CRP and rheumatoid arthritis: A study focused on deciphering if the cytokine profile found in RA patients serum changed over the course of the disease showed that, 3 months after the initial diagnosis, IL-1β was positively correlated with two of the acute phase inflammatory reactants: CRP (C reactive protein) (R2 = 0.642) and ESR (erythrocyte sedimentation rate) (R2 = 0.579) [99].