Rheumatoid factor positivity in granulomatosis with polyangiitis: implications for clinical outcomes and...

Granulomatosis with Polyangiitis (GPA) is a systemic necrotising vasculitis marked by granulomatous inflammation and small vessel involvement. Rheumatoid factor (Rf) positivity is classically linked to rheumatoid arthritis but is also observed in other autoimmune diseases, including GPA. However, the clinical implications of Rf positivity in GPA remain uncertain. The research aims to evaluate the impact of Rf positivity on clinical and laboratory parameters, organ involvement patterns, disease activity, and outcomes in GPA patients.

The single-centre cohort of 82 GPA patients were analysed retrospectively, with the patients categorised as Rf + (n=37) and Rf - (n=45). Data were collected on demographic features, laboratory findings, clinical manifestations, treatment, and outcomes. Appropriate statistical methods were employed to evaluate differences between groups.

Rf+GPA patients exhibited significantly higher levels of c-ANCA, total protein-to-albumin ratio, white blood cells (WBCs) count, neutrophil-to-lymphocyte ratio, and Birmingham Vasculitis Activity Score (BVAS), indicating heightened inflammatory and immunological activity. Arthritis was significantly more prevalent in Rf + patients, whereas skin involvement was inversely associated with Rf positivity. Despite similar overall disease durations, end-stage renal disease (ESRD) prevalence was lower in Rf + patients, potentially related to higher rituximab usage in this group.

Rf positivity in GPA is associated with distinct clinical and immunological profiles, including an arthritis-dominant phenotype and reduced skin involvement. These findings suggest that Rf may influence disease course and organ involvement patterns, highlighting its potential as a biomarker for identifying distinct clinical phenotypes in GPA management.