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Table 5 Association between the inflammatory score (GS and PD synovitis) for each joint region and a diagnosis of SpA Univariable Multivariable* Multivariable† OR 95% CI P value OR 95% CI P value OR 95% CI P value Joint region Wrist 1.43 1.02 to 2.1 0.052 Hand MCP2 1.43 1.0 to 2.2 0.077 Hand MCP3 1.56 0.9 to 2.6 0.073 Hand MCP5 1.40 0.8 to 2.5 0.22 Hand PIP2 1.19 0.7 to 1.99 0.48 Hand PIP3 0.95 0.6 to 1.4 0.83 Hand DIP2 2.33 1.4 to 4.3 0.002 1.99 0.96 to 4.57 0.07 2.49 1.39 to 5.05 0.004 Hand DIP3 2.03 1.2 to 3.4 0.004 1.37 0.72 to 2.84 0.34 Knee 3.30 1.5 to 12.0 0.019 3.23 1.34 to 12.4 0.02 3.43 1.41 to 13.50 0.025 Foot MTP1 1.24 1.02 to 1.5 0.046 1.0 0.78 to 1.30 0.94 Foot PIP3 1.38 0.6 to 3.1 0.38 Demographics Age 0.98 0.94 to 1.03 0.59 0.98 0.94 to 1.03 0.65 BMI 1.25 1.10 to 1.46 0.001 1.25 1.10 to 1.45 0.001 *Included only the sites with p value <0.05 in the univariable analysis. Values highlighted in bold are statistically significant. †Included the sites that were associated with the diagnosis of SpA in the LASSO model. Multivariable analyses were adjusted for age and BMI. BMI, body mass index; DIP, distal interphalangeal; GS, greyscale; LASSO, Least Absolute Shrinkage and Selection Operator; MCP, metacarpophalangeal; MTP, metatarsophalangeal; PD, power Doppler; PIP, proximal interphalangeal; SpA, spondyloarthritis.
Feasibility and inter-rater reliability The median time to complete the SONAR-7 score was 10 min. Inter-rater reliability was assessed by two coau- thors on a random sample of 23 study participants, including a total of 200 joint images. Using Cohen’s kappa, agreement was excellent for B-mode synovitis ( κ =0.83) and near perfect for Doppler signal ( κ =0.92). For NBF, Cohen’s kappa was 0.54, while prevalence- adjusted bias-adjusted kappa was 0.89, reflecting high agreement despite the low prevalence of NBF. DISCUSSION Musculoskeletal US is becoming increasingly used in patients with SpA for diagnostic and prognostic purposes. However, joint US examination can be time-consuming, and there is currently no consensus on the number of joints to be examined and which specific sites should be assessed during sonographic evaluation of synovitis in PsA and axSpA. We hereby describe a new fast and effi- cient US score that includes the seven peripheral joints with the highest specificity for a diagnosis of SpA. Several studies of peripheral joint US in patients with SpA employed US scores developed for rheumatoid arthritis (RA), such as the German US7, which excluded key SpA joints, such as the DIP joints. 24 Previous joint US scores in patients with PsA include the Sonography in Large Joints in Rheumatology score, which only eval- uated the large joints (shoulder, elbow, knee and hip) and the ‘five targets power Doppler for psoriatic disease’
score, which scored only a single anatomical site per target domain, resulting in potential underestimation of the total disease burden in patients with widespread involvement. 11 12 In 2014, Ficjan et al proposed a reduced US synovitis score ‘PsA-Son22’ that demonstrated good sensitivity and feasibility in PsA; however, it has not been validated in other series or in axSpA. 10 25 To the best of our knowledge, this is the first study comparing the char- acteristics of joint US synovitis between patients with PsA and axSpA. Previous studies have focused on PsA and studies in patients with axSpA only evaluated the large joints, such as the hip, shoulder, foot or ankle, without assessment of any of the smaller joints. Regarding the prevalence and distribution of lesions, our study demonstrated that abnormal synovial thick- ening was observed in a significantly higher percentage of joints in patients with SpA versus HC (31.1% vs 19.2% of joints). Both SpA subgroups showed comparable inflammatory joint US features (B-mode and Doppler), an aspect that has not previously been described in the literature. While the PsA group had higher SJC than the axSpA group, both groups showed comparable TJC. Other studies have reported a higher percentage of SH (52%–60%) in PsA. 26 27 The lower proportions of inflam- matory findings in the current study may be related to the fact that almost 85% of patients with SpA were currently treated with a biologic disease-modifying antirheumatic drug (DMARD) and 12.1% were on a targeted synthetic DMARD, which could have led to a significant reduction
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Elsehrawy GG, et al . RMD Open 2026; 12 :e006802. doi:10.1136/rmdopen-2026-006802
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