Predicting Rheumatoid Arthritis in At-risk Individuals

Classification of rheumatoid arthritis: is it time to revise the criteria?

Classification criteria have been developed for rheumatoid arthritis (RA) and other rheumatic diseases in order to gather a homogeneous patient population for clinical studies and facilitate the timely implementation of therapeutic measures. Although classification criteria are not intended to be used for diagnosis, they are frequently used to support the diagnostic process in clinical practice, including clinical decision-making. The 2010 American College of Rheumatology (ACR)/European Alliance of Associations for Rheumatology (EULAR) classification criteria for RA are capable of identifying the majority of symptomatic patients with RA already in the earliest stages of the disease who are not yet showing radiographic changes. These patients will also profit from the early implementation of therapy with disease-modifying antirheumatic drugs (DMARDs). However, the risk of misclassification is higher as compared with the former 1987 ACR criteria, which were considerably less sensitive to the recognition of patients with early RA. Of note, the presence of rheumatoid factors (RFs) and anticitrullinated protein antibodies (ACPAs) has been attributed equal weight in the 2010 ACR/EULAR criteria and may contribute up to 50% of the score needed for being classified as RA. However, while ACPAs have been proven to be the most specific serological markers of RA, the specificity of RF is moderate, especially at lower titres. This may lead to the misclassification of RF-positive patients and, consequently, the unjustified implementation of DMARD therapy. Therefore, issues arise on how comprehensive the criteria should be and whether they should be updated and adapted to findings from the past two decades that might increase both their specificity and sensitivity.

Association of indoor dampness indicators with rheumatic diseases/symptoms in older adults: A comparative cross-sectional study in Chongqing and Beijing

Dampness is strongly associated with rheumatic diseases, which particularly affect the older adults. Tackling dampness is therefore important, especially given that climate change is expected to exacerbate rheumatic diseases; however, limited studies have compared the risk of rheumatic diseases in older adults based on humidity levels across different regions. To explore this, a comparative cross-sectional study was conducted to collect information on the residential characteristics, lifestyles, and health outcomes of 2000 individuals aged 60-74 years from Chongqing and Beijing. From this data, we tested for an association between six indoor dampness indicators and rheumatic related diseases/symptoms. The results showed that the risk values for joint pain were higher in Chongqing than in Beijing. Moreover, the risk of joint stiffness increased more strongly in Chongqing than in Beijing as the cumulative number of dampness exposure indicators increased. The key indoor dampness indicators affecting rheumatic diseases were different for Chongqing and Beijing. Overall, this study compared the risk of rheumatic diseases in older adults in the north and south of China because of dampness exposure and, from these, provided suggestions for modifying the indoor environments to prevent or reduce rheumatic symptoms.

Should ACR/EULAR criteria be revised changing the RF and ACPA scores?

Current classification criteria for rheumatoid arthritis (RA) encompass clinical and immunological items and are capable of correctly identifying the majority of symptomatic RA patients. The presence of positive rheumatoid factor (RF) and/or and anti-cyclic citrullinated protein/peptide antibodies (ACPA) gaining increasing importance according to their serological titer eases the recognition of RA, yet the debate is open on whether this scoring system ought to be optimized by hierarchizing ACPA or the combination of ACPA and RF over single positivity, prioritizing specificity over sensitivity. The risk of misdiagnosis and misclassification are often entangled, yet they are not the same. In fact, while ideal diagnosis requires 100% sensitivity and specificity, classification criteria are conceived to gather a homogeneous patient population, favoring specificity over sensitivity. Nevertheless, as they are frequently summoned to support the diagnostic process in clinical practice, issues arise on how comprehensive those should be and on how frequently they should be updated in light of novel acquisitions regarding measurable RA-related abnormalities. In this viewpoint two different views on the topic are confronted, discussing the performance of available criteria and the potentiality and pitfalls of their refinement according to novel data on ACPA and RF contribution and emergence of newly discovered specificities.

Stakeholder perceptions of preventive approaches to rheumatoid arthritis: qualitative study of healthcare professionals' perspectives on predictive and preventive strategies

BACKGROUND

There is increasing research interest in the development of preventive treatment for individuals at risk of rheumatoid arthritis (RA). Previous studies have explored the perceptions of at-risk groups and patients about predictive and preventive strategies for RA, but little is known about health care professionals' (HCPs) perspectives.

METHODS

One-to-one semi-structured qualitative interviews were conducted (face-to-face or by telephone) with HCPs. Audio recordings of the interviews were transcribed, and the data were analysed by thematic analysis.

RESULTS

Nineteen HCPs (11 female) were interviewed, including ten GPs, six rheumatologists and three rheumatology nurse specialists. The thematic analysis identified four organising themes: 1) Attributes of predictive and preventive approaches; 2) Ethical and psychological concerns; 3) Implementation issues and 4) Learning from management of other conditions. Theme 1 described necessary attributes of predictive and preventive approaches, including the type and performance of predictive tools, the need for a sound evidence base and consideration of risks and benefits associated with preventive treatment. Theme 2 described the ethical and psycho-social concerns that interviewees raised, including the potential negative economic, financial and psychological effects of risk disclosure for 'at-risk' individuals, uncertainty around the development of RA and the potential for benefit associated with the treatments being considered. Theme 3 describes the implementation issues considered, including knowledge and training needs, costs and resource implications of implementing predictive and preventive approaches, the role of different types of HCPs, guidelines and tools needed, and patient characteristics relating to the appropriateness of preventive treatments. Theme 4 describes lessons that could be learned from interviewees' experiences of prediction and prevention in other disease areas, including how preventive treatment is prescribed, existing guidelines and tools for other diseases and issues relating to risk communication.

CONCLUSIONS

For successful implementation of predictive and preventative approaches in RA, HCPs need appropriate training about use and interpretation of predictive tools, communication of results to at-risk individuals, and options for intervention. Evidence of cost-efficiency, appropriate resource allocation, adaptation of official guidelines and careful consideration of the at-risk individuals' psycho-social needs are also needed.

Global, regional, and national burden of rheumatoid arthritis, 1990-2020, and projections to 2050: a systematic analysis of the Global Burden of Disease Study 2021

Background

Rheumatoid arthritis is a chronic autoimmune inflammatory disease associated with disability and premature death. Up-to-date estimates of the burden of rheumatoid arthritis are required for health-care planning, resource allocation, and prevention. As part of the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021, we provide updated estimates of the prevalence of rheumatoid arthritis and its associated deaths and disability-adjusted life-years (DALYs) by age, sex, year, and location, with forecasted prevalence to 2050.

Methods

Rheumatoid arthritis prevalence was estimated in 204 countries and territories from 1990 to 2020 using Bayesian meta-regression models and data from population-based studies and medical claims data (98 prevalence and 25 incidence studies). Mortality was estimated from vital registration data with the Cause of Death Ensemble model (CODEm). Years of life lost (YLL) were calculated with use of standard GBD lifetables, and years lived with disability (YLDs) were estimated from prevalence, a meta-analysed distribution of rheumatoid arthritis severity, and disability weights. DALYs were calculated by summing YLLs and YLDs. Smoking was the only risk factor analysed. Rheumatoid arthritis prevalence was forecast to 2050 by logistic regression with Socio-Demographic Index as a predictor, then multiplying by projected population estimates.

Findings

In 2020, an estimated 17·6 million (95% uncertainty interval 15·8-20·3) people had rheumatoid arthritis worldwide. The age-standardised global prevalence rate was 208·8 cases (186·8-241·1) per 100 000 population, representing a 14·1% (12·7-15·4) increase since 1990. Prevalence was higher in females (age-standardised female-to-male prevalence ratio 2·45 [2·40-2·47]). The age-standardised death rate was 0·47 (0·41-0·54) per 100 000 population (38 300 global deaths [33 500-44 000]), a 23·8% (17·5-29·3) decrease from 1990 to 2020. The 2020 DALY count was 3 060 000 (2 320 000-3 860 000), with an age-standardised DALY rate of 36·4 (27·6-45·9) per 100 000 population. YLDs accounted for 76·4% (68·3-81·0) of DALYs. Smoking risk attribution for rheumatoid arthritis DALYs was 7·1% (3·6-10·3). We forecast that 31·7 million (25·8-39·0) individuals will be living with rheumatoid arthritis worldwide by 2050.

Interpretation

Rheumatoid arthritis mortality has decreased globally over the past three decades. Global age-standardised prevalence rate and YLDs have increased over the same period, and the number of cases is projected to continue to increase to the year 2050. Improved access to early diagnosis and treatment of rheumatoid arthritis globally is required to reduce the future burden of the disease.

Funding

Bill & Melinda Gates Foundation, Institute of Bone and Joint Research, and Global Alliance for Musculoskeletal Health.

The Symptoms in Persons At Risk of Rheumatoid Arthritis (SPARRA) questionnaire: predicting clinical arthritis development

OBJECTIVE

There is a need to better define symptom characteristics associated with arthritis development in individuals at risk of rheumatoid arthritis (RA). We investigated whether reported symptoms in at-risk individuals could predict arthritis development and whether predictive symptoms differed between seropositive and seronegative at-risk individuals.

METHOD

At-risk individuals from four cohorts (Netherlands, UK, Sweden, and Switzerland) completed the Symptoms in Persons At Risk of Rheumatoid Arthritis (SPARRA) questionnaire. Participants had either (i) anti-citrullinated protein antibodies and/or rheumatoid factor, or (ii) relevant symptoms with or without RA antibodies. Follow up was ≥ 24 months or until clinical arthritis development. Stepwise forward selection created SPARRA prediction models for the combined group and for a seropositive subgroup.

RESULTS

Of 214 participants, the mean age was 50 years, 67% were female, and 27% (n = 58) developed clinical arthritis after a median time of 7 months. Four symptoms predicted arthritis development: self-reported joint swelling, joint pain moving from side to side (combined group only), feeling pins and needles in the joints, and often feeling fatigued (predicting non-arthritis).

CONCLUSION

Specific symptoms can provide useful information to estimate a person's RA risk. Differences in predictive symptoms between seropositive and seronegative at-risk individuals need to be further investigated. Future research is needed to determine whether changes in symptoms over time improve prediction and to determine the value of SPARRA in optimizing the selection of individuals who need to consult a rheumatologist.

Preferences for preventive treatments for rheumatoid arthritis: discrete choice survey in the UK, Germany and Romania

OBJECTIVE

To quantify preferences for preventive therapies for rheumatoid arthritis (RA) across three countries.

METHODS

A web-based survey including a discrete choice experiment was administered to adults recruited via survey panels in the UK, Germany and Romania. Participants were asked to assume they were experiencing arthralgia and had a 60% chance of developing RA in the next 2 years and completed 15 choices between no treatment and two hypothetical preventive treatments. Treatments were defined by six attributes (effectiveness, risks and frequency/route of administration) with varying levels. Participants also completed a choice task with fixed profiles reflecting subjective estimates of candidate preventive treatments. Latent class models (LCMs) were conducted and the relative importance of attributes, benefit-risk trade-offs and predicted treatment uptake was subsequently calculated.

RESULTS

Completed surveys from 2959 participants were included in the analysis. Most participants preferred treatment over no treatment and valued treatment effectiveness to reduce risk more than other attributes. A five-class LCM best fitted the data. Country, perceived risk of RA, health literacy and numeracy predicted class membership probability. Overall, the maximum acceptable risk for a 40% reduction in the chance of getting RA (60% to 20%) was 21.7%, 19.1% and 2.2% for mild side effects, serious infection and serious side effects, respectively. Predicted uptake of profiles reflecting candidate prevention therapies differed across classes.

CONCLUSION

Effective preventive pharmacological treatments for RA were acceptable to most participants. The relative importance of treatment attributes and likely uptake of fixed treatment profiles were predicted by participant characteristics.

Autoimmune pre-disease

Approximately 5% of the world-wide population is affected by autoimmune diseases. Overall, autoimmune diseases are still difficult to treat, impose a high burden on patients, and have a significant economic impact. Like other complex diseases, e.g., cancer, autoimmune diseases develop over several years. Decisive steps in the development of autoimmune diseases are (i) the development of autoantigen-specific lymphocytes and (often) autoantibodies and (ii) potentially clinical disease manifestation at a later stage. However, not all healthy individuals with autoantibodies develop disease manifestations. Identifying autoantibody-positive healthy individuals and monitoring and inhibiting their switch to inflammatory autoimmune disease conditions are currently in their infancy. The switch from harmless to inflammatory autoantigen-specific T and B-cell and autoantibody responses seems to be the hallmark for the decisive factor in inflammatory autoimmune disease conditions. Accordingly, biomarkers allowing us to predict this progression would have a significant impact. Several factors, such as genetics and the environment, especially diet, smoking, exposure to pollutants, infections, stress, and shift work, might influence the progression from harmless to inflammatory autoimmune conditions. To inspire research directed at defining and ultimately targeting autoimmune predisease, here, we review published evidence underlying the progression from health to autoimmune predisease and ultimately to clinically manifest inflammatory autoimmune disease, addressing the following 3 questions: (i) what is the current status, (ii) what is missing, (iii) and what are the future perspectives for defining and modulating autoimmune predisease.

Disease mechanisms in preclinical rheumatoid arthritis: A narrative review

In the last decades, the concept of preclinical rheumatoid arthritis (RA) has become established. In fact, the discovery that disease mechanisms start years before the onset of clinical RA has been one of the major recent insights in the understanding of RA pathogenesis. In accordance with the complex nature of the disease, preclinical events extend over several sequential phases. In a genetically predisposed host, environmental factors will further increase susceptibility for incident RA. In the initial steps of preclinical disease, immune disturbance mechanisms take place outside the joint compartment, namely in mucosal surfaces, such as the lung, gums or gut. Herein, the persistent immunologic response to altered antigens will lead to breach of tolerance and trigger autoimmunity. In a second phase, the immune response matures and is amplified at a systemic level, with epitope spreading and widening of the autoantibody repertoire. Finally, the synovial and bone compartment are targeted by specific autoantibodies against modified antigens, initiating a local inflammatory response that will eventually culminate in clinically evident synovitis. In this review, we discuss the elaborate disease mechanisms in place during preclinical RA, providing a broad perspective in the light of current evidence.

Perspectives of at-Risk Individuals on Preventive Intervention for Rheumatoid Arthritis: A Mini Review

There has been intense research focus on the biological mechanisms underlying the transition from health to disease for rheumatoid arthritis (RA) over recent years, and it is now well established that a state of autoimmunity precedes the development of symptoms for a large proportion of patients. This has led to an increased interest in the identification of at-risk groups and the potential for preventive intervention. The ability of several immunomodulatory agents to delay or prevent RA is under investigation and novel cellular therapies are in development. Preventive approaches are also being assessed in other chronic autoimmune diseases. For example, an anti-CD3 antibody has recently been shown to delay progression to type 1 diabetes in non-diabetic relatives of patients identified as being at high risk. The identification and treatment of individuals as being at risk of a disease where there is a degree of uncertainty around the potential for benefit is socially and ethically challenging. Recently reported difficulties in recruitment to RA prevention trials have underlined the importance of understanding the perspectives of at-risk individuals to identify barriers and facilitators that need to be addressed in order for preventive strategies to be acceptable. Understanding of their preferences for benefits and risks of preventive interventions can inform efficient intervention prioritization, prevention trial design and the development of informational resources for those at risk. In this review we summarize current knowledge of preferences for RA prevention and make recommendations for further research needed to ensure efficient development of preventive therapies and clinical implementation.

Impact of autoimmune serology test results on RA classification and diagnosis

Rheumatoid arthritis (RA) is the most common systemic autoimmune disease and also the most severe arthritic disorder. The measurement of rheumatoid factor (RF) and anti-citrullinated protein antibodies (ACPA) in serum supports the diagnosis of RA, which gained increasing significance over the last 65 years. However, a high variability between RF and ACPA methods has been described, impacting the diagnostic performance of the current ACR/EULAR RA classification criteria.

The great number of commercially available assays, often lacking traceability to an international standard, is a major factor attributing to this in-between assay variability. The adoption of an international standard for ACPA, as is since long available for rheumatoid factor, is therefore highly desirable.

Further harmonization in clinical interpretation of RF/ACPA assays could be obtained by harmonization of the cut-offs, for both the low and high antibody levels, based on predefined specificity in disease controls. Reporting test result specific likelihood ratios (LR) adds value in the interpretation of autoantibody tests. However, a good understanding of the control population used to define antibody test result interval-associated LRs is crucial in defining the diagnostic performance characteristics of antibody serology.

Finally, specificity in RA classification can be improved by refining serological weight scoring taking into account the nature of the antibody, the antibody level and double RF + ACPA positivity.

Oral health-related quality of life in patients with early rheumatoid arthritis is associated with periodontal inflammation and painful temporomandibular disorders: a cross-sectional study

OBJECTIVES

To evaluate oral health-related quality of life (OHRQoL) in early rheumatoid arthritis (ERA) patients and individuals at risk of rheumatoid arthritis (RA) compared to healthy controls, and to explore possible associated factors.

MATERIALS AND METHODS

Fifty ERA patients, 50 at-risk individuals, and 50 age and gender matched healthy controls were recruited. OHRQoL (Oral Health Impact Profile-14 (OHIP-14)); number of decayed, missing, and filled teeth (DMFT); denture use; periodontal inflamed surface area (PISA); xerostomia (xerostomia inventory (XI)); and possible TMD (-pain) diagnoses were recorded. The groups were compared on these variables. Subsequently, backward multiple regression analyses were performed for the ERA and at-risk groups, with OHRQoL as the dependent variable and gender, age, DMFT, denture use, PISA, XI, non-painful TMD, and TMD pain as independent variables.

RESULTS

At-risk individuals had higher XI scores (U = 789.5, z = -3.181, p = 0.001, r = -0.32) and higher prevalence of TMD pain (p = 0.046, OR = 4.57; 95% CI 0.92-22.73) than healthy controls and higher OHIP-14 scores than the ERA group (U = 894.5, z = -2.418, p = 0.016, r = -0.24), while no difference in OHIP-14 was found between the control group and both other groups. For ERA patients, OHRQoL was associated with PISA and TMD pain (R2 = 0.498, p < 0.001). For at-risk individuals, OHRQoL was associated with XI score (R2 = 0.410, p < 0.001).

CONCLUSIONS

Alertness of health professionals to TMD pain and periodontal inflammation in ERA patients and to xerostomia and TMD pain in at-risk individuals is recommended.

CLINICAL RELEVANCE

The results of this study address orofacial aspects that require attention of health professionals in the timeframe around RA onset.

TRIAL REGISTRATION

Dutch National Trial Register (NTR, NTR6362).

Temporomandibular disorders in patients with early rheumatoid arthritis and at-risk individuals in the Dutch population: a cross-sectional study

OBJECTIVE

To evaluate the prevalence of temporomandibular disorders (TMD) in patients with early rheumatoid arthritis (ERA) and individuals at-risk of RA.

METHODS

150 participants were recruited in three groups (50 per group): (1) patients with ERA (2010 EULAR criteria) (2) at-risk individuals and (3) healthy controls. All participants were tested for seropositivity of rheumatoid factor and anticitrullinated protein antibodies. A possible TMD diagnosis was determined according to the standardised and validated diagnostic criteria for TMD (DC/TMD) in five categories: myalgia, arthralgia, articular disc displacement, degenerative joint disease and headache attributed to TMD. Results were tested for the prevalence of TMD (all categories combined) and TMD pain (myalgia and/or arthralgia). To investigate a possible role for bruxism, a probable sleep and/or awake bruxism diagnosis was determined based on self-report and several clinical features.

RESULTS

The prevalence of any TMD diagnosis did not differ between the three groups. However, at-risk individuals more often had a TMD-pain diagnosis than healthy controls (p=0.046). No such difference was found between the ERA group and the control group. However, within the ERA group, seronegative patients had a TMD-pain diagnosis more often than seropositive patients (4/12 (33%) vs 3/38 (8%), p=0.048). Participants with a TMD-pain diagnosis were more often diagnosed with probable sleep bruxism than those without a TMD-pain diagnosis.

CONCLUSION

The prevalence of TMD pain is increased in individuals at-risk of RA and seronegative ERA patients, and is associated with bruxism signs and symptoms. These results suggest that health professionals should be alert to TMD pain in these groups.

Marine-Derived Biologically Active Compounds for the Potential Treatment of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic, systemic autoimmune disease with a prevalence rate of up to 1% and is significantly considered a common worldwide public health concern. Commercially, several traditional formulations are available to treat RA to some extent. However, these synthetic compounds exert toxicity and considerable side effects even at lower therapeutic concentrations. Considering the above-mentioned critiques, research is underway around the world in finding and exploiting potential alternatives. For instance, marine-derived biologically active compounds have gained much interest and are thus being extensively utilized to confront the confines of in practice counterparts, which have become ineffective for 21st-century medical settings. The utilization of naturally available bioactive compounds and their derivatives can minimize these synthetic compounds' problems to treat RA. Several marine-derived compounds exhibit anti-inflammatory and antioxidant properties and can be effectively used for therapeutic purposes against RA. The results of several studies ensured that the extraction of biologically active compounds from marine sources could provide a new and safe source for drug development against RA. Finally, current challenges, gaps, and future perspectives have been included in this review.

Patients' and rheumatologists' perceptions on preventive intervention in rheumatoid arthritis and axial spondyloarthritis

BACKGROUND

Individuals at risk of developing rheumatoid arthritis (RA) may benefit from lifestyle or pharmacological interventions aimed at primary prevention. The same may apply to individuals at risk of axial spondyloarthritis (axSpA). Our aim was to investigate and compare the willingness of individuals at risk of RA or axSpA and rheumatologists to initiate preventive intervention.

METHODS

Individuals at risk of RA (arthralgia and anti-citrullinated protein antibodies and/or rheumatoid factor positivity without arthritis (RA-risk cohort; n = 100)), axSpA (first-degree relatives of HLA-B27-positive axSpA patients (SpA-risk cohort; n = 38)), and Dutch rheumatologists (n = 49) completed a survey on preventive intervention which included questions about disease perception, lifestyle intervention, and preventive medication.

RESULTS

At-risk individuals reported willingness to change median 7 of 13 lifestyle components in the areas of smoking, diet, and exercise. In contrast, 35% of rheumatologists gave lifestyle advice to ≥ 50% of at-risk patients. The willingness to use 100% effective preventive medication without side effects was 53% (RA-risk), 55% (SpA-risk), and 74% (rheumatologists) at 30% disease risk which increased to 69% (RA-risk) and 92% (SpA-risk and rheumatologists) at 70% risk. With minor side effects, willingness was 26%, 29%, and 31% (at 30% risk) versus 40%, 66%, and 76% (at 70% risk), respectively.

CONCLUSIONS

Risk perception and willingness to start preventive intervention were largely similar between individuals at risk of RA and axSpA. Although the willingness to change lifestyle is high among at-risk individuals, most rheumatologists do not advise them to change their lifestyle. In contrast, rheumatologists are more willing than at-risk patients to start preventive medication.

Preclinical rheumatoid arthritis and rheumatoid arthritis prevention

PURPOSE OF REVIEW

This review is to provide an update on the current understanding of rheumatoid arthritis (RA) development related to disease development prior to the onset clinically apparent synovitis (i.e. Pre-RA), and opportunities for disease prevention.

RECENT FINDINGS

A growing number of studies have demonstrated that serum elevations of autoantibodies rheumatoid factor, antibodies to citrullinated protein/peptide antigens (ACPAs) and antibodies to other posttranslationally modified proteins (e.g. carbamylated proteins) are highly predictive of future development of inflammatory arthritis/RA during a period that can be termed Pre-RA. Other factors including genetic, environmental, symptoms and imaging findings can also enhance prediction. Moreover, several novel biomarkers and changes in autoantibodies (e.g. glycosylation of variable domains) have been identified in Pre-RA. There has also been growing evidence that initiation and propagation of RA-related autoimmunity during the Pre-RA phase may be related to mucosal processes. The discovery of Pre-RA has also underpinned the development of several clinical prevention trials in RA; specifically, the PRAIRI study demonstrated that a single dose of rituximab can delay the onset of clinically apparent IA in at-risk individuals. Additional studies are evaluating the ability of drugs including abatacept, hydroxychloroquine and methotrexate to prevent or delay future RA.

SUMMARY

The results from ongoing natural history and prevention trials in RA should further inform several critical issues in RA prevention including identification and enrolment of individuals at high-risk of imminent RA, the efficacy, safety and cost-effectiveness of prevention, and potentially the identification of new targets for prevention.

The Natural History of Rheumatoid Arthritis

PURPOSE

This article reviews the phases of rheumatoid arthritis (RA) development in terms of the evolution of disease, with a focus on events that occur before the first appearance of clinically apparent inflammatory arthritis. This presynovitis period is defined in individuals who eventually develop classified RA as the pre-RA phase. We include additional discussion of the relevance of this model of RA development to the concept of disease prevention.

METHODS

The information provided in this review was identified through searches of the medical literature through MEDLINE and a review of references from published manuscripts as well as information obtained by the authors through attendance at various conferences and working groups related to pre-RA.

FINDINGS

It is now well established that RA develops in a series of phases. The first of these phases is believed to be the presence of genetic and/or environmental risk factors for RA in the absence of detectable systemic autoimmunity in the blood. After this phase, autoimmunity may be detectable through a variety of means (eg, autoantibodies, autoreactive cells) in peripheral blood; in addition, there is emerging evidence that perhaps initiation and early propagation of RA-related autoimmunity may occur at mucosal sites. The presence of autoimmunity detectable in the blood through serologic or other testing is followed in most individuals by a propagation phase that is characterized by an expansion of autoimmunity, inflammation, and symptoms. This transition may be associated with similar or different genetic and environmental factors that initially triggered autoimmunity, as well as continued mucosal inflammation and local RA-related autoantibody production. Eventually, clinically detectable inflammatory arthritis develops that can be classified as RA.

IMPLICATIONS

Understanding the phases of RA development are critical to the development of preventive strategies for this disease.

Considerations for Optimal Trial Design for Rheumatoid Arthritis Prevention Studies

The field of rheumatology has made major contributions to medicine through the identification of cellular and molecular targets and with the development of therapies for the treatment of an impressive range of immune-mediated rheumatic diseases. In recent years new milestones have been achieved. These include the recognition of an "at risk" state, defined by distinct clusters of characteristics, including disease-specific autoantibodies in serum and symptom complexes that include inflammatory joint pain. Studies seeking to prevent high-risk individuals from progressing to a state of clinically apparent arthritis have been initiated. Here, exploiting the current evidence base, an experimental framework to inform trial design is described, taking into consideration study patient phenotypes and highlighting the impact of risk stratification and the options available for therapeutic intervention according to the different phases of the preclinical syndrome. Pragmatic primary end points and suggestions for a set of risk-focused trial outcome measures are proposed, including both clinical assessments and patient-reported outcome measures. Rheumatoid arthritis prevention studies provide an important experimental framework for generating deeper insights into risk stratification and for refining trial design in the future. To this end, a research agenda is suggested, together with some considerations for imaging and for biological sampling. This commentary concludes with some of the operational issues that arise from such studies and addresses some of the challenges associated with recruitment and retention of the at-risk trial participant.