Prospective double-blind study on the value of musculoskeletal ultrasound by dermatologists as a screening instrument for psoriatic arthritis

Abstract Objectives This study evaluated musculoskeletal ultrasound (MSUS) use by dermatologists previously trained on a novel handheld, chip-based ultrasound device (HHUD) to screen for early PsA. Methods Twelve dermatologists were recruited to screen psoriasis patients for PsA using the novel HHUD in one major hospital in Bonn (Germany) and six private practices in surrounding regions. Patient screening was based on medical history, clinical examination, and the GEPARD questionnaire paired with an MSUS examination of up to three painful joints. All screened patients were then referred to rheumatologists, who determined the final diagnosis. The screening effect of MSUS was assessed according to its sensitivity and specificity before and after its application. Results Between 1 October 2020 and 26 May 2021, a total of 140 psoriasis patients with arthralgia participated in this study. PsA was diagnosed in 19 (13.6%) cases. Before applying MSUS, dermatologists’ screening sensitivity and specificity were recorded as 88.2% and 54.4%, respectively, while after applying MSUS the sensitivity and specificity changed to 70.6% and 90.4%, respectively. MSUS led to a change of PsA suspicion in 46 cases, with PsA no longer being suspected in 45 of them. Conclusion This study was able to demonstrate that PsA screening using MSUS by previously trained dermatologists can lead to more precise PsA detection and potentially decreased rheumatologist referral rates.