Use of antibodies recognizing cyclic citrullinated peptide in the differential diagnosis of joint involvement in systemic sclerosis

Objective: To determine the prevalence of anti-cyclic citrullinated peptide (CCP) antibodies in systemic sclerosis (SSc) and to assess any association between the presence of anti-CCP, radiographic features, and clinical manifestations. Materials and methods: Anti-CCP antibodies and rheumatoid factor (RF) were tested in serum samples from 75 patients with SSc (64 women and 11 men), with a mean age of 59.4 years (range 24-85) with either diffuse (dcSSc) and limited (lcSSc) cutaneous involvement. As a control group, 22 age- and sex-matched healthy controls (HCs) were examined. Standard radiographs of the hands and wrists were examined in each patient. Results: The presence of anti-CCP was found in sera of 10.6% (8/75) patients with SSc (lcSSc 3 of 44, 6.8%; dcSSc 5 of 31, 16.1%). None of the HCs was positive for anti-CCP. The positivity of RF was observed in 19 of 75 (25.3%) SSc patients (lcSSc 10 of 44, 22.7%; dcSSc 9 of 31, 29%). Statistically significant association was found between anti-CCP positivity and the presence of arthritis (p < 0.0001) and marginal erosions (p=0.001). Conclusion: Our data show that joint involvement is a common presenting feature of SSc. In this report, we show that anti-CCP antibodies can be detected also in patients with SSc, but they are generally less commonly present than in adults with rheumatoid arthritis (RA). Thus, the finding of high titers of anti-CCP antibodies may help to define the diagnosis of overlap syndrome SSc/RA and facilitate diagnosis and appropriate treatment.