Specialized dermatological-rheumatological patient management improves diagnostic outcome and patient journey in psoriasis and psoriatic arthritis: a four-year analysis

BACKGROUND: Management of psoriasis patients with arthralgia suffering from suspected psoriatic arthritis (PsA) requires an interdisciplinary approach involving dermatologists and rheumatologists. The aim of the study was to analyze the specialized dermatological-rheumatological management of these patients before and after foundation of a PsA center. METHODS: A retrospective cohort study of all dermatological-rheumatological consultations during two periods was conducted. Period one, from April 1st, 2016 to February 28th, 2018 versus period two, from March 1st, 2018 to January 31st, 2020, after foundation of a PsA center. Clinical data on patient characteristics including psoriasis subtypes, clinical symptoms and signs, disease activity scores, classification criteria and comorbidities as well as patient journey were extracted and analyzed. RESULTS: Four hundred four consultations were studied. Close collaboration in a PsA center lead to a relevantly shortened patient journey concerning rheumatological complaints: period 1: median (IQR): 36.0 (10.0–126.0) months, period 2: median (IQR): 24.0 (6.0–60.0) months. Established scores and classification criteria such as GEPARD or CASPAR did not assist in diagnosis of PsA. Arthralgia (p = 0.0407), swollen joints (p = 0.0151), morning stiffness (p = 0.0451) and dactylitis (p = 0.0086) helped to distinguish between osteoarthritis and PsA. CONCLUSIONS: Clinical signs and symptoms, scores and classification criteria usually assessed were less helpful than expected in diagnosis of PsA. Close collaboration in a specialized PsA center yielded the fastest way of diagnosis.