Supplementary Material for: Higher prevalence of generalized pustular psoriasis in Asia? A population-based study using claim data in China and a systematic review

Background: Few studies have reported the burden of generalized pustular psoriasis (GPP), a severe and potentially life-threatening skin disease, especially at a national level. Objectives: To estimate the nationwide burden of GPP in China and make a systemic review of the published data. Methods: We conducted a population-based study using Urban Basic Medical Insurance in China from 2012 to 2016. GPP cases were identified by primary diagnoses including the international classification of Diseases codes (ICD-10: L40.1 and ICD-9: 694.3). A systematic review was conducted using relevant databases up to January 2022. Results: The crude prevalence and incidence of GPP in 2016 were 1.403 (95% confidence interval [CI]: 1.115– 1.691) and 0.629 (95% CI: 0.483 – 0.775) per 100,000 person-years, respectively. The rates were higher in males than in females for both prevalence (1.429 vs. 1.135) and incidence (0.635 vs. 0.520). The prevalence and incidence showed a bimodal age distribution, with the first peak occurring in the 0–3 years age group and the second peak occurring in the 30–39 years age group. The per-capita total cost per year for one patient with GPP was 609.26 (±45.77) U.S. dollars. Seven studies were identified in a systematic review, according to which the prevalence (per 100,000) of GPP tended to be higher in Asian countries (0.746 – 8.178 in Japan and 12.230 in Korea) than in France (0.176), Sweden (6.25) and Brazil (0.7). Conclusions: This is the largest study concerning the disease burden of GPP, and in this study, the prevalence seemed to be higher in Asia. Although the direct economic burden of GPP did not seem high during the study period, the future usage of biologics and the humanistic burden should also be considered for policy-related decision-making.