In addition, we analyzed the proportion of patients with RA with clinical and serological parameters predictive of severity of the disease, in relation to IL-6 tertile values, finding a significantly higher proportion of patients in the high tertile of IL-6 with morning stiffness >30 min (p < 0.01), functional disability defined by HAQ-DI ≥1 (p < 0.05), moderate–high clinical activity (p < 0.01), hsCRP ≥10 mg/L (p < 0.05), and double-positive (RF+/Anti-CCPs+) high autoantibodies (p < 0.05) (Figure 1). Here, IL6 is linked to rheumatoid arthritis.