Subgroup analysis by region showed significant differences in CRP concentrations between RA-ILD and RA groups in Asia (MD = 9.98; 95% CI: 0.06-19.89; P = 0.05), Europe (MD = 5.98; 95% CI: 2.58-9.39; P < 0.001), and Africa (MD = 8.10; 95% CI: 3.02-13.19; P < 0.001), but not in the Americas (MD = 12.18; 95% CI: -8.22-32.57; P = 0.24). This evidence concerns the gene CRP and rheumatoid arthritis.