The prevalence of psoriatic arthritis in psoriatic patients in Tehran, Iran.

BACKGROUND Psoriatic arthritis is an inflammatory arthritis which is associated with psoriasis. There is no general agreement in the literature regarding the epidemiology of psoriatic arthritis. In this study, we evaluated the prevalence of psoriatic arthritis in a relatively large number of psoriatic patients. METHODS Three hundred and twenty patients with psoriasis were evaluated in a cross-sectional study. The psoriasis area and severity index, family history, demographic variables, and some other factors (e.g., clinical type and location of the disease) were assessed. The patients were examined for signs of arthropathy and the suspects were referred to a rheumatologist for further evaluation and confirmation of the diagnosis. RESULTS Psoriatic arthritis was observed in 29 (9.1%) patients. The prevalence of Psoriatic arthritis in men (10.1%) was not statistically different from that of women (7.8%). The most common type of psoriasis in all patients, with and without psoriatic arthritis, was chronic plaque psoriasis. The mean+/-SD psoriasis area and severity index was significantly (P<0.05) higher in patients with psoriatic arthritis (24.33+/-10.36) than those without psoriatic arthritis (10.70+/-8.44). Nail involvement was significantly more common in patients with psoriatic arthritis than those without psoriatic arthritis. HLA B27 was the most common HLA detected in patients with psoriatic arthritis. CONCLUSION Dermatologists are usually the first physicians to detect signs and symptoms of psoriatic arthritis and need to work closely with rheumatologists to establish the diagnosis and start appropriate treatments which will address both the skin and the joint disease.