Approximately 30% of people with psoriasis are at risk of developing a disease called psoriatic arthritis. This form of arthritis results in joint stiffness, pain, and swelling. Treatments include Non-steroidal anti-inflammatory drugs (NSAIDs) and immunosuppressant medications. This disease can impair quality of life and lead to destruction of affected joints if left untreated.[1]
For an accurate diagnosis, the Classification of Psoriatic Arthritis (CASPAR) criteria is often used. Three points from the following five criteria (bolded) must be met for a diagnosis of psoriatic arthritis:[1]
| Criteria | Points |
|---|---|
| Evidence of psoriasis | |
| Current psoriasis | 2 |
| Personal history of psoriasis | 1 |
| Family history of psoriasis | 1 |
| Nail dystrophy (splitting, pitting, or thickening of the nails) | 1 |
| Negative rheumatoid factor test (a blood marker used to diagnose rheumatoid arthritis) | 1 |
| Dactylitis (swelling of a finger) | |
| Current dactylitis | 1 |
| Personal history of dactylitis | 1 |
| Extra bone formation near joints of the hand or foot (confirmed by x-ray) | 1 |