Impact of the combined presence of erosions and ACPA on rheumatoid arthritis disease activity over time: results from the METEOR registry

Clinical Features of ACPA-Negative and ACPA-Positive Variants of Rheumatoid Arthritis

The aim of the study was to investigate the features of the clinical picture of the disease in patients with ACPA-negative and ACPA-positive variants of rheumatoid arthritis.

MATERIALS AND METHODS

: The study included patients with a reliable diagnosis of rheumatoid arthritis (RA) according to the criteria of ACR/EULAR 2010. Depending on the ACPA values, two groups of patients were recruited: ACPA-positive and ACPA-negative, comparable in gender, age, duration of the disease, and therapy. The nature of the onset and course of the disease and the activity of RA were evaluated (according to the DAS28, SDAI, CDAI indices).

RESULTS AND DISCUSSION

: The study involved 79 patients with ACPA-negative variant of RA and 79 ACPA-positive patients. The age of patients (Me [IR] (in years)) with the ACPA(-) variant was 52 [39; 62]; with the ACPA(+) variant, 54 [42; 62]; the duration of the disease (in months) was 59 [23; 122] and 48 [17; 84], respectively. In ACPA(+) patients, a higher disease activity was determined (by the indices DAS 28crp, DAS28esr, SDAI, CDAI), higher values of C-reactive protein and erythrocyte sedimentation rate, and a greater number of painful and swollen joints (p < 0.05). According to the localization of the involved joints, arthritis of the proximal interphalangeal, metacarpal, wrist and shoulder joints was more often determined in ACPA(+) patients. Systemic manifestations of RA at the time of examination and in the anamnesis were statistically significantly more common in ACPA(+) (32.9%) than in ACPA(-) (17.7%) patients. Of the systemic manifestations, rheumatoid nodules were more common in ACPA(+) patients, whereas a tendency to a higher frequency of neuropathy, sclerites, and episcleritis was revealed in ACPA(-) patients.

CONCLUSIONS

. In patients with ACPA(-) subtype, clinical signs of joint damage and the inflammatory component are less pronounced compared to ACPA(+). However, the mixed picture of manifestation, the less "bright" course of the disease, the absence of characteristic immunological biomarkers necessitate long-term and careful monitoring of this group of patients. At the same time, the subjective severity of the disease and dysfunction due to ankylosing joints do not differ from the ACPA(+) variant of RA.

Citrullinated Antigens with Multiple Citrulline Similar Motif in the Diagnosis of Rheumatoid Arthritis: A Preliminary Single-Center Study

The presence of anti-citrullinated protein antibodies (ACPAs) in the serum is one of the immunological features of rheumatoid arthritis (RA). Anti-cyclic citrullinated peptide (CCP) assay has been widely used in clinic for the diagnosis of RA. However, up to 40% of RA patients are anti-CCP negative and the diagnostic sensitivity in this population needs to be improved for better clinical management. In this study, peptides with Multiple Citrulline Similar Motif (MCSM) were synthesized and a new ELISA system, which we called RA_CP, was developed to detect citrullinated antigens with MCSM present in the serum. 106 RA,48 other arthritis patients and 41 sex- and age-matched healthy controls (HCs) were included in this study. Patients with RA have a significantly higher amount of citrullinated antigens with MCSM than other arthritis patients and HCs. RA patients with positive anti-CCP are also MCSM positive, whereas 75% anti-CCP negative patients are positive for MCSM. The diagnostic sensitivity for anti-CCP and MCSM was 81.1% and 95.3%, while the specificity was 100% and 94.4%, respectively. ROC curve analyses showed that the area under the curve (AUC) values were 0.906 (95% CI: 0.860-0.951) for anti-CCP and 0.948 (95% CI: 0.912-0.985) for MCSM while the combination of MCSM and anti-CCP test has the highest AUC (0.971, 95% CI: 0.946-0.996). Our results suggest that detection of citrullinated antigens with MCSM has improved sensitivity compared with anti-CCP assay and could serve as a biomarker in diagnosis of RA patients.