Psoriatic arthritis: an evolving matter

A STORY OF CLASSIFICATION CRITERIA Several sets of criteria were proposed over the years for classifying psoriatic arthritis. Recent are the CASPAR criteria. The patient must have inflammatory articular disease ( joint, spine or entheses) with three points from the following five categories: (1) evidence of current psoriasis or a personal or familial history of psoriasis; (2) typical psoriatic nail dystrophy; (3) absence of rheumatoid factor; (4) current dactylitis or a history of dactylitis; (5) radiographic evidence of juxta articular new bone formation. A score of 2 is assigned to current psoriasis; all other features are assigned a score of 1. These classification criteria allow the inclusion of many patients and various clinical phenotypes (including axial forms) in a definition of psoriatic arthritis. The question is if psoriatic arthritis fits into the spondyloarthritis frame too. Over the past few years, the ASAS group (Assessment in SpondyloArthritis international Society) developed and proposed new classification criteria for axial and peripheral forms of spondyloarthritis. These classifications allow the recognition of several clinical or phenotypical presentations of the disease: axial spondyloarthritis, radiographic (corresponding to ankylosing spondylitis), nonradiographic; peripheral articular erosive or not erosive, and enthesitis spondyloarthitis. These presentations are somewhat different from the several phenotypic forms of psoriatic arthritis described earlier by Moll and Wright in 1972, but this illustrates that, in current practice, it is more the phenotypic presentation than the nosological classification that matters.