IL18 and rheumatoid arthritis: As for proinflammatory cytokines, patients with RA and PPHL had higher median (IQR) levels of IL-18 (21.65 (10.80–26.75) vs. 13.29 (10.17–19.23); p = 0.039) and TNF-α (1.49 (0.98–5.16) vs. 1.14 (0.98–1.68); p = 0.036) than the other patients.