Clinical features of psoriatic arthritis in Korean patients with psoriasis: a cross-sectional observational study of 196 patients with psoriasis using psoriatic arthritis screening questionnaires.

The prevalence and clinical features of psoriatic arthritis (PsA) in psoriasis patients vary widely in different countries, and studies on Korean population are rarely reported. The aim of this study was to investigate the clinical features of PsA in a Korean population of patients with psoriasis by using psoriatic arthritis screening questionnaires. A cross-sectional observational study was conducted, and consecutive psoriatic patients were evaluated for PsA by using two kinds of psoriatic arthritis screening questionnaires: Psoriatic Arthritis Screening and Evaluation tool (PASE) and Psoriasis Epidemiology Screening Tool (PEST). Psoriatic patients with higher score in screening questionnaires were referred to rheumatologist for confirmative diagnosis of PsA. Among 196 psoriasis patients screened by PASE and PEST, total prevalence of PsA was 11.2 % (n = 22/196) with 59.1 % of the cases being newly diagnosed. Compared with patients without PsA, patients with PsA had more extensive psoriasis, higher frequency of pustular and inverse type of psoriasis, and lower frequency of plaque type of psoriasis. Spondylitis was the most common manifestation pattern, followed by polyarthritis, oligoarthritis, predominant distal interphalangeal arthritis, and arthritis mutilans. Our findings are consistent with a low prevalence of PsA among patients with psoriasis in Asia. We also confirm a spondylitis as the most common pattern of PsA in Korea. PsA screening questionnaires can be a simple and useful tool to screen PsA in patients with psoriasis.