SPP1 and rheumatoid arthritis: While we have previously reported that soluble IL-6 receptors (sIL-6R) predict clinical remission (defined by the criteria of CDAI, SDAI, and DAS28-ESR) at week 24 in biologic-naïve patients with RA[9], OPN that we report this time has a higher predictive value than sIL-6R (AUC for predicting SDAI remission by sIL-6R and OPN, 0.63 and 0.70, respectively).