Objectives: To investigate the optimal number and combination of joints to be assessed by power Doppler ultrasonography (PDUS) in daily practice for rheumatoid arthritis (RA).
Methods: PDUS were performed in 24 joints, including all proximal interphalangeal, metacarpophalangeal (MCP), and bilateral wrist and knee joints in 234 patients with RA. PD signals were scored semiquantitatively from 0 to 3 in each joint, and total PD score-24 was calculated by summing them up as comprehensive assessment.
Results: Positive PD signals were more frequently found in bilateral wrist, knee, and the second and third MCP joints than the other joints. The individual PD scores of these 8 joints also showed higher correlation coefficients with total PD score-24 (rs ≥ 0.4). Among the sum PD scores of various selected joint combinations, the score of the combination of 8 joints (total PD score-8), including bilateral second and third MCP, wrist, and knee joints, showed the highest sensitivity and negative predictive value (98.1% and 96.2%, respectively). Total PD score-8 showed high correlation with the total PD score-24 (rs = 0.97, p < 0.01).
Conclusions: Total PD score-8 is simple and efficient enough for monitoring disease activity and judging imaging remission of RA in daily practice.
Keywords: Power Doppler; Rheumatoid arthritis; Ultrasound.