IL15RA and Arthritis: Presence of ≥1 ACPA reactivity, ultrasound-detected tenosynovitis, IL-6 levels and IL-15Rα levels were identified as significant independent predictors for arthritis progression (Figs 3–4) and after utilizing Bonferroni adjustment, these predictors remained significant with the exception of IL-15Rα, which was borderline significant.