[Use and application in clinical practice of the CASPAR criteria].

Several classification criteria for psoriatic arthritis have been proposed in the literature but it is still unclear which one of them best represents the diseases' ample spectrum. None of these classification criteria have been universally accepted. New classification criteria (CASPAR) have been recently published. Their application is simple, fast and easy to perform. In addition, they show two important qualities. One is that they allow for the diagnosis of psoriatic arthritis even when there is no skin disease present at the moment of diagnosis. The other is is that it enables us to classify a patient as having psoriatic arthritis in spite of a positive rheumatoid factor. The CASPAR criteria have a sensitivity of 91.4% and a specificity of 98.7%. It seems, in contrast, that it is not as high for recent-onset psoriatic arthritis. Therefore establishing the definition of inflammatory arthritis becomes paramount.