CRP and rheumatoid arthritis: One hundred sixteen (89.9%) RA-SS patients were RF positive, and 117 (90.7%) were ACPA positive, with the median age, RA duration, and DAS28-CRP at the first visit of 51 (IQR 45–61) years, 24 (IQR 8–120) months, and 3.86 (IQR 2.78–4.74), respectively, corresponding to those of RA-noSS patients with 75.6%, 86.7%, 55 (IQR 46–64) years, 24 (6–84) months, and 3.81 (2.9–4.91) (Table 1, Table S1).