RARRES2 and rheumatoid arthritis: Serum eNAMPT concentrations were significantly more elevated in RA patients compared with controls (P = 0.013). In this study, eNAMPT levels correlated with those of chemerin (r = 0.328, P ≤ 0.01) and with the chemerin/eNAMPT ratio (r = −0.599, P ≤ 0.01).