Assessment of Patients with Psoriatic Arthritis: A Review of Currently Available Measures

To date, specific measures to assess disease activity in PsA have not been validated. The tools used for assessment of psoriatic peripheral joint disease have been "borrowed" from the assessment of RA. While, in general, some of these outcome measures perform well in PsA, the distinct distribution of joint involvement coupled with the unique patterns of synovitis and periarticular inflammation demand that these measures be appropriately and carefully adapted. In order to capture the wide variation that characterizes the clinical presentation seen among patients with PsA, a larger number of joints should be assessed. Moreover, because of the frequency and severity of back involvement in PsA, assessment of spinal mobility and pain is required. Many clinical methods used to assess axial disease in AS have not proven to be reliable, and even measures deemed appropriate in AS require validation in PsA. Specific assessment of common features of PsA, including dactylitis, enthesitis, and tendonitis, requires further study. In addition, available techniques for radiographic evaluation of patients with RA may not fully record the specific changes noted among patients with PsA. Moreover, the utility of newer imaging techniques in the assessment of joint and spinal inflammation in patients with PsA requires further study. Finally, it is important to evaluate whether the same instruments can be used for the various patterns of PsA. Rigorous validation of currently used techniques, combined with the development of new assessment tools, is urgently required to fully assess the therapeutic response in PsA. In our view, a consensus development of a core set of outcome domains, psychometric evaluation of candidate instruments in patients with PsA, and construction of response criteria from clinical trials that have used such instruments constitute the research agenda for PsA