Rheumatoid factor and anticitrullinated protein antibodies in rheumatoid arthritis: diagnostic value, associations with radiological progression rate, and extra-articular manifestations

A comparative study on the diversity of clinical features between the sero-negative and sero-positive rheumatoid arthritis patients

To investigate the similarities and differences in clinical features between the sero-negative and sero-positive rheumatoid arthritis (RA) patients. Two hundred and sixty-two RA patients who fulfilled the 1987 ACR RA Classification Criteria were enrolled into this study. They were divided into sero-negative and sero-positive group depending on the presence or absence of rheumatoid factor (RF) and anti-cyclic citrullinate peptide (anti-CCP). The clinical features were compared between these two groups. Forty-six (17.6%) RA patients were classified as sero-negative group. The disease onset of sero-negative RA patients was later than that of sero-positive RA patients (52.4 ± 15.9 vs. 47.4 ± 15.5 years, P < 0.05). At the end of the first 2 years after disease onset, bone erosion shown in the hand X-ray occurred in 4 out of 24 (16.7%) patients with sero-negative RA. However, only 5.2% (5/97) patients with sero-positive RA developed bone erosion (P < 0.05). In the sero-positive RA patients, the titer of RF was correlated with swollen joint counts (SJC), tender joint counts (TJC), erythrocyte sedimentation rate (ESR), and disease activity score in 28 joints (DAS28) (P < 0.05), but anti-CCP was not. Sero-negative and sero-positive RA are probably two distinct disease subtypes driven by different mechanisms.

Antibodies against cyclic citrullinated peptides of IgG, IgA and IgM isotype and rheumatoid factor of IgM and IgA isotype are increased in unaffected members of multicase rheumatoid arthritis families from northern Sweden

BACKGROUND

Rheumatoid factors (RFs) and antibodies against cyclic citrullinated peptides (CCPs) of IgG, IgA and IgM isotype have been shown to precede disease onset by years.

OBJECTIVE

To evaluate serological risk markers in first-degree relatives from multicase families in relation to genetic and environmental risk factors.

METHODS

51 multicase families consisting of 163 individuals with rheumatoid arthritis (RA) (mean±SD age, 60±14 years; disease duration 21 years; 71.8% female) and with 157 first-degree relatives unaffected by RA (54±17 years; 59.9% female) were recruited. Isotypes of antibodies against CCPs (IgG, IgA and IgM) and RFs (IgM and IgA) were determined using automated enzyme immunoassays. Cut-off levels were established using receiver operating characteristic curves based on values for 100 unrelated healthy controls.

RESULTS

The concentrations and frequencies of all anti-CCP and RF isotypes were significantly increased in first-degree relatives and patients with RA compared with unrelated healthy controls. The relative distribution of IgA and IgM isotypes was higher than IgG in the relatives, whereas the IgG isotype dominated in patients with RA. The patients carried human leucocyte antigen-shared epitope (HLA-SE) significantly more often than the relatives (71.4% vs 53.9%, p=0.01), while the frequency of the PTPN22 T variant was similar. HLA-SE, combined with smoking, was significantly related to all combinations of anti-CCP and RF isotypes in patients with RA. No such relationships were found for the first-degree relatives.

CONCLUSIONS

All anti-CCP and RF isotypes analysed occurred more commonly in unaffected first-degree relatives from multicase families than in controls, but with different isotype distribution from patients with RA.

Genetic risk score predicting risk of rheumatoid arthritis phenotypes and age of symptom onset

Background

Cumulative genetic profiles can help identify individuals at high-risk for developing RA. We examined the impact of 39 validated genetic risk alleles on the risk of RA phenotypes characterized by serologic and erosive status.

Methods/Principal Findings

We evaluated single nucleotide polymorphisms at 31 validated RA risk loci and 8 Human Leukocyte Antigen alleles among 542 Caucasian RA cases and 551 Caucasian controls from Nurses' Health Study and Nurses' Health Study II. We created a weighted genetic risk score (GRS) and evaluated it as 7 ordinal groups using logistic regression (adjusting for age and smoking) to assess the relationship between GRS group and odds of developing seronegative (RF− and CCP−), seropositive (RF+ or CCP+), erosive, and seropositive, erosive RA phenotypes. In separate case only analyses, we assessed the relationships between GRS and age of symptom onset.

In 542 RA cases, 317 (58%) were seropositive, 163 (30%) had erosions and 105 (19%) were seropositive with erosions. Comparing the highest GRS risk group to the median group, we found an OR of 1.2 (95% CI = 0.8–2.1) for seronegative RA, 3.0 (95% CI = 1.9–4.7) for seropositive RA, 3.2 (95% CI = 1.8–5.6) for erosive RA, and 7.6 (95% CI = 3.6–16.3) for seropositive, erosive RA. No significant relationship was seen between GRS and age of onset.

Conclusions/Significance

Results suggest that seronegative and seropositive/erosive RA have different genetic architecture and support the importance of considering RA phenotypes in RA genetic studies.

A systematic review of serum biomarkers anti-cyclic citrullinated Peptide and rheumatoid factor as tests for rheumatoid arthritis

This systematic review assesses the current status of anti-cyclic citrullinated peptide (anti-CCP) and rheumatoid factor (RF) tests in the diagnosis and prognosis of rheumatoid arthritis (RA). We reviewed publications on tests and biomarkers for early diagnosis of RA from English-language MEDLINE-indexed journals and non-MEDLINE-indexed sources. 85 publications were identified and reviewed, including 68 studies from MEDLINE and 17 non-MEDLINE sources. Anti-CCP2 assays provide improved sensitivity over anti-CCP assays and RF, but anti-CCP2 and RF assays in combination demonstrate a positive predictive value (PPV) nearing 100%, greater than the PPV of either of the tests alone. The combination also appears to be able to distinguish between patients whose disease course is expected to be more severe and both tests are incorporated in the 2010 ACR Rheumatoid Arthritis Classification Criteria. While the clinical value of anti-CCP tests has been established, differences in cut-off values, sensitivities and specificities exist between first-, second- and third-generation tests and harmonization efforts are under way. Anti-CCP and RF are clinically valuable biomarkers for the diagnosis and prognosis of RA patients. The combination of the two biomarkers in conjunction with other clinical measures is an important tool for the diagnosis and management of RA patients.

Suppression of colitis in mice by Cl-amidine: a novel peptidylarginine deiminase inhibitor

Inflammatory bowel diseases (IBDs), mainly Crohn's disease and ulcerative colitis, are dynamic, chronic inflammatory conditions that are associated with an increased colon cancer risk. Inflammatory cell apoptosis is a key mechanism for regulating IBD. Peptidylarginine deiminases (PADs) catalyze the posttranslational conversion of peptidylarginine to peptidylcitrulline in a calcium-dependent, irreversible reaction and mediate the effects of proinflammatory cytokines. Because PAD levels are elevated in mouse and human colitis, we hypothesized that a novel small-molecule inhibitor of the PADs, i.e., chloramidine (Cl-amidine), could suppress colitis in a dextran sulfate sodium mouse model. Results are consistent with this hypothesis, as demonstrated by the finding that Cl-amidine treatment, both prophylactic and after the onset of disease, reduced the clinical signs and symptoms of colitis, without any indication of toxic side effects. Interestingly, Cl-amidine drives apoptosis of inflammatory cells in vitro and in vivo, providing a mechanism by which Cl-amidine suppresses colitis. In total, these data help validate the PADs as therapeutic targets for the treatment of IBD and further suggest Cl-amidine as a candidate therapy for this disease.

MicroRNAs in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic and severe autoimmune disease that affects joint tissues, bone, and cartilage. However, the pathogenesis of RA is still unclear. Autoantibodies such as rheumatoid factor and anti-cyclic citrullinated peptide are useful tools for early diagnosis, monitoring disease activity, and predicting prognosis. Recently, many groups have focused their attention on the role of microRNAs in the pathogenesis of RA, as well as a potential biomarker to monitor RA. In fact, the expression of some microRNAs, such as miR-146a, is upregulated in different cell types and tissues in RA patients. MicroRNAs in RA could also be considered as possible future targets for new therapeutic approaches.

Genetics of rheumatoid arthritis: what have we learned?

Rheumatoid arthritis (RA) is a chronic autoimmune disease affecting 0.5–1% of the population worldwide. The disease has a heterogeneous character, including clinical subsets of anti-citrullinated protein antibody (ACPA)-positive and APCA-negative disease. Although the pathogenesis of RA is poorly understood, progress has been made in identifying genetic factors that contribute to the disease. The most important genetic risk factor for RA is found in the human leukocyte antigen (HLA) locus. In particular, the HLA molecules carrying the amino acid sequence QKRAA, QRRAA, or RRRAA at positions 70–74 of the DRβ1 chain are associated with the disease. The HLA molecules carrying these “shared epitope” sequences only predispose for ACPA-positive disease. More than two decades after the discovery of HLA-DRB1 as a genetic risk factor, the second genetic risk factor for RA was identified in 2003. The introduction of new techniques, such as methods to perform genome-wide association has led to the identification of more than 20 additional genetic risk factors within the last 4 years, with most of these factors being located near genes implicated in immunological pathways. These findings underscore the role of the immune system in RA pathogenesis and may provide valuable insight into the specific pathways that cause RA.

Immune complexome analysis of serum and its application in screening for immune complex antigens in rheumatoid arthritis

BACKGROUND

Analysis of circulating immune complexes (CICs) produced during an immune response may be useful in elucidating some aspects of this process. Identification of antigens incorporated into CICs provides information that may be helpful in developing diagnostic and treatment strategies for autoimmune diseases, infection, cancer, and transplantation therapy, and such information might be more relevant than information on free antigens. Because CICs may contain many antigens, comprehensive identification and profiling of such antigens is more effective than immunoblotting detection.

METHODS

We developed a novel proteomic strategy (immune complexome analysis) in which immune complexes (ICs) are separated from serum, digested directly with trypsin, and then subjected to nano-liquid chromatography-tandem mass spectrometry for identifying and profiling antigens in CICs. We applied this strategy to the analysis of CICs in 21 rheumatoid arthritis (RA) patients. Serum samples from 13 healthy donors and 8 osteoarthritis patients were used as controls.

RESULTS

CICs containing thrombospondin-1 (TSP-1) and platelet factor 4 (PF4) were found in the serum of 81% and 52% of RA patients, respectively, and in none of the controls.

CONCLUSIONS

The ICs in the serum of a majority of the RA patients contained TSP-1 or PF4, and these ICs may have potential as alternative biomarkers. Our technique for immune complexome analysis uses routine clinical samples, simple protocols, and widely available equipment. This method may be generally applicable to the study of the relationship between CICs and certain diseases associated with the immune response in animals and humans.

Antibodies against β-fibrin synthetic peptides: a study of their association with the immunogenetic background and disease course of rheumatoid arthritis patients

Preliminary studies have shown the potential application for the diagnosis of Rheumatoid Arthritis (RA) patients with a severe disease course of an epitopic domain of β-fibrin. The aim of the present work was the analysis of the presence of antibodies against several β-fibrin synthetic peptides in relation to the immunogenetic background and disease course in a clinically well-defined RA patient cohort. Our results indicated that positive patients against anti-β-fibrin synthetic peptides have a higher percentage of HLA-DRB1 shared epitope (SE) than negative patients. We also observed that the presence of SE alleles was significantly associated with a higher level of anti-[Cit(376)]βfib(365-383) antibodies. When analyzing the effect of different SE alleles, we found a significant positive association between carriers of QRRAA allele and [Cit(376)]βfib(365-383) (Odds ratio 3.77; CI95%: 1.41-10.08). These results suggest that the anti-β-fibrin status is associated with the immunogenetic background of RA patients.

The relevance of citrullinated vimentin in the production of antibodies against citrullinated proteins and the pathogenesis of rheumatoid arthritis

Antibodies against citrullinated proteins (ACPAs) are highly specific for RA. Since the discovery of these antibodies, several of studies that focused on the presence and identity of citrullinated proteins in the joints of RA patients have been carried out. The best-known antigens that bind ACPAs are citrullinated filaggrin, Type II collagen (CII), α-enolase, fibrinogen and vimentin. This review compares citrullinated filaggrin, CII, α-enolase and fibrinogen with vimentin in their contribution to ACPA triggering, and gives an overview of the literature in which the role of citrullinated and non-citrullinated vimentin in the onset of ACPA production and the pathogenesis of RA is discussed.

Genetic basis of autoantibody positive and negative rheumatoid arthritis risk in a multi-ethnic cohort derived from electronic health records

Discovering and following up on genetic associations with complex phenotypes require large patient cohorts. This is particularly true for patient cohorts of diverse ancestry and clinically relevant subsets of disease. The ability to mine the electronic health records (EHRs) of patients followed as part of routine clinical care provides a potential opportunity to efficiently identify affected cases and unaffected controls for appropriate-sized genetic studies. Here, we demonstrate proof-of-concept that it is possible to use EHR data linked with biospecimens to establish a multi-ethnic case-control cohort for genetic research of a complex disease, rheumatoid arthritis (RA). In 1,515 EHR-derived RA cases and 1,480 controls matched for both genetic ancestry and disease-specific autoantibodies (anti-citrullinated protein antibodies [ACPA]), we demonstrate that the odds ratios and aggregate genetic risk score (GRS) of known RA risk alleles measured in individuals of European ancestry within our EHR cohort are nearly identical to those derived from a genome-wide association study (GWAS) of 5,539 autoantibody-positive RA cases and 20,169 controls. We extend this approach to other ethnic groups and identify a large overlap in the GRS among individuals of European, African, East Asian, and Hispanic ancestry. We also demonstrate that the distribution of a GRS based on 28 non-HLA risk alleles in ACPA+ cases partially overlaps with ACPA- subgroup of RA cases. Our study demonstrates that the genetic basis of rheumatoid arthritis risk is similar among cases of diverse ancestry divided into subsets based on ACPA status and emphasizes the utility of linking EHR clinical data with biospecimens for genetic studies.

HLA-DR1001 presents "altered-self" peptides derived from joint-associated proteins by accepting citrulline in three of its binding pockets

OBJECTIVE

HLA-DRB1*1001 (DR1001) is a shared epitope allele associated with rheumatoid arthritis (RA). The present study was undertaken to assess the capacity of DR1001 to accommodate citrulline in its binding pockets and to identify citrullinated T cell epitopes derived from joint-associated proteins.

METHODS

The binding of peptide derivatives containing citrulline, arginine, and other amino acid substitutions was measured. A prediction algorithm was developed to identify arginine-containing sequences from joint-associated proteins that preferentially bind to DR1001 upon citrullination. Unmodified and citrullinated versions of these sequences were synthesized and were utilized to stimulate CD4+ T cells from healthy subjects and RA patients. Responses were measured by class II major histocompatibility complex tetramer staining and confirmed by isolating CD4+ T cell clones.

RESULTS

DR1001 accepted citrulline, but not arginine, in 3 of its anchoring pockets. The prediction algorithm identified sequences that preferentially bound to DR1001 with arginine replaced by citrulline. Three of these sequences elicited CD4+ T cell responses. T cell clones specific for these sequences proliferated only in response to citrullinated peptides.

CONCLUSION

Conversion of arginine to citrulline generates "altered-self" peptides that can be bound and presented by DR1001. Responses to these peptides implicate the corresponding proteins (fibrinogen α, fibrinogen β, and cartilage intermediate-layer protein) as relevant antigens. The finding of preferential responses to citrullinated sequences suggests that altered peptide binding affinity due to this posttranslational modification may be an important factor in the initiation or progression of RA. As such, measuring responsiveness to these peptides may be useful for immunologic monitoring.

Prognostic Factors of Radiological Damage in Rheumatoid Arthritis: A 10-year Retrospective Study

Objective.

To describe the longterm clinical and radiological outcomes in rheumatoid arthritis (RA) in a cohort in northwestern Greece; and to investigate predictive factors of radiological damage at the 10-year followup in patients with RA.

Methods.

We studied the disease course and outcome of 144 patients with RA and radiographs of the hands and wrists available at baseline and at 10 years. Baseline measurements and time-averaged measures of swollen joint count (SJC) and inflammatory markers [erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP)] were tested in univariate analysis, and then those presenting a statistically significant association with either Larsen score at 10 years or annual progression rate were included in 2 logistic regression models in order to determine relevant independent prognostic factors.

Results.

A significant clinical improvement was noted, associated with a decrease of inflammatory markers along the timepoints. Larsen score and the number of erosive joints were increased. In the univariate analysis, both final Larsen score at 10 years and accelerated annual radiological progression rate were significantly associated with baseline radiographic measurements (Larsen score and number of erosive joints), the presence of autoantibodies [anticyclic citrullinated peptide antibodies (anti-CCP) and rheumatoid factor of IgA and IgM isotype], disease duration, and time-averaged measures of ESR, CRP, and SJC. In the logistic regression analysis, the baseline Larsen score, anti-CCP antibodies, and time-averaged CRP presented significant and independent associations with Larsen score at 10 years. An accelerated annual radiological progression rate was also predicted by baseline Larsen score and time-averaged measures of SJC and CRP.

Conclusion.

Despite clinical improvement, the radiologic progression of RA continues over time, because of the underlying inflammatory process. Baseline radiographic damage, anti-CCP antibodies, and time-averaged CRP constitute the main predictive factors of poor radiologic outcome in the long term.

Citrullinated vimentin as an important antigen in immune complexes from synovial fluid of rheumatoid arthritis patients with antibodies against citrullinated proteins

INTRODUCTION

Rheumatoid arthritis (RA) is an inflammatory disease, which results in destruction of the joint. The presence of immune complexes (IC) in serum and synovial fluid of RA patients might contribute to this articular damage through different mechanisms, such as complement activation. Therefore, identification of the antigens from these IC is important to gain more insight into the pathogenesis of RA. Since RA patients have antibodies against citrullinated proteins (ACPA) in their serum and synovial fluid (SF) and since elevated levels of citrullinated proteins are detected in the joints of RA patients, citrullinated antigens are possibly present in IC from RA patients.

METHODS

IC from serum of healthy persons, serum of RA patients and IC from synovial fluid of RA patients and Spondyloarthropathy (SpA) patients were isolated by immunoprecipitation. Identification of the antigens was performed by SDS-PAGE, mass spectrometry and immunodetection. The presence of citrullinated proteins was evaluated by anti-modified citrulline (AMC) staining.

RESULTS

Circulating IC in the serum of RA patients and healthy controls contain fibrinogenβ and fibronectin, both in a non-citrullinated form. Additionally, in IC isolated from RA SF, fibrinogenγ and vimentin were identified as well. More importantly, vimentin and a minor portion of fibrinogenβ were found to be citrullinated in the isolated complexes. Moreover these citrullinated antigens were only found in ACPA+ patients. No citrullinated antigens were found in IC from SF of SpA patients.

CONCLUSIONS

Citrullinated fibrinogenβ and citrullinated vimentin were found in IC from SF of ACPA+ RA patients, while no citrullinated antigens were found in IC from SF of ACPA- RA patients or SpA patients or in IC from serum of RA patients or healthy volunteers. The identification of citrullinated vimentin as a prominent citrullinated antigen in IC from SF of ACPA+ RA patients strengthens the hypothesis that citrullinated vimentin plays an important role in the pathogenesis of RA.

Correlation of anti-cyclic citrullinated antibody with hand joint erosion score in rheumatoid arthritis patients

BACKGROUND/AIMS

To examine the correlation between radiological joint damage and serological parameters in early rheumatoid arthritis (RA).

METHODS

This retrospective study reviewed the records of 216 patients diagnosed with RA and classified them according to disease duration: group 1, </= 24 months; group 2, > 24 months; and group 3, all patients combined. The extent of joint damage was assessed from plain radiographs using a modified version of the Larsen method and compared among groups.

RESULTS

The mean radiographic joint damage score was significantly higher in patients who had established RA (10.1 points) compared with those who had early RA. In group 1, the inflammatory parameters, erythrocyte sedimentation rate, and C-reactive protein were positively correlated with the joint damage score, but rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP) antibody were not. A subgroup analysis revealed that the anti-CCP positive patients in groups 1 and 2 had greater joint damage scores than did the anti-CCP negative patients, but no difference in RF was observed between subgroups. Anti-CCP positivity was not significantly correlated with joint damage sores in group 3.

CONCLUSIONS

Anti-CCP positivity was significantly correlated with more severe joint damage at diagnosis. A correlation was observed between the radiological joint damage score and inflammatory parameters in early and established RA, indicating that anti-CCP can serve as a diagnostic tool and predict structural joint damage. These findings suggest anti-CCP positive patients should receive aggressive therapeutic intervention.

Antibodies against cyclic citrullinated peptide don't decrease after 6 months of infliximab treatment in refractory rheumatoid arthritis

Anti-citrullinated peptide antibodies (ACPA) and the rheumatoid factor (RF) are well-established serological markers for rheumatoid arthritis (RA). ACPA are very useful in the diagnosis of RA, especially at the early stages of the disease when ACPA have a greater diagnostic value than RF. The aim of the study was to assess the influence of infliximab treatment on RF IgM and ACPA serum levels and RA activity during 6 months of treatment. Thirty-two patients with refractory RA were treated with infliximab during a 6-month period. At baseline, 3 and 6 months of treatment the patients were examined for the number swollen and tender joints out of 28 (SJC, TJC) and the visual analogue scale of arthritis activity according to the patient (VAS). Serum samples were tested for erythrocyte sedimentation rate (ESR), C-reactive protein level (CRP), ACPA and RF IgM. The disease activity score (DAS-28) parameter was also calculated at the same time. During the course of our study, we observed statistically significant improvement in ESR, CRP, TJC, SJC, VAS DAS-28, and RF IgM after 3 and 6 months of infliximab treatment when compared to the baseline, whereas the ACPA level remained unchanged after 3 and 6 months of treatment (P = 0.96 and P = 0.85). The changes in the ACPA level are not a factor for evaluation of successful infliximab treatment but the changes in RF IgM are. According to different behavior of these antibodies during infliximab treatment, we suggest that the roles of ACPA and RF in the pathogenesis of RA are different.

Association of IL4R single-nucleotide polymorphisms with rheumatoid nodules in African Americans with rheumatoid arthritis

INTRODUCTION

To determine whether IL4R single-nucleotide polymorphisms (SNPs) rs1805010 (I50V) and rs1801275 (Q551R), which have been associated with disease severity in rheumatoid arthritis (RA) patients of European ancestry, relate to the presence of rheumatoid nodules and radiographic erosions in African Americans.

METHODS

Two IL4R SNPs, rs1805010 and rs1801275, were genotyped in 749 patients from the Consortium for Longitudinal Evaluation of African-Americans with Early Rheumatoid Arthritis (CLEAR) registries. End points were rheumatoid nodules defined as present either by physical examination or by chest radiography and radiographic erosions (radiographs of hands/wrists and feet were scored using the modified Sharp/van der Heijde system). Statistical analyses were performed by using logistic regression modeling adjusted for confounding factors.

RESULTS

Of the 749 patients with RA, 156 (20.8%) had rheumatoid nodules, with a mean age of 47.0 years, 84.6% female gender, and median disease duration of 1.9 years. Of the 461 patients with available radiographic data, 185 (40.1%) had erosions (score>0); their mean age was 46.7 years; 83.3% were women; and median disease duration was 1.5 years. Patients positive for HLA-DRB1 shared epitope (SE) and autoantibodies (rheumatoid factor (RF) or anti-cyclic citrullinated peptide (CCP)) had a higher risk of developing rheumatoid nodules in the presence of the AA and AG alleles of rs1801275 (odds ratio (OR)adj=8.08 (95% confidence interval (CI): 1.60-40.89), P=0.01 and ORadj=2.97 (95% CI, 1.08 to 8.17), P=0.04, respectively). Likewise, patients positive for the HLA-DRB1 SE and RF alone had a higher risk of developing rheumatoid nodules in presence of the AA and AG alleles of rs1801275 (ORadj=8.45 (95% CI, 1.57 to 45.44), P=0.01, and ORadj=3.57 (95% CI, 1.18 to 10.76), P=0.02, respectively) and in the presence of AA allele of rs1805010 (ORadj=4.52 (95% CI, 1.20 to 17.03), P=0.03). No significant association was found between IL4R and radiographic erosions or disease susceptibility, although our statistical power was limited by relatively small numbers of cases and controls.

CONCLUSIONS

We found that IL4R SNPs, rs1801275 and rs1805010, are associated with rheumatoid nodules in autoantibody-positive African-American RA patients with at least one HLA-DRB1 allele encoding the SE. These findings highlight the need for analysis of genetic factors associated with clinical RA phenotypes in different racial/ethnic populations.

The role of rheumatoid arthritis genetic susceptibility markers in the prediction of erosive disease in patients with early inflammatory polyarthritis: results from the Norfolk Arthritis Register

OBJECTIVES

Recent whole-genome and candidate gene association studies in RA have identified a number of single nucleotide polymorphisms (SNPs) that predispose to disease with moderate risk. It remains poorly understood how recently identified genetic factors may contribute to RA severity. We therefore sought to investigate the role of recently identified RA susceptibility SNP markers in predicting erosive outcome in patients with recent-onset inflammatory polyarthritis (IP).

METHODS

DNA and X-ray data were available for 1049 patients who were registered between 1990 and 2003 with the Norfolk Arthritis Register (NOAR); a primary care-based inception cohort of patients with recent-onset IP. Demographic and clinical data were recorded at inclusion, and at yearly assessments thereafter. Patients were genotyped for 18 SNP markers. The presence of serum anti citrullinated peptide antibodies (ACPAs) was assessed in samples collected at inclusion to the NOAR. The association of serological and genetic markers with poor radiological (Larsen) score at Years 1 and 5, and erosions at Years 1 and 5 was investigated.

RESULTS

Baseline ACPA positivity was associated with erosive disease and higher radiological damage. SNP markers within the TRAF1/C5 locus were associated with erosive disease at Year 1 [rs2900180: odds ratio (OR) 1.53 (95% CI 1.14, 2.05)] and Year 5 [rs2900180: OR 1.47 (95% CI 1.07, 2.02)]. None of the SNP markers tested was associated with Larsen score.

CONCLUSION

Our results are in keeping with a previous report and suggest that the TRAF1/C5 region is associated with risk of development of radiological erosions in IP/RA patients. The finding requires replication in other large data sets.

Autoantibodies in rheumatoid arthritis: rheumatoid factors and anticitrullinated protein antibodies

Rheumatoid arthritis (RA) is a systemic inflammatory autoimmune disease, characterized by chronic, erosive polyarthritis and by the presence of various autoantibodies in serum and synovial fluid. Since rheumatoid factor (RF) was first described, a number of other autoantibodies have been discovered in RA patients. The autoantigens recognized by these autoantibodies include cartilage components, chaperones, enzymes, nuclear proteins and citrullinated proteins. However, the clinical significances and pathogenic roles of these antibodies are largely unknown except for RF and anticitrullinated protein antibodies (ACPAs), whose clinical usefulness has been acknowledged due to their acceptable sensitivities and specificities, and prognostic values. This review presents and discusses the current state of the art regarding RF and ACPA in RA.

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

Introduction

To investigate whether baseline levels of anti-citrullinated protein antibody (ACPA) or IgM rheumatoid factor (IgM-RF) and changes in the year thereafter are associated with disease activity, functional and radiographic outcome in early arthritis patients, and provide additional information over baseline autoantibody status.

Methods

In 545 early arthritis patients ACPA and IgM-RF levels, disease activity (DAS28), the Health Assessment Questionnaire (HAQ) and Sharp/Van der Heijde Score (SHS) were assessed annually. Baseline status, levels and first-year changes of the autoantibodies were associated with these measures at the two-year follow-up and sub-analysed according to autoantibody status.

Results

The mean age was 52.7 years, 69% was female, at baseline 56% was ACPA positive, 47% IgM-RF positive. At the two-year follow-up the mean DAS28 was 2.88, and the median HAQ and SHS were 0.38 and 1, respectively. At one year, ACPA and IgM-RF levels had decreased by 31% and 56%, respectively. A switch from negative to positive occurred in 2% for ACPA and 3% for IgM-RF. Positive ACPA and RF status were both associated with SHS at two years (P < 0.001), but baseline levels only showed a minor correlation of ACPA with DAS28 and HAQ at two years. Level changes were not associated with the outcome parameters.

Conclusions

Baseline levels and first-year changes of ACPA and IgM-RF are hardly associated with outcome after two years. Seroconversion seldom occurs. Therefore, it does not appear useful to repeat ACPA or IgM-RF measurements.

Rheumatoid arthritis: Disease or syndrome?

Rheumatoid arthritis (RA) has been described in the medical literature for over two hundred years, but its etiology remains unknown. RA displays phenotypic heterogeneity, and it is a relatively prevalent clinical entity: it affects approximately 1% of the population, resulting in enormous pathologic sequelae. Earlier studies targeting the cause(s) of RA suggested potential infectious involvement, whereas more recent reports have focused on a genetic origin of the disease. However, neither infection nor genetics, nor any other single factor is currently accepted as causative of RA. In this article we review studies relating to the etiology of RA, and those of several related matters, and we conclude that the literature indeed does provide insight into the causes underlying the initiation of RA pathogenesis. Briefly, given the remarkable phenotypic variation of RA, especially in its early stages, as well as a number of other characteristics of the condition, we contend that RA is not a discrete clinical entity with a single etiological source. Rather, we argue that it represents a common clinical endpoint for various starting points, each of which is largely guided by as yet poorly understood aspects of the genetic background of the affected individual. Adoption of this alternative view of the origin of RA will have significant consequences for future research and for development of new therapeutic interventions for this burdensome condition.

[Is rheumatoid arthritis without anti-citrullinated peptide antibody a genetically distinct subset?]

These days, rheumatoid arthritis (RA) is reported to be subclassified into two subsets by anti-citrullinated peptide antibody (ACPA) positivity. Clinically, ACPA positive RA tends to develop more severe arthritis than ACPA negative RA. In addition, a lot of reported susceptibility genes to RA (ie. HLA-DRB1(*)04, PTPN22, TRAF1/C5, CTLA4) are found to be associated only with ACPA positive RA but not with ACPA negative RA. It is getting clear that HLA-DRB1(*)04, which was believed to be primarily associated with RA, is not a primary risk factor but ACPA is. Then, a hypothesis for the disease mechanism of ACPA positive RA is set as follows; citrullination possibly due to smoking, etc, provokes ACPA production in individuals who have susceptibility alleles of genes including HLA, followed by joint inflammation in autoantibody-dependent manner. The search for susceptibility genes for ACPA negative RA is slowly progressing, but only a few genes are so far reported: HLA-DRB1(*)03 for Caucasian, HLA-DRB1(*)09 for Japanese, IRF5 and STAT4. When we investigate the disease mechanisms of RA, we should manage independently the two disease subsets : ACPA positive and ACPA negative RA.

Anti-citrullinated peptide antibody assays and their role in the diagnosis of rheumatoid arthritis

Increasingly, assays for the detection of anti-citrullinated peptide antibodies (ACPA) are used in RA diagnosis. This review summarizes the biologic basis and development of ACPA assays, available ACPA assays and their performance characteristics, and diagnostic properties of ACPA alone and compared to rheumatoid factor (RF) in early RA. We also review correlations, precision, costs and cost-effectiveness, availability, stability and reproducibility of the available assays. Taken together, data indicate that ACPA has a higher specificity than RF for early RA, good predictive validity, high sensitivity, apparent cost-effectiveness and good stability and reproducibility. Given its superior performance characteristics and increasing availability, ACPA is emerging as the most useful single assay for the diagnosis of RA.

Clinical approaches to early inflammatory arthritis

Several advances have been made in the understanding of the pathogenesis, as well as in the clinical evaluation and treatment, of early inflammatory arthritis. The presence of anti-citrullinated protein antibodies (ACPAs) has emerged as a major new biomarker for use in clinical practice. The presence of ACPAs can be used to divide patients with early arthritis into subsets that are phenotypically similar but have varying pathogenetic and prognostic features. Although the detection of ACPAs is a major development in the diagnosis and prognosis of rheumatoid arthritis (RA), prediction of the outcome of arthritis at the individual level can still be much improved. For patients diagnosed with RA, and who have active polyarthritis, treatment is not dependent on the assessment of prognostic factors, as these patients are best treated with combination therapy; over 40% of these patients achieve remission with such treatment. In patients who present with oligoarthritis, however, management should be based on the assessment of prognostic factors. The success of early treatment of inflammatory arthritis and the recognition of a measurable preclinical phase of RA offer hope that treating the disease before it becomes clinically active might be possible.

Prevalence of autoantibodies to cyclic citrullinated peptide in patients with rheumatic diseases other than rheumatoid arthritis: a French multicenter study

Our objective was to evaluate the prevalence of autoantibodies to cyclic citrullinated peptides (anti-CCP aAbs) in a cohort of patients with a variety of inflammatory or non-inflammatory rheumatic diseases other than rheumatoid arthritis (RA). Six hundred and nine serum samples were tested for anti-CCP aAbs and for rheumatoid factor (RF) using enzyme-linked immunosorbent assays and immunonephelometry. The prevalence of anti-CCP aAbs and RF reached 10% and 25%, respectively, using the positive cutoff value suggested by the manufacturers. Using a higher cutoff value (50 U/ml) for both aAbs, the prevalence was lower with 6% and 16%, respectively. The specificity of both markers for RA thus reached 94% and 84%, respectively. Anti-CCP aAbs were found to be elevated in inflammatory and also in non-inflammatory rheumatic diseases in the same proportion. Clinical data obtained for 36 positive patients showed that 17% developed RA within 5 years. In conclusion, anti-CCP aAbs are clearly more specific than RF for RA. Follow-up of anti-CCP aAbs-positive patients with inflammatory or non-inflammatory rheumatic diseases other than RA could be important considering the predictive value of these aAbs for the development of RA.

Diagnostic and prognostic value of antibodies against chimeric fibrin/filaggrin citrullinated synthetic peptides in rheumatoid arthritis

INTRODUCTION

Evidence suggests that citrullinated fibrin(ogen) may be a potential in vivo target of anticitrullinated protein/peptide antibodies (ACPA) in rheumatoid arthritis (RA). We compared the diagnostic yield of three enzyme-linked immunosorbent assay (ELISA) tests by using chimeric fibrin/filaggrin citrullinated synthetic peptides (CFFCP1, CFFCP2, CFFCP3) with a commercial CCP2-based test in RA and analyzed their prognostic values in early RA.

METHODS

Samples from 307 blood donors and patients with RA (322), psoriatic arthritis (133), systemic lupus erythematosus (119), and hepatitis C infection (84) were assayed by using CFFCP- and CCP2-based tests. Autoantibodies also were analyzed at baseline and during a 2-year follow-up in 98 early RA patients to determine their prognostic value.

RESULTS

With cutoffs giving 98% specificity for RA versus blood donors, the sensitivity was 72.1% for CFFCP1, 78.0% for CFFCP2, 71.4% for CFFCP3, and 73.9% for CCP2, with positive predictive values greater than 97% in all cases. CFFCP sensitivity in RA increased to 80.4% without losing specificity when positivity was considered as any positive anti-CFFCP status. Specificity of the three CFFCP tests versus other rheumatic populations was high (> 90%) and similar to those for the CCP2. In early RA, CFFCP1 best identified patients with a poor radiographic outcome. Radiographic progression was faster in the small subgroup of CCP2-negative and CFFCP1-positive patients than in those negative for both autoantibodies. CFFCP antibodies decreased after 1 year, but without any correlation with changes in disease activity.

CONCLUSIONS

CFFCP-based assays are highly sensitive and specific for RA. Early RA patients with anti-CFFCP1 antibodies, including CCP2-negative patients, show greater radiographic progression.

The effect of parental consanguinity on the clinical and laboratory findings of rheumatoid arthritis

AIMS

We aimed to evaluate the frequency of consanguinity among the parents of patients with rheumatoid arthritis (RA) and the influence of parental consanguinity on several clinical and laboratory parameters which reflect the severity of the disease.

METHODS AND PATIENTS

The study population consisted of 265 patients with RA which were divided into two groups with respect to the presence or absence of consanguinity between their parents. The frequency of parental consanguinity was compared with the general population. The two groups were compared with respect to family history of RA, the age of onset, the age at which RA was diagnosed, duration of the disease, the presence of rheumatoid nodules, vasculitis, serositis and the need for orthopaedic surgery, amyloidosis, the presence and level of rheumatoid factor and anti-cyclic citrullinated peptide antibodies, erosive changes on radiographs, and the need for anti-tumour necrosis factor therapy.

RESULTS

Twenty-one patients (8%) had parents who were consanguineous, which was not more frequent compared with the general population (14%). The mean age of disease onset and the mean age at which RA was diagnosed were lower in patients with parental consanguinity, although the difference was not statistically significant. The other clinical and laboratory parameters were also not different between the two groups.

CONCLUSION

The present data suggests that parental consanguinity has no effect on disease severity, and the frequency of consanguinity is not increased among the parents of patients with RA. A possible exception is the earlier disease onset and age at diagnosis which needs to be confirmed by larger studies.

The role of anti-mutated citrullinated vimentin antibodies in the diagnosis of early rheumatoid arthritis

OBJECTIVE

Anti-mutated citrullinated vimentin (MCV) antibodies have been reported as a fairly sensitive serological marker of rheumatoid arthritis (RA). We evaluated the diagnostic value of anti-MCV in a large cohort of Chinese patients with early RA.

METHODS

One hundred seventy patients with early RA (<1 yr duration), 66 with other rheumatic diseases, 10 with infectious diseases, and 60 healthy individuals were included in our study. Serum anti-MCV and second-generation anti-cyclic citrullinated peptide antibodies (anti-CCP2) were measured by ELISA, and rheumatoid factor (RF) was measured by rate nephelometry. The associated clinical data of patients with early RA were also evaluated. Then disease activity was scored by the formula for Disease Activity Score (DAS)28, and the degree of radiological changes was assessed by Sharp score.

RESULTS

The prevalence of serum anti-MCV in patients with early RA (78.2%, 133/170) was significantly higher than that of other rheumatologic patients and patients with infectious diseases. It was 12% (3/25) in systemic lupus erythematosus, 9.5% (2/21) in primary Sjögren's syndrome, 10% (1/10) in systemic sclerosis, 20% (2/10) in ankylosing spondylitis, 12.5% (1/8) in viral hepatitis type B, and 0% (0/2) in tuberculosis. Anti-MCV was not found in the serum of healthy subjects. The sensitivities of anti-MCV, anti-CCP2, and RF tests for early RA were 78.2%, 61.8%, and 72.4%, respectively, and the specificities were 93.4%, 96.3%, and 80.1%. The combination of anti-MCV and anti-CCP2 positivity showed a very high specificity (97.8%) and positive predictive value (97.1%), but a low sensitivity (58.8%). The sensitivity reached 81.2% when the union of anti-MCV and anti-CCP2 positivities was used as one combined criterion. Statistically, anti-MCV had significant correlation with anti-CCP2 (r=0.587, p=0.01, 2-tailed) and RF (r=0.389, p=0.01, 2-tailed). In addition, it had an interesting correlation with radiological assessment (r=0.349, p=0.05, 2-tailed). The anti-MCV had no significant correlation with other factors, such as erythrocyte sedimentation rate, C-reactive protein, antikeratin antibody, antiperinuclear factor, global visual analog scale score for joint pain, IgA, IgG, IgM, C3, C4, hidden rheumatoid factor for IgA (HRFIgA), HRFIgG, and DAS28.

CONCLUSION

Anti-MCV is a novel diagnostic marker for early RA. It may be more useful if the anti-CCP2 assay is performed concomitantly to diagnose patients with early RA.

[Diagnostic utility of anti-cyclic citrullinated peptide antibody in early rheumatoid arthritis]

Current therapeutic strategies against rheumatoid arthritis (RA) employ increasingly aggressive regimens from an early stage of the disease ; thus, serological markers more specific than IgM-rheumatoid factor (IgM-RF) are desirable. Anti-cyclic citrullinated peptide (anti-CCP) antibody has been reported as a useful and highly specificity marker for the diagnosis of RA. To clarify the diagnostic utility of anti-CCP antibody in early RA, we measured serum concentrations of anti-CCP antibody, IgM-RF, anti-agalactosyl IgG antibody and matrix metalloproteinase (MMP)-3 in 184 polyarthritis patients who showed onset symptoms within the previous 2 years. The diagnostic sensitivity of anti-CCP antibody in early RA was 60.0%, equivalent to IgM-RF (66.3%) and anti-agalactosyl IgG antibody (66.0%). Specificity, positive predictive values and diagnostic accuracy of anti-CCP antibody were the best among the four tested makers. In 38 patients who initially did not meet the ACR criteria for RA, but were diagnosed with RA during the course, the diagnostic sensitivity of anti-CCP antibody was 55.3%. On the other hand, the disease activity score (DAS) 28 of anti-CCP antibody positive and the negative patients was 5.16 and 5.34, respectively. Our data indicated that determination of anti-CCP antibody was useful for early diagnosis of RA.

Rheumatoid arthritis

Rheumatoid arthritis is a systemic, inflammatory, autoimmune disorder. Enhanced understanding of molecular pathogenesis has enabled development of innovative biological agents that target specific parts of the immune system. These treatments have changed the course and face of rheumatoid arthritis and outcomes for patients and society. New knowledge has emerged of how environmental factors interact with susceptibility genes and the immune system in the pathogenesis of a major subset of rheumatoid arthritis. Research undertaken on the longitudinal disease process and molecular pathology of joint inflammation has led to new therapeutic strategies that promote early use of disease-modifying drugs with tight disease control and distinct and quantifiable treatment goals. Today, such approaches can halt most cases of joint destruction but not all instances of joint inflammation and comorbidity. Understanding the cause and pathogenesis of different rheumatoid arthritis subsets will lead not only to individualised treatments during early phases of the illness but also, possibly, to disease prevention.

Deforming arthropathy in systemic lupus erythematosus

Systemic lupus erythematosus is an autoimmune and inflammatory disease characterized by a variety of symptoms, including arthropathy. The clinical presentation of joint involvement varies, ranging from arthralgia without erosions or deformity to an erosive arthropathy and severe functional disability. This paper reviews the main forms of deforming arthropathy observed in lupus patients. It includes a) non-erosive arthropathy (it is the most frequent form and characterized as Jaccoud's), b) erosive symmetrical polyarthritis with deformities similar to rheumatoid arthritis, named as rhupus, and c) mild deforming arthropathy. Even though enough such cases of patients have been reported in the international bibliography, no definite criteria for their diagnosis have been published yet. The use of contemporary radiological and immunological methods will facilitate their prevention and treatment.

[New autoanti-bodies in rheumatoid arthritis: anti-citrullinated protein or peptide autoanti-bodies and the others]

New treatment strategies require that rheumatoid arthritis (RA) be diagnosed as early as possible. New diagnostic markers were required, because rheumatoid factors (RF), until now criteria for classification of RA, are not sufficiently specific and sometimes appear late, thereby limiting their diagnostic usefulness. The objective of this review is to describe the current state of knowledge and more particularly to analyze the interest of new RA autoanti-bodies, called anti-peptide or anti-citrullinated protein anti-bodies (ACPA). Other autoanti-bodies have been described, including anti-Sa, anti-alpha enolase, and anti-calpastatin autoanti-bodies. Nonetheless, their diagnostic value remains limited compared to ACPA. Accordingly, in daily practice today, the only autoanti-bodies that must be tested for to diagnose RA are the ACPAs and RFs. The discovery of ACPA (initially called anti-keratin and anti-perinuclear anti-bodies) was a major step forward for the laboratory diagnosis of RA. The tests most often used routinely areenzyme-linked immunosorbent assays(ELISA) with cyclic citrullinated peptides, whence the name anti-CCP autoanti-bodies. Accordingly, the two terms ACPA and anti-CCP can both be used. The diagnostic value, in particular their specificity, is on the order of 95%, regardless of the method of identification. These markers are very useful and are often present earlier than RF. These ACPA also have prognostic value because they are associated with more aggressive forms of RA. On the other hand, their value over time, in particular, their fluctuation as a function of treatment, is more controversial. In practice, it is recommended to test for both RF and ACPA in a diagnostic work-up for early RA. During follow-up, the value of testing for these autoanti-bodies has not been demonstrated, but additional studies are still necessary with the anti-CCP autoanti-bodies and the new anti-citrullinated protein autoanti-bodies.

Diagnostic performance and predictive value of rheumatoid factor, anti-cyclic-citrullinated peptide antibodies and HLA-DRB1 locus genes in rheumatoid arthritis

BACKGROUND

We evaluated the significance of the genes, defined as DRB1*04 or DRB1*01, in rheumatoid arthritis (RA) patients. We focused on the role of genetic and serologic markers to predict disease activity and destructive process of joints.

METHODS

Sixty patients with RA were examined. Radiographic changes were evaluated by (Larsen score) and disease activity was measured by disease activity score 28 (DAS28). The markers analyzed were: erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), rheumatoid factor (RF), anti-cyclic citrullinated peptides (anti-CCP2) and HLA-DRB1 alleles typed by PCR.

RESULTS

In this study, anti-CCP antibodies, CRP, RF and AKA were detected in 83.3%, 56.7%, 71.7% and 52% of patients respectively. HLA-DRB1*01 was found in 45% of patients and 35% of them had one or two HLA-DRB1*04 alleles. According to DRB1*04 subtypes, (DRB1* 0405) was present in of 80% them. For prediction of grade of activity, the independent predictors were anti-CCP (OR 19.6), and DRB1*04 positive allele (OR 5.1). The combination of DRB1*04 + anti-CCP antibodies gave increase in the specificity and positive predictive value to 92% and 90 respectively. As regards to the prediction of radiological joint damage, the independent predictors were HLA-DRB1*04, HLA-DRB1*01, RF, and CRP > 18 (OR 5.5, 4.5, 2.5, 2.0 respectively).

CONCLUSION

Our findings suggest that anti-CCP2 is superior to RF for the detection of RA and provided predictive information on joint destruction and disease activity. The presence of RA associated antibodies (ACCP or RF) and/or the SE genes are indicative for a poorer radiological outcome and higher grade of activity.

Anti-CCP2 is an adjunct to, not a surrogate for, rheumatoid factor in the diagnosis of rheumatoid arthritis: diagnostic utility of anti-CCP2 antibodies in Egyptian patients with rheumatoid arthritis

OBJECTIVES

To examine the diagnostic utility of the second generation of anti-cyclic citrullinated peptide (anti-CCP2) antibodies versus rheumatoid factor (RF) in rheumatoid arthritis (RA), and to study the association between anti-CCP2 and RA disease parameters.

METHODS

Fifty consecutive Egyptian patients with RA, 37 patients with other rheumatic diseases, and 10 healthy controls were recruited for testing for anti-CCP2 and immunoglobulin M (IgM) rheumatoid factor (RF). Assessment measures included the Disease Activity Score (DAS28) for disease activity, the Health Assessment Questionnaire - Disability Index (HAQ-DI) for disability and the Short Erosion Narrowing Score (SENS) for radiological damage.

RESULTS

The sensitivities of anti-CCP2 and IgM-RF in RA patients were 70% and 52%, with specificities of 91.5% and 89.4%, respectively. There was 73.2% agreement between anti-CCP2 and RF for all groups tested (kappa = 0.42, p<0.001) but agreement was only 66% for RA patients (kappa = 0.31, p<0.05). Anti-CCP2 had superior diagnostic properties [sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV)] than RF, but using both RF and anti-CCP2 enhanced the sensitivity to 78%, when either test was positive, and the specificity to 100%, with a PPV of 1, when both tests were positive. Anti-CCP2 titre was significantly correlated with disease severity [rheumatoid nodules, rheumatoid factor (RF), and radiological damage] and HAQ-DI (p<0.05) but not with parameters of disease activity.

CONCLUSION

Anti-CCP2 has superior diagnostic and prognostic properties in RA compared with RF. It should not replace RF as a serological test; however, since using both tests modestly increases sensitivity and markedly enhances specificity, so that diagnosis of RA is highly probable when both tests are positive.

Identification of patients with arthritis and arthritis-related functional limitation using administrative data

OBJECTIVE

To develop algorithms on the basis of administrative data to identify patients with arthritis and arthritis-related functional limitation (AFL).

STUDY DESIGN AND SETTING

In this retrospective study, 361 enrollees of a health plan underwent a clinical examination to confirm arthritis and assessment of functional limitation on the basis of responses to the health assessment questionnaire. Administrative data were obtained on these subjects and included arthritis drugs dispensed, as well as outpatient and emergency department diagnoses and procedures (including radiographic studies, arthritis procedures, and laboratory tests). Composite risk scores for arthritis and AFL were created on the basis of the association of arthritis-related healthcare utilization with confirmed arthritis and AFL. Algorithms were then developed on the basis of the composite risk scores using logistic regression models.

RESULTS

The algorithm using the arthritis composite score to identify arthritis patients had an area under the ROC curve (AUC) of 0.74, sensitivity of 75 percent and specificity of 57 percent. Similarly, the algorithm using the AFL composite score to identify patients with AFL had an AUC of 0.73, sensitivity of 62 percent, and specificity of 75 percent.

CONCLUSION

The developed algorithms will enable health plans to screen their enrollees for persons with arthritis and AFL. This will facilitate enrollment of patients with arthritis and AFL in disease management programs and/or targeted interventions.

Value of anti-mutated citrullinated vimentin antibodies in diagnosing rheumatoid arthritis

We assessed the diagnostic value of anti-mutated citrullinated vimentin antibodies (anti-MCV) and compared it with those of anti-cyclic citrullinated peptide antibodies (anti-CCP), IgA (ARF), IgM (MRF) and IgG (GRF) rheumatoid factors for rheumatoid arthritis (RA). Serum samples of 170 RA patients, with early and established RA, and 309 controls were tested for anti-MCV, anti-CCP, ARF, MRF and GRF using commercially available ELISA kits. Cut off of different tests was determined with ROC curves. The sensitivity and the specificity of anti-MCV were 74.1 and 79%, respectively. Sixty-five of 309 (21%) controls were anti-MCV positive. Sensitivity and specificity of anti-CCP were 72.4 and 96.1%, respectively. Only 12 of 309 (3.9%) controls were anti-CCP positive. Sensitivity of ARF, MRF and GRF were 64.1, 65.9 and 68.2%, respectively. Their specificity was 79.6, 74.4 and 68.9%, respectively. No significant association was observed between the antibodies tested and extrarticular manifestations. Anti-MCV shows comparable sensitivity but lower specificity than that of anti-CCP. They do not appear to be very useful in the diagnosis of RA.

Anti-citrullinated protein/peptide antibodies (ACPA) in rheumatoid arthritis: specificity and relation with rheumatoid factor

Anti-citrullinated protein/peptide antibodies (ACPA) are highly specific and sensitive markers for rheumatoid arthritis (RA). For instance, for the anti-CCP2 assay, sensitivities ranging from 55% to 80% and specificities ranging from 90% to 98% have been reported. Despite their high specificity, recent reports have suggested that ACPA may be found in some patients with other rheumatic autoimmune diseases, including psoriatic arthritis, systemic lupus erythematosus and Sjögren's syndrome. Also, the differences between the classical rheumatoid factor (RF) and ACPA, as well as the complementarity between both tests have recently been demonstrated more clearly. Indeed, both antibody systems have a different association with specific RA features like extra-articular manifestations, a different association with the HLA shared epitope and, behave differently following anti-TNF therapy.

Performance of automated measurement of antibodies to cyclic citrullinated peptide in the routine clinical laboratory

OBJECTIVE

To evaluate the performing technical and clinical characteristics of an automated system for routine measurement of anticyclic citrullinated peptide antibodies (aCCP), a new marker for rheumatoid arthritis (RA).

MATERIAL AND METHODS

Reproducibility, repeatability and linearity of aCCP, as measured by an automated fluorescent enzyme immunoassay (FEIA/Phadia), were evaluated and compared with the performance of a manual ELISA technique (Axis Shield Diagnostics). Clinical verification of both methods included estimation of sensitivity in RA patients (n = 42) and specificity in well-characterized non-RA autoimmune disease controls (n = 49) and healthy subjects (n = 39).

RESULTS

Precision studies showed a coefficient of variation between 4.9 % and 10 % for the FEIA technique and between 6.35% and 19% for the ELISA technique. Both systems showed good linear response. Sensitivity of aCCP for RA was 74% for FEIA and 79% for ELISA. Specificity was 100% for both methods, as calculated for healthy subjects. For non-RA-diseased controls, specificities of 98% and 94% were obtained for FEIA and ELISA, respectively. Both methods were concordant in 97% of cases. Increasing the cut-off for the ELISA system from >5 U/mL to >11 U/mL resulted in lower sensitivity (71.4%) but higher specificity (98.0%), i.e. improved discriminating power between RA and non-RA and 100% agreement between both methods.

CONCLUSION

Automated FEIA measurement of aCCP in the routine clinical laboratory improves imprecision compared to the manual ELISA. Our preliminary results suggest that an increase in cut-off for the ELISA can improve specificity to RA from 94% to 98 %.