Identification of a distinct imaging phenotype may improve the management of palindromic rheumatism

Ultrasonographic Insights into Peripheral Psoriatic Arthritis: Updates in Diagnosis and Monitoring

Psoriatic arthritis (PsA) is a chronic inflammatory arthritis associated with psoriasis, characterized by heterogeneous clinical manifestations and variable disease progression. Ultrasonography has emerged as a valuable tool in the diagnosis and monitoring of PsA, providing real-time visualization of joint and soft tissue abnormalities. This review highlights recent advancements in ultrasonographic techniques for the assessment of PsA, including the identification of typical features, the role of power Doppler imaging in detecting active inflammation, and the potential of ultrasound for guiding treatment decisions. Additionally, we discuss the utility of ultrasound in assessing treatment response and monitoring disease progression in patients with PsA, with a focus on novel imaging modalities. By elucidating the evolving role of ultrasonography in PsA management, this article aims to enhance clinicians' understanding of its utility in facilitating early diagnosis, optimizing treatment strategies, and improving patient outcomes.

Vitamin D Status in Palindromic Rheumatism: A Propensity Score Matching Analysis

OBJECTIVE

To determine whether there is a correlation between vitamin D levels and palindromic rheumatism (PR) as an at-risk phenotype of rheumatoid arthritis (RA).

METHODS

A total of 308 participants were enrolled in this cross-sectional study. We recorded their clinical characteristics and performed propensity-score matching (PSM). Serum 25(OH)D3 levels were determined via enzyme-linked immunosorbent assay.

RESULTS

Our PSM resulted in 48 patients with PR and 96 matched control individuals. The multivariate regression analysis we performed after the PSM did not show a significant increase in PR risk in patients with vitamin D deficiency/insufficiency. There was no significant correlation between levels of 25(OH)D3 and frequency/duration of attacks, number of joints affected, and duration of symptoms before diagnosis (P ≥ .05). Mean (SD) serum levels of 25(OH)D3 in patients with and without progression to RA were 28.7 (15.9) ng/mL and 25.1 (11.4) ng/mL, respectively.

CONCLUSION

Based on the results, we found no clear association between vitamin D serum levels and the risk, severity, and rate of PR progressing into RA.

Identification of Distinct Genetic Profiles of Palindromic Rheumatism Using Whole-Exome Sequencing

OBJECTIVE

Previous studies have underlined the genetic susceptibility in the pathogenesis of palindromic rheumatism (PR), but the known PR loci only partially explain the disease's genetic background. We aimed to genetically identify PR by whole-exome sequencing (WES).

METHODS

This multicenter prospective study was conducted in 10 Chinese specialized rheumatology centers between September 2015 and January 2020. WES was performed in 185 patients with PR and in 272 healthy controls. PR patients were divided into PR subgroups who were negative for anti-citrullinated protein antibody (ACPA-) and positive for ACPA (ACPA+) according to ACPA titer (cutoff value 20 IU/liter). We conducted whole-exome association analysis for the WES data. We used HLA imputation to type HLA genes. In addition, we used the polygenic risk score to measure the genetic correlations between PR and rheumatoid arthritis (RA) and the genetic correlations between ACPA- PR and ACPA+ PR.

RESULTS

Among 185 patients with PR enrolled in our study, 50 patients (27.02%) were ACPA+ and 135 PR patients (72.98%) were ACPA-. We identified 8 novel loci (in the ACPA- PR group: ZNF503, RPS6KL1, HOMER3, HLA-DRA; in the ACPA+ PR group: RPS6KL1, TNPO2, WASH2P, FANK1) and 3 HLA alleles (in the ACPA- PR group: HLA-DRB1*0803 and HLA-DQB1; in the ACPA+ PR group: HLA-DPA1*0401) that were associated with PR and that surpassed genome-wide significance (P < 5 × 10-8 ). Furthermore, polygenic risk score analysis showed that PR and RA were not similar (R2 < 0.025), whereas ACPA+ PR and ACPA- PR showed a moderate genetic correlation (0.38 < R2 < 0.8).

CONCLUSION

This study demonstrated the distinct genetic background between ACPA- and ACPA+ PR patients. Additionally, our findings strengthened that PR and RA were not genetically similar.

Pain in the joints and beyond; the challenge of rheumatoid arthritis

Pain is a common and often debilitating symptom for people living with rheumatoid arthritis. Although pain is a generic feature of inflammation and often improves with successful treatment that targets inflammatory pathways, pain experience can persist. Emerging data suggest that the magnitude of pain relief might vary according to the therapeutic target of pharmacological intervention within the inflammatory cascade. Both inflammatory and non-inflammatory causes contribute to the pain experience, which depends on tissue origin, peripheral sensory mechanisms and their transmission, integration, and interpretation within the nervous system. Contemporary neuroimaging is transforming our understanding of these mechanisms and the role of sensory, emotional, and cognitive contributions to the experience of pain. This understanding paves the way for therapeutic approaches that recognise the existence of multiple, cognitively driven, supraspinal mechanisms for pain modulation and could complement pharmacological inflammation suppression. Such approaches include neuropsychological interventions that have the potential to modify human brain cortical structure and reduce suffering that is often associated with pain experience.

When and how should we use imaging in individuals at risk of rheumatoid arthritis?

In recent years rheumatologists have begun to shift focus from early rheumatoid arthritis (RA) to studying individuals at risk of developing the disease. It is now possible to use blood, clinical and imaging biomarkers to identify those at risk of progression before the onset of clinical synovitis. The use of imaging, in particular ultrasound (US) and magnetic resonance imaging (MRI), has become much more widespread in individuals at-risk of RA. Numerous studies have demonstrated that imaging can help us understand RA pathogenesis as well as identifying individuals at high risk of progression. In addition, imaging techniques are becoming more sophisticated with newer imaging modalities such as high-resolution peripheral quantitative computed tomography (HR-pQRCT), nuclear imaging and whole body-MRI (WB-MRI) starting to emerge. Imaging studies in at risk individuals are heterogeneous in nature due to the different at-risk populations, imaging modalities and protocols used. This review will explore the available imaging modalities and the rationale for their use in the main populations at risk of RA.

The value of MRI for detecting subclinical joint inflammation in clinically suspect arthralgia

In the last decade, much research has focused on the development of rheumatoid arthritis (RA) and the symptomatic phase preceding the onset of clinical arthritis. Observational studies on imaging have revealed that subclinical joint inflammation in patients with arthralgia at risk for RA precedes and predicts the onset of clinically apparent arthritis. Moreover, the results of two placebo-controlled randomised proof-of-concept trials in patients with arthralgia and MRI-detected subclinical inflammation studies will soon be available. The initial results are encouraging and suggest a beneficial effect of DMARD treatment on subclinical inflammation. Since this may increase the necessity to detect subclinical joint inflammation in persons with arthralgia that are at risk for RA, we will here review what has been learnt about subclinical inflammation in at-risk individuals by means of imaging. We will focus on MRI as this method has the best sensitivity and reproducibility. We evaluate the prognostic value of MRI-detected subclinical inflammation and assess the lessons learnt from MRIs about the tissues that are inflamed early on and are associated with the clinical phenotype in arthralgia at risk for RA, for example, subclinical tenosynovitis underlying pain and impaired hand function. Finally, because long scan times and the need for intravenous-contrast agent contribute to high costs and limited feasibility of current MRI protocols, we discuss progress that is being made in the field of MRI and that can result in a future-proof way of imaging that is useful for assessment of joint inflammation on a large scale, also in a society with social distancing due to COVID-19 restrictions.

Controversies in rheumatology: Ultrasound for monitoring of RA - do we need it?

Clinical joint examination is the cornerstone for evaluation of patients with rheumatoid arthritis (RA). However, since large discrepancies have been shown even between experienced rheumatologists in evaluation of joint inflammation, and tender joints may have limited value in reflecting inflammation, ultrasound has in the last decennials been introduced in the clinical assessments of RA patients. Ultrasound has high accordance with other imaging modalities and enables detection of clinically difficult pathologies and contributes to assessments of joints difficult to evaluate clinically. However, there is no general agreement on the optimal use of ultrasound in rheumatology and the prevalence of machines as well as the level of experience is highly different across the countries. In addition, standardized use of ultrasound in treat-to-target follow-up of RA patients was found not to have any added value. Thus, how to use ultrasound in monitoring of RA patients is open for debate. The present article will discuss the pros and cons for using ultrasound in the clinical setting.

Long-term outcome of patients with palindromic rheumatism treated with methotrexate

OBJECTIVE

Palindromic rheumatism (PR) is characterized by self-resolving and short duration attacks of arthritis/periarthritis. The present study was performed to report the results of PR treatment with methotrexate (MTX).

METHODS

We reviewed the charts of 152 patients with diagnosis of PR. Inclusion criteria were diagnosis of PR according to the criteria of Weismann, age ≥16, active disease and treatment with MTX for at least 6 months. Disease outcome was assessed by reaching remission and prevention of disease evolution to chronic arthritis. Remission was defined as stopping the attacks for 12 weeks and prednisolone dose ≤5 mg/d. MTX treatment failure was defined as failure to achieve remission, the need to add other disease-modifying antirheumatic drugs and disease progression to chronic arthritis.

RESULTS

Fifty-nine patients were included in the study. Median duration of follow-up was 43 months. Attacks were controlled in 89.8% of patients. In 80% of the patients remission occurred during 12 months after starting treatment with MTX. Treatment failed in 20.3% of patients. Wrist joint involvement and positive rheumatoid factor (RF) were significantly more common in the MTX treatment-failed group. In RF positive patients evolution to rheumatoid arthritis was more common than in RF negative patients. No significant differences were observed in remission rate and evolution to rheumatoid arthritis in anticitrullinated C peptide positive and negative patients.

CONCLUSIONS

The present study, demonstrated the efficacy of MTX in controlling PR in seropositive and seronegative patients over a median of 43 months of treatment.

Stages of Lyme Arthritis

BACKGROUND/HISTORICAL PERSPECTIVE

Lyme arthritis was described in 1977, after an apparent outbreak of juvenile idiopathic arthritis in Lyme, Connecticut. The evolution of the disease has been meticulously described with presentation dependent on disease duration and previous therapy.

SUMMARY INTEGRATING PUBLISHED LITERATURE

Erythema migrans is typically the first manifestation. Untreated patients often develop early disseminated disease, characterized by migratory polyarthralgia, potentially with cardiac and/or neurologic sequelae. If untreated, most patients develop late Lyme arthritis, characterized as a monoarthritis or oligoarthritis, typically involving the knees. Serologies are strongly positive at this stage; if positive, Lyme PCR from synovial fluid confirms the diagnosis. Doxycycline is recommended for late Lyme arthritis, although amoxicillin or ceftriaxone may be considered.Initial antibiotic therapy for late Lyme arthritis is insufficient for a subset of patients. However, serologies and synovial fluid PCR are not useful at determining whether infection persists after oral therapy. As such, ceftriaxone is recommended in patients with inadequate response to doxycycline or amoxicillin.Approximately 10% of patients have persistent arthritis despite antimicrobial therapy, termed postinfectious Lyme arthritis, which is thought to be related to prolonged inflammation and unique microbial and host interaction. Therapy at this stage relies on immunosuppression and/or synovectomy.

MAJOR CONCLUSIONS AND FUTURE RESEARCH

Lyme arthritis provides unique insights into the complex interplay between microbes and host immunity. The progression from localized erythema migrans to early disseminated disease and late Lyme arthritis allows insight into arthritis initiation, and the study of postinfectious Lyme arthritis allows further insight into mechanisms of arthritis persistence.

EULAR points to consider for conducting clinical trials and observational studies in individuals at risk of rheumatoid arthritis

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.

Enthesitis in Psoriatic Arthritis, the Sonographic Perspective

Purpose of Review

To provide an overview of the ultrasound (US) studies focusing on enthesitis in psoriatic arthritis (PsA).

Recent Findings

Last-generation US equipment has demonstrated the ability to detect subtle morphostructural and vascular abnormalities at entheseal level. US is able to identify pathologic changes in both “classical” (i.e., the site of attachment of tendons, ligaments, and joint capsules into the bone) and “functional” entheses (i.e., anatomical regions where tendons or ligaments wrap around bony pulleys).

Summary

US has the potential to be the first-line method in the assessment of enthesitis. In the present review we critically discussed the current definitions of US enthesitis, the scoring systems, and the main fields of application (i.e., the detection of enthesitis in PsA and psoriasis, the identification of different disease subsets, and the assessment of response to treatment).

Intensive therapy for moderate established rheumatoid arthritis: the TITRATE research programme

Background

Rheumatoid arthritis is a major inflammatory disorder and causes substantial disability. Treatment goals span minimising disease activity, achieving remission and decreasing disability. In active rheumatoid arthritis, intensive management achieves these goals. As many patients with established rheumatoid arthritis have moderate disease activity, the TITRATE (Treatment Intensities and Targets in Rheumatoid Arthritis ThErapy) programme assessed the benefits of intensive management.

Objectives

To (1) define how to deliver intensive therapy in moderate established rheumatoid arthritis; (2) establish its clinical effectiveness and cost-effectiveness in a trial; and (3) evaluate evidence supporting intensive management in observational studies and completed trials.

Design

Observational studies, secondary analyses of completed trials and systematic reviews assessed existing evidence about intensive management. Qualitative research, patient workshops and systematic reviews defined how to deliver it. The trial assessed its clinical effectiveness and cost-effectiveness in moderate established rheumatoid arthritis.

Setting

Observational studies (in three London centres) involved 3167 patients. These were supplemented by secondary analyses of three previously completed trials (in centres across all English regions), involving 668 patients. Qualitative studies assessed expectations (nine patients in four London centres) and experiences of intensive management (15 patients in 10 centres across England). The main clinical trial enrolled 335 patients with diverse socioeconomic deprivation and ethnicity (in 39 centres across all English regions).

Participants

Patients with established moderately active rheumatoid arthritis receiving conventional disease-modifying drugs.

Interventions

Intensive management used combinations of conventional disease-modifying drugs, biologics (particularly tumour necrosis factor inhibitors) and depot steroid injections; nurses saw patients monthly, adjusted treatment and provided supportive person-centred psychoeducation. Control patients received standard care.

Main outcome measures

Disease Activity Score for 28 joints based on the erythrocyte sedimentation rate (DAS28-ESR)-categorised patients (active to remission). Remission (DAS28-ESR < 2.60) was the treatment target. Other outcomes included fatigue (measured on a 100-mm visual analogue scale), disability (as measured on the Health Assessment Questionnaire), harms and resource use for economic assessments.

Results

Evaluation of existing evidence for intensive rheumatoid arthritis management showed the following. First, in observational studies, DAS28-ESR scores decreased over 10–20 years, whereas remissions and treatment intensities increased. Second, in systematic reviews of published trials, all intensive management strategies increased remissions. Finally, patients with high disability scores had fewer remissions. Qualitative studies of rheumatoid arthritis patients, workshops and systematic reviews helped develop an intensive management pathway. A 2-day training session for rheumatology practitioners explained its use, including motivational interviewing techniques and patient handbooks. The trial screened 459 patients and randomised 335 patients (168 patients received intensive management and 167 patients received standard care). A total of 303 patients provided 12-month outcome data. Intention-to-treat analysis showed intensive management increased DAS28-ESR 12-month remissions, compared with standard care (32% vs. 18%, odds ratio 2.17, 95% confidence interval 1.28 to 3.68; p = 0.004), and reduced fatigue [mean difference –18, 95% confidence interval –24 to –11 (scale 0–100); p < 0.001]. Disability (as measured on the Health Assessment Questionnaire) decreased when intensive management patients achieved remission (difference –0.40, 95% confidence interval –0.57 to –0.22) and these differences were considered clinically relevant. However, in all intensive management patients reductions in the Health Assessment Questionnaire scores were less marked (difference –0.1, 95% confidence interval –0.2 to 0.0). The numbers of serious adverse events (intensive management n = 15 vs. standard care n = 11) and other adverse events (intensive management n = 114 vs. standard care n = 151) were similar. Economic analysis showed that the base-case incremental cost-effectiveness ratio was £43,972 from NHS and Personal Social Services cost perspectives. The probability of meeting a willingness-to-pay threshold of £30,000 was 17%. The incremental cost-effectiveness ratio decreased to £29,363 after including patients’ personal costs and lost working time, corresponding to a 50% probability that intensive management is cost-effective at English willingness-to-pay thresholds. Analysing trial baseline predictors showed that remission predictors comprised baseline DAS28-ESR, disability scores and body mass index. A 6-month extension study (involving 95 intensive management patients) showed fewer remissions by 18 months, although more sustained remissions were more likley to persist. Qualitative research in trial completers showed that intensive management was acceptable and treatment support from specialist nurses was beneficial.

Limitations

The main limitations comprised (1) using single time point remissions rather than sustained responses, (2) uncertainty about benefits of different aspects of intensive management and differences in its delivery across centres, (3) doubts about optimal treatment of patients unresponsive to intensive management and (4) the lack of formal international definitions of ‘intensive management’.

Conclusion

The benefits of intensive management need to be set against its additional costs. These were relatively high. Not all patients benefited. Patients with high pretreatment physical disability or who were substantially overweight usually did not achieve remission.

Future work

Further research should (1) identify the most effective components of the intervention, (2) consider its most cost-effective delivery and (3) identify alternative strategies for patients not responding to intensive management.

Trial registration

Current Controlled Trials ISRCTN70160382.

Funding

This project was funded by the National Institute for Health Research (NIHR) Programme Grants for Applied Research programme and will be published in full in Programme Grants for Applied Research; Vol. 9, No. 8. See the NIHR Journals Library website for further project information.

Palindromic Rheumatism: Just a Pre-rheumatoid Stage or Something Else?

Palindromic rheumatism (PR), a unique clinical entity, has a characteristic clinical presentation with a relapsing/remitting course. It is established that most patients with PR evolve to chronic disease, of which rheumatoid arthritis (RA) is by far the most common. The relationship between PR and RA is unclear, with similarities and differences between the two, and not all patients evolve to RA in the long-term. Therefore, PR is clearly a pre-RA stage for most, but not all, patients. Autoimmunity plays a substantial role in PR, with the same characteristic autoantibody profile observed in RA, although with some differences in the immune response repertoire. Autoinflammation may also be relevant in some cases of PR. Prognostic factors for RA progression are identified but their exact predictive value is not clear. There are several unmet needs in PR, such as the diagnostic criteria and clinical case definition, the pathogenic mechanisms involved in the unusual clinical course, and the evolution to RA, and our understanding of the therapeutic strategy that could best avoid progression to persistent and potentially destructive arthritis.

Palindromic rheumatism: a unique and enigmatic entity with a complex relationship with rheumatoid arthritis

INTRODUCTION

Palindromic rheumatism (PR) is a form of relapsing/remitting arthritis that may evolve to chronic rheumatic disease, mainly rheumatoid arthritis (RA). The exact nature of PR is unclear, as it may be considered a disease in itself, an abortive form of RA or just a pre-RA stage.

AREAS COVERED

The authors review the most relevant epidemiological and clinical aspects of PR, especially the pathogenetic role of autoimmunity in PR, with most patients having a characteristic autoantibody profile similar to that observed in RA. The role of autoinflammation is also discussed. A literature review on the rate of RA progression and its prognostic factors was analyzed. Data on the efficacy of drug therapies used to treat PR are presented. PubMed was searched using the terms 'palindromic rheumatism' OR 'palindromic arthritis'.

EXPERT OPINION

PR is a disease entity with a close but unclear relationship with RA. In PR there is an unmet need, which is to clarify the clinical spectrum and elucidate the risk factors for evolution to RA. The role of autoimmunity and the autoinflammatory component should be investigated. Since most patients evolve to RA, PR may display a unique therapeutic opportunity to avoid this evolution.

How should we treat palindromic rheumatism? A systematic literature review

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.

Anti-carbamylated protein antibody isotype pattern differs between palindromic rheumatism and rheumatoid arthritis

Background

A restricted response against citrullinated peptides/proteins, with less isotype usage, has been found in palindromic rheumatism (PR) in comparison with rheumatoid arthritis (RA). We hypothesized that this different antibody response may be observed for other post-translational modified proteins. We compared the prevalence and isotype usage of two specificities of anti-carbamylated peptide/protein antibodies (Anti-CarP) in patients with PR and RA.

Methods

Cross-sectional study including 54 patients with pure PR and 53 patients with RA, matched by sex, age, disease duration and ACPA. Anti-CarP specificities were determined by home-made enzyme-linked immunosorbent assay tests using a synthetic chimeric fibrin/filaggrin homocitrullinated peptide (CFFHP) and fetal calf serum (FCS) homocitrullinated protein as antigens. IgG, IgA and IgM isotypes were measured.

Results

Anti-CarP were positive (CFFHP or FCS) in 24% and 64% of patients with PR and RA, respectively (p < 0.005). All Anti-CarP isotype proportions were significantly lower in PR than in RA: Anti-CarP-IgG (24% versus 51%), Anti-CarP-IgA (7% versus 34%) and Anti-CarP-IgM (7% versus 36%). Mean titers of Anti-CarP isotypes were also lower in PR. In Anti-CarP positive patients, the isotype distribution differed between PR and RA: IgG Anti-CarP was used in all PR patients and in 79% of RA patients. By contrast, a significantly lower isotype usage of both IgA (31% versus 53%) and IgM (31% versus 56%) was observed in PR patients. No significant differences in clinical or demographic characteristics were observed according to Anti-CarP status in PR patients, except for a higher prevalence of ACPA and higher mean titers of ACPA and rheumatoid factor in Anti-CarP positive patients.

Conclusion

Anti-CarP are found in patients with PR but in a lower proportion and with a different isotype usage from in RA, suggesting a distinct B cell response to homocitrullinated antigens in PR.

The Role of Ultrasound Across the Inflammatory Arthritis Continuum: Focus on "At-Risk" Individuals

In individuals at-risk of developing inflammatory arthritis, the value of an ultrasound (US) scan assessment to predict progression has been demonstrated repeatedly. However, depending on recruitment criteria, these individuals may be at different stages in the arthritis development continuum, therefore representing a heterogeneous population. As a consequence, the predictive value of ultrasound results may differ between cohorts. As other reviews have focused on the challenges in population recruitment or have combined biomarkers predicting value according to one recruitment pathway, we wanted to focus on the sole use of ultrasound assessment and its variation according to population recruitment criteria. In this review, we discuss the use of ultrasound in the different at-risk populations across the inflammatory arthritis disease continuum. This review demonstrates that although some sub-population data is scarce, ultrasound is best predictive in three at-risk populations: those with a positive ACPA test in the context of non-specific MSK symptoms, those with clinically suspect arthralgia and those with palindromic rheumatism. We consider that ultrasound assessment will be a cornerstone in prediction risk modeling and prevention studies of the preclinical phases of IA in the future.

The Role of Musculoskeletal Ultrasound in the Rheumatoid Arthritis Continuum

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.

Tendon and ligament mechanical loading in the pathogenesis of inflammatory arthritis

Mechanical loading is an important factor in musculoskeletal health and disease. Tendons and ligaments require physiological levels of mechanical loading to develop and maintain their tissue architecture, a process that is achieved at the cellular level through mechanotransduction-mediated fine tuning of the extracellular matrix by tendon and ligament stromal cells. Pathological levels of force represent a biological (mechanical) stress that elicits an immune system-mediated tissue repair pathway in tendons and ligaments. The biomechanics and mechanobiology of tendons and ligaments form the basis for understanding how such tissues sense and respond to mechanical force, and the anatomical extent of several mechanical stress-related disorders in tendons and ligaments overlaps with that of chronic inflammatory arthritis in joints. The role of mechanical stress in 'overuse' injuries, such as tendinopathy, has long been known, but mechanical stress is now also emerging as a possible trigger for some forms of chronic inflammatory arthritis, including spondyloarthritis and rheumatoid arthritis. Thus, seemingly diverse diseases of the musculoskeletal system might have similar mechanisms of immunopathogenesis owing to conserved responses to mechanical stress.

Rheumatoid Arthritis Initiating as Palindromic Rheumatism: A Distinct Clinical Phenotype?

Objective.

To analyze the prevalence of preexisting palindromic rheumatism (PR) in patients with established rheumatoid arthritis (RA) and to evaluate whether these patients have a distinctive clinical and serological phenotype.

Methods.

Cross-sectional study in patients with established RA. Preexisting PR was determined using a structured protocol and confirmed by retrospective review of medical records. Demographic, clinical, radiological, immunological, and therapeutic features were compared in patients with and without PR.

Results.

Included were 158 patients with established RA (78% female) with a mean disease duration since RA onset of 5.1 ± 2.7 years. Preexisting PR was recorded in 29 patients (18%). The median time from the onset of PR to progression to RA was 1.2 years. No between-group differences in demographic features, current disease activity, radiographic erosive disease, or disability were observed. Patients with PR had a higher prevalence of smoking (72% vs 40%). Positive rheumatoid factor, anticitrullinated peptide antibodies, and anticarbamylated protein antibodies were numerically higher in patients with PR. No differences in treatment were observed except for greater hydroxychloroquine (HCQ) use in patients with PR (38% vs 6%). Palindromic flares persisted in a significant proportion of patients during the RA course, including patients in clinical remission or receiving biological disease-modifying antirheumatic drugs.

Conclusion.

Eighteen percent of patients with RA had a history compatible with PR previous to RA onset. No specific clinical or serological phenotype was identified in these patients, although higher HCQ use and smoking prevalence were identified. Palindromic flares may persist during the RA disease course despite treatment.