Prevalence of psoriatic arthritis in Chinese population with psoriasis: A multicenter study conducted by experienced rheumatologists

BACKGROUND: Reports on the prevalence of psoriatic arthritis (PsA) among Chinese patients with psoriasis are very limited. This study, conducted by rheumatologists, estimated the prevalence of PsA in a large number of Chinese patients with psoriasis. METHODS: Consecutive patients with a confirmed diagnosis of psoriasis attending nine dermatology clinics in five hospitals were recruited. All psoriasis patients were asked to complete a questionnaire comprising 16 questions to identify possible cases of PsA. All patients with one or more positive answers to the questionnaire were evaluated by two experienced rheumatologists. RESULTS: A total of 2434 psoriasis patients, including 1561 males and 873 females, were enrolled. Both the questionnaire and rheumatologists' examinations were completed in the dermatology clinics. The results identified 252 patients with PsA, comprising 168 males and 84 females. The overall prevalence of PsA among psoriasis patients was 10.4% (95% confidence interval [95% CI], 9.1%–11.7%). By sex, the prevalence was 10.8% (95% CI, 9.2%–12.5%) for males and 9.6% (95% CI, 7.7%–11.9%) for females and there was no significant sex difference in the prevalence of PsA (P = 0.38). Of the 252 PsA patients, 125 (49.6%, 95% CI, 41.3%–59.1%) were newly diagnosed by rheumatologists. Consequently, the prevalence of undiagnosed PsA among psoriasis patients was 5.2% (95% CI, 4.4%–6.2%). CONCLUSION: The prevalence of PsA in the Chinese population with psoriasis is about 10.4%, which is almost double that of previous reports in the Chinese population, but lower than that in Caucasians.