When comparing 25OHD levels with indicators of disease activity (DAS28), impact of the disease [Rheumatoid Arthritis Impact Diseases score (RAID)], and HAQ, the authors found a negative correlation in RA patients: DAS28-CRP (p < 0.001), RAID (p = 0.05), and HAQ (p = 0.04) [57]. This evidence concerns the gene CRP and rheumatoid arthritis.