OP0029 PROSPECTIVE, DOUBLE-BLIND STUDY ON THE VALUE OF HANDHELD MUSCULOSKELETAL ULTRASOUND PERFORMED BY DERMATOLOGISTS FOR DETECTION OF PSORIATIC ARTHRITIS - THE PsoSone STUDY

Abstract

BackgroundThe early diagnosis of psoriatic arthritis (PsA) requires a close interdisciplinary cooperation between rheumatology and dermatology. Recent publications underlined the key role of dermatologists in this process (1). Despite available screening tools like questionnaires, there is a need to increase sensitivity and specificity of diagnostic screening tools for PsA. Musculoskeletal ultrasonography (MSUS) has been shown to be a reliable tool for diagnosing PsA, even in preclinical situations. However, the use of MSUS screening by dermatologists in the early detection of PsA has not been studied so far.ObjectivesThe purpose of this study was to assess the accuracy of early PsA identification by dermatologists who have been previously trained in MSUS utilizing an innovative handheld-ultrasound device (Butterfly IQ).MethodsTwelve dermatologists have been trained in MSUS (2) previously by a newly designed curriculum. Six working at the clinic for Dermatology and Allergology of the University Hospital Bonn, while the remaining six serve in private practices. The MSUS training curriculum focused mainly on detecting joint effusion and synovial hyperperfusion in all joints. After successful training, these colleagues were provided with handheld-ultrasound devices in order to screen 140 psoriasis patients presenting with arthralgia. Dermatologists were asked to determine whether or not the patient had PsA based on the medical history, clinical examination, and GEPARD questionnaire. Subsequently a MSUS exam of up to three painful joints was conducted by the dermatologists using the provided handheld-ultrasound devices. The post MSUS decision was also recorded. All prescreened patients were then referred to blinded board-certified rheumatologists with MSUS certification (EFSUMB level II and III), which repeated medical history, clinical examination and MSUS. We investigated the impact of MSUS on the sensitivity and specificity of early PsA diagnosis by comparing dermatologists’ pre- and post-ultrasound PsA suspicion with the final diagnosis determined by the rheumatologist.ResultsIn total, 140 patients were enrolled. PsA was detected in 24 cases. The sensitivity of dermatologists’ pre-MSUS PsA suspicion was 81.0 %, while the specificity was 54.5 %. After conducting MSUS the sensitivity and specificity changed to 61.9% and 90.9%, respectively. The MSUS findings lead the dermatologists to change their presumed PsA diagnosis in 46 cases, with PsA being ruled out in 45 of them.ConclusionWe were able to demonstrate that targeted MSUS performed by dermatologists increases specificity while decreasing sensitivity, perhaps leading to fewer referrals to rheumatologists and an earlier diagnosis of PsA.