Anti-cyclic citrullinated peptide antibody predicts functional disability in patients with rheumatoid arthritis in a large prospective observational cohort in Japan

Decoding the Clinical Significance of Immunoglobulin G4 in Rheumatoid Arthritis

Immunoglobulin (Ig) G4 accounts for 4-6% of the total IgG in a healthy human. Several evidence-based studies have suggested that the level of IgG4 is significantly elevated in autoimmune diseases, including rheumatoid arthritis (RA). The clinical significance of IgG4 in RA with regard to disease activity, severity, and treatment response remains elusive. We consecutively recruited 174 patients with RA from our rheumatology clinic. All subjects were assessed for their disease activity based on DAS28, radiographic joint damage based on the Modified Sharp Score (MSS), the functional capacity based on the Health Assessment Questionnaire -Disability Index (HAQ-DI), and treatment responsiveness using the European League Against Rheumatism (EULAR) response criteria. The serum IgG4 of the recruited subjects was measured via the ELISA test. The mean serum IgG4 level was 60.23 ± 30.08 mg/dL. We found that serum IgG4 had significant positive correlations with disease activity (r = 0.406; p < 0.001), ESR (r = 0.155; p = 0.041), CRP (r = 0.269; p < 0.001), joint damage (r = 0.195; p = 0.012) and functional disability (r = 0.909; p < 0.001). Subjects with elevated IgG4 (IgG4 > 86 mg/dL) had significantly higher ESR, CRP, HAQ-DI, and DAS 28 and a poorer treatment response compared to the group with non-elevated IgG4. After multivariate analysis, only HAQ-DI (OR = 4.229, 95% CI 1.302, 15.751, p = 0.018) and DAS28 (OR = 3.743, 95% CI 1.062, 13.193, p = 0.040) remained significantly associated with elevated serum IgG4. The preliminary findings of this study could suggest serum IgG4 to be a potential biomarker of disease activity and functional disability in RA.

Significance of Type II Collagen Posttranslational Modifications: From Autoantigenesis to Improved Diagnosis and Treatment of Rheumatoid Arthritis

Collagen type II (COL2), the main structural protein of hyaline cartilage, is considerably affected by autoimmune responses associated with the pathogenesis of rheumatoid arthritis (RA). Posttranslational modifications (PTMs) play a significant role in the formation of the COL2 molecule and supramolecular fibril organization, and thus, support COL2 function, which is crucial for normal cartilage structure and physiology. Conversely, the specific PTMs of the protein (carbamylation, glycosylation, citrullination, oxidative modifications and others) have been implicated in RA autoimmunity. The discovery of the anti-citrullinated protein response in RA, which includes anti-citrullinated COL2 reactivity, has led to the development of improved diagnostic assays and classification criteria for the disease. The induction of immunological tolerance using modified COL2 peptides has been highlighted as a potentially effective strategy for RA therapy. Therefore, the aim of this review is to summarize the recent knowledge on COL2 posttranslational modifications with relevance to RA pathophysiology, diagnosis and treatment. The significance of COL2 PTMs as a source of neo-antigens that activate immunity leading to or sustaining RA autoimmunity is discussed.

Presence of Autoantibodies in Males and Females With Rheumatoid Arthritis: A Systematic Review and Metaanalysis

OBJECTIVE

Rheumatoid arthritis (RA) is more common in females, and although the cause of RA is unknown, it is characterized by the production of autoantibodies. The aims of this study were to determine whether RA-associated autoantibodies are more often found in females than males and to identify factors that influence the relationship between sex and seropositivity.

METHODS

Databases were searched and studies of RA (N ≥ 100) were included if they reported proportion of seropositive patients with RA by sex. Metaanalyses and metaregression were conducted using the random-effects model. Covariates regressed were smoking, age, BMI, Health Assessment Questionnaire-Disability Index (HAQ-DI), and the Disease Activity Score in 28 joints (DAS28).

RESULTS

Eighty-four studies with a total of 141,381 subjects with rheumatoid factor (RF) seropositivity and 95,749 subjects with anticitrullinated protein antibody (ACPA) seropositivity met inclusion criteria. The mean age of participants ranged from 37 to 68 years and the proportion of female subjects ranged from 9% to 92%. Results indicated that females were less likely than males to be seropositive: odds ratio (OR) 0.84 [95% CI 0.77-0.91] for RF and OR 0.88 [95% CI 0.81-0.95] for ACPA. BMI, smoking, mean age, DAS28, and HAQ-DI did not affect the relationship between sex and seropositivity.

CONCLUSION

Although studies report that females have higher RA disease activity than males and that seropositivity predicts worse outcomes, females were less likely to be seropositive than males.

Oral Health-Related Quality of Life in Patients with Rheumatoid Arthritis

Introduction

The assessment of the quality of life (QOL) in rheumatoid arthritis (RA) patients is of great importance for health researchers, health planners, and clinical specialists. Thus, the present study aimed to evaluate the oral health-related quality of life in patients with RA.

Materials and Methods

In this case-control study, data were collected by two standard questionnaires filled by 80 patients with rheumatoid arthritis and 80 healthy individuals. They were analyzed using independent t-test, chi-square test, Mann-Whitney test, Pearson's correlation coefficient, and Kruskal-Wallis test in SPSS 21.

Results

The mean of Health Assessment Questionnaire (HAQ) score in RA patients and control groups was 1.17± 0.89 and 0.35±0.12, respectively, and the mean of General Oral Health Assessment Index (GOHAI) score in patients and control groups was 37.46±9.53 and 53.21±11.35, respectively; 62.5% of the patients got HAQ score more than or equal to 1 (≥1) and 91.2% got GOHAI score less than or equal to 50 (≤50).

Conclusion

The results of the present study suggested that most of the patients with RA had a poor oral health quality of life. Deterioration of disease and aging decrease the GOHAI and the oral health quality of life of patients.

Detection of IgM-rheumatoid factor and anti-citrullinated protein antibodies in healthy horses and their comparison

Rheumatoid factor (RF) is used in human and veterinary medicine in the form of IgM RF traditionally to support the diagnosis of rheumatoid arthritis (RA). In the latest diagnostic criteria, presence of anti - citrullinated protein antibodies (ACPA) was added to the grading system for the diagnosis of RA in humans. A change which is not integrated or routinely used in veterinary medicine. The criteria changed partly because of RF's diagnostic shortcomings, which include its increased titer detection in humans with non-rheumatoid diseases, inability to predict the disease and increased titers over the limit in the older population. Clinical signs similar to human RA were reported in horses in a condition known as idiopathic polysynovitis. Similarities in the clinical presentation to RA raised a question to the usability of RF and ACPA in horses. In our study, sixty clinically healthy horses, ranging from 3 days to 30 years of age, were evaluated for their serum levels of IgM RF. 55 of these horses were tested for ACPA, using methods of ELISA measuring Anti - CFG (Anti citrullinated fibrinogen antibody). The results of the study demonstrated the existence of an age-dependent increase in the level of IgM RF up to the age of about 9 years and ACPA's independence of the horse's age as well as both markers independence of the horse sex.

Breach of autoreactive B cell tolerance by post-translationally modified proteins

Objectives

Over 50% of patients with rheumatoid arthritis (RA) harbour a variety of anti-modified protein antibodies (AMPA) against different post-translationally modified (PTM) proteins, including anti-carbamylated protein (anti-CarP) antibodies. At present, it is unknown how AMPA are generated and how autoreactive B cell responses against PTM proteins are induced. Here we studied whether PTM foreign antigens can breach B cell tolerance towards PTM self-proteins.

Methods

Serum reactivity towards five carbamylated proteins was determined for 160 patients with RA and 40 healthy individuals. Antibody cross-reactivity was studied by inhibition experiments. Mass spectrometry was performed to identify carbamylated self-proteins in human rheumatic joint tissue. Mice were immunised with carbamylated or non-modified (auto)antigens and analysed for autoantibody responses.

Results

We show that anti-CarP antibodies in RA are highly cross-reactive towards multiple carbamylated proteins, including modified self-proteins and modified non-self-proteins. Studies in mice show that anti-CarP antibody responses recognising carbamylated self-proteins are induced by immunisation with carbamylated self-proteins and by immunisation with carbamylated proteins of non-self-origin. Similar to the data observed with sera from patients with RA, the murine anti-CarP antibody response was, both at the monoclonal level and the polyclonal level, highly cross-reactive towards multiple carbamylated proteins, including carbamylated self-proteins.

Conclusions

Self-reactive AMPA responses can be induced by exposure to foreign proteins containing PTM. These data show how autoreactive B cell responses against PTM self-proteins can be induced by exposure to PTM foreign proteins and provide new insights on the breach of autoreactive B cell tolerance.

Anti-citrullinated peptide antibodies and their value for predicting responses to biologic agents: a review

Anti-citrullinated peptide antibodies (ACPAs) play an important pathogenic role both at the onset and during the disease course. These antibodies precede the clinical appearance of rheumatoid arthritis (RA) and are associated with a less favorable prognosis, both clinically and radiologically. The objective of this work was to conduct a comprehensive review of studies published through September 2015 of ACPAs' role as a predictor of the therapeutic response to the biological agents in RA patients. The review also includes summary of the biology and detection of ACPAs as well as ACPAs in relation to joint disease and CV disease and the possible role of seroconversion. The reviews of studies examining TNF inhibitors and tocilizumab yielded negative results. In the case of rituximab, the data indicated a greater probability of clinical benefit in ACPA(+) patients versus ACPA(-) patients, as has been previously described for rheumatoid factor. Nonetheless, the effect is discreet and heterogeneous. Another drug that may have greater effectiveness in ACPA(+) patients is abatacept. Some studies have suggested that the drug is more efficient in ACPA(+) patients and that those patients show greater drug retention. In a subanalysis of the AMPLE trial, patients with very high ACPA titers who were treated with abatacept had a statistically significant response compared to patients with lower titers. In summary, the available studies suggest that the presence of or high titers of ACPA may predict a better response to rituximab and/or abatacept. Evidence regarding TNFi and tocilizumab is lacking. However, there is a lack of studies with appropriate designs to demonstrate that some drugs are superior to others for ACPA(+) patients.

Anti-CCP antibodies are not a marker of severity in established rheumatoid arthritis: a magnetic resonance imaging study

INTRODUCTION

The presence of anti-CCP is an important prognostic tool of rheumatoid arthritis (RA). But research is still ongoing on its relationship with disease activity and functional capacity.

OBJECTIVES

To study the relationship between anti-CCP and disease activity, functional capacity and structural damage indexes, by means of conventional radiography (CR) and magnetic resonance imaging (MRI), in cases of established RA.

METHODS

Cross-sectional study with RA patients with 1-10 disease duration. Participants underwent clinical evaluation with anti-CCP. Disease activity was assessed using the Clinical Disease Activity Index (CDAI), and functional capacity through the Health Assessment Questionnaire (HAQ). CR analysis was carried out by the Sharp van der Heijde index (SvdH), and MRI analysis by RAMRIS (Rheumatoid Arthritis Magnetic Resonance Image Scoring).

RESULTS

We evaluated 56 patients, with a median (IqR) age of 55 (47.5-60) years; 50 (89.3%) participants were female and 37 (66.1%) were positive for anti-CCP. Medians (IqR) of CDAI, HAQ, SvdH and RAMRIS were 14.75 (5.42-24.97) 1.06 (0.28-1.75), 2 (0-8) and 15 (7-35), respectively. There was no association between anti-CCP and CDAI, HAQ and SvdH and RAMRIS scores.

CONCLUSION

Our results have not established an association of anti-CCP with the severity of disease. To date, we cannot corroborate anti-CCP as a prognostic tool in patients with established RA.

Determinants of Disability in Rheumatoid Arthritis: A Community-Based Cohort Study

Longitudinal care of a community-based cohort of patients with rheumatoid arthritis (RA) was evaluated retrospectively. Candidate determinants of disability included visual analog scales (VAS) for patient global assessment and pain, comorbidities, and medications. The outcome was the 'patient-acceptable symptom state' for disability as defined by the Health Assessment Questionnaire (HAQ) disability index, using a cutoff of <1.04. Two-sample t tests and multivariable logistic regression were used to determine odds ratios (OR) for associations between predictor variables and disability. Out of a total of 99 patients, 28 (28%) patients had HAQ ≥1.04 at their last visit. The greatest odds of not attaining the patient-acceptable symptom state in a multivariable model was associated with corticosteroids (OR: 5.1; p=0.02), antidepressants (OR: 5.3; p=0.02), and female sex (OR: 6.5; p=0.05). In the era of biologic therapy, female sex, corticosteroids, and antidepressants remain profound determinants of disability highlighting the need to understand the underlying mechanisms.

Anticarbamylated protein antibodies are associated with long-term disability and increased disease activity in patients with early inflammatory arthritis: results from the Norfolk Arthritis Register

Objectives

Anticarbamylated protein (anti-CarP) antibodies are a novel family of autoantibodies recently identified in patients with inflammatory arthritis. The aim of this study was to investigate their association with long-term outcomes of disability and disease activity over 20 years’ follow-up in a cohort of patients with inflammatory polyarthritis (IP).

Methods

Norfolk Arthritis Register recruited adults with recent-onset swelling of ≥2 joints for ≥4 weeks from 1990 to 2009. At baseline, Health Assessment Questionnaire (HAQ) and 28 joint disease activity scores (DAS28) were obtained, and C reactive protein, rheumatoid factor (RF), anticitrullinated protein antibodies (ACPA) and anti-CarP antibodies were measured. Further HAQ scores and DAS28 were obtained at regular intervals over 20 years. Generalised estimating equations were used to test the association between anti-CarP antibody status and longitudinal HAQ and DAS28 scores; adjusting for age, gender, smoking status, year of inclusion and ACPA status. Analyses were repeated in subgroups stratified by ACPA status. The relative association of RF, ACPA and anti-CarP antibodies with HAQ and DAS28 scores was investigated using a random effects model.

Results

1995 patients were included; 1310 (66%) were female. Anti-CarP antibodies were significantly associated with more disability and higher disease activity, HAQ multivariate β-coefficient (95% CI) 0.12 (0.02 to 0.21), and these associations remained significant in the ACPA-negative subgroups. The associations of RF, ACPA and anti-CarP antibodies were found to be additive in the random effects model.

Conclusions

Anti-CarP antibodies are associated with increased disability and higher disease activity in patients with IP. Our results suggest that measurement of anti-CarP antibodies may be useful in identifying ACPA-negative patients with worse long-term outcomes. Further, anti-CarP antibody status provided additional information about RF and ACPA.

Anti-CCP antibodies are not a marker of severity in established rheumatoid arthritis: a magnetic resonance imaging study

INTRODUCTION

The presence of anti-CCP is an important prognostic tool of rheumatoid arthritis (RA). But research is still ongoing on its relationship with disease activity and functional capacity.

OBJECTIVES

To study the relationship between anti-CCP and disease activity, functional capacity and structural damage indexes, by means of conventional radiography (CR) and magnetic resonance imaging (MRI), in cases of established RA.

METHODS

Cross-sectional study with RA patients with 1-10 years of disease duration. Participants underwent clinical evaluation with anti-CCP. Disease activity was assessed using the Clinical Disease Activity Index (CDAI), and functional capacity through the Health Assessment Questionnaire (HAQ). CR analysis was carried out by the Sharp van der Heijde index (SvdH), and MRI analysis by RAMRIS (Rheumatoid Arthritis Magnetic Resonance Image Scoring).

RESULTS

We evaluated 56 patients, with a median (IqR) age of 55 (47.5-60.0) years; 50 (89.3%) participants were female and 37 (66.1%) were positive for anti-CCP. Medians (IqR) of CDAI, HAQ, SvdH and RAMRIS were 14.75 (5.42-24.97) 1.06 (0.28-1.75), 2 (0-8) and 15 (7-35), respectively. There was no association between anti-CCP and CDAI, HAQ and SvdH and RAMRIS scores.

CONCLUSION

Our results have not established an association of anti-CCP with the severity of disease. To date, we cannot corroborate anti-CCP as a prognostic tool in patients with established RA.

Predicting joint destruction in rheumatoid arthritis with power Doppler, anti-citrullinated peptide antibody, and joint swelling

OBJECTIVE

To determine combined evaluation of musculoskeletal ultrasonography (MSUS) and power Doppler (PD) signals, anti-citrullinated peptide antibody (ACPA), and other clinical findings improve the prediction of joint destruction in rheumatoid arthritis (RA).

METHODS

We performed a retrospective study of 331 RA patients (female n = 280 and male n = 51, mean age: 57.9 ± 13.2 years) who underwent MSUS from 2002 to 2012. Correlations with progression of joint destructions in 1,308 2nd and 3rd metacarpophalangeal (MCP) joints and various factors including PD signals of the same joints, clinical findings, age, disease duration at the study entry, gender, observation period, radiographic bone scores according to modified Sharp-van der Heijde methods, ACPA, and rheumatoid factor (RF) were analyzed in patient- and joint-based fashions, using univariate and multivariate logistic regression analyses and generalized linear mixed model.

RESULTS

Patients' characteristics were as follows: mean disease duration: 5.7 ± 7.5 years, observation period: 4.6 ± 2.6 years, RF positivity: 79.9%, and ACPA positivity: 77.5%. PD-positive 2nd and 3rd joints showed higher rate of joint destruction, especially in ACPA-positive patients. Moreover, PD-positive joints in ACPA-positive patients showed joint destruction even in joints without swelling. Multivariate analysis determined PD, swollen joint (SJ), observation period, basal radiographic bone scores, and ACPA as independent risks for joint destruction.

CONCLUSION

PD, SJ, basal radiographic bone scores, and ACPA are independent predictors for the joint destruction of 2nd and 3rd MCPs in RA; thus, considering these factors would be useful in daily practice.

Associations of rheumatoid factor and anti-citrullinated peptide antibody with disease progression and treatment outcomes in patients with rheumatoid arthritis

The objective of this study was to investigate the association of rheumatoid factor (RF) and anti-citrullinated peptide antibodies (ACPA) status with disease progression and treatment outcomes in patients with rheumatoid arthritis (RA). A total of 276 adult patients who fulfilled the American College of Rheumatology 1987 classification criteria for RA were recruited from the Rheumatology clinic, Siriraj Hospital, from January 2011 to December 2012. Demographic, clinical, and laboratory data were collected at baseline and every 3 months up to 1 year of follow-up. RF and ACPA were measured at baseline. Radiography of the hands and feet was performed at baseline and 1 year. Patients with RF+/ACPA+ had significantly more severe disease activity and impaired functional status than those who had RF-/ACPA-. Although they received more aggressive treatment with methotrexate and combination of non-biologic, disease-modifying antirheumatic drug than other groups, fewer patients in this group achieved remission at 1 year of follow-up, especially when compared to RF-/ACPA- group (12 vs. 18 %). For radiographic erosion, patients with the presence of either RF or ACPA had a higher proportion of hand erosion than seronegative patients at baseline (77, 73, 83, and 32 %, p < 0.001 for RF+/ACPA+, RF+/ACPA-, RF-/ACPA+, and RF-/ACPA-, respectively). After 1 year of follow-up, patients who developed new erosion at the hands were more prevalent in RF+/ACPA+ (32 %) and RF+/ACPA- (33 %) groups. However, "newly developed" feet erosion was most common in RF+/ACPA- group (40 %) than in other groups. Patients with positive either RF or ACPA or both have more severe and aggressive disease that requires intensive treatment to improve outcomes.

Health Assessment Questionnaire disability progression in early rheumatoid arthritis: systematic review and analysis of two inception cohorts

Objective

The Health Assessment Questionnaire is widely used for patients with inflammatory polyarthritis (IP) and its subset, rheumatoid arthritis (RA). In this study, we evaluated the progression of HAQ scores in RA (i) by systematically reviewing the published literature on the methods used to assess changes in functional disability over time and (ii) to study in detail HAQ progression in two large prospective observational studies from the UK.

Methods

Data from two large inception cohorts, ERAS and NOAR, were studied to determine trajectories of HAQ progression over time by applying latent class growth models (LCGMs) to each dataset separately. Age, sex, baseline DAS28, symptom duration, rheumatoid factor, fulfilment of the 1987 ACR criteria and socio-economic status (SES) were included as potential predictors of HAQ trajectory subgroup membership.

Results

The literature search identified 49 studies showing that HAQ progression has mainly been based on average changes in the total study population. In the HAQ progression study, a LCGM with four HAQ trajectory subgroups was selected as providing the best fit in both cohorts. In both the cohorts, older age, female sex, longer symptom duration, fulfilment of the 1987 ACR criteria, higher DAS28 and lower SES were associated with increased likelihood of membership of subgroups with worse HAQ progression.

Conclusion

Four distinct HAQ trajectory subgroups were derived from the ERAS and NOAR cohorts. The fact that the subgroups identified were nearly identical supports their validity. Identifying distinct groups of patients who are at risk of poor functional outcome may help to target therapy to those who are most likely to benefit.

Anti-cyclic citrullinated peptide antibody is a good indicator for the diagnosis of rheumatoid arthritis

Objectives: Anti-cyclic citrullinated peptide (CCP) antibody has recently been used in the classification of rheumatoid arthritis (RA). This antibody is more specific than rheumatoid factor (RF) for the diagnosis of RA. The study objectives were to determine the sensitivity, specificity, positive and negative predictive values of anti-CCP in RA diagnosis.

Methodology: Eighty RA patients and 80 non-RA individuals were included in the study. Blood was collected from both arms of study subjects and tested for anti-CCP and RF antibodies. Relevant clinical information and laboratory profiles of the RA patients were evaluated using patients’ medical records and Integrated Laboratory Management System (ILMS), respectively.

Results: The sensitivity and specificity of anti-CCP were 35% and 100% respectively. The positive and negative predictive values were 100% and 61%, respectively. Positive anti-CCP was found significantly associated with multiple joint pain (p< 0.001) and hand’s joints pain (p=0.01), symmetrical joints involvement (p=0.015) and high CRP value (p<0.001). Anti-CCP was also found to have positive association with RF (p<0.001).

Conclusion: Anti-CCP is highly specific for the diagnosis of RA. High positive predictive value should be taken into consideration for effective treatment.

Old drugs, old problems: where do we stand in prediction of rheumatoid arthritis responsiveness to methotrexate and other synthetic DMARDs?

Methotrexate (MTX) is the central drug in the management of rheumatoid arthritis (RA) and other immune mediated inflammatory diseases. It is widely used either in monotherapy or in association with other synthetic and biologic disease modifying anti-rheumatic drugs (DMARDs). Although comprehensive clinical experience exists for MTX and synthetic DMARDs, to date it has not been possible to preview correctly whether or not a patient will respond to treatment with these drugs. Predicting response to MTX and other DMARDs would allow the selection of patients based on their likelihood of response, thus enabling individualized therapy and avoiding unnecessary adverse effects and elevated costs. However, studies analyzing this issue have struggled to obtain consistent, replicable results and no factor has yet been recognized to individually distinguish responders from nonresponders at treatment start. Variables possibly influencing drug effectiveness may be disease-, patient- or treatment-related, clinical or biological (genetic and nongenetic). In this review we summarize current evidence on predictors of response to MTX and other synthetic DMARDs, discuss possible causes for the heterogeneity observed and address its translation into daily clinical practice.

Onset of polyarticular juvenile idiopathic arthritis with both anti-cyclic citrullinated peptide antibodies and rheumatoid factor in a 3-year-old girl

This report describes 3 year old girl with the unusual presentation of polyarticular juvenile idiopathic arthritis (JIA) with anti-cyclic citrullinated peptide (anti-CCP) antibodies and a positive rheumatoid factor (RF). She was initially treated with a nonsteroidal anti-inflammatory drug (NSAID; ibuprofen) followed by methotrexate (MTX, 10 mg/m2/week) and prednisolone (0.25 mg/kg/day), but these treatments were ineffective. Administration of tocilizumab, a humanized antihuman interleukin-6 receptor monoclonal antibody, promptly improved her clinical manifestations, and she has been in complete remission (DAS28 <2.6) without bone erosion and/or destruction. Positivity for both antibodies (anti-CCP and RF) can forecast the severity of JIA (radiographic bone destruction). In such cases the administration of biologic remissive therapy may be prudent early in the disease course.

Serum anti-cyclic citrullinated peptide antibodies may predict disease activity in rheumatoid arthritis

To define the relationship between serum anti-cyclic citrullinated peptide antibodies (anti-CCP) and disease activity, and to construct a new disease activity index by using anti-CCP in rheumatoid arthritis (RA). One hundred and five RA patients were included. Disease activity based on DAS28-ESR and serum anti-CCP was measured. There was correlation between serum anti-CCP and DAS28-ESR. (R (2) = 0.71, P value < 0.01). New disease activity index was developed by replacing anti-CCP with ESR in DAS28-ESR. There was correlation between new model and DAS28-ESR. (R (2) = 0.91, P value < 0.01) The new composite index best cut-off values corresponding to DAS28-ESR values of 2.6, 3.2, and 5.1 were 3.21, 3.38, and 4.74, respectively. There was agreement between new model and DAS28-ESR for determination of patients in different disease activity categories. (Kappa = 0.71, P value < 0.01). The new disease activity index that applies serum anti-CCP may predict disease activity in RA.