Objective: The aim of this study was to investigate the characteristics of power Doppler (PD) subclinical synovitis in patients with RA who achieve clinical remission free from physical synovitis.
Methods: Twenty-nine RA patients were consecutively enrolled. All of the patients had achieved clinical remission [simplified disease activity index (SDAI) 3.3] for at least 6 months at the musculoskeletal ultrasound (MSKUS) examination. Additionally, none of the patients exhibited tender joints at 68 sites or swollen joints at 66 sites. MSKUS of bilateral wrist and finger joints, including the first to fifth MCP joints, the first IP joint and the second to fifth PIP joints, was performed and the findings obtained by grey scale (GS) and PD were graded on a semi-quantitative scale from 0 to 3.
Results: The median disease duration upon the introduction of DMARDs was 3 months and that at MSKUS examination was 21 months. The percentages of patients with PD synovitis in at least one joint were PD grade 1, 58.6%; PD grade 2, 31.0% and PD grade 3, 6.9%. The use of biological agents was low in patients with PD synovitis grade 2 (P < 0.05). The presence of US bone erosion was high by patient (P < 0.05) and by joint (P < 0.0001) with PD synovitis as compared with those without PD synovitis. However, no correlations were found between PD synovitis measures and serum biomarkers, including angiogenesis factors.
Conclusion: PD subclinical synovitis correlates with several clinical characteristics, whereas conventional serum biomarkers are not useful for indicating the presence of subclinical PD synovitis.
Keywords: bone erosion; musculoskeletal ultrasonography (MSKUS); remission; rheumatoid arthritis (RA); synovitis.