Background/Purpose: Citrulline and vimentin are some of the proteins used as antigens for anti-citrullinated proteins antibodies (ACPAs) detection for the diagnosis of rheumatoid arthritis (RA). In our country, anti-mutated citrullinated vimentin (anti-MCV) kit is 50% cheaper than the anti-cyclic citrullinated peptide (anti-CCP3) kit. The aim of our study was to evaluate the diagnostic value of anti-MCV compared to anti-CCP3 and rheumatoid factor (RF) and to explore the relationship between them and disease activity

Methods: Consecutive patients ≥ 18 years with RA (ACR 1987 and ACR/EULAR 2010 criteria) were included. The control group consisted of 73 subjects with undifferentiated arthritis, SLE, Psoriatic Arthritis, Sjögren’s Syndrome and Erosive Osteoarthritis (non RA arthritis). Anti-MCV and anti-CCP3 were determined by ELISA and RF by immunoturbidimetry. The cutoff value for the three methods was ≥ 20 IU/ml. Sensitivity (S), Specificity (E), Positive and Negative Predictive Values (PPV, NPV) and Likelihood Ratio (LR) of the RF, anti-CCP3 and anti-MCV were assessed using a two way table (Table). Binary logistic regression analyses were performed, using high disease activity (DAS28>5.1) as dependent variable. According to the RF, anti-CCP3 and anti-MCV concentrations, three groups of patients were obtained: low concentrations (under 25 percentile); intermediate concentrations (between 25 and 75 percentile) and high concentrations (above 75 percentile).The values of DAS28 for these three groups were compared by ANOVA and post-hoc tests

Results: 234 patients were evaluated (161 RA and 73 controls). In the RA group, 85% were female, the mean age was 53 (18-91) years, the median symptoms duration was 120 months (IQR 39-180) and 31(19%) were early RA patients (<2 years). Mean DAS28 was 3.6 (±1.5); and the median HAQ 0.75 (IQR 0.25-1.25). The median of RF was 104 IU/ml (IQR 35-225); anti-CCP3 180 IU/ml (IQR 95-210) and anti-MCV 300 IU (IQR 55-1000). Higher values of DAS28 were observed in the group of patients with RF > 225 IU/ml (mean DAS28 4.3 p = 0.006) and also in patients with anti-MCV > 1000 IU (DAS28 4.2 p=0.01). There were no differences for anti-CCP3. In early RA patients, a multivariate analysis (adjusted by symptom duration) showed that anti-MCV levels were associated with high disease activity. The OR estimated for the association between high disease activity and anti-MCV ≥ 1000 IU in early RA patients was 11.8 (CI 95%1.049-132.9). There was not significant association between RF, anti- MCV nor anti-CCP3 and DAS28 > 5.1 in established RA patients.                                                                           

Table.

	S	E	PPV	NPV	LR
Anti-MCV	93.4	83.6	93	85	5.69
Anti-CCP3	83.7	84.9	93	69	5.54
RF	84.9	84.9	93	71	5.62

Conclusion: In our study, anti-MCV compared to anti-CCP3 and RF had a higher sensitivity with equal specificity. We found increased RA activity in patients with higher titers of RF and anti-MCV

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/diagnostic-value-of-anti-citrullinated-proteins-antibodies-in-rheumatoid-arthritis/