Differing X-ray patterns in seronegative and seropositive rheumatoid arthritis

Area of Science:

• Rheumatology
• Radiology
• Immunology

Background:

• Rheumatoid arthritis (RA) erosivity is predicted by anti-citrullinated protein antibody (ACPA) and rheumatoid factor (RF) status.
• Previous studies noted qualitative radiographic differences, like carpal fusion, between seronegative RA (snRA) and seropositive RA (spRA).

Purpose of the Study:

• To quantitatively and qualitatively compare radiographic differences between snRA and spRA using advanced imaging techniques.
• To explore potential pathophysiological distinctions underlying these RA subtypes.

Main Methods:

• Compared total Sharp/van der Heijde scores (TSS) for erosions and joint space narrowing (JSN) in matched snRA and spRA cohorts.
• Utilized digital X-ray radiogrammetry (DXR) for bone density and structural analysis.
• Performed qualitative assessment of radiographs to identify non-quantifiable differences.

Main Results:

• Seropositive RA patients exhibited significantly more erosions and joint space narrowing across most joint compartments compared to seronegative RA.
• While carpal fusion and DXR scores did not differ, qualitative analysis revealed distinct patterns: snRA showed periarticular ossifications and carpal shortening, while spRA had more CMC joint damage.
• Erosion load differences were significant in the foot and MCP joints, but not wrists or PIP joints.

Conclusions:

• Seronegative and seropositive RA demonstrate distinct quantitative and qualitative radiographic features.
• These differences suggest underlying pathophysiological variations between RA subtypes.
• This study provides systematic, quantitative evidence of differential X-ray manifestations in RA.