Ultrasound evaluation of muscle quality in rheumatoid arthritis: a reliability study of the Spanish Ultrasound Muscle Assessment in Rheumatoid Arthritis (Spanish Ultrasound Muscle Assessment in RA (SpUMAR)) score
Authors' conclusion
Multiobserver assessment of muscle quality using the SpUMAR score demonstrated acceptable reliability in patients with RA.
Study context
- Population
- Patients with rheumatoid arthritis (RA); static US images of the four bellies of the quadriceps muscle
- Participants
- 57 patients164 US images
- Outcome
- Interobserver and intraobserver reliability of the SpUMAR score for muscle quality
Methodological detailssemiquantitative 0-3 ultrasound score, 15 expert rheumatologists, two scoring rounds
- Semiquantitative 0-3 ultrasound score
- 15 expert rheumatologists
- Two scoring rounds
Main finding
As reported in the abstract
Reliability of SpUMAR
- Interobserver reliability, round 1
- 0.57 [0.54-0.60] (Gwet's AC2 [95% CI]; moderate)
- Interobserver reliability, round 2
- 0.54 [0.51-0.57] (Gwet's AC2 [95% CI]; moderate)
- Interobserver percent agreement, round 1
- 81.76%
- Interobserver percent agreement, round 2
- 80.28%
- Intraobserver reliability between rounds
- 0.66 [0.64-0.68] (Gwet's AC2 [95% CI]; good)
Further findings
Agreement between scores of 20 images with incorrect US settings and their original scores
- Round 1
- 0.27 [0.21-0.33] (κ [95% CI]; poor)
- Round 2
- 0.30 [0.24-0.36] (κ [95% CI]; poor)
Original publication
Ultrasound evaluation of muscle quality in rheumatoid arthritis: a reliability study of the Spanish Ultrasound Muscle Assessment in Rheumatoid Arthritis (SpUMAR) score. Arthritis Res Ther. Published 24 April 2026. doi:10.
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