Inflammatory Arthritis in Systemic Sclerosis is Problematic Save

Inflammatory arthritis (IA) is a common manifestation in systemic sclerosis (SSc), affecting nearly one-third of patients.

A prospective study of SSc patients enrolled in the Australian Scleroderma Cohort Study assessed the frequency and the associations of IA with SSc and serological parameters. 

From a total cohort of 1,717 SSc patients, 572 had IA (33.3%)) over a median follow-up of 4.3 (1.7-8.4) years. The median onset age of IA was 59.5 years, with a median lag time from SSc disease to IA onset of 7.9 years.

IA occurred less frequently in those with PAH (7.2% vs 11.3%, p=0.007). There was no significant difference between those with and without IA in terms of age at SSc onset, gender, ethnicity, or smoking status. Patient characteristics by IA status are summarised in Table 1.  

The presence of IA was associated with

• Diffuse SSc (OR 1.33, 95%CI 1.01-1.74, p=0.042)
• Joint contractures and tendon friction rubs, OR 1.70, 95%CI 1.34-2.15, p<0.001)
• Myositis (OR 2.11, 95%CI 1.39-3.20, p<0.001)
• Sicca symptoms (OR 1.57, 95%CI 1.14-2.16, p=0.006)
• Negatively associated with Pulmonary arterial hypertention (OR 0.52, 95% CI 0.35-0.78, p=0.002).

Serologies were not associated with IA, as rheumatoid factor (OR 1.13, 95%CI 0.88-1.44, p=0.331) and antibodies to U1RNP (OR 1.46, 95%CI 0.89-2.39, p=0.129) were not significantly associated.  Anti-cyclic citrullinated protein antibodies were infrequent but were more common in IA-SSc patients (7.5% vs 1.5%, p<0.001) than those without IA.

IA was significiantly associated with a lower quality of life and more disability.  It is unknown if effective treatment of IA alters the outcome of SSc.