Diagnostic criteria for psoriatic arthritis (CASPAR)*.
| Established inflammatory musculoskeletal disease (joint, spine, or entheseal), with 3 or more of the following: | |
| 1. Psoriasis | |
| (a) Current† | Psoriatic skin or scalp disease present today as judged by a qualified health professional |
| (b) History | A history of psoriasis that may be obtained from patient or qualified health professional |
| (c) Family history | A history of psoriasis in a first- or second-degree relative according to patient report |
| 2. Nail changes | Typical psoriatic nail dystrophy including onycholysis, pitting, and hyperkeratosis observed on current physical examination |
| 3. A negative test for rheumatoid factor | By any method except latex but preferably by ELISA or nephelometry, according to the local laboratory reference range |
| 4. Dactylitis | |
| (a) Current | Swelling of an entire digit |
| (b) History | A history of dactylitis recorded by a qualified health professional |
| 5. Radiological evidence of juxtaarticular new bone formation | Ill-defined ossification near joint margins (but excluding osteophyte formation) on plain radiographs of hand and foot |