical care and should also be useful in clinical trials., Primary Funding Source: National Institute for Health and Care Research Leeds Biomedical Research Centre., Competing Interests: Disclosures: Disclosures can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M23-0272.

Objectives: Current evidence suggests that periodontal disease could be a causal risk factor for rheumatoid arthritis (RA) onset and progression. Earlier periodontal intervention in individuals at risk of RA could provide a unique opportunity to prevent or delay the onset of RA. This study aimed to explore the acceptability of periodontal treatment as a measure to potentially prevent RA among at-risk individuals and healthcare professionals., Methods: Semistructured interviews were conducted with anti-CCP positive at-risk individuals (CCP+ at risk) and a range of healthcare professionals. At-risk participant data were analysed using reflexive thematic analysis; subsequent coding of healthcare professional data was deductive, based on a preidentified set of constructs., Results: Nineteen CCP+ at-risk and 11 healthcare professionals participated. Three themes (six subthemes) were identified: (1) understanding risk (knowledge of shared at-risk factors; information and communication); (2) oral health perceptions and experiences (personal challenges and opportunities for dental intervention and oral health maintenance; external barriers) and (3) oral health treatment and maintenance (making oral health changes with the aim of preventing RA; acceptability of participation in periodontal research)., Conclusions: Periodontal disease is common in individuals at risk of RA, but the impact of poor oral health may not be well understood. Oral health information should be tailored to the individual. CCP+ at-risk participants and healthcare professionals identified seeking dental treatment can be hindered by dental phobia, treatment costs or inability to access dentists. While CCP+ at-risk individuals may be reluctant to take preventive medications, a clinical trial involving preventive periodontal treatment is potentially acceptable., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Objectives: Specific guidelines for managing RA patients in clinical remission for ≥6 months on cs-DMARDs are lacking. Tapering of treatment is encouraged, however, without validated biomarkers for success. We aimed to assess the rate of sustained remission after 12 months in patients who either (i) followed structured cs-DMARD tapering or (ii) continued therapy, focusing on the added value of biomarkers as predictors of outcome., Methods: RA patients fulfilling 3v-DAS28CRP<2.6 for ≥6 months on stable cs-DMARD therapy were included. Patients were offered structured tapering, with 117 accepting tapering and 83 continuing therapy. Clinical, ultrasound, immunological (T-cell subsets) and patient-reported outcome (PRO) data were collected. The primary endpoint was the proportion of patients in sustained remission without relapse after 12 months. Regression analyses were used to identify predictors of sustained remission., Results: Of those who tapered, 64% remained in clinical remission after 12 months compared with 80% (p=0.018) of patients on stable treatment. In the tapering group, higher levels of CRP, TJC, % inflammation-related T-cell (IRC) and PROs were associated with flare (all p<0.05), with a trend for total PD (p=0.066). A model predicting sustained remission retained RAQoL, total PD and IRC (85% accuracy, AUROC=0.893, p<0.0001). In the non-tapering group, higher CRP, ESR, SJC and shorter disease duration (all p<0.05) were associated with flare, with no parameter able to predict sustained remission., Conclusions: In the tapering group, the combination of clinical, PRO, US and T-cell parameters demonstrated added value for predicting sustained remission compared with clinical parameters alone. These data may inform best tapering practice.

Background: Predicting progression to clinical arthritis in individuals at-risk of developing rheumatoid arthritis is a prerequisite to developing stratification groups for prevention strategies. Selecting accurate predictive criteria is the critical step to define the population at-risk. While positivity for anti-citrullinated protein antibodies (ACPA) remains the main recruitment biomarker, positivity for other autoantibodies (AutoAbs) identified before the onset of symptoms, may provide additional predictive accuracy for stratification., Objective: To perform a multiple AutoAbs analysis for both the prediction and the time of progression to inflammatory arthritis (IA)., Methods: 392 individuals were recruited based on a new musculoskeletal complaint and positivity for ACPA or rheumatoid factor (RF). ELISAs were performed for ACPA, RF, anti-nuclear Ab, anti-carbamylated protein (anti-CarP) and anti-collagen AutoAbs. Logistic and COX regression were used for analysis., Results: Progression to IA was observed in 125/392 (32%) of cases, of which 78 progressed within 12 months. The AutoAbs ACPA, RF, anti-CarP were individually associated with progression (p<0.0001) and improved prediction when combined with demographic/clinical data (Accuracy >77%; area under the curve (AUC) >0.789), compared with prediction using only demographic/clinical data (72.9%, AUC=0.760). Multiple AutoAbs testing provided added value, with +6.4% accuracy for number of positive AutoAbs (AUC=0.852); +5.4% accuracy for AutoAbs levels (ACPA/anti-CarP, AUC=0.832); and +6.2% accuracy for risk-groups based on high/low levels (ACPA/RF/anti-CarP, AUC=0.837). Time to imminent progression was best predicted using ACPA/anti-CarP levels (AUC=0.779), while the number of positive AutoAbs was/status/risk were as good (AUC=0.778)., Conclusion: We confirm added value of multiple AutoAbs testing for identifying progressors to clinical disease, allowing more specific stratification for intervention studies., Competing Interests: Competing interests: LAT is mentioned as an inventor on a patent describing a method to detect anti-CarP antibodies., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY. Published by BMJ.)

Objectives: To investigate whether anti-CCP2-positive at-risk individuals with musculoskeletal (MSK) symptoms but without clinical synovitis (CCP2+ at-risk) develop US subclinical synovitis before inflammatory arthritis and if US subclinical synovitis can be predicted., Methods: First, US scans of CCP2+ at-risk individuals who developed inflammatory arthritis ('progressors') were reviewed for subclinical synovitis prior to inflammatory arthritis development. Patients in whom the pre-progression US scan was negative but the scan was conducted >6 months before progression were excluded. Subsequently, regression analyses were performed to identify predictors of US synovitis in CCP2+ at-risk individuals without baseline US abnormalities who had one or more longitudinal US scan and a complete dataset., Results: US subclinical synovitis was detected in one or more scan in 75 of 97 progressors (77.3%) {median time to inflammatory arthritis development from first evidence of US synovitis 26.5 weeks [interquartile range (IQR) 7-60]}, in whom one or more scan was available, excluding those with a negative scan >6 months from inflammatory arthritis development (n = 38). In 220 CCP2+ at-risk individuals with normal baseline US scans, who had one or more longitudinal US scan and a complete dataset, US synovitis was detected in 69/220 (31.4%) [median time to first developing US synovitis 56.4 weeks (IQR 33.0-112.0)]. In the multivariable analysis, only anti-CCP3 antibodies were predictive for the development of US synovitis [odds ratio 4.75 (95% CI 1.97, 11.46); P < 0.01]., Conclusions: In anti-CCP2+ at-risk individuals, a stage of subclinical synovitis usually precedes the development of inflammatory arthritis. Anti-CCP2+/CCP3+ individuals without clinical or US subclinical synovitis may represent the optimal window of opportunity for intervention to prevent joint disease., (© The Author(s) 2021. Published by Oxford University Press on behalf of the British Society for Rheumatology.)

Objectives: To assess antibody and T cell responses to SARS-CoV-2 vaccination in patients with rheumatoid arthritis (RA) on disease-modifying antirheumatic drugs (DMARDs)., Methods: This prospective study recruited 100 patients with RA on a variety of DMARDs for antibody and T cell analysis, pre-vaccination and 4 weeks post-vaccination. Positive antibody response was defined as sera IgG binding to ≥1 antigen. Those that remained seronegative after first vaccination were retested 4 weeks after second vaccination; and if still seronegative after vaccination three. A T cell response was defined an ELISpot count of ≥7 interferon (IFN)γ-positive cells when exposed to spike antigens. Type I IFN activity was determined using the luminex multiplex assay IFN score., Results: After vaccine one, in patients without prior SARS-CoV-2 exposure, 37/83 (45%) developed vaccine-specific antibody responses, 44/83 (53%) vaccine-specific T cell responses and 64/83 (77%) developed either antibody or T cell responses. Reduced seroconversion was seen with abatacept, rituximab (RTX) and those on concomitant methotrexate (MTX) compared to 100% for healthy controls (p<0.001). Better seroconversion occurred with anti-tumour necrosis factor (TNF) versus RTX (p=0.012) and with age ≤50 (p=0.012). Pre-vaccine SARS-CoV-2 exposure was associated with higher quantitative seroconversion (≥3 antibodies) (p<0.001). In the subgroup of non-seroconverters, a second vaccination produced seroconversion in 54% (19/35), and after a third in 20% (2/10). IFN score analysis showed no change post-vaccine., Conclusion: Patients with RA on DMARDs have reduced vaccine responses, particularly on certain DMARDs, with improvement on subsequent vaccinations but with approximately 10% still seronegative after three doses., Competing Interests: Competing interests: BS: Speaker fees for Pfizer and Galapagos, L-AB: Honoraria for UCB, Abbvie and Galapagos, KM: Personal: Abbvie, Lilly, UCB.Grants: Lilly, Gilead, FD: received research support and consultancies, not related to the topic of this manuscript from ABBVIE, AstraZeneca, Boehringer-Ingelheim, Capella, Chemomab, Kymab, Mitsubishi-TanabePaul Emery: Grants : AbbVie, BMS, Lilly, Samsung. Consulting fees: BMS, AbbVie, MSD, Pfizer, Novartis, and Roche. Payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events:Abbvie, Gilead, Lilly, Novartis., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Objectives: There is increasing interest in identifying individuals at-risk of rheumatoid arthritis (RA) and initiating early treatment to prevent or delay the onset of arthritis. We aimed to describe the perceptions and experiences of at-risk individuals and to inform the conduct of clinical trials and studies, and clinical practice., Methods: A systematic review and thematic synthesis of qualitative studies was conducted. Two review authors independently screened studies for inclusion, appraised their methodological quality using the Critical Appraisal Skills Programme checklist and assessed confidence in the findings using the Grading of Recommendations Assessment, Development and Evaluation-Confidence in Evidence from Reviews of Qualitative Research approach., Results: Seven studies involving 115 individuals at-risk of developing RA were included. Three major themes (seven subthemes) were identified: understanding the risk of developing RA (knowledge of RA and identification of potential risk factors); preventive interventions to reduce the risk of developing RA (understanding the value and role of preventive interventions, and engagement with preventive interventions); and perceptions of predictive testing for RA (benefits of predictive testing, decision to undertake predictive testing and concerns about predictive testing). Moderate confidence in most review findings was evident., Conclusion: While there are clear benefits in informing individuals at-risk of RA about their risk following predictive testing and offering preventive treatment, there are potential barriers to engagement, intensified by the burden of uncertainty. Identification of the optimum approaches for presenting risk information, including the risks and benefits of engaging with preventive interventions, is urgently needed to support individuals at-risk of RA in their decision making., Prospero Registration Number: CRD42021236034., Competing Interests: Competing interests: Professor DA is an ARD Board Member., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY. Published by BMJ.)

Background: Musculoskeletal (MSK) symptoms are among the commonest reasons for primary care assessments; however, few individuals will be diagnosed with an inflammatory arthritis (IA) within the following year. The purpose of this study was to investigate, in individuals with new MSK symptoms, the association between patient factors and risk of progression to IA, in order to optimise primary care referrals to rheumatology., Methods: Individuals ≥16 years old with new non-specific MSK symptoms and no clinical synovitis were recruited by primary care across the UK from July 2007 until May 2019. Those testing positive for the anti-CCP2 assay (anti-CCP+) were invited to Leeds for follow-up. Subjects with a negative result (anti-CCP-) were sent a 1-year questionnaire, and general practitioners were contacted to confirm whether the individual had been diagnosed with an IA by a rheumatologist. Predictors for progression were assessed using multivariable regression analysis., Results: Six thousand seven hundred eighty individuals were recruited: 3% were anti-CCP+, of whom 45% progressed to IA, predominantly rheumatoid arthritis. Anti-CCP+ participants with high antibody levels had an odds ratio (OR) for progression to IA of 9.42 [P < 0.001, 95% CI (3.13-28.30)], hand pain, OR 2.74 [P = 0.043, 95% CI (1.03-7.27)] and foot pain, OR 4.10 [P = 0.003, 95% CI (1.59-10.54)]. In low-level anti-CCP+ individuals, absence of pain in hands or feet had a negative predictive value of 96% for progression to IA. One-year follow-up data were available for 5640 anti-CCP- individuals, of whom 53 were diagnosed with IA (0.93%). Pain in hands, OR 2.51 [P = 0.018, 95% CI (1.17-5.39)] or knees, OR 3.03 [P = 0.003, 95% CI (1.47-6.25)] were associated with development of IA within 12 months., Conclusions: This is the largest prospective primary care study of individuals at risk of IA, and the first one to prospectively investigate the outcome of MSK symptoms in a large anti-CCP- cohort. High anti-CCP levels and pain in hands/feet indicated an increased likelihood of progression to IA. In patients with low anti-CCP level and no pain in the hands/feet, progression is unlikely. In anti-CCP- patients, those with hand or knee pain were at increased risk of progression. This study demonstrates that routinely available tests and joint symptoms provide useful discrimination that may be used to prioritise referrals to rheumatology and avoid a delayed diagnosis., Trial Registration: NCT, NCT02012764 . Registered 25 January 2007., (© 2022. The Author(s).)

Objectives: The human leukocyte antigen-shared epitope (HLA-SE) alleles and smoking are the most prominent genetic and environmental risk factors for rheumatoid arthritis (RA). However, at which pre-arthritis stage (asymptomatic/symptomatic) they exert their effect is unknown. We aimed to determine whether HLA-SE and smoking are involved in the onset of autoantibody positivity, symptoms (clinically suspect arthralgia (CSA)) and/or progression to clinical arthritis., Methods: We performed meta-analyses on results from the literature on associations of HLA-SE and smoking with anti-citrullinated protein antibodies (ACPAs) in the asymptomatic population. Next, we studied associations of HLA-SE and smoking with autoantibody positivity at CSA onset and with progression to clinical inflammatory arthritis (IA) during follow-up. Associations in ACPA-positive patients with CSA were validated in meta-analyses with other arthralgia cohorts. Analyses were repeated for rheumatoid factor (RF), anti-carbamylated protein antibodies (anti-CarP) and anti-acetylated protein antibodies (AAPA)., Results: Meta-analyses showed that HLA-SE is not associated with ACPA positivity in the asymptomatic population (OR 1.06 (95% CI:0.69 to 1.64)), whereas smoking was associated (OR 1.37 (95% CI: 1.15 to 1.63)). At CSA onset, both HLA-SE and smoking associated with ACPA positivity (OR 2.08 (95% CI: 1.24 to 3.49), OR 2.41 (95% CI: 1.31 to 4.43)). During follow-up, HLA-SE associated with IA development (HR 1.86 (95% CI: 1.23 to 2.82)), in contrast to smoking. This was confirmed in meta-analyses in ACPA-positive arthralgia (HR 1.52 (95% CI: 1.08 to 2.15)). HLA-SE and smoking were not associated with RF, anti-CarP or AAPA-positivity at CSA onset. Longitudinally, AAPA associated with IA development independent from ACPA and RF (HR 1.79 (95% CI: 1.02 to 3.16)), anti-CarP did not., Conclusions: HLA-SE and smoking act at different stages: smoking confers risk for ACPA and symptom development, whereas HLA-SE mediates symptom and IA development. These data enhance the understanding of the timing of the key risk factors in the development of RA., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Despite growing interest, there is no guidance or consensus on how to conduct clinical trials and observational studies in populations at risk of rheumatoid arthritis (RA)., Methods: An European League Against Rheumatism (EULAR) task force formulated four research questions to be addressed by systematic literature review (SLR). The SLR results informed consensus statements. One overarching principle, 10 points to consider (PTC) and a research agenda were proposed. Task force members rated their level of agreement (1-10) for each PTC., Results: Epidemiological and demographic characteristics should be measured in all clinical trials and studies in at-risk individuals. Different at-risk populations, identified according to clinical presentation, were defined: asymptomatic, musculoskeletal symptoms without arthritis and early clinical arthritis. Study end-points should include the development of subclinical inflammation on imaging, clinical arthritis, RA and subsequent achievement of arthritis remission. Risk factors should be assessed at baseline and re-evaluated where appropriate; they include genetic markers and autoantibody profiling and additionally clinical symptoms and subclinical inflammation on imaging in those with symptoms and/or clinical arthritis. Trials should address the effect of the intervention on risk factors, as well as progression to clinical arthritis or RA. In patients with early clinical arthritis, pharmacological intervention has the potential to prevent RA development. Participants' knowledge of their RA risk may inform their decision to participate; information should be provided using an individually tailored approach., Conclusion: These consensus statements provide data-driven guidance for rheumatologists, health professionals and investigators conducting clinical trials and observational studies in individuals at risk of RA., Competing Interests: Competing interests: KM: honoraria from Abbvie, Eli Lilly & Co and UCB; grants from Eli Lilly & Co and Gilead. HJS: none declared. AK: speakers bureau, consultancy: AbbVie, Bristol-Myers Squibb, Celgene, Eli Lilly & Co, Gilead, Merck Sharp and Dohme, Novartis and Pfizer. DAR: scientific advisor for GSK. AIC, JDC and APC: none declared. CID: honoraria from Roche, Chugai, Pfizer, BMS, MSD, Biogen, Abbvie, Sandoz, Janssen, Novartis, Fresenius Kabi and Sanofi; research grants from Pfizer, MSD and Schwa Medico. KR: speaker fees from Abbvie. PE: expert advice to Pfizer, Abbvie, Amgen, MSD, Roche, Sanofi, BMS, Novartis, Eli Lilly & Co, Gilead, Samsung and Celltrion; grants from Abbvie, Eli Lilly & Co, BMS and Samsung., (© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: There is significant interest in determining risk factors in individuals at risk of rheumatoid arthritis (RA). A core set of risk factors for clinical arthritis development has not been defined., Methods: A literature search and systematic literature review (SLR) was conducted to identify risk factors in individuals at risk of RA using Medline, Embase, PubMed and Central databases., Results: 3854 articles were identified by the literature search. After screening of titles, 138 abstracts were reviewed and 96 articles finally included. Fifty-three articles included data on risk factors including autoantibodies, subclinical inflammation on imaging, clinical features, serum and cellular biomarkers and genetic markers. Risk factors were dependent on the at-risk population. There was good evidence for serum anticitrullinated protein antibodies (ACPA) levels, as risk factors for arthritis in all at-risk populations (n=13 articles). Subclinical inflammation on ultrasound (n=12) and MRI (n=6) was reported as a risk factor in multiple studies in at-risk individuals with musculoskeletal (MSK) symptoms and undifferentiated arthritis (UA). Clinical features were reported as a risk factor in at-risk individuals with MSK symptoms and UA (n=13). Other risk factors, including serum and cellular markers were less frequently reported., Conclusions: Risk factors for arthritis development in RA are specific to the at-risk population. Serum ACPA confers risk in all populations; subclinical inflammation on imaging and clinical features confer risk in at-risk individuals with MSK symptoms. This SLR informed the EULAR taskforce for points to consider on conducting clinical trials and studies in individuals at risk of RA., Competing Interests: Competing interests: KM: honoraria from AbbVie, Lilly, UCB; grants from Lilly, Gilead. HJS: none declared. AK: speakers bureau, consultancy: AbbVie, Bristol-Myers Squibb, Celgene, Eli-Lilly, Gilead, Merck Sharp and Dohme, Novartis and Pfizer. DA-R: scientific advisor for GSK. ADM: none declared. JK: none declared. DA: none declared. PE: expert advice to Pfizer, AbbVie, Amgen, MSD, Roche, Sanofi, BMS, Novartis, Lilly, Gilead, Samsung, Celltrion; grants from AbbVie, Lilly, BMS, Samsung. The review was not registered. Data collection forms and other materials used in the review available from authors on request., (© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Objective: Individuals with newly diagnosed RA have a distinct microbiome when compared with healthy controls. However, little is known as to when these microbiome perturbations begin. Using a prospective at-risk cohort of individuals positive for anti-citrullinated protein (anti-CCP) antibody with new onset musculoskeletal symptoms, but without clinical arthritis, we investigated for the presence of a gut dysbiosis before the onset of RA., Methods: The gut microbiota of 25 anti-CCP positive individuals without clinical synovitis were sequenced targeting the V4 region of the 16S rRNA gene. Using a publicly available database, a control population of 44 individuals, approximately matched in age, gender, diet and ethnicity was selected for comparison, using the same sequencing methodology. Median interval between sample collection and progression to RA was 188 days. Taxonomic analysis was performed using QIIME and MEGAN, and statistical analysis using R software., Results: There were significant differences (P =0.01) at family level in gut microbiomes of anti-CCP positive individuals vs controls. The anti-CCP positive population had an overabundance of Lachnospiraceae, Helicobacteraceae, Ruminococcaceae, Erysipelotrichaceae and Bifidobacteriaceae, among others. Five individuals progressed to RA between sample collection and analysis. Clustering of the progressor population was observed on a phylogenetic network created using a probabilistic similarity index (Goodall's index)., Conclusions: Anti-CCP positive at-risk individuals without clinical synovitis appear to have a distinct gut microbiome compared with healthy controls. Phylogenetic clustering was observed in individuals who progressed to RA, suggesting that distinct taxa are associated with the development of RA many months before its onset., (© The Author(s) 2020. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Objectives: To investigate the prevalence, distribution and predictive value for the development of inflammatory arthritis (IA) of conventional radiography (CR) bone erosions (BE) in anti-CCP positive (CCP+) at-risk individuals with musculoskeletal (MSK) symptoms but without clinical synovitis., Methods: Baseline CR of the hands and feet of 418 CCP+ at-risk individuals were analysed. The presence of US-BE was explored in the anatomical areas in which CR-BE were reported. Hands and feet CR at the time of progression were analysed in a subset of individuals who developed IA (73/123, 59.3%). Logistic regression analyses were performed to calculate the predictive value of baseline CR-BE for the development of IA in 394 CCP+ individuals with ≥1 follow-up visit., Results: BE were detected in 17/418 (4.1%) CCP+ at-risk individuals (median Simple Erosions Narrowing Score-BE = 2.0, IQR: 1.0-2.0; median Sharp van der Heijde score-BE = 4.0, IQR: 3.0-8.5), most frequently in the foot joints (11/17, 64.7% individuals). A total of 123/394 (31.2%) CCP+ at-risk individuals developed IA; 7/17 (41.2%) with, and 116/377 (30.8%) without BE on CR (P = 0.37). US-BE were found in 4/7 (57.1%) individuals with CR-BE who developed IA, but only in 1/10 (10.0%) who did not. At the time of progression, new BE were detected in 4/73 (5.5%) CCP+ individuals on repeated CR. In the regression analyses, baseline CR-BE were not predictive for the development of IA., Conclusions: In CCP+ at-risk individuals with MSK symptoms, CR-detected BE are uncommon and do not predict the development of IA., (© The Author(s) 2020. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Objectives: An increased prevalence of periodontitis and perturbation of the oral microbiome has been identified in patients with rheumatoid arthritis (RA). The periodontal pathogen Porphyromonas gingivalis may cause local citrullination of proteins, potentially triggering anti-citrullinated protein antibody production. However, it is not known if oral dysbiosis precedes the onset of clinical arthritis. This study comprehensively characterised the oral microbiome in anti-cyclic citrullinated peptide (anti-CCP) positive at-risk individuals without clinical synovitis (CCP+at risk)., Methods: Subgingival plaque was collected from periodontally healthy and diseased sites in 48 CCP+at risk, 26 early RA and 32 asymptomatic healthy control (HC) individuals. DNA libraries were sequenced on the Illumina HiSeq 3000 platform. Taxonomic profile and functional capability of the subgingival microbiome were compared between groups., Results: At periodontally healthy sites, CCP+at risk individuals had significantly lower microbial richness compared with HC and early RA groups (p=0.004 and 0.021). Microbial community alterations were found at phylum, genus and species levels. A large proportion of the community differed significantly in membership (523 species; 35.6%) and structure (575 species; 39.1%) comparing CCP+at risk and HC groups. Certain core species, including P. gingivalis , had higher relative abundance in the CCP+at risk group. Seventeen clusters of orthologous gene functional units were significantly over-represented in the CCP+at risk group compared with HC (adjusted p value <0.05)., Conclusion: Anti-CCP positive at-risk individuals have dysbiotic subgingival microbiomes and increased abundance of P. gingivalis compared with controls. This supports the hypothesis that the oral microbiome and specifically P. gingivalis are important in RA initiation., Competing Interests: Competing interests: ZC reports scholarship from the China Scholarship Council during the conduct of the study. Dr TD and JM reports grants from Colgate Palmolive, outside the submitted work. KM reports grants from the National Institute for Health Research (NIHR) Leeds Biomedical Research Unit and grants from Leeds Biomedical Research Centre during the conduct of the study. DD reports grants from NIHR, grants from Wellcome Trust, during the conduct of the study; grants from Colgate Palmolive, outside the submitted work. PE reports grants and personal fees from Pfizer, Merck Sharp & Dohme, AbbVie, Bristol-Myers Squibb, Roche, Samsung, Sandoz, and Eli Lilly and Company; and personal fees from Novartis and UCB outside the submitted work., (© Author(s) (or their employer(s)) 2021. No commercial re-use. See rights and permissions. Published by BMJ.)

Objectives: To perform a systematic literature review (SLR) analysing all studies that reported on the efficacy and safety of pharmacological treatments for palindromic rheumatism (PR)., Methods: We performed a SLR using PubMed, Embase and Cochrane databases. Three main aspects of PR were considered: treating flares, preventing recurrence of flares (i.e. achieving remission), and preventing progression to RA or to other persistent arthritis. Quality assessment of the studies was performed using the Newcastle-Ottawa Scale (NOS)., Results: Twenty-seven articles met the inclusion criteria: 6 (22.2%) retrospective studies, 8 (29.6%) longitudinal studies, and 13 (48.1%) case series/case reports. No randomized controlled trials (RCTs) were found. Most of the studies (21/27, 77.7%) had a high risk of bias according to NOS. Non-steroidal anti-inflammatory drugs were the most commonly reported treatments for flares of PR, with variable results. Anti-malarials, such as hydroxychloroquine and chloroquine phosphate, showed efficacy in reducing the frequency of the flares and, to a lesser extent, in preventing progression to RA. There was minimal evidence in support of other conventional/biological disease modifying anti-rheumatic treatments, or corticosteroids., Conclusion: Although a frequent clinical dilemma for rheumatologists, the pharmacological management of PR has not been thoroughly evaluated, with no RCTs reported. Of all therapies, antimalarials have been the best studied and may be capable of reducing the recurrence of flares. The optimum treatment strategy for PR remains largely undefined and should be evaluated by robust RCTs in well-defined PR cohorts., Competing Interests: Declaration of Competing Interest Kulveer Mankia reports personal fees from Abbvie, UCB and Eli Lilly, outside the submitted work. Paul Emery reports consultant fees from BMS, AbbVie, Gilead, Galapagos, Lilly, MSD, Pfizer, Novartis, Roche, and Samsung outside the submitted work. He also reports research grants from UCB, AbbVie, Lilly, Novartis, BMS, Pfizer, MSD and Roche, outside the submitted work., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Objective: To 1) determine the prevalence of anti-cyclic citrullinated peptide 3 (anti-CCP3) antibodies in anti-CCP2 antibody-positive (anti-CCP2+) at-risk individuals, and 2) explore the additional value of anti-CCP3 antibodies in anti-CCP2+ at-risk individuals for predicting progression to inflammatory arthritis., Methods: Stored serum samples obtained from 347 anti-CCP2+ (BioPlex 2200; Bio-Rad) at-risk individuals without clinical synovitis were tested for anti-CCP3 antibodies. Anti-CCP2 titers were categorized as low or high, and anti-CCP3 titers were categorized as negative, low, or strong. Progression to inflammatory arthritis was defined as the development of clinical synovitis in ≥1 joint. Only subjects with ≥1 follow-up visit were included in the progression analysis (n = 291)., Results: In the 347 samples included, anti-CCP3 antibody titers tended to be either negative (n = 138 [39.7%]) or strongly positive (n =189 [54.4%]), with very few subjects showing a low titer (n = 20 [5.7%]). In contrast, for anti-CCP2 antibodies, more low titers were observed (n = 103 [29.7%]). Eighty-eight of 291 subjects (30.2%) developed inflammatory arthritis. The rate of progression to inflammatory arthritis in the low-titer anti-CCP2 group and the high-titer anti-CCP2 group fell from 7.5% to 3.3% and from 38.9% to 9.8%, respectively, when anti-CCP3 was negative. Progression in the high-titer anti-CCP2 group increased from 38.9% to 48.4% when anti-CCP3 was strongly positive. The area under the curve was 0.72 for anti-CCP2 (95% confidence interval [95% CI] 0.66, 0.78) and 0.76 for anti-CCP3 (95% CI 0.70, 0.81) for assessment of progression. In the multivariable analysis, the odds ratio for the development of inflammatory arthritis in anti-CCP3+ subjects was 1.73 (95% CI 1.20, 2.51) (P < 0.01)., Conclusion: Anti-CCP3 antibodies improve the prediction of inflammatory arthritis in anti-CCP2+ at-risk individuals. The impact of anti-CCP3 antibody status for the risk stratification of individuals with high-titer anti-CCP2 is particularly notable., (© 2020 The Authors. Arthritis & Rheumatology published by Wiley Periodicals LLC on behalf of American College of Rheumatology.)

Competing Interests: Competing interests: None declared.

Objectives: To investigate, in anti-cyclic citrullinated peptide antibody positive (CCP+) at-risk individuals without clinical synovitis, the prevalence and distribution of ultrasound (US) bone erosions (BE), their correlation with subclinical synovitis and their association with the development of inflammatory arthritis (IA)., Methods: Baseline US scans of 419 CCP+ at-risk individuals were analysed. BE were evaluated in the classical sites for rheumatoid arthritis damage: the second and fifth metacarpophalangeal (MCP2 and MCP5) joints, and the fifth metatarsophalangeal (MTP5) joints. US synovitis was defined as synovial hypertrophy (SH) ≥2 or SH ≥1+power Doppler signal ≥1. Subjects with ≥1 follow-up visit were included in the progression analysis (n=400)., Results: BE were found in ≥1 joint in 41/419 subjects (9.8%), and in 55/2514 joints (2.2%). The prevalence of BE was significantly higher in the MTP5 joints than in the MCP joints (p<0.01). A significant correlation between BE and US synovitis in the MTP5 joints was detected (Cramer's V=0.37, p<0.01). The OR for the development of IA (ever) was highest for the following: BE in >1 joint 10.6 (95% CI 1.9 to 60.4, p<0.01) and BE and synovitis in ≥1 MTP5 joint 5.1 (95% CI 1.4 to 18.9, p=0.02). In high titre CCP+ at-risk individuals, with positive rheumatoid factor and BE in ≥1 joint, the OR increased to 16.9 (95% CI 2.1-132.8, p<0.01)., Conclusions: In CCP+ at-risk individuals, BE in the feet appear to precede the onset of clinical synovitis. BE in >1 joint, and BE in combination with US synovitis in the MTP5 joints, are the most predictive for the development of clinical arthritis., Competing Interests: Competing interests: This study was conducted while ADM was an ARTICULUM Fellow. KM reports personal fees from AbbVie, UCB and Eli Lilly, outside the submitted work. RJW has received honoraria from AbbVie, Novartis and GE for ultrasound-related educational activities. PE reports consultant fees from BMS, AbbVie, MSD, Pfizer, Novartis and Roche, outside the submitted work. He also reports research grants from UCB, AbbVie, BMS, Pfizer, MSD and Roche, outside the submitted work., (© Author(s) (or their employer(s)) 2020. No commercial re-use. See rights and permissions. Published by BMJ.)

Purpose of Review: Rheumatoid arthritis (RA) is no longer considered a fixed phenotype but rather a disease continuum. This review outlines the current and potential value of applying ultrasound (US) along this continuum: from the prediction of progression to RA in at-risk individuals, to confirmation of the early diagnosis of RA, as well as the consideration of differential diagnoses, and the use in disease monitoring and defining remission., Recent Findings: In individuals at-risk of RA (i.e., positive autoantibodies with symptoms but without synovitis), US has shown a promising predictive value for the development of clinical arthritis, providing the opportunity to improve risk stratification (and disease prevention) of these individuals. The detection of inflammation on US in patients with early undifferentiated arthritis, in which a definite diagnosis cannot be reached, could predict evolution to persistent arthritis, mostly RA. This, in addition to the US potential ability to identify disease specific patterns for different rheumatic conditions, might facilitate early diagnosis and, therefore, improve the management of patients with RA, or other types of inflammatory arthritides. US has also demonstrated the capability to predict radiographic progression, and relapse risk after treatment discontinuation, in RA patients in remission according to the clinical instruments, raising implications in the management, including therapy discontinuation, of these patients. US has an undeniable value in the management of patients at different stages along the RA continuum. Further research is needed to identify which groups of patients benefit the most from US imaging.

The outcome of treatment of patients with rheumatoid arthritis (RA) has qualitatively improved in recent years due to better and earlier treatment approaches, and new drugs. It is now generally accepted that the phenotype of RA is the end-point of a disease continuum. Large retrospective studies have identified anti-citrullinated protein antibodies (ACPAs) and rheumatoid factor in the stored serum of patients, years before the development of clinical RA. Recent data suggest mucosal sites such as the oral mucosa (in particular the periodontium), lung and gut may be the sites where auto-immunity is initiated. The role of bacteria at these sites is reviewed. Much recent work has focussed on the role of high resolution imaging namely ultrasound and magnetic resonance imaging in identifying subclinical inflammation in at-risk individuals with early musculoskeletal symptoms (e.g. arthralgia) but without clinical synovitis. Importantly, the first musculoskeletal site involved is usually not the joint (synovium). Sub-clinical disease predicts the onset of clinical arthritis, and its timing, in symptomatic at-risk individuals. These and other predictive markers will be described. The ability to identify patients at-risk of RA before joint involvement has led to interventions aimed at preventing/delaying disease. Once arthritis occurs, rapid remission is the target of therapy. The percentage of patients with RA achieving clinical remission has improved markedly compared with a few decades ago. The optimum outcome is to induce remission sufficiently profound so that therapy can be stopped, without flare, that is drug-free remission, which is effectively cure. Limitations of the tools used to measure remission, the outcome of tapering therapy, and new approaches to achieve successful drug cessation are described. Overall, this article reviews progress towards meeting the unmet needs of prevention/cure., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Palindromic rheumatism is a distinctive syndrome that has a long-recognized association with rheumatoid arthritis (RA). Palindromic rheumatism is characterized by intermittent flares of pain, erythema and swelling in and around the joints, which are typically severe and unpredictable. The observation that most patients with palindromic rheumatism have RA-related autoantibodies and that many eventually develop RA has led to palindromic rheumatism often being viewed as a relapsing-remitting variant of RA. However, the clinical and imaging phenotypes of palindromic rheumatism suggest important distinctions from RA and imply underlying mechanistic differences between the two conditions. Furthermore, the pattern of inflammation seen in palindromic rheumatism has interesting parallels with that seen in other groups of symptomatic individuals at risk of developing RA. In this Review, we explore the concept of palindromic rheumatism as part of the RA continuum and propose an updated disease paradigm for this unique syndrome.

Objectives: To use high-resolution imaging to characterise palindromic rheumatism (PR) and to compare the imaging pattern observed to that seen in new-onset rheumatoid arthritis (NORA)., Methods: Ultrasound (US) assessment of synovitis, tenosynovitis and non-synovial extracapsular inflammation (ECI) was performed during and between flares in a prospective treatment-naive PR cohort. MRI of the flaring region was performed where possible. For comparison, the same US assessment was also performed in anticyclic citrullinated peptide (CCP) positive individuals with musculoskeletal symptoms (CCP+ at risk) and patients with NORA., Results: Thirty-one of 79 patients with PR recruited were assessed during a flare. A high frequency of ECI was identified on US; 19/31 (61%) of patients had ECI including 12/19 (63%) in whom ECI was identified in the absence of synovitis. Only 7/31 (23%) patients with PR had synovitis (greyscale ≥1 and power Doppler ≥1) during flare. In the hands/wrists, ECI was more prevalent in PR compared with NORA and CCP+ at risk (65% vs 29 % vs 6%, p<0.05). Furthermore, ECI without synovitis was specific for PR (42% PR vs 4% NORA (p=0.003) and 6% CCP+ at risk (p=0.0012)). Eleven PR flares were captured by MRI, which was more sensitive than US for synovitis and ECI. 8/31 (26%) patients with PR developed RA and had a similar US phenotype to NORA at progression., Conclusion: PR has a distinct US pattern characterised by reversible ECI, often without synovitis. In patients presenting with new joint swelling, US may refine management by distinguishing relapsing from persistent arthritis., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2019. No commercial re-use. See rights and permissions. Published by BMJ.)

There is an epidemiological association between periodontitis and rheumatoid arthritis (RA), which is hypothesised to lead to enhanced generation of RA-related autoantibodies that can be detected years before the onset of RA symptoms. Periodontitis is a common dysbiotic disease; tissue damage occurs because the immune system fails to limit both the resident microbial community and the associated local immune response. Certain periodontal bacteria, including Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans, may contribute to RA autoantibody production through direct post-translational modification of proteins or, indirectly, by influencing neutrophil-mediated neo-epitope generation. Oral bacteria that invade the blood may also contribute to chronic inflammatory responses and generation of autoantibodies. The putative association between periodontitis and the development of RA raises the potential of finding novel predictive markers of disease and disease progression and for periodontitis treatment to be included in the future as an adjunct to conventional RA immunotherapy or as part of a preventive strategy., (Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.)

Palindromic rheumatism (PR) is a syndrome characterised by recurrent, self-resolving inflammatory attacks in and around the joints. An association between PR and rheumatoid arthritis (RA) has long been postulated; a significant proportion of PR patients eventually develop RA and the majority also have anti-CCP antibodies. Therefore, PR is often considered a prodrome of RA. However, the clinical and imaging phenotype of PR has several important distinctions from RA. This suggests that despite the similarities, distinct disease mechanisms are at play. Given the paucity of evidence-based therapy in PR, a better understanding of these mechanisms will be important for refined and targeted therapeutic approaches for this important condition., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Purpose of Review: Progress in our understanding of the preclinical events in rheumatoid arthritis (RA) has provided important insights into disease pathogenesis. Studying prospective cohorts of individuals at risk for RA development offers the opportunity to accurately characterize the sequence of events in preclinical disease as well as quantify the risk of different preclinical phenotypes. These data may provide the basis for preventive strategies in RA., Recent Findings: RA-related systemic autoimmunity and inflammation occur long before clinical arthritis. There is growing evidence that initiating events may occur at mucosal surfaces including the periodontium, lung and gut and may be influenced by the local microbiome. For potential preventive strategies to be feasible, it is important that individuals at high risk for RA development can be readily identified from the general population. To this end, studying multiple biomarkers in prospective cohorts of at-risk individuals enables risk prediction in different at-risk phenotypes. RA prevention using immunomodulation is currently being investigated in individuals at high risk of RA development., Summary: The prospective study of at-risk individuals can provide invaluable aetiological insights as well as facilitating accurate risk prediction data. In this way, high-risk individuals may be identified for preventive interventions.

The systemic autoantibodies that characterize rheumatoid arthritis (RA) are detectable well before patients develop disease and may originate from sites distant to the synovial joints. There is growing evidence that local autoimmune processes occur at mucosal sites in the earliest phases of RA, as well as in predisposed individuals who have not yet progressed to clinical disease. Mucosal autoimmunity has been described at the oral mucosa, lung, and gut in these subjects, and it is conceivable that different sites may provide the primary trigger for systemic autoimmunity in different individuals. At the oral mucosa and lung, risk factors such as periodontal disease and smoking may contribute to autoimmunity by driving the local generation of citrullinated autoantigens. A break in immune tolerance could lead to localized and then systemic autoimmunity, a hypothesis compatible with an etiological model for anti-citrullinated protein antibody (ACPA) positive RA. At the gut mucosa, the composition of the intestinal microbiome is central to local immune regulation. Here, there is evidence from animal models that alteration of the local microbiome can influence the balance of pro- and anti-inflammatory T cells and promote the development of autoimmune disease. In this review, we discuss the evidence for localized mucosal autoimmunity in those with preclinical and early RA. Autoimmunity at the oral mucosa, lung, and gut will be considered as potential initiating sites of RA-related autoimmunity.