Usefulness of anti-cyclic citrullinated peptide antibody and rheumatoid factor to detect rheumatoid arthritis in patients with systemic sclerosis.

OBJECTIVES

The purpose of this study was to determine the prevalence of anti-CCP antibodies (anti-CCP Abs) and to assess associations between the presence of anti-CCP Ab and arthritis or arthralgia in SSc patients.

METHODS

Serum samples were obtained from 146 SSc patients. Anti-CCP Ab, anti-agalactosyl (AG) IgG Ab, IgM-RF, IgG-RF and MMP-3 were determined, respectively.

RESULTS

The presence of anti-CCP Ab was found in 18/146 (12%) patients with SSc. Elevated levels of anti-AG IgG Abs, IgM- and IgG-RFs were observed in 50/146 (34%), 17/146 (12%) and 4/146 (3%), respectively. Serum anti-CCP Ab levels were significantly elevated in SSc-RA overlap patients compared with SSc patients with or without arthralgia (P < 0.05 or P < 0.001, respectively). Serum MMP-3 levels did not correlate with the presence of arthritis or arthralgia but were significantly associated with modified Rodnan total skin thickness score. In SSc-RA overlap patients, 10/11 (91%) patients were positive for two or more RA-related Abs.

CONCLUSIONS

The serum titre of anti-CCP Ab is higher in SSc-RA overlap patients than in SSc patients with or without arthralgia. The finding of high titres of anti-CCP Abs and the elevated levels combinatory with other RA-related Abs may help to define the diagnosis of SSc-RA overlap. MMP-3 might be a better marker to assess skin involvement rather than joint involvement in SSc patients.