OBJECTIVES: To evaluate levels of anti-carbamylated protein (anti-CarP) antibodies in rheumatoid arthritis (RA) patients and to determine their association with serological parameters and disease activity. Methods: A cross-sectional study involving 105 multiethnic RA patients (48 rheumatoid factor [RF]-positive and 57 RF-negative patients) was conducted at Hospital Universiti Sains Malaysia, Kelantan, Malaysia, from January 2015 to February 2016. Fifty healthy controls (HCs) were included. C-reactive protein (CRP), RF, anti-cyclic citrullinated peptide (anti-CCP) and anti-CarP antibodies were measured. A health assessment questionnaire (HAQ) was administered to the study participants and 28-joint Disease Activity Score (DAS28) were obtained. Results: The level of anti-CarP antibodies was significantly increased in the RA patients compared with HCs (p=0.042). The presence of anti-CarP antibodies was significantly associated with RF (p=0.019) and the HAQ (p=0.010). A significant association between the presence of anti-CarP antibodies and the DAS28 was not found (p=0.632). Conclusion: Our study provides further evidence that the level of anti-CarP antibodies is significantly elevated in RA patients.
Study site: Rheumatology clinic, Hospital Universiti Sains Malaysia
OBJECTIVES: The prognostic significance of rheumatoid factor (RF) and anticyclic citrullinated peptide antibody (anti-CCP) in rheumatoid arthritis (RA) remains contentious due to the conflicting lines of evidence. This study aims to determine the association between RF isotypes and anti-CCP with disease severity in RA patients from three ethnic groups.
METHODS: A total of 147 RA patients from three different ethnic groups (Malays, Chinese, and Indians) who fulfilled the 1987 American College of Rheumatology (ACR) revised criteria for RA were recruited into this study. The seroprevalence of RF isotypes immunoglobulin (Ig)A, IgG, and IgM, as well as anti-CCP was determined using commercial enzyme-linked immunosorbent assay (ELISA) kits. Multinomial regression analysis was performed to assess the independent effects of autoantibody status on the development of deforming and erosive RA and the presence of extra-articular manifestations (EAM).
RESULTS: In Chinese patients, we found a significant association (p < 0.05) between IgG RF and anti-CCP and the presence of erosive disease, as well as IgM RF and IgG RF with the presence of joint deformities. In Indian patients, IgM RF was associated with deforming disease, whereas none of the antibodies were associated with disease severity in Malay patients. Multinomial regression analysis revealed that IgG RF was the most important predictor variable for erosive disease in Chinese patients, and IgM RF the only predictor variable associated with deforming disease in both Chinese and Indian RA patients.
CONCLUSIONS: There is variability in the phenotypic association of RF isotypes and anti-CCP in relation to disease severity of RA in the three ethnic groups. RF, in particular, IgG and IgM, may be better prognosticators of severe disease in Chinese and Indian patients.
BACKGROUND: To investigate the associations between HLA-DRB1 shared epitope (SE) alleles and rheumatoid arthritis in subsets of rheumatoid arthritis defined by autoantibodies in three Asian populations from Malaysia.
METHODS: 1,079 rheumatoid arthritis patients and 1,470 healthy controls were included in the study. Levels of antibodies to citrullinated proteins (ACPA) and rheumatoid factors were assessed and the PCR-SSO method was used for HLA-DRB1 genotyping.
RESULTS: The proportion of ACPA positivity among Malay, Chinese and Indian rheumatoid arthritis patients were 62.9%, 65.2% and 68.6%, respectively. An increased frequency of SE alleles was observed in ACPA-positive rheumatoid arthritis among the three Asian ethnic groups. HLA-DRB1*10 was highly associated with rheumatoid arthritis susceptibility in these Asian populations. HLA-DRB1*0405 was significantly associated with susceptibility to rheumatoid arthritis in Malays and Chinese, but not in Indians. HLA-DRB1*01 did not show any independent effect as a risk factor for rheumatoid arthritis in this study and HLA-DRB1*1202 was protective in Malays and Chinese. There was no association between SE alleles and ACPA- negative rheumatoid arthritis in any of the three Asian ethnic groups.
CONCLUSION: The HLA-DRB1 SE alleles increase the risk of ACPA-positive rheumatoid arthritis in all three Asian populations from Malaysia.
Rheumatoid arthritis (RA) is a chronic debilitating inflammatory disease affecting mainly the joint, surrounding tissue and other extra-articular structures in the body. RA can lead to destruction of bone and cartilage which may cause severe disability and it is characterized by the presence of serum rheumatoid factor (RF). The anti-cyclic citrullinate peptide (anti-CCP) antibody is another serum biomarker used in RA diagnosis with higher sensitivity and specificity.In this cross-sectional study with retrospective record review, 159 established RA patients from Hospital Universiti Sains Malaysia (HUSM) were recruited. Enzyme-linked immunosorbent assays (ELISAs) for serum RF and anti-CCP were performed. Our goal was to evaluate the significance of anti-CCP antibody in predicting the disease activity and progression in terms of radiological and extra-articular manifestations upon diagnosis.Of the 159 RA patients included in this study, mean age was 48.3 years old and majority (n = 134; 84.3%) were female. A total of 83 (52.2%) and 99 (62.3%) patients had anti-CCP antibody and RF, respectively. Mean Disease Activity Score-28 for Rheumatoid Arthritis with erythrocyte sedimentation rate (ESR) (DAS28-ESR) score for all patients was 4.74 (medium and high disease activity). Fifty-eight (36.5%) patients had radiological defects and 49 (30.8%) patients had extra-articular involvement manifested by rheumatoid nodule, pulmonary involvement, and anemia.In terms of anti-CCP antibody association with clinical and laboratory parameters, a significant co-occurrence of RF and anti-CCP antibody (P = .002) was observed. Anti-CCP antibody was significantly associated with radiological defects in which majority of patients with such defects (n = 40/58; 68.9%) were positive for anti-CCP antibody (P = .001). However, there was no significant difference between mean and classes of disease activity score and extra-articular manifestations between different anti-CCP antibody groups. In addition, extra-articular manifestations were not associated with high disease activity upon RA diagnosisThere was a significant association between anti-CCP antibody positivity and positive RF. Radiological defects were the sole clinical parameter significantly associated with anti-CCP antibody positivity, indicating that patients positive for anti-CCP antibody should be routinely monitored for radiological defects and their onset.
AIM: The purpose of this study is to compare the prevalence of rheumatoid factor (RF) isotypes and second generation anti-cyclic citrullinated peptides (anti-CCP) in Malaysian rheumatoid arthritis (RA) patients.
METHODS: In this cross-sectional study, 147 established RA patients from three ethnic groups were recruited from a major rheumatology clinic in Malaysia. Enzyme-linked immunosorbent assays (ELISA) for serum RF isotypes IgA, IgG and IgM as well as second-generation anti-CCP were performed and the prevalence of each auto-antibody was compared in the three ethnic groups.
RESULTS: The anti-CCP was the most prevalent auto-antibody in each of the ethnic groups, followed closely by RF IgM and RF IgG. Rheumatoid factor IgA was the least prevalent across all three ethnic groups. The anti-CCP-RF IgM combination provided the best test sensitivity. Seroprevalence of anti-CCP was strongly associated with the presence of each of the RF isotypes. The seroprevalence of RF and anti-CCP did not increase or decrease with advancing age, age at onset and disease duration.
CONCLUSION: When used alone, anti-CCP provides a diagnostic advantage over RF IgM on the basis of test sensitivity. Considering the high cost of the anti-CCP assay, step-wise serum testing with IgM RF followed by anti-CCP may provide a more economically sensible option to optimize test sensitivity for RA.
Study site: Rheumatology clinic, Hospital Tuanku Jaafar, Seremban, Negeri Sembilan, Malaysia
AIM: The main objective of this study is to elucidate the role of immunoglobulin A (IgA) rheumatoid factor (RF) in predicting the clinical response to tumour necrosis factor α inhibitors (TNFi) among patients with rheumatoid arthritis (RA).
METHOD: We recruited all patients with RA who were ever on TNFi for a minimum duration of 3 months at our centre. Based on the European League Against Rheumatism response criteria, subjects were further divided into responders and non-responders. Age-matched RA patients who were on conventional disease-modifying anti-rheumatic drugs and in remission were enrolled as controls. Subjects were tested for quantitative values of IgA, IgM, IgG RF and anti-citrulinated cyclic peptides (CCP). Further, all subjects were assessed for the disease activity score that includes 28 joints (DAS28) and Stanford Health Assessment Questionnaire (HAQ) 8-item Disability Index (HAQ-DI).
RESULTS: A total of 31 subjects with RA who had received TNFi and 15 controls were enrolled in this study. There was a trend for the non-responders (n = 10) to have higher levels of all isotypes of RF and anti-CCP. However, only the IgA RF and anti-CCP levels were significantly higher in the non-responder group compared to the responders and controls (P = 0.001, P = 0.034, respectively). On multivariate analysis, only the IgA RF remained significant (OR 0.989; 95% CI 0.980-0.999; P = 0.026).
CONCLUSION: IgA RF is potentially a novel predictor of response to TNFi in RA patients. Testing for pretreatment IgA RF levels could be a reasonable consideration before commencement of TNFi.
Study site: Pusat Perubatan Universiti Kebangsaan Malaysia (PPUKM), Kuala Lumpur, Malaysia