TY - JOUR T1 - The Challenge and Need of Defining Axial Psoriatic Arthritis JF - The Journal of Rheumatology JO - J Rheumatol SP - 2633 LP - 2634 DO - 10.3899/jrheum.091023 VL - 36 IS - 12 AU - JOSÉ LUIS FERNÁNDEZ-SUEIRO Y1 - 2009/12/01 UR - http://www.jrheum.org/content/36/12/2633.abstract N2 - Psoriatic arthritis (PsA) is a complex rheumatic disease in terms of clinical evaluation; joint polymorphism and the presence of dactylitis, enthesitis, and skin and nail involvement contribute little to clarifying the best definition for clinical evaluation1.Although the CASPAR criteria were developed with the aim of achieving wide consensus on the classification of PsA, several points within these criteria were left unresolved2. By definition, according to these criteria, a patient can be classified as having PsA if there is an inflammatory musculoskeletal disease, including peripheral arthritis, spinal disease, or enthesitis, together with other characteristic features of PsA.Spinal involvement has long been recognized in PsA (axPsA). Since early descriptions recognizing inflammatory back disease as one of the patterns of joint involvement in PsA, several reports have dealt with the issue of PsA spinal involvement3. The prevalence of involvement varies due to the lack of an accepted definition of spinal involvement in axPsA; according to several reports, spinal involvement in patients with PsA ranges from 25% to 70% of cases4⇓–6.Despite these limitations, recent work has demonstrated that, if the spine is involved, several measurements borrowed from … Address correspondence to Dr. J.L. Fernández-Sueiro, Rheumatology Division, Hospital Universitario Juan Canalejo, C/ Xubias, 84, 15006, La Coruña, Galicia, Spain. E-mail: L.sueiro{at}canalejo.org ER -