Significance of combined anti-CCP antibodies and rheumatoid factor in a New Zealand cohort of patients with systemic sclerosis.

Background: Systemic sclerosis (SSc) can present as an overlap syndrome with rheumatoid arthritis (SSc-RA overlap).

Objective: To evaluate the frequency of rheumatoid factor (RF) and anticyclic citrullinated peptide antibodies (anti-CCP) in our SSc cohort and their association with clinical features.

Methods: Data were gathered prospectively from the Waikato Hospital Systemic Sclerosis Clinics. Patients with SSc and SOS (systemic sclerosis overlap syndrome) underwent baseline auto-antibody profiling including RF and anti-CCP along with annual clinical review.

Results: Our cohort comprised of 132 patients (two had incomplete data); 115 (87.1%) were female. Out of 89 limited cutaneous SSc (lcSSc) patients, arthralgia, synovitis, contractures, tendon crepitus and erosions on imaging were found in three, 10, 31, five and nine patients, respectively. Within the 33 diffuse cutaneous SSc (dcSSc) patients, arthralgia, synovitis, contractures, tendon crepitus and erosion were found in 15, five, 27, five and one patient, respectively. In the 10 SOS patients, arthralgia, synovitis and contractures were found in six, three and two patients; none had tendon crepitus or erosions. RF positivity was found in 15.7%, 9% and 20% of patients with lcSSc, dcSSc and SOS, and anti-CCP positivity was found in 13.5%, 6.1% and 0% in lcSSc, dcSSc and SOS patients. A statistically significant relationship of double antibody positivity with arthralgia (P = 0.03) and erosions (P < 0.001) was found. Anti-CCP positivity association with erosions was significant at P = 0.007.

Conclusion: Our study confirms that articular manifestations are common in SSc. Statistically significant associations of double antibody positivity with arthralgia and erosions were demonstrated. Significant association between anti-CCP antibody and erosions was also confirmed.