A multiple regression analysis revealed a significant positive association between the anti-PPAD IgG titers and changes in the DAS28-CRP at 6 months later (P = 0.006, odds ratio = 0.39, 95% confidence interval = 0.18 to 1.00), after adjusting for age, gender, smoking, periodontal condition, and RA-related SNPs (Table 6). This evidence concerns the gene CRP and rheumatoid arthritis.