Assessment of anti-CarP antibodies, disease activity and quality of life in rheumatoid arthritis patients on conventional and biological disease-modifying antirheumatic drugs

OBJECTIVE: Good biomarkers are important to guide decisions in the clinical management of rheumatoid arthritis (RA). RA patients harbor antibodies directed against carbamylated proteins which may predict joint damage. This study investigated whether antibodies against carbamylated proteins (anti-CarP) may serve as surrogate prognostic markers. MATERIAL AND METHODS: Fifty-three patients with a diagnosis of rheumatoid arthritis according to ACR 1987 criteria were included. Blood samples were analyzed for CarP antibody levels using the ELISA method. Quality of life (QoL) was assessed by the WHO SF-36 questionnaire, and disease activity was assessed using the DAS28 calculator. Newly diagnosed patients were assessed at the first visit and at 12 weeks of treatment, while a single assessment was made for patients already on maintenance therapy. RESULTS: Out of 53 patients, 22 had titers of anti-CarP above the cut-off range and considered as positive for anti-CarP antibodies. Anti-CarP antibody serum level was significantly higher in patients with deformity of joints and with erosions in comparison to those without any destructive changes (p < 0.05). There was a weak positive correlation between anti-CarP and DAS 28 (p > 0.05). Also there was a weak negative correlation in all domains of quality of life with anti-CarP antibody titers (p > 0.05). There was no significant correlation between titers of anti-CarP antibodies and presence or absence of rheumatoid factor. CONCLUSIONS: Serum levels of anti-CarP antibodies in RA patients with joint erosions/deformities were much higher than in those without any joint damage. Anti-CarP antibodies may have good prognostic value in RA patients with erosions. Disease activity and QoL of RA patients improved during treatment, but no correlation was found between DAS 28/QoL and anti-CarP antibody serum levels.