To investigate the optimal number and combination of joints to be assessed by power Doppler ultrasonography (PDUS) in daily practice for rheumatoid arthritis (RA).
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.
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).
Total PD score-8 is simple and efficient enough for monitoring disease activity and judging imaging remission of RA in daily practice.