Background/Purpose: Positive for auto-antibodies such as rheumatoid factor (RF) and anti-citrullinated peptide antibodies (CCP) or having high autoantibody titers is associated with the progression of joint destruction in patients with rheumatoid arthritis (RA) (van Steenbergen HW, et al. Ann Rheum Dis. 2015;74:e3. and Hecht C, et al. Ann Rheum Dis. 2015;74:2151-6.). Therefore, we evaluated the relationship between RF or CCP levels and ultrasound synovial findings.

Methods: A total of 750 RA patients who underwent ultrasound examination from January 2017 to August 2020 were continuously included. Ultrasound examination was performed at the of bilateral first to fifth metacarpophalangeal (MCP) joints, first interphalangeal (IP) and second to fifth proximal interphalangeal (PIP) joints, wrist joints (three part of radial, medial and ulnar) and first to fifth metatarsophalangeal (MTP) joints. Both grayscale (GS) and power Doppler (PD) findings were scored to grade 0-3 by a semi-quantitative method, and the sum of GS was defined as the GS score and the sum of PD as the PD score. Patients were classified into a negative group and a positive group according to RF and CCP titers, and the positive group was further classified into quartiles (Q1-Q4) according to those levels, and disease activity and ultrasound synovial findings were compared.

Results: There were 655 cases in the RF positive group and 565 cases in the CCP positive group. RF positive group were divided into quartiles such as Q1: 15 < RF ≤ 72, Q2: 72 < RF ≤ 158, Q3: 72 < RF ≤ 379, Q4: 379 < RF ≤ 8160, and CCP positive group were divided into quartiles such as Q1: 4.5 ≤ CCP ≤ 36.0, Q2: 36.0 < CCP ≤ 95.6, Q3: 95.6 < CCP ≤ 308.0, Q4: 308.0 < CCP. There was no difference in disease duration or disease activity both in the RF and CCP positive group and the negative group, but the ultrasound synovitis scores were significantly worse in both GS and PD score in the positive groups. Among the RF and CCP positive groups, the ultrasound synovitis score tended to be high in the high RF and CCP group, and the highest in the Q4 group.

Conclusion: We evaluated the relationship between RF or CCP levels and ultrasound synovitis. Ultrasound synovial findings were significantly worse in positive group than negative group on both RF and CCP, regardless of disease activity. Moreover, high titer of RF or CCP levels tended to be higher ultrasound synovitis. Patients with high titer of RF or CCP levels should be considered to treat more earlier and intensively.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-level-of-rf-or-anti-ccp-antibody-affect-ultrasound-synovial-findings-in-patients-with-rheumatoid-arthritis/