PO:06:082 | Correlation between ultrasonographic parameters and the Krenn synovitis score in patients with chronic infiammatory arthropathy undergoing ultrasound-guided synovial biopsy: a prospective cohort study

Maria Capita¹, Carlo Garaffoni¹, Marianna Tamussin¹, Serena Ceccato¹, Giovanni Lanza², Alessandra Bortoluzzi¹, Marcello Govoni¹, Ettore Silvagni¹ | ¹Unità di Reumatologia, Azienda Ospedaliero - Universitaria S. Anna, Cona (FE); ²Anatomia Patologica, Dipartimento di Medicina Traslazionale Università di Ferrara, Cona (FE), Italy

Background. The aim of this study is to analyze, in a cohort of patients with chronic inflammatory arthropathy, the correlation between ultrasonographic parameters and the Krenn Synovitis Score (KSS) – a validated semi-quantitative scale for the histological classification of synovitis, used to evaluate the degree of synovial inflammation.

Materials and Methods. We included patients aged ≥18 years with a diagnosis of RA, according to the 2010 ACR/EULAR classification criteria, or PsA, according to the CASPAR criteria, were recruited. Eligible participants were required to be candidates for initiation or modification of DMARD therapy and to have complete ultrasonographic data at baseline, defined as a polyarticular assessment using the Global OMERACT–EULAR Synovitis Score (GLOESS) and ultrasound evaluation of the biopsy site. Each patient underwent an ultrasound-guided synovial biopsy of a clinically involved joint (knee or wrist). Synovial tissue specimens were evaluated by an experienced pathologist to determine the KSS. Statistical analyses were conducted using Spearman’s rank correlation coefficient, a non-parametric measure of association.

Results. A total of 63 patients were evaluated (58 with RA and 5 with PsA). Among them, 92% (58/63) had failed at least one csDMARD, and 51% (32/63) had failed at least one b/tsDMARD. The mean (SD) polyarticular GLOESS value was 15 (12), while the median (IQR) KSS was 6 (4.00, 6.00) (Table 1). GLOESS (rho = 0.23, p = 0.013), gray-scale (GS) intensity (rho = 0.35, p < 0.001), and the degree of joint effusion (rho = 0.27, p = 0.004) at the biopsy site showed a positive correlation with the KSS (Figure 1). Regarding the KSS sub-items, a positive correlation was observed between all ultrasound variables and the degree of inflammatory infiltrate on histological examination (rho = 0.38, p < 0.001 for GS; rho = 0.30, p = 0.002 for effusion; rho = 0.23, p = 0.014 for PD). No statistically significant correlation was found between Power Doppler (PD) signal intensity of the examined joint and the overall KSS (rho = 0.16, p = 0.1), lining score (rho = 0.10, p = 0.3), or stroma score (rho = –0.05, p = 0.6).

Conclusions. In the examined patient cohort, a positive correlation was observed between the polyarticular GLOESS score and the KSS, as well as between ultrasonographic parameters at the biopsy site and the degree of inflammatory infiltrate on histological assessment. Moreover, only specific ultrasound variables such as gray-scale intensity and the extent of joint effusion at the biopsy site showed a positive correlation with KSS, whereas no such correlation was confirmed for the Power Doppler (PD) signal. These findings, together with the rho values indicating a weak correlation, suggest that synovitis is influenced by factors not fully identifiable through ultrasound assessment alone, supporting the role of KSS and synovial biopsy as valuable tools for a more accurate characterization of chronic inflammatory arthropathies.