Are anti-CCP antibodies in psoriatic arthritis patients a biomarker of erosive disease?

To determine the frequency of anticyclic citrullinated peptide (CCP) antibodies in a cohort of psoriatic arthritis (PsA) patients and to compare clinical, serological and radiological characteristics between PsA patients with and without anti-CCP antibodies. Patients with PsA, according to classification criteria for PsA, were consecutively recruited from an outpatient rheumatology clinic. Demographic and clinical data were collected in all cases. Serum samples from all patients were analyzed for rheumatoid factor and anti-CCP antibodies. Radiographs of hands and feet were obtained and the presence of erosions was recorded. The study included 81 patients; 43 (53 %) were men, with a median age of 45.7 years (interquartile range (IQR) 39-72) and median disease duration of 9.4 years (IQR 2-14). Anti-CCP antibodies were found in 11 patients (13.5 %), median titer 174.9 U/ml. Polyarticular involvement (72.7 vs. 17.1 %), frequency of erosive disease (72.7 vs. 37.1 %) and use of tumor necrosis factor-α inhibitors (54.5 vs. 28.5 %) were significantly higher in PsA patients with anti-CCP positivity. Anti-CCP negative PsA patients had predominantly more oligoarticular (62.8 vs. 27.2 %) and nail (81.4 vs. 36.3 %) involvement. Presence of enthesitis, dactylitis and Psoriasis Area Severity Index scores were similar in both groups. Anti-CCP antibodies were found in a subset of PsA patients, and their presence was associated with more severe disease phenotype. Further studies in a larger population are needed to define the role of anti-CCP as a biomarker of erosive disease in PsA.