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CASPAR Criteria for Psoriatic Arthritis: Diagnostic Guidelines and Application

CASPAR Criteria (ClASsification Criteria for Psoriatic ARthritis)

Developed 2006; validated internationally. Used for clinical trial enrollment and clinical diagnosis support.

Entry Requirement

Inflammatory articular disease (joint, spine, or entheseal)—past or present.

Criteria Items (Need ≥3 Points)

CriterionPointsDetails
Current psoriasis2Active psoriatic skin/nail lesion judged by rheumatologist/dermatologist
Personal history of psoriasis1Patient-reported; confirmed by physician if possible
Family history of psoriasis11st/2nd degree relative; if current/personal history absent
Nail dystrophy1Pitting, onycholysis, hyperkeratosis on exam
Negative rheumatoid factor1By any method (preferably ELISA/nephelometry)
Dactylitis (current or history)1Sausage digit; clinician-verified or imaging
Juxta-articular new bone formation1X-ray: ill-defined ossification near joint (excl. osteophytes)

Key Features

  • No imaging mandatory (unlike ASAS axial SpA criteria).
  • Psoriasis weighted heavily (current = 2 pts = 2/3 of threshold).
  • Sensitivity ~91%, Specificity ~98% in validation cohorts.
  • Not for non-inflammatory pain (fibromyalgia, OA).

Clinical Application

  1. Confirm inflammatory articular disease (history + exam + labs + imaging).
  2. Apply CASPAR items systematically.
  3. If ≥3 points: classification as PsA supported.
  4. If <3 points: consider alternative (RA, axial SpA, crystal, viral, osteoarthritis)—but clinical judgment prevails.

Limitations

  • Classification ≠ diagnostic criteria (though used diagnostically).
  • May miss early/pre-radiographic PsA without skin/nail involvement.
  • Family history relies on patient recall.
  • Doesn't capture disease activity/severity.

Beyond Classification

  • GRAPPA treatment guidelines use domain-based approach.
  • Treat-to-target: MDA, DAPSA, PASDAS.
  • Monitor: tender/swollen joints, enthesitis count, dactylitis count, BSA/PASI, HAQ, CRP.

CASPAR standardizes PsA identification—enabling research, clinical communication, and appropriate treatment access.

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