Anti-carbamylated protein antibodies in psoriatic arthritis patients: Relation to disease activity, severity and ultrasonographic scores

Background: Anticarbamylated proteins (anti-CarP) are a novel family of antibodies recently identified in patients with inflammatory arthritis. Aim of the work: To investigate the anti-CarP serum levels in psoriatic arthritis (PsA) patients. The relation of anti-CarP to disease activity and severity as well as to the ultrasonographic findings and scores were well thought-out. Patients and methods: Forty-five PsA patients diagnosed according to the classification of psoriatic arthritis (CASPAR) criteria. 45 matched controls were included. The erythrocyte sedimentation rate (ESR), C-reactive protein and serum anti-CarP antibody were measured. PsA disease activity was recorded according to the modified disease activity score (DAS28). The severity and extent of psoriasis was assessed by the psoriasis area severity index (PASI). Musculoskeletal ultrasound (US) of the small hand joints was performed using grey scale (GS) and power Doppler (PD) to derive composite scores based on abnormal counts and severity. Results: The mean age of the patients was 44.58 ± 6.76 years, 40 females and 5 males (F:M 8:1), disease duration 4.93 ± 3.17 years. Serum levels of anti-CarP antibody were increased in PsA patients (33.48 ± 14.05) compared to controls (12.21 ± 4.71 ng/ml) (p < 0.001). The mean DAS28 was 4.61 ± 1.59 There was a significant correlation between anti-CarP antibody and each of DAS28, ESR, CRP, PASI, the GS and PD joint counts (r = 0.97, r = 0.97, r = 0.97, r = 0.97, r = 0.96, r = 0.9 respectively) as well as with the US joint scores; GSJS and PDJS (r = 0.98, r = 0.97 respectively) denoting severity. Conclusions: Anti-CarP antibody might represent a promising marker to predict joint damage and disease activity in PsA patients