Reproducibility and inter-reader agreement of a scoring system for ultrasound evaluation of hip osteoarthritis

To evaluate the intra-reader and inter-reader agreements of ultrasonographic assessments of hip joints in patients with hip osteoarthritis.

Ultrasonography was performed on 100 patients with hip osteoarthritis at 14 MHz using a 8-15 MHz linear probe. Dynamic sweeps of the hip and representative still images were used for the analysis. A semiquantitative grading score was introduced in the evaluation of the ultrasound pictures and compared with an overall ultrasound evaluation. The evaluation was performed by a specialist in ultrasonography and a rheumatologist trained in musculoskeletal ultrasound examination. Clinical pain assessment and joint aspiration were obtained in parallel with the ultrasonography.

Intraobserver agreement represented by intraclass correlation coefficients (ICC) (exact agreement in percentage; unweighted kappa values) showed good to excellent correlation, 0.8 with regard to the osteophyte score, 0.78 with regard to the femoral head score, 0.71 with regard to the fluid score and 0.69 with regard to the synovial profile score. Interobserver agreement was fair to good with corresponding ICC 0.65, 0.63, 0.45 and 0.6, respectively. In comparison, the ICC for the global osteoarthritis and synovial assessments were 0.7 and 0.72, respectively, for the intraobserver rating and 0.56 and 0.58, respectively, for the interobserver rating.

This study suggests that ultrasound is a reproducible method for the assessment of changes in the osseous surface and synovium-related inflammation. The semiquantitative scoring system presented seemed to match the global assessment of a trained ultrasound investigator and might be used by less-trained investigators.