To analyze the clinical characteristics of anti-cyclic citrullinated peptide (CCP) antibody-negative rheumatoid arthritis (RA) patients.

To retrospectively analyze the medical records of RA patients hospitalized in the department of rheumatology and immunity of Peking University Third Hospital from January 2013 to December 2018, we collected the baseline characteristics, joint manifestations, extra-articular manifestations, and laboratory parameters of RA patients, and compared the differences between anti-CCP antibody-negative patients and anti-CCP antibody-positive patients by U test and chi-square test.

A total of 486 RA patients were included in this study, including 153 anti-CCP antibody-negative patients (31.5%) and 333 anti-CCP antibody-positive patients (68.5%). Compared with anti-CCP antibody-positive group, anti-CCP antibody-negative group had shorter disease course (U=-4.750, P<0.01) and the pro-portion of morning stiffness, shoulder or elbow joint involvement, and hand arthritis (P<0.05) was lower, while the incidence of phlebothrombosis of leg (χ²=4.100, P=0.043) was higher, as well as thrombocytosis (U=-2.179, P=0.029) and elevation of CRP (U=-2.154, P=0.03). Subgroup analysis based on RF showed that CCP RF⁺ group had higher percentage of women (P=0.042) and higher incidence of interstitial lung disease ( χ²=5.652, P=0.017) and secondary Sjögren's syndrome (χ²=11.211, P=0.001), compared with CCP RF^- group.

anti-CCP antibody-negative-patients have similar clinical char-acteristics with anti-CCP antibody-positive group, but the involvement of shoulder or elbow joint and hand arthritis are less common in anti-CCP antibody-negative group. Meanwhile the incidence of phlebothrombosis of leg is higher, and the level of platelet(PLT) and C-reactive protein (CRP) is higher, suggesting that anti-CCP antibody-negative RA may have more vident inflammatory response.

Arthritis, rheumatoid; Anti-cyclic citrullinated peptide antibody; Clinical characteristics