Correlation between Musculoskeletal Ultrasound Grading and Disease Activity Score 28 in Rheumatoid Arthritis Patients Who Achieved Clinical Remission: A Cross-sectional Study

Abstract Background: Clinical remission in rheumatoid arthritis (RA), defined by conventional measures, may not reflect the complete absence of synovial inflammation. This study aimed to investigate the correlation between musculoskeletal ultrasound (MSK US) findings and Disease Activity Score 28 (DAS28) in RA patients who achieved clinical remission. Materials and Methods: This cross-sectional study included 45 RA patients fulfilling the 2010 American College of Rheumatology criteria who achieved clinical remission (DAS28 <2.6). Patients underwent a comprehensive clinical assessment and MSK US examination of 22 joints, including bilateral wrists, metacarpophalangeal and proximal interphalangeal joints. Synovial hypertrophy (SH) was assessed using Grey-scale ultrasound (B-mode), and synovial vascularity was evaluated using power Doppler (PD). The OMERACT semi-quantitative Szkudlarek scale was used for ultrasound grading. Spearman’s rank correlation coefficient ( r s ) was used to analyse the relationship between DAS28 scores and ultrasound findings. Results: Despite clinical remission, MSK US detected subclinical synovitis in 26.67% of patients. Among patients in DAS28-erythrocyte sedimentation rate (ESR) remission ( n = 28), 17.9% showed SH on B-mode and 10.7% demonstrated positive PD signals. In the DAS28-C-reactive protein (CRP) remission group ( n = 42), 19.0% had SH and 16.7% showed PD positivity. A weak but statistically significant positive correlation was found between DAS28-ESR and combined ultrasound scores ( r s = 0.31, P = 0.039), while the correlation between DAS28-CRP and ultrasound findings was weak and not statistically significant ( r s = 0.26, P = 0.085). Conclusion: MSK US can detect subclinical synovitis in a substantial proportion of RA patients who have achieved clinical remission according to DAS28 criteria. The weak correlation between clinical disease activity measures and ultrasound findings suggests that conventional assessment tools may not fully capture ongoing inflammatory processes. Incorporating MSK US into the routine assessment of RA patients in clinical remission may provide valuable information for treatment decisions and potentially prevent disease progression. It may serve as an adjunct tool for remission assessment by identifying subclinical synovitis in RA patients classified as being in clinical remission.