CASPAR Criteria for Psoriatic Arthritis: Diagnosis & Guidelines

The Classification Criteria for Psoriatic Arthritis (CASPAR) were developed in 2006 to improve the accuracy of diagnosing psoriatic arthritis (PsA).

The CASPAR criteria are based on a combination of clinical features and laboratory findings.

The CASPAR criteria for PsA are as follows:

1. Presence of inflammatory arthritis: This is the most important criterion, and it requires that a person have at least one swollen or tender joint.

2. Evidence of psoriasis: This can include any of the following:

- A history of psoriasis

- Current psoriasis

- Psoriatic nail changes

- A family history of psoriasis

3. Absence of rheumatoid factor: This is a blood test that is often positive in people with rheumatoid arthritis, but it is usually negative in people with PsA.

4. Absence of anti-cyclic citrullinated peptide (anti-CCP) antibodies: This is another blood test that is often positive in people with rheumatoid arthritis, but it is usually negative in people with PsA.

5. Sacroiliitis: This is inflammation of the sacroiliac joints, which are located at the base of the spine. Sacroiliitis can be seen on X-rays or magnetic resonance imaging (MRI).

6. Dactylitis: This is inflammation of an entire finger or toe. Dactylitis can be seen on X-rays or MRI.

7. Enthesitis: This is inflammation of the entheses, which are the areas where tendons and ligaments attach to bone. Enthesitis can be seen on X-rays or MRI.

8. Minimal radiographic changes of PsA: These changes can be seen on X-rays or MRI, and they include:

- Joint erosions

- Joint space narrowing

- Osteophyte formation

- Ankylosis (fusion of the joints)

To meet the CASPAR criteria for PsA, a person must have at least 3 of the following criteria:

- Inflammatory arthritis

- Evidence of psoriasis

- Absence of rheumatoid factor

- Absence of anti-CCP antibodies

- Sacroiliitis

- Dactylitis

- Enthesitis

- Minimal radiographic changes of PsA

The CASPAR criteria are not perfect, and they may not be able to diagnose all cases of PsA. However, they are a useful tool for diagnosing PsA and for differentiating it from other types of arthritis.