TY - JOUR T1 - To Lump or Split When Assessing Psoriatic Arthritis — Not Mutually Exclusive? JF - The Journal of Rheumatology JO - J Rheumatol SP - 307 LP - 309 DO - 10.3899/jrheum.190867 VL - 47 IS - 3 AU - WILLIAM TILLETT AU - PHILIP HELLIWELL Y1 - 2020/03/01 UR - http://www.jrheum.org/content/47/3/307.abstract N2 - Arguably, the most important advances in modern clinical care have arisen not through the development of new drugs but instead through a recognition that the Gestalt approach to disease assessment is simply not adequate when it comes to selecting and assessing response to therapy. Accurate and regular assessment with an appropriate measurement instrument gives the clinician and patient reliable information to track disease trajectory and make treatment decisions. Achieving consensus on a single disease-specific instrument has considerable advantages, facilitating adoption of international treatment guidelines, and interpretation of data from trials, cohorts, and registries to make translation into routine care seamless1. In the context of rheumatoid arthritis (RA), the 28-joint count Disease Activity Score (DAS28) has been widely adopted as the most frequently used generally continuous measure of activity. The DAS28 has established cutpoints for high, moderate, and low disease activity and remission. The term near remission is increasingly preferred because it better differentiates those with some residual disease from those in true remission. Clinicians are used to the measure and what the numbers mean clinically, and this has allowed a smooth translation of research findings into clinical practice, including the implementation of treat to target and adoption of clinical guidelines. It has been harder to achieve this consensus in the field of psoriatic arthritis (PsA), with no current agreement on the most appropriate instrument to adopt. Why is this the case, and what are the key barriers2?The greatest challenge in the adoption of a composite measure for routine care in PsA has been philosophical: should we incorporate multiple domains of disease into a single measure to identify the totality of disease, or should we focus on 1 domain at a time for accurate assessment and to avoid diluting responsiveness? PsA may manifest in a variety … Address correspondence to W. Tillett, Royal National Hospital for Rheumatic Diseases, Upper Borough Walls, Bath BA1 1RL, UK. E-mail: w.tillett{at}nhs.net ER -