If PsA is not identified classification criteria for rheumatoid arthritis and managed appropriately, progressive joint damage with deformities and disability may result. Several classification criteria have been proposed, but none have been widely accepted or validated. The CASPAR criteria permit the diagnosis of PsA in spite of low rheumatoid factor positivity. They offer classification criteria that are simple and easy to use with a high degree of specificity and good sensitivity.
PsA often is missed in primary care physicians’ and dermatologists’ offices. The quality of life in patients who have PsA is reported to be much worse than in those who have only psoriasis. The advent of effective new therapies, such as biologic agents, has made widely accepted and validated classification criteria imperative for PsA research trials to be meaningful. This is the fifth article in a series on new or modified classification and diagnostic criteria for various rheumatologic conditions. ACR diagnostic criteria for fibromyalgia syndrome and their modification as survey criteria. In this article, we describe the classification criteria for PsA. The Moll and Wright Classification Criteria for PsA, proposed in 1973, are the oldest and best known.
Several other classification criteria had been proposed over the years, but none have been widely accepted or validated. With the Moll and Wright criteria, patients who had cutaneous psoriasis and musculoskeletal involvement, such as dactylitis, enthesitis, and tendinitis, could not be classified as having PsA. The lack of universally accepted criteria had hampered clinical research in PsA—variability in case identification led to heterogeneous study populations, making interpretation and application of study results difficult. In addition, the exact prevalence of PsA had been difficult to estimate because accepted diagnostic and classification criteria were lacking. 2004 to develop a new set of validated classification criteria. Patients were consecutively enrolled from more than 30 rheumatology clinics in 13 countries—588 patients with PsA and 536 controls with other forms of inflammatory arthritis matched for approximate disease duration. Data were collected prospectively to compare existing classification criteria and derive new classification criteria for PsA.