Table 1.

Classification criteria for PsA (CASPAR*), after Taylor et al7.

Established inflammatory musculoskeletal disease (joint, spine, or entheseal) with 3 or more of the following.
1. Psoriasis(a) CurrentPsoriatic skin or scalp disease present today as judged by a qualified health professional
(b) HistoryA history of psoriasis that may be obtained from patient or qualified health professional
(c) Family historyA history of psoriasis in a first or second degree relative according to patient report
2. Nail changesTypical psoriatic nail dystrophy including onycholysis, pitting, and hyperkeratosis observed on current physical examination
3. A negative test for RFBy any method except latex but preferably by ELISA or nephelometry, according to the local laboratory reference range
4. Dactylitis(a) CurrentSwelling of an entire digit
(b) HistoryHistory of dactylitis recorded by a qualified health professional
5. Radiological evidence of juxtaarticular new bone formationIll-defined ossification near joint margins (but excluding osteophyte formation) on plain radiographs of hand and foot
  • * The CASPAR criteria have specificity of 98.7% and sensitivity of 91.4%.

  • Patient must accrue ≥ 3 points total: Only one of the 3 subcriteria in criterion 1 may be applied, with 2 points accrued with fulfillment of criterion 1a, and 1 point for fulfillment of either 1b or 1c. Only one of the 2 subcriteria in criterion 4 may be applied, with 1 point for either 4a or 4b. The remaining points may be scored using criteria 2, 3, and 5, each of which may be assigned a score of 1. CASPAR: ClASsification of Psoriatic ARthritis; RF: rheumatoid factor: PsA: psoriatic arthritis.