Diagnostic Criteria for PsA

Since psoriatic arthritis presents with such a variety of symptoms, many people experience a delay in diagnosis or are misdiagnosed. Early and aggressive treatment for psoriatic arthritis is critical to prevent or delay the potentially disabling and disfiguring progression of the disease. To aid in diagnosis, researchers have worked to create diagnostic criteria. While several diagnostic criteria have been proposed, there is no universal consensus.1,2 The CASPAR and Moll and Wright Criteria are classification criteria that are used to help guide a diagnosis of PsA.

Classification Criteria for Psoriatic Arthritis (CASPAR) Criteria

The Classification Criteria for Psoriatic Arthritis (CASPAR) criteria published in 2006 has been gaining acceptance in both research and clinical practice. Statistically developed through validated study, the CASPAR criteria have been evaluated as simple, easy to use and with a high degree of specificity and sensitivity.2,3

The diagnosis of psoriatic arthritis based on the CASPAR criteria requires the presence of inflammatory arthritis (in the joints, spine, or entheses – connective tissue between tendons and bone) with more than 3 points from 5 categories.  The presence of current psoriasis is assigned 2 points, while all other clinical features are assigned 1 point:

  • Current psoriasis, prior personal history of psoriasis, or family history of psoriasis
  • Nail psoriasis, including onycholysis (detachment of nail from the nail bed), pitting, and hyperkeratosis (thickening of the nail)
  • Absence of rheumatoid factor in blood tests
  • Current or prior history of dactylitis (sausage-like inflammation of the fingers and/or toes)
  • Radiographic evidence of periarticular new bone formation (excluding osteophytes) on x-rays of the hand or foot1-3

Previous Criteria – Moll and Wright Criteria

Researchers Moll and Wright established the original criteria for psoriatic arthritis in 1973, which is the oldest and most widely known guide to diagnosing psoriatic arthritis. 2 To meet the Moll and Wright classification for psoriatic arthritis, a person with psoriasis who presented with inflammatory arthritis, and had a negative blood test for rheumatoid arthritis, must also meet one of these five subtypes:

  • Polyarticular, symmetric arthritis – affecting many joints on mirror sides of the body
  • Oligoarticular and asymmetric – fewer than five joints affected, occurring only on one side of the body
  • Distal interphalangeal joint predominant – affecting mainly the joints furthest from the center of the body in the fingers and toes
  • Spondylitis predominant – affecting mainly the joints between the vertebrae in the spine
  • Arthritis mutilans – the most severe form of psoriatic arthritis which causes digital shortening of the fingers or toes associated with severe bone destruction3
Written by: Emily Downward | Last reviewed: October 2016.
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