Core items to be included in a definition of moderate psoriatic arthritis: literature review and expert opinion

Evidence-based treatment recommendations for psoriatic arthritis (PsA) suggest that treatment should be individualised but acknowledge the difficulty of correctly defining levels of activity (mild, moderate and severe). The aim of this study was to define the parameters or disease characteristics that should be included in a future definition of moderate PsA. Mixed. methods: (1) literature review to identify previous assessment tools used to classify patients into mild, moderate and severe forms, and (2) survey of rheumatologists, and experts in PsA, to obtain their opinion on the degree of validation and applicability of published definitions and tools, and on the parameters that should be included in a future definition of moderate PsA. We propose eight domains/items to be included in a definition of moderate PsA: number of active joints and inflamed entheses, physician global assessment (by visual analogue scale), dactylitis, body surface area (BSA) affected by psoriasis, psoriasis in special locations, and absence of hip involvement. The Disease Activity Index for Psoriatic Arthritis (DAPSA) score would be supported as part of this definition, as would the Psoriatic Arthritis Impact of Disease (PsAID) index. This study proposes a set of items/domains to be included in a definition of moderate PsA based on literature and expert opinion, which can be the starting point for further development and validation studies of the proposed items.