Abstract

The aesthetic features of pigmentation, specifically eye and skin color, show a significant correlation with the biological etiology of autoimmune diseases, challenging traditional views. The present study assessed the interplay between pigmentation traits and diagnostic classification, as well as treatment strategies, within a population of patients afflicted with rheumatoid arthritis (RA), spondyloarthritis (SpA). A cross-sectional retrospective analysis was conducted involving 215 patients diagnosed with RA, ankylosing spondylitis (AS), or psoriatic arthritis (PsA). Ocular and cutaneous pigmentation (brown, blue, green; light vs dark shades), were recorded alongside demographic, diagnostic, and therapeutic data. A structural equation model (SEM) was employed to evaluate the impact of pigmentation on diagnostic and treatment outcomes. Individuals with darker skin tones were significantly associated with SpA diagnoses (β=-0.344, p

Key words: Autoimmune rheumatic diseases, phenotypic characteristics, rheumatoid arthritis, spondyloarthritis, structural equation modeling