Evaluation of the novel ultrasound score for large joints in psoriatic arthritis and ankylosing spondylitis: six month experience in daily clinical practice

BACKGROUND: To evaluate the utility of the recently introduced SOLAR score (sonography of large joints in Rheumatology), which has been validated in RA patients, in a cohort of patients with Psoriatic Arthritis (PsA) and Ankylosing Spondylitis (AS) presenting with involvement of large peripheral joints. METHODS: The recently established SOLAR score has been designed to determine the degree of inflammation in the shoulder, the elbow, the hip and the knee joint in patients suffering from RA. Since large joints are frequently involved in PsA and AS, synovitis and synovial vascularity were scored semiquantitatively (grade 0–3) by grey scale (GSUS) and power Doppler ultrasound (PDUS) utilizing the validated scoring system. Each joint was scanned from different angles, the knee joint for example was divided into four areas to score for synovitis: the suprapatellar longitudinal, the medial longitudinal, the lateral longitudinal, and the posterior region. Each area was scored from 0–3, so a maximum score of 12 could be achieved. PsA and AS patients presenting with peripheral joint disease involving large joints were examined at baseline, 3 and 6 months after initiation of local or systemic therapy (DMARDs/Biologics). For evaluation of the inflammatory status, the erythrocyte sedimentation rate (ESR) was determined. RESULTS: A cohort of 126 patients were enclosed, and 83 of these were followed for 6 months. At baseline before modification of the therapy, patients received DMARDs (n = 83), DMARDs plus biologics (n = 30), or biologic monotherapy (n = 29). Following intervention, all US scores demonstrated a marked improvement. The GSUS and the PDUS scores for all joint areas, except the PDUS score of the hip, exhibited a significant improvement (p < 0.05), while the GSUS of the knee showed even a highly significant (p < 0.001) change. The ESR displayed a significant decrease from 27 to 19 mm (p < 0.002) representing good treatment response. CONCLUSION: The SOLAR score, which has been recently introduced for RA patients, is a very suitable instrument for the qualitative and quantitative evaluation of large joint involvement in PsA and AS patients and allows for treatment monitoring.