RMD Open
Data collection For all participants, data were collected on age, sex, body mass index (BMI), comorbidities and current and past medications. Moreover, erythrocyte sedimentation rate, C reactive protein (CRP) and human leucocyte anti- gen-B27 were collected in patients with SpA. Clinical assessment Arthritis was evaluated using a 68-tender joint count (TJC-68) and a 66-swollen joint count (SJC-66). Enthesitis was assessed using the Spondyloarthritis Research Consortium of Canada (SPARCC) score 13 and the Maastricht Ankylosing Spondylitis Enthesitis Score (MASES). 14 For disease activity assessment, the following indices were recorded: the Disease Activity Score in 28 joints (DAS28-CRP) in all patients with SpA; the Ankylosing Spondylitis Disease Activity Score (ASDAS), the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), the Bath Ankylosing Spondylitis Functional Index and the Bath Ankylosing Spondylitis Metrology Index (BASMI) in patients with axSpA and the Disease Activity in Psori- atic Arthritis (DAPSA) score in patients with PsA. In addition, the Health Assessment Questionnaire (HAQ) 15 was completed by all patients with SpA. All participants completed the Global Physical Activity Questionnaire (GPAQ), 16 the short form-12 health survey (SF-12) 17 and the Fibromyalgia Rapid Screening Tool (FiRST). 18 US examination The US examination was performed by one of six board- certified rheumatologists, each with at least 10 years of experience in musculoskeletal US, and all are members of the Swiss SONAR group (https://www.irheuma.com/ de/rheumatology-a-z/s/sonar). Investigators performed the US evaluation on the same day as the clinical exam- ination. US assessment protocol This included a minimum of 22 joints (11 joints bilat- erally) in accordance with the ‘psoriatic arthritis sono- graphic 22-joint (PsA-Son22)’ score. 10 Moreover, any clinically tender or swollen joint was also examined by US. The standard 22 joints included: wrists, metacar- pophalangeal (MCP) joints 2, 3 and 5, proximal inter- phalangeal (PIP) joints 2–3, distal interphalangeal (DIP) joints 2–3, knees, metatarsophalangeal (MTP) joint 1 and foot PIP3 in a standardised manner according to European Alliance of Associations for Rheumatology (EULAR) and SONAR guidelines (for more details, see online supplemental file). 19 20 Ultrasonographic evaluation and grading were performed in adherence to the definitions established by the Outcome Measures in Rheumatology (OMERACT) US working group. 19 All joints were assessed by grey- scale ultrasound (GSUS) and power Doppler ultrasound (PDUS) for synovial hypertrophy (SH) and PD, respec- tively, and each lesion was scored individually according to the OMERACT semi-quantitative scale (range 0–3).
have reported a prevalence of arthritis ranging from 18% to 58% in axSpA. 5 Hence, accurate assessment of syno- vitis in both PsA and axSpA is crucial and standardisation is therefore essential. Power Doppler (PD) and B-mode (greyscale (GS)) US are more sensitive methods for detecting synovitis, tenosynovitis and enthesitis compared with clinical examination. 6 In addition, the US can evaluate disease activity and response to therapy more objectively, potentially allowing for more judicious adjustment of immunosuppressive medications. 7 However, there is no current consensus regarding the specific joints that should be examined by US for the evaluation of synovitis in SpA—both PsA and axSpA. 8 Since US examination can be time-consuming if applied to a large number of joints, identifying the minimal optimal combination of joints for US evaluation is crucial. 9 Several scores have been proposed for joint US assess- ment in patients with PsA, while no studies have evaluated the small peripheral joints in patients with axSpA. 10–12 Developing a fast and practical US scoring of synovitis for patients with PsA and axSpA that could be used in both interventional trials and clinical practice requires the evaluation of the lowest number of joints, while retaining high specificity for SpA. Moreover, the speci- ficity of a synovitis score in patients with axSpA compared with healthy individuals is unknown, particularly as mechanical stress and ageing might induce comparable changes in otherwise immunologically healthy persons. Given these unmet needs, the main aim of this research was to examine which combination of joints best discrim- inates between patients with SpA and healthy controls (HC). Consequently, we propose a concise and feasible joint US score (SONography in Arthritis and Rheuma- tism (SONAR)-7) for use by clinicians in daily practice. Thereafter, we aimed to assess the diagnostic perfor- mance of this US score, as well as its associations with disease activity measurements, in comparison with previ- ously published US scores.
PATIENTS AND METHODS Study population
This cross-sectional, multicentre study was conducted across Switzerland at six hospital rheumatology clinics. Patients with SpA registered within the Swiss Clinical Quality Management in Rheumatic Diseases (SCQM) registry were included in the study if they fulfilled either the Assessment of SpondyloArthritis International Society criteria or the Modified New York criteria for axSpA or the ClASsification criteria for Psoriatic ARthritis for PsA. Participants aged <18 years, HC with any inflammatory rheumatic disease, patients with SpA with another rheu- matic disease, patients with prior joint replacements or prosthetic implants and pregnant or breastfeeding women were excluded.
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Elsehrawy GG, et al . RMD Open 2026; 12 :e006802. doi:10.1136/rmdopen-2026-006802
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