IL6 and rheumatoid arthritis: In this study, we observed a significant association between pro-inflammatory cytokine IL-6 levels and circulating RTEs in undifferentiated arthritis (p = 0.019, adjusted R2 = 0.30), early RA (p = 0.016, adjusted R2 = 0.30) and established RA (p = 0.021, adjusted R2 = 0.29) patients [Fig. 1d], but not in arthralgia patients (p = 0.63, adjusted R2 = 0.14; data not shown).