Examination of Intra and Interrater Reliability with a New Ultrasonographic Reference Atlas for Scoring of Synovitis in Patients with Rheumatoid Arthritis

Objective: Synovitis in patients with rheumatoid arthritis (RA) may be scored semiquantitatively (0-3) for B-mode (BM) and power Doppler (PD) ultrasonography. The objective was to assess the reliability of BM and PD examinations with a novel ultrasonographic atlas as reference.

Methods: Representative ultrasound images (including scores 0-3) of BM and PD from 24 different joints were collected to develop an ultrasonographic atlas. Ten RA patients were assessed twice by five rheumatologists performing BM and PD scoring (0-3) of 16 joints bilaterally (metacarpophalangeal 1-5, wrist (radiocarpal, intercarpal, radioulnar), elbow, knee, talocrural and metatarsophalangeal 1-5), with the novel ultrasonographic atlas as a reference.

Results: The median (range) percentages of exact agreements for BM/PD assessments were 73.1 (70.3-80.6)/83.7 (76.7-87.6) and for close agreement 98.1 (96.2-99.7)/98.0 (96.8-98.4) with weighted κ values of median (range) 0.77 (0.70-0.83) for BM and 0.83 (0.73-0.86) for PD. The intrarater intraclass correlation coefficients (ICC) for BM/PD scores were 0.95 (0.93-0.99)/0.97 (0.95-0.99) and interrater ICC were 0.95 (0.86-0.99)/0.97 (0.94-1.00). Scoring of 32 joints was completed in median 15 min (range 12-20).

Conclusion: With the use of an ultrasonographic atlas as reference high intra and interrater reliability was found for BM and PD scoring. This novel atlas may be a useful resource in clinical practice and research.