Levels of anti-citrullinated protein antibodies and IgM rheumatoid factor are not associated with outcome in early arthritis patients: a cohort study

Clinical Features of ACPA-Negative and ACPA-Positive Variants of Rheumatoid Arthritis

The aim of the study was to investigate the features of the clinical picture of the disease in patients with ACPA-negative and ACPA-positive variants of rheumatoid arthritis.

MATERIALS AND METHODS

: The study included patients with a reliable diagnosis of rheumatoid arthritis (RA) according to the criteria of ACR/EULAR 2010. Depending on the ACPA values, two groups of patients were recruited: ACPA-positive and ACPA-negative, comparable in gender, age, duration of the disease, and therapy. The nature of the onset and course of the disease and the activity of RA were evaluated (according to the DAS28, SDAI, CDAI indices).

RESULTS AND DISCUSSION

: The study involved 79 patients with ACPA-negative variant of RA and 79 ACPA-positive patients. The age of patients (Me [IR] (in years)) with the ACPA(-) variant was 52 [39; 62]; with the ACPA(+) variant, 54 [42; 62]; the duration of the disease (in months) was 59 [23; 122] and 48 [17; 84], respectively. In ACPA(+) patients, a higher disease activity was determined (by the indices DAS 28crp, DAS28esr, SDAI, CDAI), higher values of C-reactive protein and erythrocyte sedimentation rate, and a greater number of painful and swollen joints (p < 0.05). According to the localization of the involved joints, arthritis of the proximal interphalangeal, metacarpal, wrist and shoulder joints was more often determined in ACPA(+) patients. Systemic manifestations of RA at the time of examination and in the anamnesis were statistically significantly more common in ACPA(+) (32.9%) than in ACPA(-) (17.7%) patients. Of the systemic manifestations, rheumatoid nodules were more common in ACPA(+) patients, whereas a tendency to a higher frequency of neuropathy, sclerites, and episcleritis was revealed in ACPA(-) patients.

CONCLUSIONS

. In patients with ACPA(-) subtype, clinical signs of joint damage and the inflammatory component are less pronounced compared to ACPA(+). However, the mixed picture of manifestation, the less "bright" course of the disease, the absence of characteristic immunological biomarkers necessitate long-term and careful monitoring of this group of patients. At the same time, the subjective severity of the disease and dysfunction due to ankylosing joints do not differ from the ACPA(+) variant of RA.

Prognostic Factors for Radiographic Progression in Patients with Seronegative Rheumatoid Arthritis

(1) Background: It has long been suggested that seronegative rheumatoid arthritis (RA) represents a clinical entity quite distinct from that of seropositive. However, analytical studies of seronegative RA dedicated to clinical outcomes regarding radiographic progression and related risk factors are scarce. The aim of this study is to evaluate radiographic outcome and prognostic factors for radiographic progression in patients with seronegative rheumatoid arthritis. (2) Methods: Subjects included RA patients reported as seronegative for both rheumatoid factor and anti-citrullinated protein antibody, who were treated at Jeju National University Hospital in South Korea between 2003 and 2016, including follow-up of at least 2 years. All patients fulfilled 1987 ACA or 2010 ACR/EULAR RA criteria. Radiographic progression was measured by yearly change in the Sharp van der Heijde (SvdH) score during follow-up periods. Medical records, laboratory and radiographic data were retrospectively analyzed, and linear regression analysis was performed to evaluate prognostic factors for radiographic progression in patients with seronegative rheumatoid arthritis. (3) Results: In total, 116 patients with seronegative RA were observed and 43 (37.1%) patients demonstrated radiographic damage during follow-up period. Mean age at diagnosis was 48 years and 86 (74.1%) patients were female. Symptom duration at diagnosis was 1.3 years and mean follow-up duration was 5.2 years. Patients with radiographic damage at diagnosis were 14 (12.1%) and mean SvdH score was 6.8 at diagnosis. Radiographic damage and SvdH at diagnosis significantly correlated with radiographic progression in patients with seronegative RA after adjusting age, sex, symptom duration, number of active synovitis, and CRP at diagnosis (β-coefficient 6.5 ± 1.84; p = 0.001 and β-coefficient 0.12 ± 0.02; p < 0.001, respectively). (4) Conclusions: This study determined that radiographic damage and SvdH at diagnosis were predictive factors in progression of radiographic damage in patients with seronegative rheumatoid arthritis. A large comparative study dedicated to this issue in seronegative RA is required.

Inhibitory activity of FOXP3+ regulatory T cells reveals high specificity for displaying immune tolerance in remission state rheumatoid arthritis

Immune regulation status may indicate immunological remission in rheumatoid arthritis (RA). This cross-sectional study aimed to determine the Regulatory T cell (Treg) properties, together with 14 plasma cytokines levels between active RA and clinical remission patients. Peripheral blood (PB) Foxp3+ Treg was collected from RA patients for determination of Treg inhibitory activity using a co-culture system. Other PB T cell types and plasma cytokines were determined by flow-cytometry. The Treg results were analyzed according to the disease activity score-28 (DAS28). Then sensitivity and specificity were calculated for the indication of the remission status. The number and inhibitory activity of Treg are higher in the clinical remission as compared to the active RA (p value < 0.0001). Also, Treg: CD4+CD25+CD127+ cell ratio demonstrates the similar result (p value < 0.05). Treg inhibitory activity is inversely correlated with the DAS28. Specificity and positive likelihood ratio of inhibitory activity for indicating remission status are 92.31% (95% CI 63.97-99.81) and 11.14 (95% CI 1.67-74.14), respectively. Treg inhibitory activity is a promising prognostic marker and probably represents the immunological remission status in RA.

Repeat serological testing for anti-citrullinated peptide antibody after commencement of therapy is not helpful in patients with seronegative rheumatoid arthritis

AIM

To Investigate the prevalence of seroconversion to ACPA after commencement of triple disease-modifying anti-rheumatic drug (DMARD) treat-to-target therapy.

BACKGROUND

Anti-citrullinated peptide antibody (ACPA) and rheumatoid factor (RF) define 'seropositive' rheumatoid arthritis (RA). Both predict unfavourable disease course, development of extra-articular features and treatment outcomes. We investigated the prevalence of seroconversion to ACPA after commencement of triple disease-modifying anti-rheumatic drug (DMARD) treat-to-target therapy.

METHODS

DMARD-naïve patients with RA according to the 1987 American College of Rheumatology criteria and disease duration of <96 weeks were enrolled. RF and ACPA levels were recorded at baseline and sequentially during triple DMARD therapy.

RESULTS

A total of 368 patients were followed for a median of 272 weeks. Of 154 patients seronegative for ACPA at recruitment, 10 (6.5%) seroconverted at some point. Nine of these were positive for RF at baseline and baseline RF titre was predictive of seroconversion. Four (2.6%) patients remained seropositive. No patients seroconverted from negative to positive for both RF and ACPA. Median time to seroconversion for ACPA was 29 months.

CONCLUSION

Persistent seroconversion of ACPA from negative to positive after diagnosis in patients with RA is uncommon. ACPA and RF double negative patients are highly unlikely to ever develop ACPA positivity with a risk <1%. It is therefore unlikely to be helpful or cost effective to perform serial ACPA measurements in patients with seronegative RA after commencement of a treat-to-target strategy.

Anti-cyclic citrullinated peptide antibody predicts the development of rheumatoid arthritis in patients with undifferentiated arthritis

BACKGROUND

Clinical outcomes of undifferentiated arthritis (UA) are diverse, and only 40% of patients with UA develop rheumatoid arthritis (RA) after 3 years. Discovering predictive markers at disease onset for further intervention is critical. Therefore, our objective was to analyze the clinical outcomes of UA and ascertain the predictors for RA development.

METHODS

We performed a prospective, multi-center study from January 2013 to October 2016 among Chinese patients diagnosed with UA in 22 tertiary-care hospitals. Clinical and serological parameters were obtained at recruitment. Follow-up was undertaken in all patients every 12 weeks for 2 years. Predictive factors of disease progression were identified using multivariate Cox proportional hazards regression.

RESULTS

A total of 234 patients were recruited in this study, and 17 (7.3%) patients failed to follow up during the study. Among the 217 patients who completed the study, 83 (38.2%) patients went into remission. UA patients who developed RA had a higher rheumatoid factor (RF)-positivity (42.9% vs. 16.8%, χ = 8.228, P = 0.008), anti-cyclic citrullinated peptide (CCP) antibody-positivity (66.7% vs. 10.7%, χ = 43.897, P < 0.001), and double-positivity rate of RF and anti-CCP antibody (38.1% vs. 4.1%, χ = 32.131, P < 0.001) than those who did not. Anti-CCP antibody but not RF was an independent predictor for RA development (hazard ratio 18.017, 95% confidence interval: 5.803-55.938; P < 0.001).

CONCLUSION

As an independent predictor of RA, anti-CCP antibody should be tested at disease onset in all patients with UA.

Predictors of good response to conventional synthetic DMARDs in early seronegative rheumatoid arthritis: data from the ESPOIR cohort

Background and objective

Early seronegative rheumatoid arthritis (RA) is considered a specific entity, especially regarding diagnostic issues and prognosis. Little is known about its potentially different initial clinical presentation and outcome. We aimed to determine predictors of good response to conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs) in seronegative RA patients with early inflammatory arthritis.

Patients and methods

Patients from the ESPOIR cohort with early inflammatory arthritis fulfilling the 2010 ACR/EULAR classification criteria for RA despite negativity for both rheumatoid factor and anti-CCP antibodies. The primary endpoint was a good or moderate EULAR response assessed after 1 year of follow-up, given at least 3 months of treatment with a csDMARD. Secondary objectives were to compare the early therapeutic response to methotrexate (MTX) and leflunomide (LEF) versus other csDMARDs (hydroxychloroquine, sulfasalazine) and to identify factors associated with functional disability (Health Assessment Questionnaire-Disability Index [HAQ-DI] > 0.5 at 1 year) and structural progression (van der Heijde-modified total Sharp score > 1 and > 5 points at 1 year). Logistic regression analysis was used to determine independent predictors of outcomes.

Results

One hundred seventy-two patients were analyzed. Overall, 98/172 (57%) patients received MTX during the first year of follow-up. A good or moderate EULAR response at 1 year was associated with early use of csDMARDs (i.e., within 3 months after the first joint swelling) on univariate and multivariable analysis (odds ratio = 2.41 [95% confidence interval 1.07–5.42], p = 0.03). Response rates were not affected by other classical prognostic factors (i.e., baseline DAS28). Presence of erosions at baseline was associated with Sharp score progression > 1 point and > 5 points (both p = 0.03) at 1 year. HAQ-DI ≥ 1 at inclusion and active smoking were significantly associated with HAQ-DI > 0.5 at 1 year.

Conclusion

Our results suggest that delay in initiation of csDMARD more than baseline clinical, biological, or imaging features predominantly affects the outcome in early seronegative RA. These findings confirm that the usual therapeutic concepts in RA (early treatment, tight control, and treat-to-target) should be applied similarly to both seropositive and seronegative disease forms.

Trial registration

ClinicalTrials.gov: NCT03666091. Registered September 11, 2018.

Does immunological remission, defined as disappearance of autoantibodies, occur with current treatment strategies? A long-term follow-up study in rheumatoid arthritis patients who achieved sustained DMARD-free status

OBJECTIVES

Sustained disease-modifying antirheumatic drug (DMARD)-free status, the sustained absence of synovitis after cessation of DMARD therapy, is infrequent in autoantibody-positive rheumatoid arthritis (RA), but approximates cure (ie, disappearance of signs and symptoms). It was recently suggested that immunological remission, defined as disappearance of anti-citrullinated protein antibodies (ACPA) and rheumatoid factor (RF), underlies this outcome. Therefore, this long-term observational study determined if autoantibodies disappear in RA patients who achieved sustained DMARD-free remission.

METHODS

We studied 95 ACPA-positive and/or RF-positive RA patients who achieved DMARD-free remission after median 4.8 years and kept this status for the remaining follow-up (median 4.2 years). Additionally, 21 autoantibody-positive RA patients with a late flare, defined as recurrence of clinical synovitis after a DMARD-free status of ≥1 year, and 45 autoantibody-positive RA patients who were unable to stop DMARD therapy (during median 10 years) were studied. Anti-cyclic citrullinated peptide 2 (anti-CCP2) IgG, IgM and RF IgM levels were measured in 587 samples obtained at diagnosis, before and after achieving DMARD-free remission.

RESULTS

13% of anti-CCP2 IgG-positive RA patients had seroreverted when achieving remission. In RA patients with a flare and persistent disease this was 8% and 6%, respectively (p=0.63). For anti-CCP2 IgM and RF IgM, similar results were observed. Evaluating the estimated slope of serially measured levels revealed that RF levels decreased more in patients with than without remission (p<0.001); the course of anti-CCP2 levels was not different (p=0.66).

CONCLUSIONS

Sustained DMARD-free status in autoantibody-positive RA was not paralleled by an increased frequency of reversion to autoantibody negativity. This form of immunological remission may therefore not be a treatment target in patients with classified RA.

Outcome of patients with early arthritis without rheumatoid factor and ACPA and predictors of rheumatoid arthritis in the ESPOIR cohort

OBJECTIVE

To describe the disease course of patients with early arthritis without rheumatoid factor (RF) and anti-citrullinated protein auto-antibodies (ACPA) in an inception cohort. To determine baseline predictors of fulfilling 2010 ACR/EULAR criteria for rheumatoid arthritis (RA) for these patients within 3 years.

METHOD

Patients included in the multicenter ESPOIR cohort were compared at baseline and 3 years by whether they were negative for RF and ACPA ("seronegative") or positive for RF and/or ACPA ("seropositive"). Univariate analysis was used to determine the association between baseline variables in seronegative patients and RA classification. Stepwise multiple logistic regression was used to identify predictors of RA classification within 3 years, estimating odds ratios (ORs).

RESULTS

Among 354 seronegative patients, 224/340 with available data (65.9%) fulfilled RA classification at baseline and 189/233 (81.1%) at 3 years. As compared with seropositive patients, seronegative patients had lower DAS28 (p = 0.002) and lower modified total Sharp score (mTSS; p = 0.026) at baseline; DAS28 remission was similar (p = 0.634), but radiographic progression rate was lower in seronegative patients (p <  0.001) at 3 years. In seronegative patients, factors predicting RA classification within 3 years were additive (OR = 3.61), bilateral (OR = 2.59) and hand, wrist or forefeet involvement (OR = 3.87); presence of a trigger event (OR = 3.57); pain at rest (OR = 2.76); morning stiffness (OR = 2.62); number of tender joints (OR = 23.73); and mTSS (OR = 2.56).

CONCLUSION

"Seronegative" patients have less active disease at baseline and less radiographic progression during follow-up than "seropositive" patients. With inflammatory pain, symmetric involvement of numerous small joints and erosive disease, a classification of RA is likely.

Antibody modified gold nanoparticles for fast colorimetric screening of rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by chronic joint inflammation and one of the main causes of chronic disability worldwide with high prevalence in the ageing population. RA is characterized by autoantibody production, synovial inflammation and bone destruction, and the most accepted biomarker is rheumatoid factor (RF) autoantibodies. In this work, we developed a low-cost approach for the detection and quantification of the RF marker. This colorimetric immunosensor is based on gold nanoprobe crosslinking that results in extensive aggregation in the presence of the pentameric IgM RF. Aggregation of the nanoconjugates yields a color change from red to purple that can be easily observed by the naked eye. The interaction between nanoconjugates and the specific target was confirmed via dynamic light scattering (DLS), Raman spectroscopy and atomic force microscopy (AFM) imaging. This conceptual system shows a LOD of 4.15 UA mL^-1 IgM RF (clinical threshold is set for 20 IU mL^-1). The one-step biosensor strategy herein proposed is much faster than conventional detection techniques, without the need for secondary antibodies, additional complex washing or signal amplification protocols. To the best of our knowledge this is the first report on target induced aggregation of gold nanoprobes for quantitative colorimetric autoantibody detection.

Assessing prognosis and prediction of treatment response in early rheumatoid arthritis: systematic reviews

BACKGROUND

Rheumatoid arthritis (RA) is a chronic, debilitating disease associated with reduced quality of life and substantial costs. It is unclear which tests and assessment tools allow the best assessment of prognosis in people with early RA and whether or not variables predict the response of patients to different drug treatments.

OBJECTIVE

To systematically review evidence on the use of selected tests and assessment tools in patients with early RA (1) in the evaluation of a prognosis (review 1) and (2) as predictive markers of treatment response (review 2).

DATA SOURCES

Electronic databases (e.g. MEDLINE, EMBASE, The Cochrane Library, Web of Science Conference Proceedings; searched to September 2016), registers, key websites, hand-searching of reference lists of included studies and key systematic reviews and contact with experts.

STUDY SELECTION

Review 1 - primary studies on the development, external validation and impact of clinical prediction models for selected outcomes in adult early RA patients. Review 2 - primary studies on the interaction between selected baseline covariates and treatment (conventional and biological disease-modifying antirheumatic drugs) on salient outcomes in adult early RA patients.

RESULTS

Review 1 - 22 model development studies and one combined model development/external validation study reporting 39 clinical prediction models were included. Five external validation studies evaluating eight clinical prediction models for radiographic joint damage were also included. c-statistics from internal validation ranged from 0.63 to 0.87 for radiographic progression (different definitions, six studies) and 0.78 to 0.82 for the Health Assessment Questionnaire (HAQ). Predictive performance in external validations varied considerably. Three models [(1) Active controlled Study of Patients receiving Infliximab for the treatment of Rheumatoid arthritis of Early onset (ASPIRE) C-reactive protein (ASPIRE CRP), (2) ASPIRE erythrocyte sedimentation rate (ASPIRE ESR) and (3) Behandelings Strategie (BeSt)] were externally validated using the same outcome definition in more than one population. Results of the random-effects meta-analysis suggested substantial uncertainty in the expected predictive performance of models in a new sample of patients. Review 2 - 12 studies were identified. Covariates examined included anti-citrullinated protein/peptide anti-body (ACPA) status, smoking status, erosions, rheumatoid factor status, C-reactive protein level, erythrocyte sedimentation rate, swollen joint count (SJC), body mass index and vascularity of synovium on power Doppler ultrasound (PDUS). Outcomes examined included erosions/radiographic progression, disease activity, physical function and Disease Activity Score-28 remission. There was statistical evidence to suggest that ACPA status, SJC and PDUS status at baseline may be treatment effect modifiers, but not necessarily that they are prognostic of response for all treatments. Most of the results were subject to considerable uncertainty and were not statistically significant.

LIMITATIONS

The meta-analysis in review 1 was limited by the availability of only a small number of external validation studies. Studies rarely investigated the interaction between predictors and treatment.

SUGGESTED RESEARCH PRIORITIES

Collaborative research (including the use of individual participant data) is needed to further develop and externally validate the clinical prediction models. The clinical prediction models should be validated with respect to individual treatments. Future assessments of treatment by covariate interactions should follow good statistical practice.

CONCLUSIONS

Review 1 - uncertainty remains over the optimal prediction model(s) for use in clinical practice. Review 2 - in general, there was insufficient evidence that the effect of treatment depended on baseline characteristics.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42016042402.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Clinical predictors of inadequate response to conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) including methotrexate (MTX) in untreated rheumatoid arthritis patients: A single-center observational study

Objectives: To investigate predictors of inadequate response to first conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) including methotrexate (MTX) in untreated rheumatoid arthritis (RA) patients in daily clinical practice.Methods: Inadequate response to MTX or other csDMARDs was defined as being not low disease activity at 12 months in more than 3 of 4 composite measures, and discontinuation or start of biologic DMARDs. The association between baseline factors and csDMARDs-IR was assessed by univariate and multivariate logistic regression analyses.Results: Four hundred and eleven and 146 patients were started on MTX and other csDMARDs, respectively; 218 patients were responsive to MTX, with a response rate of 47.0%. Tender joint count (TJC, ≥6 in 28joints, odds ratio [OR] = 1.67, 95% confidence interval [CI] 1.06-2.64) and CRP (≥1.0 mg/dL, OR = 1.72, 95%CI: 1.10-2.70) at baseline were identified as predictors on multivariate logistic regression analysis. TJC (OR = 3.60, 95%CI: 1.29-10.00) was the factor identified as a predictor of the development of other csDMARDs-IR.Conclusion: In this observational study, patients with untreated RA at risk of inadequate response to MTX included those with a higher TJC and higher CRP, while a higher TJC was the only independent predictor of an inadequate response to csDMARDs other than MTX.

Only rheumatoid factor-positive subset of anti-citrullinated peptide/protein antibody-negative rheumatoid arthritis may seroconvert to anti-citrullinated peptide/protein antibody-positive

AIM

Anti-citrullinated peptide/protein antibody (ACPA) has been reported to occur in about 60% of patients with early rheumatoid arthritis (RA), and about 80% in patients with established RA. While ACPA seroconversion is possible, previous reports have shown that it rarely occurs. We retrospectively determined the proportion of patients who underwent ACPA seroconversion and described the clinical characteristics of these cases.

METHODS

ACPA-negative RA patients who had undergone ACPA assessment more than once with an interval of 3 months or longer were investigated for ACPA seroconversion. The clinical characteristics of seroconverted patients were assessed.

RESULTS

In 149 ACPA-negative RA patients, only eight patients (5.4%) converted to ACPA-positive during follow-up. We found that all eight of the seroconverted cases were positive for rheumatoid factor (RF) and showed bone erosions by X-ray. Of 56 ACPA-negative RF-positive RA patients, 14.3% of them seroconverted to ACPA-positive. None of the ACPA-negative RF-negative RA patients seroconverted to ACPA-positive.

CONCLUSION

The proportion of total RA patients who experienced seroconversion from ACPA-negative to ACPA-positive was 5.4%. When ACPA-negative RA patients were subdivided into RF-negative and RF-positive subsets, only the RF-positive subset seroconverted to ACPA-positive. These results imply that RF-negative and RF-positive patients are distinct subsets within ACPA-negative RA patients.

Regulation of autoantibody activity by the IL-23-TH17 axis determines the onset of autoimmune disease

The checkpoints and mechanisms that contribute to autoantibody-driven disease are as yet incompletely understood. Here we identified the axis of interleukin 23 (IL-23) and the TH17 subset of helper T cells as a decisive factor that controlled the intrinsic inflammatory activity of autoantibodies and triggered the clinical onset of autoimmune arthritis. By instructing B cells in an IL-22- and IL-21-dependent manner, TH17 cells regulated the expression of β-galactoside α2,6-sialyltransferase 1 in newly differentiating antibody-producing cells and determined the glycosylation profile and activity of immunoglobulin G (IgG) produced by the plasma cells that subsequently emerged. Asymptomatic humans with rheumatoid arthritis (RA)-specific autoantibodies showed identical changes in the activity and glycosylation of autoreactive IgG antibodies before shifting to the inflammatory phase of RA; thus, our results identify an IL-23-TH17 cell-dependent pathway that controls autoantibody activity and unmasks a preexisting breach in immunotolerance.

Correlation of Demographic and Clinical Characteristics with Rheumatoid Factor Seropositivity in Rheumatoid Arthritis Patients

BACKGROUND

The rheumatoid factor (RF) blood test is the most commonly adopted test for the diagnosis of rheumatoid arthritis (RA). RA patients who are seropositive for RF might face a greater likelihood of developing more aggressive symptoms.

METHODS

Our goal was to study the demographic and clinical characteristics, as well as their correlation with RF seropositivity, among a series of 80 RA patients aged ≥ 18 years who attend Hospital Universiti Sains Malaysia (HUSM).

RESULTS

Of the 80 RA patients included in this study, 66 (82.5%) were female and 14 (17.5%) were male. No significant associations between RF seropositivity and demographic and/or clinical characteristics or other laboratory investigations were observed, including gender, morning stiffness, individual joint involvement (from multiple sites of the body), and erythrocyte sedimentation rate (ESR) measurement. However, a significant association between RF seropositivity and patients aged ≥ 50 was found (P = 0.032).

CONCLUSION

RF seropositivity was found to be more common in much older RA patients.

Sequential high-content profiling of the IgG-autoantibody repertoire reveals novel antigens in rheumatoid arthritis

Background

The aim was to identify novel diagnostic autoantibody candidates for rheumatoid arthritis (RA) by comprehensive screening for autoreactivity.

Method

We incubated 5892 recombinant proteins coupled to fluorescent beads, with patients’ sera for the detection of IgG-autoantibodies in three independent patient cohorts: A (n = 72 patients with established RA); B/B- (n = 116 patients with early RA (B) and n = 51 CCP-negative patients with early RA from B (B-)); and C (n = 184 patients with early seronegative RA), in comparison to matched healthy controls. Intersects of significantly increased autoantibodies as determined by the Mann-Whitney test were sought.

Result

Screening of 5892 antigens in RA cohorts A and B, or the seronegative cohorts B- and C revealed intersects of 23 and 13 significantly increased autoantibodies, respectively. Reactivity to three antigens was increased in all cohorts tested: N-acetylglucosamine-1-phosphate transferase, gamma subunit (GNPTG), heterogeneous nuclear ribonucleoprotein A1-like 2 (HNRNPA1), and insulin-like growth factor binding protein 2 (IGFBP2).

Conclusions

Comprehensive sequential screening for autoantibodies reveals novel candidates for diagnostic markers in both seropositive and seronegative RA and suggests new fields of research into the pathogenesis of RA.

Patients with seronegative RA have more inflammatory activity compared with patients with seropositive RA in an inception cohort of DMARD-naïve patients classified according to the 2010 ACR/EULAR criteria

OBJECTIVES

To compare the presentation of seropositive and seronegative early rheumatoid arthritis (RA) in disease-modifying antirheumatic drug (DMARD)-naïve patients classified according to the 2010 American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) criteria.

METHODS

All patients had symptom duration from first swollen joint <2 years and were DMARD naïve with an indication for DMARD treatment. Patients were stratified as seropositive (positive rheumatoid factor (RF)+ and/or anticitrullinated peptide antibody (ACPA)+) or seronegative (RF- and ACPA-), and disease characteristics were compared between groups.

RESULTS

A total of 234 patients were included, and 36 (15.4%) were seronegative. Ultrasonography (US) scores for joints (median 55 vs 25, p<0.001) and tendons (median 3 vs 0, p<0.001), number of swollen joints (median 17 vs 8, p<0.001), disease activity score (DAS; mean 3.9 vs 3.4, p=0.03) and physician global assessment (mean 49.1 vs 38.9, p=0.006) were significantly higher in seronegative patients compared with seropositive. Total van der Heijde-modified Sharp score, Richie Articular Index and patient-reported outcome measures were similar between groups.

CONCLUSIONS

Seronegative patients had higher levels of inflammation, assessed both clinically and by US, than seropositive patients. These differences may reflect the high number of involved joints required for seronegative patients to fulfil the 2010 ACR/EULAR classification criteria for RA.

TRIAL REGISTRATION NUMBER

NCT01205854; Pre-results.

How does established rheumatoid arthritis develop, and are there possibilities for prevention?

Established rheumatoid arthritis (RA) is a chronic state with more or less joint damage and inflammation, which persists after a phase of early arthritis. Autoimmunity is the main determinant of persistence. Although the autoimmune response is already fully developed in the phase of early arthritis, targeted treatment within the first months produces better results than delayed treatment. Prevention of established RA currently depends on the success of remission-targeted treatment of early disease. Early recognition is aided by the new criteria for RA. Further improvement may be possible by even earlier recognition and treatment in the at-risk phase. This requires the improvement of prediction models and strategies, and more intervention studies. Such interventions should also be directed at modifiable risk factors such as smoking and obesity. The incidence of RA has declined for decades in parallel with the decrease of smoking rates; however, a recent increase has occurred that is associated with obesity.

Impact of baseline anti-cyclic citrullinated peptide-2 antibody concentration on efficacy outcomes following treatment with subcutaneous abatacept or adalimumab: 2-year results from the AMPLE trial

Objectives

To examine whether baseline anti-cyclic citrullinated peptide-2 (CCP2) antibody status and concentration correlated with clinical outcomes in patients treated with abatacept or adalimumab on background methotrexate (MTX) in the 2-year AMPLE (Abatacept versus adaliMumab comParison in bioLogic-naïvE rheumatoid arthritis subjects with background MTX) study.

Methods

In this exploratory analysis, anti-CCP2 antibody concentration was measured at baseline, and antibody-positive patients were divided into equal quartiles, Q1–Q4, representing increasing antibody concentrations. Clinical outcomes analysed by baseline anti-CCP2 status and quartile included change from baseline in disease activity and disability and remission rates.

Results

Baseline characteristics were generally comparable across quartiles and treatment groups. In both treatment groups, anti-CCP2 antibody-negative patients responded less well than antibody-positive patients. At year 2, improvements in disease activity and disability and remission rates were similar across Q1–Q3, but were numerically higher in Q4 in the abatacept group; in contrast, treatment effects were similar across all quartiles in the adalimumab group.

Conclusions

In AMPLE, baseline anti-CCP2 positivity was associated with a better response for abatacept and adalimumab. Patients with the highest baseline anti-CCP2 antibody concentrations had better clinical response with abatacept than patients with lower concentrations, an association that was not observed with adalimumab.

Trial registration number

NCT00929864.

Serum RANKL levels associate with anti- citrullinated protein antibodies in early untreated rheumatoid arthritis and are modulated following methotrexate

INTRODUCTION

Receptor activator of nuclear factor kappa B ligand (RANKL) is a key regulator of bone metabolism. Anti-citrullinated protein antibodies (ACPA) have been suggested to cause bone destruction by osteoclast activation. We investigated the relationship between RANKL and ACPA in patients with early untreated rheumatoid arthritis (RA).

METHODS

Patients with newly diagnosed untreated RA (n = 183) were analyzed at baseline and 3 months after initiating methotrexate (MTX) treatment. Serum RANKL (total RANKL), ACPA (anti-CCP2) and ACPA specificities (anti-citrullinated (cit)-vimentin, anti-cit-enolase and anti-cit-fibrinogen) were determined by enzyme-linked immunosorbent assay (ELISA). Synovial RANKL expression was evaluated by immunohistochemistry in a small group of patients (n = 15). The relationship between anti-cit-vim antibodies and bone destruction was further validated in 1116 RA patients included in the EIRA cohort. Pearson's chi-square test, Wilcoxon rank sum test, Wilcoxon signed rank test and linear regression models were used.

RESULTS

Serum RANKL concentration was significantly higher (p <0.05) in ACPA-positive (median: 689 pmol/L, IQR 342-1253) compared with ACPA-negative (median: 159 pmol/L, IQR 96-243) patients and this difference was also seen for synovial RANKL expression. Serum RANKL associated with ACPA (p <0.05) and bone erosions in rheumatoid factor (RF)-negative patients (n = 59). Among ACPA specificites, anti-cit-vimentin (amino acids 60-75) was associated with higher RANKL concentration and higher prevalence of bone erosion (p <0.05). Significant reductions in both serum RANKL and ACPA levels were observed after 3 months of MTX treatment (p <0.05).

CONCLUSIONS

RANKL was elevated in ACPA-positive and in anti-cit-vimentin-positive patients with early untreated RA and associated with bone erosions. These findings give further support for an early direct pathogenic link between ACPA and bone destruction in RA.

Rheumatoid factor and anti-citrullinated protein antibody positivity, but not level, are associated with increased mortality in patients with rheumatoid arthritis: results from two large independent cohorts

Introduction

This study aimed to investigate rheumatoid factor (RF) and anti-citrullinated protein antibody (ACPA) status and levels as predictors of mortality in two large cohorts of patients with early inflammatory arthritis (EIA).

Methods

Data from the Norfolk Arthritis Register (NOAR) and Leiden Early Arthritis Clinic (EAC) cohorts were used. At baseline, patients had demographic data and smoking status recorded; RF, ACPA and inflammatory markers were measured in the local laboratories. Patients were flagged with national death registers until death or censor date. Antibody status was stratified as negative, low or high positive by RF and ACPA levels individually. In addition, patients were grouped as seronegative, RF positive, ACPA positive or double antibody (RF and ACPA) positive. Cox regression models explored associations between antibody status and mortality adjusting for age, sex, smoking status, inflammatory markers and year of enrolment.

Results

A total of 4962 patients were included, 64% were female. Median age at onset was 56 (NOAR) and 54 (EAC) years. In NOAR and EAC respectively, 35% and 42% of patients were ACPA/RF positive. When antibody status was stratified as negative, low or high positive, there were no consistent findings between the two cohorts. Double antibody positivity was associated with excess mortality in both cohorts compared to seronegative patients: NOAR and EAC respective adjusted HR (95% confidence interval) 1.35 (1.09 to 1.68) and 1.58 (1.16 to 2.15).

Conclusions

Patients with EIA who are seropositive for both RF and ACPA have increased mortality compared to those who are single positive or seronegative. Antibody level in seropositive patients was not consistently associated with excess mortality.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-014-0483-3) contains supplementary material, which is available to authorized users.

Prognosis of seronegative patients in a large prospective cohort of patients with early inflammatory arthritis

OBJECTIVE

Rheumatoid factor (RF) and anticitrullinated protein antibodies (ACPA) are believed to be associated with more severe rheumatoid arthritis; however, studies in early inflammatory arthritis (EIA) have yielded conflicting results. Our study determined the prognosis of baseline ACPA-negative and RF-negative patients.

METHODS

Patients enrolled in the Canadian Early Arthritis Cohort had IgM RF and IgG anticyclic citrullinated peptide antibodies 2 (anti-CCP2) measured at baseline. Remission was defined as a Disease Activity Score of 28 joints (DAS28) < 2.6 using logistic regression accounting for confounders at 12-month and 24-month followup.

RESULTS

Of the 841 patients, 216 (26%) were negative for both RF and anti-CCP2. Compared to seropositive subjects, seronegative subjects were older (57 ± 15 vs 51 ± 14 yrs), more males proportionately (31% vs 23%), and had shorter length of symptoms (166 ± 87 vs 192 ± 98 days), and at baseline had higher mean swollen joint count (SJC; 8.8 ± 6.8 vs 6.5 ± 5.6), DAS28 (5.0 ± 1.6 vs 4.8 ± 1.5), and erosive disease (32% vs 24%, p < 0.05). Treatment was similar between the 2 groups. At 24-month followup, seronegative compared to seropositive subjects had greater mean change (Δ ± SD) in disease activity measures: ΔSJC counts (-6.9 ± 7.0 vs -5.1 ± 5.9), ΔDAS28 (-2.4 ± 2.0 vs -1.8 ± 1.8), and ΔC-reactive protein (-11.0 ± 17.9 vs -6.4 ± 17.5, p < 0.05). Accounting for confounders, antibody status was not significantly associated with remission. However, at 12-month followup, ACPA-positive subjects were independently more likely to have new erosive disease (OR 2.94, 95% CI 1.45-5.94).

CONCLUSION

Although seronegative subjects with EIA have higher baseline DAS28 compared to seropositive subjects, they have a good response to treatment and are less likely to develop erosive disease during followup.

Rheumatoid factor and anti-CCP do not predict progressive joint damage in patients with early rheumatoid arthritis treated with prednisolone: a randomised study

OBJECTIVE

To analyse if predictors of radiographic progression differ between patients treated with or without prednisolone in early rheumatoid arthritis (RA). Radiographs of hands and feet were assessed using the modified Sharp/van der Heijde score and radiographic progression was defined as an increase in the total Sharp score above 5.8 (the smallest detectable change).

DESIGN

Prospective, randomised study of patients with early RA.

SETTING

Secondary level of care; six participating centres from southern Sweden; both urban and rural populations.

PARTICIPANTS

In all, 225 patients, 64% women, with a diagnosis of RA according to the American College of Rheumatology criteria, were included if they were between 18 and 80 years of age and had a disease duration of less than 1 year.

INTERVENTION

The patients were randomised to 7.5 mg prednisolone daily for 2 years (P-group; n=108) or no prednisolone (NoP-group; n=117) when they started with their first disease-modifying anti-rheumatic drug and were prospectively followed for 2 years.

RESULTS

The frequency of patients with radiographic progression after 2 years was 26% in the P-group and 39% in the NoP-group (p=0.033). Relevant interactions between treatment and rheumatoid factor (RF) (p=0.061) and between treatment and anti-cyclic citrullinated peptide 2 (anti-CCP) (p=0.096) were found. RF and anti-CCP independently predicted radiographic progression only in the NoP-group, OR (95% CI) 9.4 (2.5 to 35.2), p=0.001 and OR (95% CI) 8.7 (2.5 to 31.3), p=0.001, respectively.

CONCLUSIONS

The presence of RF and anti-CCP predicted radiographic progression in patients not treated with prednisolone but failed to predict progression in patients treated with this drug. The data suggest that early treatment with prednisolone may modulate not only inflammation but also autoimmunity-associated pathogenetic mechanisms.

TRIAL REGISTRATION NUMBER

ISRCTN20612367.

Repeated Anticitrullinated Protein Antibody and Rheumatoid Factor Assessment Is Not Necessary in Early Arthritis: Results from the ESPOIR Cohort

Objective.

Presence and levels of anticyclic citrullinated peptide antibodies (anti-CCP) and rheumatoid factor (RF) contribute to the classification and prognosis of rheumatoid arthritis (RA). The objective was to determine the usefulness of repeating anti-CCP/RF measurements during the first 2 years of followup in patients with early arthritis.

Methods.

In patients with early undifferentiated arthritis, serial anti-CCP and RF were measured using automated second-generation assays every 6 months for 2 years. Frequencies of seroconversions (from negative to positive or the reverse) and changes in antibody levels during followup were determined.

Results.

In all, 775 patients, mean (SD) age 48.2 (12.5) years, mean symptom duration 3.4 (1.7) months, 76.6% female, were analyzed; 614 (79.2%) satisfied the American College of Rheumatology/European League Against Rheumatism 2010 classification criteria for RA at baseline. At baseline, respectively for anti-CCP and RF, 318 (41.0%) and 181 (23.4%) patients were positive, of whom 298 (93.7% of the positive) and 111 (61.3% of the positive) were highly positive (above 3 × upper limit of the norm). There were only 12 anti-CCP seroconversions toward the positive (i.e., 2.6% of the anti-CCP–negative), 21 seroconversions toward the negative (6.6% of the anti-CCP–positive), and 8 (1.0%) changes to a higher anti-CCP level category during the 2-year followup; respectively for RF, 27 (4.6%), 95 (52.5%), and 13 (1.7%).

Conclusion.

In this cohort of patients with early arthritis, including in the subset of patients who did not fulfill the RA criteria, antibody status showed little increase over a 2-year period. Repeated measurements of anti-CCP/RF very infrequently offer significant additional information.

Role of the clinical immunology laboratory in disease monitoring

Immunological investigations provide useful information to guide diagnosis of several disorders. Many such tests are also commonly repeated at intervals, in an effort to facilitate disease monitoring. In general however, immunology test results are often slow to alter. Furthermore, audit activity has indicated that repeated testing accounts for a substantial workload in many immunology services, which may waste resources and compromise the efficient completion of necessary tests. Consequently, the need and appropriate minimum interval between repeated testing requires critical evaluation. In this review, the clinical utility of repeated performance of several common immunology investigations has been evaluated, based upon published evidence. In some cases (e.g., paraprotein quantification, or measurement of anti-glomerular basement membrane antibodies), repeated testing provides vital clinical information and can be justified on a frequent and individualized basis. However, many other investigations provided by immunology services provide less valuable information when used to aid disease monitoring rather than diagnosis. It is hoped that the data summarized here will facilitate a more evidence-based approach to repeated testing. Such information may also assist with the local implementation of demand management strategies based upon setting of minimum retesting intervals for these investigations.

Anticitrullinated protein antibodies and rheumatoid factor fluctuate in early inflammatory arthritis and do not predict clinical outcomes

OBJECTIVE

In inflammatory arthritis, rheumatoid factor (RF) and anticitrullinated protein antibodies (ACPA) are believed to be associated with more severe clinical outcomes. Our objective was to determine whether ACPA and RF remain stable in early inflammatory arthritis and whether their trajectories over time or baseline levels predicted clinical outcomes.

METHODS

The study population consisted of patients enrolled in the Canadian Early Arthritis Cohort Study with baseline and at least 12-month followup values of RF and ACPA. Primary outcomes were Disease Activity Score (DAS) remission and the presence of erosions at 12 and 24 months. Other objectives included swollen joint count, Health Assessment Questionnaire score, and DAS.

RESULTS

At baseline, 225/342 (66%) patients were ACPA-positive and 334/520 (64%) were RF-positive. At 24 months, 15/181 (8%) ACPA-positive patients became negative. A larger number of patients changed from ACPA-negative to positive: 13/123 (11%). For RF, fluctuations were more common: 67/240 (28%) reverted from positive to negative and 21/136 (18%) converted from negative to positive. RF and ACPA fluctuations did not predict disease outcomes. Patients who remained ACPA-positive throughout followup were more likely to have erosive disease (OR 3.86, 95% CI 1.68, 8.92).

CONCLUSION

RF and ACPA have the potential to revert and convert during the early course of disease. Fluctuations in RF and ACPA were not associated with clinical outcomes.

Anti-cyclic citrullinated peptide antibody titer predicts time to rheumatoid arthritis onset in patients with undifferentiated arthritis: results from a 2-year prospective study

Introduction

The diagnostic, predictive and prognostic role of anti-cyclic citrullinated peptide (CCP) antibodies in rheumatoid arthritis (RA) patients is widely accepted. Moreover, detection of these antibodies in subjects presenting with undifferentiated arthritis (UA) is associated with a significant risk to develop the disease. On the other hand, clinical and prognostic significance of evaluating anti-CCP levels in subjects with inflammatory arthritis at disease onset has not been fully clarified. The goal of this prospective study is to analyze the value and prognostic significance of anti-CCP titer quantification in UA subjects.

Methods

Serial anti-CCP assays were measured in 192 consecutive patients presenting with UA lasting less than 12 weeks. Clinical and serological data and arthritis outcome were evaluated every 6 months until two years of follow-up.

Results

Anti-CCP positivity, at both low and high titer, and arthritis of hand joints significantly predicted RA at two years, risk increasing in subjects with high anti-CCP titers at baseline. Moreover, time to RA diagnosis was shorter in patients with high anti-CCP2 titers at enrollment with respect to those with low antibody concentration.

Conclusions

Presence of anti-CCP antibodies, at both low and high concentration, is significantly associated with RA development in subjects with recent onset UA. However, time interval from the onset of the first symptoms to the fulfilment of the classification criteria appears to be directly related to the initial anti-CCP level.

Elevated rheumatoid factor and long term risk of rheumatoid arthritis: a prospective cohort study

OBJECTIVE

To test whether elevated concentration of rheumatoid factor is associated with long term development of rheumatoid arthritis.

DESIGN

A prospective cohort study, the Copenhagen City Heart Study. Blood was drawn in 1981-83, and participants were followed until 10 August 2010.

SETTING

Copenhagen general population.

PARTICIPANTS

9712 white Danish individuals from the general population aged 20-100 years without rheumatoid arthritis at study entry.

MAIN OUTCOME MEASURES

Rheumatoid arthritis according to baseline plasma IgM rheumatoid factor level categories of 25-50, 50.1-100, and >100, versus <25 IU/mL.

RESULTS

Rheumatoid factor levels were similar from age 20 to 100 years. During 187,659 person years, 183 individuals developed rheumatoid arthritis. In healthy individuals, a doubling in levels of rheumatoid factor was associated with a 3.3-fold (95% confidence interval 2.7 to 4.0) increased risk of developing rheumatoid arthritis, with a similar trend for most other autoimmune rheumatic diseases. The cumulative incidence of rheumatoid arthritis increased with increasing rheumatoid factor category (P(trend)<0.0001). Multivariable adjusted hazard ratios for rheumatoid arthritis were 3.6 (95% confidence interval 1.7 to 7.3) for rheumatoid factor levels of 25-50 IU/mL, 6.0 (3.4 to 10) for 50.1-100 IU/mL, and 26 (15 to 46) for >100 IU/mL, compared with <25 IU/mL (P(trend)<0.0001). The highest absolute 10 year risk of rheumatoid arthritis of 32% was observed in 50-69 years old women who smoked with rheumatoid factor levels >100 IU/mL.

CONCLUSION

Individuals in the general population with elevated rheumatoid factor have up to 26-fold greater long term risk of rheumatoid arthritis, and up to 32% 10 year absolute risk of rheumatoid arthritis. These novel findings may lead to revision of guidelines for early referral to a rheumatologist and early arthritis clinics based on rheumatoid factor testing.

Long-term stability of anti-cyclic citrullinated peptide antibody status in patients with early inflammatory polyarthritis

Introduction

The utility of reassessing anti-cyclic citrullinated peptide (anti-CCP) antibody status later in disease in patients presenting with early undifferentiated inflammatory polyarthritis, particularly in those who test negative for both anti-CCP and rheumatoid factor (RF) at baseline, remains unclear. We aimed therefore to determine the stability of CCP antibody status over time and the prognostic utility of repeated testing in subjects with early inflammatory polyarthritis (IP).

Methods

Anti-CCP and RF were measured at baseline and 5 years in 640 IP patients from the Norfolk Arthritis Register, a primary care-based inception cohort. The relation between change in anti-CCP status/titer and the presence of radiologic erosions, the extent of the Larsen score, and Health Assessment Questionnaire (HAQ) score by 5 years was investigated.

Results

With a cut-off of 5 U/ml, 28% subjects tested positive for anti-CCP antibodies, 29% for RF, and 21% for both at baseline. Nine (2%) anti-CCP-negative patients seroconverted to positive, and nine (4.6%) anti-CCP-positive individuals became negative between baseline and 5 years. In contrast, RF status changed in 17% of subjects. However, change in RF status was strongly linked to baseline anti-CCP status and was not independently associated with outcome. Ever positivity for anti-CCP antibodies by 5 years did not improve prediction of radiographic damage compared with baseline status alone (accuracy, 75% versus 74%). A higher baseline anti-CCP titer (but not change in anti-CCP titer) predicted worse radiologic damage at 5 years (P < 0.0001), even at levels below the cut-off for anti-CCP positivity. Thus, a titer of 2 to 5 U/ml was strongly associated with erosions by 5 years (odds ratio, 3.6 (1.5 to 8.3); P = 0.003).

Conclusions

Repeated testing of anti-CCP antibodies or RF in patients with IP does not improve prognostic value and should not be recommended in routine clinical practice.

Anticitrullinated Protein Antibody, But Not Its Titer, Is a Predictor of Radiographic Progression and Disease Activity in Rheumatoid Arthritis

Objective.

To study the contribution of anticitrullinated protein antibody (ACPA), and especially of its titer, to radiographic progression and disease activity in rheumatoid arthritis (RA).

Methods.

Patients with RA (n = 396) who attended a Japanese clinic within 2 years after disease onset were divided into the following groups according to second-generation (ACPA-2) ACPA titer on their first visit: negative (0–4.4 U/ml; n = 115), low-positive (4.5–121 U/ml; n = 141), and high-positive (> 121 U/ml; n = 140). The ACPA-2-positive groups were further subdivided into lowest (4.5–32 U/ml), low (33–121 U/ml), high (122–277 U/ml), and highest (> 278 U/ml) quartiles. All patients were treated with disease-modifying antirheumatic drugs (DMARD) including methotrexate, but not biologics. Subsequent radiographic progression and disease activity for 2 years were prospectively evaluated using the van der Heijde-modified Sharp score (SHS) and 28-joint Disease Activity Score (DAS28).

Results.

After treatment with DMARD, the disease activity (including number of swollen joints, number of tender joints, duration of morning stiffness, DAS28-erythrocyte sedimentation rate, and DAS28-C-reactive protein) was significantly decreased in all patient groups. Disease activity and radiographic progression as revealed by the change in SHS remained relatively higher in the ACPA-2 low- and high-positive groups as compared with the ACPA-2-negative group. The relationship between the titer of ACPA-2 at baseline and subsequent radiographic progression was not exactly linear, and the extent of disease activity or radiographic progression was similar between ACPA-2 low- and high-positive groups and also between ACPA-2 lowest- and highest-positive quartile groups. The results were demonstrable in cumulative SHS probability plots, and also repeatable in seronegative patients, which indicated that the titer of ACPA-2 is not a predictor of disease activity or radiographic progression in RA, and ACPA-2-negative patients, especially those with < 3 U/ml, showed minimal radiographic progression.

Conclusion.

Presence of ACPA-2, but not its titer, at baseline is a predictor of radiographic progression or disease activity, where radiographic progression is minimal in ACPA-2-negative patients.

Should anti-citrullinated protein antibody and rheumatoid factor status be reassessed during the first year of followup in recent-onset arthritis? A longitudinal study

OBJECTIVE

Presence and levels of antibodies contribute to the classification of rheumatoid arthritis. We investigated the longitudinal course of anti-citrullinated protein antibodies (ACPA) and immunoglobin M (IgM) rheumatoid factor (RF) during the first year after arthritis onset in patients with very short disease duration.

METHODS

Patients (aged 18-75 years) with ≥ 1 swollen joint of ≤ 16 weeks' duration had assessments of ACPA (2nd generation anti-cyclic citrullinated peptide antibodies, anti-CCP2) and IgM RF at inclusion and after 3, 6, and 12 months. Frequencies of seroconversions (negative to positive and vice versa) and changes in antibody levels during followup were determined.

RESULTS

A total of 281 early arthritis patients (median duration of joint swelling 32 days, 14.2% ACPA positives, 12.8% IgM RF positives) with 978 longitudinally collected serum samples were included. Only 5 patients (1.8%) negative for both antibodies at baseline turned antibody-positive during followup, while 9 antibody-positive patients (3.2%) turned antibody-negative. ACPA was more stable than RF regarding both status and levels.

CONCLUSION

Antibody status (ACPA/RF) is a stable phenotype in very early arthritis, as seroconversion was only found in 5% of patients. Repeated measurement of ACPA or RF during the first year after onset of arthritis does not offer major additional information.

Diagnostic Accuracy of ACR/EULAR 2010 Criteria for Rheumatoid Arthritis in a 2-Year Cohort

Objective.

To evaluate the diagnostic accuracy of the 2010 American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) and 1987 ACR criteria for rheumatoid arthritis (RA), and the respective role of the algorithm and scoring of the ACR/EULAR.

Methods.

In total, 270 patients with recent-onset arthritis of < 1 year duration were included prospectively between 1995 and 1997 and followed for 2 years. RA was defined as the combination, at completion of followup, of RA diagnosed by an office-based rheumatologist and treatment with a disease-modifying antirheumatic drug or glucocorticoid. We compared the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the criteria sets in the overall population, in the subgroup meeting the tree condition for ACR/EULAR scoring, and in the overall population classified according the full tree.

Results.

At baseline, 111 of the 270 patients had better alternative diagnoses and 16 had erosions typical for RA; of the 143 remaining patients, 52 had more than 6 ACR/EULAR 2010 points (indicating definite RA) and 91 had fewer than 6 points. After 2 years, 11/16 patients with erosions and 40/52 with more than 6 points had RA. 100 of the 270 patients met the reference standard for RA. Sensitivity, specificity, PPV, and NPV of the ACR/EULAR (full tree) were 51/100 (51%), 153/170 (90%), 51/68 (75.4%), and 153/202 (75.7%), respectively. Diagnostic accuracies of the ACR/EULAR score and ACR 1987 criteria were not statistically different.

Conclusion.

Much of the improvement of the ACR/EULAR criteria was ascribable to the use of exclusion criteria in the algorithm.

The likelihood of persistent arthritis increases with the level of anti-citrullinated peptide antibody and immunoglobulin M rheumatoid factor: a longitudinal study of 376 patients with very early undifferentiated arthritis

Introduction

We wanted to assess the importance of the levels of anti-citrullinated peptide antibody (anti-CCP) and immunoglobulin M (IgM) rheumatoid factor (RF) in predicting development of persistent arthritis from undifferentiated arthritis (UA), and to investigate whether there is an added predictive value for persistent arthritis in testing for both anti-CCP and IgM RF.

Methods

Patients with UA (exclusion of definite non-rheumatoid arthritis (RA) diagnoses) included in the Norwegian very early arthritis clinic were assessed for development of persistent arthritic disease. The effect of antibody level on the likelihood of persistent arthritis was investigated, and the sensitivity and specificity for persistent arthritis for anti-CCP and IgM RF, separately and combined, was determined.

Results

A total of 376 UA patients were included (median arthritis duration 32 days). 59 (15.7%) patients were IgM RF positive, and 62 (16.5%) anti-CCP positive. One hundred, seventy-four (46.3%) had persistent disease after one year. Overlap of anti-CCP and IgM RF positivity was 58%. Sensitivity/specificity for persistent arthritis was 28/95% for IgM RF alone, 30/95% for anti-CCP alone, and 37/92% for positivity of both anti-CCP and IgM RF. The likelihood for persistent disease increased with increasing levels of both anti-CCP and IgM RF.

Conclusions

The likelihood of developing persistent arthritis in UA patients increases with the level of anti-CCP and IgM RF. Testing both anti-CCP and IgM RF has added predictive value in UA patients. This study suggests that antibody level should be taken into account when making risk assessments in patients with UA.