Psoriatic arthritis (PsA) is a painful and progressive joint disease. PsA often leaves patients with significant joint damage, functional impairment, and reduced quality of life.

It is estimated that PsA affects between 20% to 40% of psoriasis patients. Among PsA patients, approximately 20% will progress to the more severe destructive arthritis.

PsA is diagnosed using the classification of psoriatic arthritis (CASPAR) criteria. The CASPAR criteria takes into account the personal and family history of the disease, a negative test for rheumatoid factor, psoriatic nail dystrophy, and evidence of inflammatory arthritis. Diagnosis is often complicated by overlapping symptoms with other arthritic conditions, as well as variable disease expression across patients; therefore, it is possible that the prevalence of PsA among psoriasis patients far exceeds current estimates.

Currently, FDA approved medications for the treatment of PsA are most effective at controlling inflammation and arresting joint destruction, but are ineffective at reversing joint damage; therefore, it is important to identify psoriasis patients at high risk for developing PsA prior to the onset of arthritic symptoms.

PsA symptoms typically develop a decade after the appearance of cutaneous psoriasis; hence, dermatologists are uniquely positioned to screen psoriasis patients for PsA.

Prior to the introduction of the PsoriasisDX genetic test, PsA screening identified patients after the onset of the inflammatory arthritis. Once arthritic symptoms are present, the patient is at a greater risk for suffering significant joint damage (see radiographic figure).

[back to top]