CRP and rheumatoid arthritis: RF and ACPA were significantly increased in autoimmune inflammatory RA vs. OA or ReA (approximately 6-fold (RF) and >350-fold (ACPA), p < 0.001), whereas CRP levels were approximately 3-fold elevated in the RA vs. OA patient group and 8-fold higher in the RA vs. ReA group (Table 1).