PO:04:051 | Application of REMS in the assessment of fragility score and bone mineral density in axial spondyloarthritis and psoriatic arthritis with axial involvement

Silvia Valentini¹, Stefano Gentileschi¹, Pamela Bernardini², Jurgen Sota¹, Caterina Baldi¹, Sara Torracchi², Daniela Melchiorre², Sabrina Aliberti², Emilio D'Ignazio¹, Carla Caffarelli³, Luca Cantarini¹, Serena Guiducci², Bruno Frediani¹ | ¹UOC Reumatologia, Dipartimento di Scienze mediche, chirurgiche e neuroscienze, Università degli Studi di Siena; ²SOD Reumatologia, Dipartimento di Medicina Sperimentale e clinica, Università degli studi di Firenze, AOU Careggi; ³UOC Medicina Interna e della Complessità, Dipartimento di Scienze Mediche, chirurgiche e neuroscienze, Università degli Studi di Siena, Italy

Abstract

Background. Axial spondyloarthritis (axSpA) and axial psoriatic arthritis (axPsA) are known to differ in imaging features (radiography and magnetic resonance imaging) and treatment response. These conditions may also present differences in bone mass quality and bone mineral density (BMD). Radiofrequency Echographic Multi Spectrometry (REMS) is an emerging technique for bone assessment that analyzes raw, unfiltered ultrasound signals acquired during scanning of the lumbar spine and proximal femur. Unlike conventional DXA, REMS minimizes artifacts from ectopic calcifications such as syndesmophytes and osteophytes, commonly observed in these diseases. This study aimed to compare T-scores obtained with REMS and DXA to evaluate REMS reliability in assessing BMD in axSpA and axPsA, and to explore qualitative and quantitative differences in bone mass between these patient cohorts.

Materials and methods. Adult patients admitted to the Rheumatology Unit of AOU Senese and Florence Careggi were included. Participants had a confirmed diagnosis of axSpA or axPsA and were receiving treatment with biological disease-modifying antirheumatic drugs (bDMARDs) or Janus kinase inhibitors (JAKi). Patients with a prior diagnosis of osteoporosis, ongoing osteoporosis treatment or previous vertebral fractures were excluded. All patients underwent lumbar spine and femoral DXA as well as REMS scans in the same anatomical sites. BMD and Fragility Score were compared between groups. A variable (Δ) was defined as the difference between REMS and DXA T-scores at the lumbar spine and femur.

Results. Twenty-five patients were enrolled (13 axSpA; 12 axPsA) with comparable age and sex distribution. No significant differences in Δ T-scores at the lumbar spine and femur were observed compared to the general population. Concordance between REMS and DXA T-scores was assessed in relation to diagnosis (axSpA vs PsA), BMI and age. For the lumbar spine, T-score concordance was not statistically significant (p = 0.606); whereas femoral measurements showed significant concordance (p = 0.003), although the intraclass correlation coefficient (ICC) was below an acceptable range. No significant Δ differences were observed according to diagnosis or BMI at either site. A negative correlation between age and femoral Δ was noted (p = 0.02).

Conclusions. Consistent with limited existing literature, REMS demonstrates potential reliability for qualitative and quantitative assessment of bone mass in patients with axSpA and axPsA at the lumbar spine. Regarding the femur, REMS-DXA concordance did not show significant differences, highlighting the need for further validation in larger cohorts.

Keywords

• REMS
• DEXA
• Axial spondyloarthritis