CRP, CRPM and covariates were able to separate OA from E-RA (Fig. 2) with AUCs of 0.73, 0.81 and 0.83, and OA from MS-RA with AUCs of 0.88, 0.90 and 0.87 (Table 3, Fig. 2). Here, CRP is linked to rheumatoid arthritis.