Diagnostic performances of anti-cyclic citrullinated peptide antibodies in rheumatoid arthritis

Autoantibodies Serum Level and 10-Year Risk of Fractures Evaluated by FRAX® Tool in Rheumatoid Arthritis Patients

Purpose

FRAX® is a tool used for evaluation of risk of fracture in RA and non-RA patients and to identify those eligible for intervention. One of the limitations of FRAX in RA settings is that it does not consider factors known to contribute to osteoporosis such as autoantibodies. This study analysed the association of anti-mutated citrullinated vimentin antibody (anti-MCV), anti-cyclic citrullinated peptide antibody (anti-CCP), IgM rheumatoid factor (RF), IgA RF with 10-year risk of major osteoporosis and hip fracture.

Methods

FRAX® tool was used to estimate 10-year risk of major osteoporosis fracture and hip fracture in 189 RA patients over 40 years of age. Anti-MCV, anti-CCP, IgM RF and IgA RF were tested using enzyme immunoassay and analysed at different levels. Results were adjusted for various confounders including disease activity.

Results

Fifty-one (26.9%) RA patients had high (≥20%) 10-year risk of major osteoporosis fracture and 67 (35.4%) had high (>3%) 10-year risk of hip fracture. Among all the tested autoantibodies, only IgM RF at elevated levels was associated with high 10-year risk of major osteoporosis fracture (adjusted OR = 4.1, 95% CI = 1.5-11.3, p = 0.006) and of hip fracture (adjusted OR = 17.4, 95% CI = 3.7-81.3, p < 0.0001). There was no agreement between FRAX and femoral neck (FN) BMD. None of the autoantibodies tested were associated with FN osteopenia or osteoporosis including IgM RF at high levels.

Conclusion

Our study highlights the importance of quantitative measurement of autoantibodies in assessment of risk for fractures among RA patients. Our preliminary findings need to be assessed in prospective studies to determine the actual predictive value of high IgM RF levels among patients with RA.

Serological markers of rheumatoid arthritis in patients with primary biliary cholangitis and the vice versa: A Tunisian study

BACKGROUND

Primary biliary cholangitis (PBC) is an autoimmune disease of the liver characterized by destructive lymphocytic cholangitis and anti-mitochondrial antibodies (AMA). Anti-gp210 and anti-Sp100, are used for the diagnosis of PBC in AMA-negative PBC patients. Patients with PBC have a propensity to have an extrahepatic manifestation which is especially autoimmune.

OBJECTIVE

We aimed to determine the frequency of serological markers of rheumatoid arthritis (RA) (CCP-Ab or RF) in PBC patients and to do the vice versa.

METHODS

Our PBC study included 70 patients with PBC and 80 healthy blood donors (HBD) and our RA study included 75 patients with RA and 75 HBD. Anti-cyclic citrullinated peptide antibodies (CCP-Ab) and rheumatoid factor (RF) were performed by indirect ELISA. AMA, anti-Sp100 and anti-gp210 were determined by indirect immunofluorescence.

RESULTS

RA autoantibodies (CCP-Ab or RF) were more frequent in PBC patients than in HBD (65.7% vs. 8.7% p 〈10^-6). CCP-Ab were significantly more frequent in patients than in controls (15.7% vs. 2.5%; p = 0.004). Nine patients had both CCP-Ab and RF vs. none of controls (12.8% vs. 0%; p = 0.001). RF were detected in 45 patients with PBC and in 5 HBD (64.3% vs. 6.2%; p 〈10^-6). In PBC patients, RF were more frequent than CCP-Ab (64.3% vs. 15.7%; p 〈10^-6). RF-IgG were present in 18.5% of patients; RF-immunoglobulin (Ig) A in 34.3% and RF-IgM in 54.3%. These frequencies were significantly higher than those found in control group (1.2% for RF-IgG (p 〈10^-3); 0% for RF-IgA (p 〈10^-6); and 6.2% for RF-IgM (p 〈10^-6)). In our PBC patients, RF-IgA were more frequent than RF-IgG (34.3% vs. 18.5%; p = 0.03) and than CCP-Ab (34.3% vs. 15.7%; p = 0.01). Six patients had only RF-IgA versus none of the control group (8.6% vs. 0%; p = 0.01). AMA, anti-Sp100 and anti-gp 210 were absent in all RA patients.

CONCLUSIONS

Serological markers of RA were more frequent in PBC patients than in HBD and the vice versa was not true.

Anticardiolipin and anti-beta 2-glycoprotein I antibodies in patients with unexplained articular manifestations

OBJECTIVE

To determine the frequency of antiphospholipid antibodies (aPL) in patients with unexplained articular manifestations.

MATERIAL AND METHODS

Three hundred thirteen patients suffering from arthritis or arthralgia without evident cause and 266 healthy blood donors (HBD) were included in the study. Anticardiolipin antibodies (aCL) and anti-beta 2-glycoprotein I antibodies (aβ2GPI) were measured by ELISA.

RESULT

Out of the 313 patients, 250 were females and 63 were males. The mean age of patients was 49 ± 14 years (17-87 years). One hundred eleven patients have arthralgia and 202 have arthritis. The frequency of aCL and/or aβ₂ GPI (24.9%) was significantly higher in patients than in HBD (10.9%). The frequency of aβ2GPI was 23.6% in patients and 9.4% in the control group (p < 10^-3 ). aβ2GPI-IgA was significantly more frequent in patients than in the control group (20.4% vs. 7.5%, p < 10^-3 ). aβ2GPI was most commonly observed than aCL in patients (23.6% vs. 6.4%, p < 10^-6 ). IgA isotype of aβ2GPI was the most frequent in 20.4% of patients while IgG and IgM were detected in 5.4% and 2.9% respectively.

CONCLUSION

This study showed that aPL were common in patients with articular manifestations and were mainly directed against β₂ GPI. The role of these antibodies remains to be specified.

Frequency of serological markers of rheumatoid arthritis in patients with IgA anti-β2 glycoprotein I antibodies

Aim

To determine the frequency of serological markers of RA in patients with anti‐β2 glycoprotein I antibodies (aβ2GPI) of IgA isotype.

Material and Methods

A retrospective study was conducted on 67 patients with aβ2GPI‐IgA. Ninety healthy blood donors (HBD) were used as a control group. IgG anti‐cyclic citrullinated peptides antibodies (CCP‐Ab) and rheumatoid factors (RF) IgG, IgA, and IgM were detected by enzyme‐linked immunosorbent assay (ELISA).

Results

Seventeen patients and eight HBD had CCP‐Ab and/or RF (25.4% vs. 8.9%, p = 0.005, CI 95% [14.95; 35.79], odds ratio = 3.5). The frequency of CCP‐Ab was significantly higher in patients than in healthy subjects (14.9% vs. 3.3%, p = 0.009). IgA isotype of RF was significantly higher in patients than in controls (7.5% vs. 0%, p = 0.02). In male patients, CCP‐Ab and/or RF were more frequent than in healthy male subjects (37.5% vs. 11.8%, p = 0.02). In patients, no correlation was found between the levels of aβ2GPI‐IgA and CCP‐Ab (r = 0.082, p = 0.51). There was no correlation between the level aβ2GPI‐IgA and the level of the isotypes of RF (IgG, IgA, and IgM) in patients (r = 0.1, p = 0.37; r = 0.17, p = 0.17 and r = 0.07, p = 0.59 respectively).

Conclusion

Frequencies of CCP‐Ab and RF are high in patients with aβ2GPI‐IgA suggesting that these patients are susceptible to developing RA.

Frequency of serological markers of rheumatoid arthritis in adult patients with active celiac disease

BACKGROUND

Celiac disease (CD) and rheumatoid arthritis (RA) are multisystem autoimmune diseases affecting 1% of general populationa. Both diseases share genetic and immunological features.

AIM

In this retrospective study, we aim to determine the frequency of auto-antibodies of RA in adult patients with CD.

MATERIALS AND METHODS

Seventy seven adult patients with active CD were included in the present study. Ninety healthy blood donors (HBD) served as control group. Anti-cyclic citrullinated peptides antibodies (CCP-Ab) and rheumatoid factors (RF; IgA, IgG and IgM) were determined by enzyme linked immunosorbent assay (ELISA) for patients and control group. For statistical analysis, we used Chi-square or Fisher's exact test.

RESULTS

Our study included 77 adult patients with active celiac disease (57 female, 20 male). Twenty-four (31.2%) active celiac patients and 7 (7.8%) blood donors had CCP-Ab or RF (31.2% vs 7.8%, p < 10-4). Only two patients (2.6%) had both CCP-Ab and RF. IgA was the predominant isotype of RF in celiac patients (n = 18; 23.4%) while none of healthy blood donors had RF-IgA (23.4% vs 0.0%, p < 10-4).

CONCLUSION

The current study has shown that CD is associated with a high frequency of RF-IgA suggesting that celiac patients could be at a higher risk of developing RA.

IgA rheumatoid factor is associated with bone mineral density preservation in rheumatoid arthritis

INTRODUCTION

Autoantibodies such as IgM rheumatoid factor (RF) and anti-citrullinated proteins/peptides antibodies (ACPA) have previously been incriminated in systemic bone loss in rheumatoid arthritis (RA). There are, however, no data describing association of IgA RF and IgG RF with systemic bone loss.

OBJECTIVE

This study was aimed to investigate the association of RF isotypes with systemic bone loss among patients with RA.

METHODS

RF isotypes and ACPA were measured by enzyme-linked immunosorbent assay among 153 patients with RA. Bone mineral density (BMD) was assessed using dual-energy X-ray absorptiometry.

RESULTS

Ninety-four (61.4%) patients had positive IgA RF, 89 (58.2%) had positive IgG RF, 109 (71.2%) had positive IgM RF, whereas 122 (80.3%) RA patients tested positive for ACPA. Compared to the IgA RF-negative patients, IgA RF-positive patients exhibited higher disease activity and had higher RF titers. Seven (4.6%) patients had low BMD at femoral neck, 12 (7.8%) at total femur, and 47 (30.7%) at lumbar spine. IgA RF was found to be associated with protection against low BMD at spine (OR = 0.47, 95% CI = 0.23-0.95, p = 0.034). This association was further confirmed in the multivariate regression analysis taking into account several potential confounding factors (OR = 0.21, 95% CI = 0.06-0.65, p = 0.039). No association between low BMD and the presence of IgG RF or IgM RF or ACPA was found.

CONCLUSION

IgA RF for the first time ever was shown to be associated with BMD preservation at spine in RA. Key points • IgA RF was associated with protection against low spinal BMD. • No association between low BMD and the presence of IgG RF or IgM RF was found.

IgA is the predominant isotype of anti-β2 glycoprotein I antibodies in rheumatoid arthritis

Background

The aim of this study was to determine the frequency of anti‐cardiolipin antibodies (aCL) and anti‐β2 glycoprotein I antibodies (aβ2GPI) among Tunisian patients with rheumatoid arthritis (RA).

Methods

Ninety RA patients with positive anti‐cyclic citrullinated antibodies (anti‐CCP) and 90 healthy blood donors (HBD) were studied. aCL and aβ2GPI of isotype IgG, IgA and IgM were detected by ELISA.

Result

The frequency of antiphopholipid antibodies (aPL) (aCL and/or aβ2GPI) was significantly higher in patients with RA than in HBD (35.5% vs 11.1%, P = .0001). The frequencies of aCL and aβ2GPI were significantly higher in patients than in healthy subjects (15.5% vs 5.5%, P = .04 and 32.2% vs 11.1%, P = .0005 respectively). aβ2GPI‐IgA were significantly more frequent in patients than in the control group (26.7% vs 7.8%, P = .0007). In patients, aβ2GPI‐IgA were significantly more frequent than aβ2GPI‐IgG (26.7% vs. 6.7%, P = .0003) and aβ2GPI‐IgM (26.7% vs 5.6%, P = .0001). In RA patients, the frequency of aβ2GPI was significantly higher than that of aCL (32.2% vs 15.5%, P = .008). aβ2GPI‐IgA was significantly more frequent than aCL‐IgA (26.7% vs 4.4%, P = .00005). The average titer of anti‐CCP in aPL positive patients was significantly higher than in aPL negative patients (170.6 ± 50 RU/mL vs 147.7 ± 51 RU/mL, P = .04). Significant correlation was found between aβ2GPI‐IgA and anti‐CCP (r = .235, P = .026).

Conclusions

aPL and particularly aβ2GPI‐IgA are frequent in RA and are correlated with anti‐CCP.

Risk factors for cardiovascular disease in rheumatoid arthritis patients from Mato Grosso do Sul

OBJECTIVE

To identify risk factors for cardiovascular disease in patients with Rheumatoid Arthritis (RA).

MATERIAL AND METHODS

A descriptive cross-sectional study with 71 patients with established RA. The instruments used were: DAS-28, HAQ and SF-36, and the following parameters were determined: the erythrocyte sedimentation rate, capillary blood glucose; total cholesterol (TC) and its fractions, thyroid hormones, antinuclear antibodies (ANA), rheumatoid factor (RF) and antibodies against citrullinated proteins (ACPAs). Patients were classified into groups HAQ ≤ 1 (mild dysfunction) and HAQ > 1 (moderate and severe dysfunction) and, according to the HAQ scores, in groups treated with corticosteroids (CS) and without CS.

RESULTS

9 patients were male and 62 female with mean age and duration of disease of 53.45 (± 10.7) and 9.9 (± 8.6), respectively. RF was positive in 52 (76%), ACPAs in 54 (76.1%) and ANA in 12 (16.9%). Thirty-six patients (50.7%) had systemic hypertension, 9 (12.68%) diabetes mellitus, 16 (22.5%) hypothyroidism, 33 (46.5%) dyslipidemia and 8 (11.27%) were smokers. The results of TC >240 were found in 53.8% for group HAQ >1 (26) and in 24.4% for group HAQ ≤ 1 (45) (p=0.020). These groups did not differ as to presence of comorbidities or drug treatment. Triglyceride levels >200 for the group with CS (42.4%) versus without CS (18.42%) were significant (p=0.025).

CONCLUSION

An association of increased TC and triglycerides with results of HAQ ≤ 1 and with CS use was noted, reinforcing the importance of screening risk factors associated with cardiovascular disease in RA.

Validation of a prediction rule for the diagnosis of rheumatoid arthritis in patients with recent onset undifferentiated arthritis

Objectives. To validate van der Helm-van Mil score (vHvM) and new ACR/EULAR criteria for the diagnosis of rheumatoid arthritis (RA) in patients with undifferentiated arthritis (UA). Patients and Methods. Adult patients with UA (swelling ≥2 joints of less than 6 months duration, without diagnosis, and never treated with disease modifying drugs). Results. Ninety-one patients were included. Mean age: 55.6 years (SD: 17.4), 74% females. Median symptoms duration was 2 months (IR: 1–4 months). Mean van der Helm-van Mil score was 6.9 (SD: 2). After a mean followup of 6.2 months (SD: 6), 40.7% patients fulfilled ACR 1987 RA classification criteria, 28.6% fulfilled other diagnostic criteria, and 31% remained as UA. Receiver operator characteristic curve's (ROC's) area under the curve (AUC) for the vHvM score for diagnosis of RA was 0.83. A cutoff value of 6.94 showed sensitivity of 81% and 79.7% specificity. For the new ACR/EULAR criteria, the ROC AUC was 0.93, and a value equal to or greater than 6 showed 86.5% sensitivity and 87% specificity. Conclusion. van der Helm-van Mil prediction score and the new ACR/EULAR criteria proved to be valuable for the diagnosis of RA in patients with early UA.

Anti-cyclic citrullinated peptide antibodies and joint involvement in Behçet's disease

PURPOSE

We aimed to determine the prevalence of anti-cyclic citrullinated peptide (anti-CCP) antibodies in a large group of Korean patients with Behçet's disease (BD), with and without joint involvement, and to compare these findings with the prevalences of anti-CCP antibodies in patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE).

MATERIALS AND METHODS

We tested 189 patients with BD, 105 with RA, and 36 with SLE for anti-CCP antibodies and IgM rheumatoid factor in serum. We reviewed the medical records of patients with BD to investigate their personal and clinical characteristics as well as their laboratory test results.

RESULTS

Anti-CCP antibodies were detected in seven of the 189 BD patients (3.7%), at a mean titer of 30.6±44.4 U/mL, in 86 of the 105 RA patients (81.9%) with a mean titer of 198.8±205.7 U/mL, and in nine of the 36 SLE patients (25%) with a mean titer of 180.4±113.9 U/mL. One of the seven anti-CCP-positive BD patients fulfilled the diagnostic criteria for both BD and RA. Five of the seven anti-CCP-positive BD patients (71.4%) had polyarticular joint involvement, and the other two patients (28.6%) had oligoarticular involvement.

CONCLUSION

We determined the prevalence of anti-CCP antibodies in a large group of Korean BD patients with and without joint involvement. Negative anti-CCP test in patients with BD may help to differentiate BD from RA and SLE, all of which present with similar clinical features.

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.

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.

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.

Serum levels of anti-cyclic citrullinated peptide antibodies are associated with a beneficial response to traditional herbal medicine (Kampo) in rheumatoid arthritis

This study investigated the usefulness of biomarkers indicating beneficial response to traditional herbal medicine (THM) among patients with rheumatoid arthritis (RA). We assessed 34 RA patients who received keishinieppiittokaryojutsubu (KER), one of the representative THM. The observational term was 12 months, and we calculated the disease activity score of 28 joints every 3 months and evaluated the response to KER using European League Against Rheumatism (EULAR) response criteria. Additionally, serum levels of anti-cyclic citrullinated peptide antibody (ACPA) were measured by enzyme-linked immunosorbent assay at the baseline and after 6 and 12 months of the treatment with KER. As a result, 14 (41.2%) of the 34 patients were defined as responders, 13 as non-responders and 7 as out of assessment after 6 months, respectively. Pretreatment levels of serum ACPA were lower in KER responders than in non-responders (P = 0.042), although other univariate analysis did not show any significant differences in baseline clinical measures between the two groups. Furthermore, responders to KER showed a significant decrease in the serum levels of ACPA. These findings suggest that pretreatment serum levels of ACPA are a useful predictor of a good response to treatment with KER. Furthermore, a decrease in serum levels of ACPA may be an adjunctive indicator in predicting the efficacy of this kind of treatment.

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.