TY - JOUR T1 - The Difficult Task of Assessing Psoriatic Arthritis JF - The Journal of Rheumatology JO - J Rheumatol SP - 2219 LP - 2220 DO - 10.3899/jrheum.151209 VL - 42 IS - 12 AU - ALBERTO CAULI AU - MATTEO PIGA Y1 - 2015/12/01 UR - http://www.jrheum.org/content/42/12/2219.abstract N2 - Psoriatic arthritis (PsA) is a systemic inflammatory condition characterized by musculoskeletal involvement associated with cutaneous psoriasis. The PsA clinical picture is generally dominated by peripheral arthritis with or without inflammatory spinal disease, as well as enthesitis and dactylitis1. Extraarticular features belonging to the spectrum of spondyloarthropathies are also frequently observed, such as uveitis and gut inflammation2. PsA’s heterogeneous clinical spectrum is reflected in its complex pathogenesis, where genes and environmental triggers interfere with the innate and acquired immune system3,4,5,6. On this basis, it is not surprising that the definition of the key domains and instruments for the evaluation of PsA has been, and remains, challenging.The present classification of domains is based on the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) & Outcome Measures in Rheumatology (OMERACT) initiative, which proposed a framework for the long list of possible domains7,8. Three categories of domains of interest were considered: “inner core,” “outer … Address correspondence to Dr. A. Cauli, Department of Medical Sciences, Policlinico of the University of Cagliari, ss 554 Monserrato, 09042 Italy; E-mail: cauli{at}medicina.unica.it ER -