Assessment of disease activity with simplified joint ultrasonography method in rheumatoid arthritis patients

Abstract

Background/Aim: Ultrasound (US) is a highly useful tool for assessing the disease activity of rheumatoid arthritis (RA). On the other hand, examining all joints could be time-consuming and unfeasible. Defining the number of joints and which joints should be tested is essential to accurately measuring RA activity. Several simplified US methods are undergoing development for this purpose. The aim of this study was to assess the correlation between simplified 12-joint US findings and physical examination findings/disease activity in RA patients. Methods: This cohort study included 62 RA patients who had been undergoing treatment for at least three months. Multiplanar grayscale images and power Doppler (PD) of the 12 joints (bilateral elbow, wrist, second and third metacarpophalangeal [MCP] joints, knee, and ankle) were acquired and compared with clinical assessments. Disease activity was assessed using the clinical disease activity and simplified disease activity indices and disease activity score-28 (CDAI, SDAI, and DAS28, respectively). Synovial effusion, synovial proliferation, and PD US scores were calculated for 12 joints. Correlations between US scores and disease activity, clinical examination, and acute phase reactants were assessed. Results: The number of joints with PD activity and US total and US synovial proliferation scores showed weak correlations with clinical activity scores (r = 0.25, r = 0.26, and r = 0.28 for SDAI and r = 0.23, r = 0.26, and r = 0.28 for DAS28, respectively). The CDAI did not present any statistically significant correlations. The agreement between US findings and clinical joint examination was generally weak. PD activities of the second MCP joints (r = 0.84, P < 0.01) and knees (r = 0.42, P < 0.01) mostly correlated with clinical examination although it was weakly correlated at the third MCP (r = 0.152) and wrist (r = 0.148), and not correlated at the elbow (r = 0.125). Conclusion: The weak correlation between US findings and clinical examination/disease activity suggests that clinical examination alone may not be sufficient to determine joint inflammation and disease activity. US could provide a more accurate assessment of RA patients and aid in medication selection.