[Overlap between systemic sclerosis and rheumatoid arthritis: a distinct clinical entity?]

Area of Science:

• Rheumatology
• Immunology
• Autoimmune Diseases

Background:

• Systemic sclerosis (SSc) is a connective tissue disease marked by vascular injury, autoimmunity, and fibrosis.
• Musculoskeletal pain affects 40-80% of SSc patients, with arthritis being a common, sometimes misdiagnosed, feature.
• Arthritis is observed in a significant portion of SSc patients, potentially complicating diagnosis and management.

Purpose of the Study:

• To correlate arthritis occurrence in Brazilian SSc patients with clinical and laboratory findings.
• To determine the frequency of true rheumatoid arthritis (RA) overlap in SSc patients with synovitis.
• To investigate distinct clinical and laboratory manifestations across SSc patient groups with and without arthritis.

Main Methods:

• Sixty-one SSc patients were monitored for one year to assess synovitis development and progression.
• Patients were categorized into three groups: SSc without arthritis, SSc with arthritis, and SSc/RA overlap.
• Radiological hand examinations were performed on all patients at the study's conclusion.

Main Results:

• Arthritis was clinically observed in 32.8% of SSc patients; true SSc/RA overlap occurred in 6.6%.
• Positive anti-CCP antibodies were found in 20% of SSc patients with arthritis, exclusively in the SSc/RA overlap group.
• SSc patients with arthritis reported a significantly reduced quality of life (HAQ index) and showed higher incidences of gastritis and cardiac valvulopathy.

Conclusions:

• Clinical arthritis is frequent in SSc, but true co-occurrence with RA is less common.
• Anti-CCP positivity may indicate RA overlap in SSc patients with arthritis.
• Arthritis in SSc significantly impacts quality of life and is associated with specific comorbidities.