Prevalence of Psoriasis in Korea: A Population-Based Epidemiological Study Using the Korean National Health Insurance Database

Background Although psoriasis is universal in its occurrence worldwide, its prevalence varies by geographic location and race. A few hospital-based surveys have reported on the demographic characteristics in Korean patients with psoriasis. However, a nation-wide study on the prevalence of psoriasis in Korea remains uncompleted. Objective The purpose of this study was to determine the prevalence of psoriasis in Korea and to describe the demographic and social characteristics of afflicted individuals. Methods We identified patients with psoriasis using a relevant diagnostic code from the sixth revision of the Korean Standard Classification of Disease in the 2011~2015 claims database of the Health Insurance Review and Assessment Service of Korea. We estimated the annual prevalence of psoriasis and described the age and sex distribution of the patients, type and severity of psoriasis, comorbidities, type of health insurance, type of health-care institution and residence area. Patients with moderate-to-severe psoriasis were defined as those who had been treated with phototherapy, classical systemic agents, and/or biologic agents. Results The standardized prevalence of psoriasis was 453 per 100,000 individuals of the database population in 2015. We found male preponderance with a 1.3:1 male-to-female ratio, and that the largest number of patients belonged to the age group of 50s. Of the patients diagnosed with psoriasis in 2015, 83.8% had plaque psoriasis and 22.6% had moderate-to-severe psoriasis. Conclusion The annual standardized prevalence of psoriasis in Korea was 453 per 100,000 of the population in 2015.