CRP and rheumatoid arthritis: Since AP [like other bone metabolism markers like procollagen type 1 N-terminal propeptide (P1NP) or C-terminal telopeptide (CTX)] correlates with RA disease activity [35, 36], this decline may reflect both improved bone homeostasis and a control of the inflammatory activity of RA, which is consistent with reductions in DAS28-CRP and cDAI scores.