Global trends in the incidence of psoriasis from 1990 to 2019

The global, regional, and national burden of psoriasis was investigated based on the Global Burden of Disease (GBD) study.To report the incidence of psoriasis in 204 countries and territories from 21 regions according to age, sex, region, country, and socialdemographic index (SDI) between 1990 and 2019.Estimates from the GBD 2019 study were used to analyse the incidence of psoriasis at the global, regional, and national levels. The estimated annual percentage changes (EAPCs) in the age-standardized incidence rate (ASIR) were calculated to quantify trends between 1990 and 2019.From 1990 to 2019, the global incidence of psoriasis increased by 26.53%, but the ASIR of psoriasis decreased, with an EAPC of -0.77 (95% confidence interval [CI]: -0.78 to -0.76). In 2019, the highest ASIRs of psoriasis (112.58 per 100,000 population; 95% uncertainty interval, 108.89 to 116.07) were observed in high-SDI regions. The male-to-female ratio for psoriasis incidence peaked globally in the 50-54-year-old age group and peaked in the 75-79-year-old age group in high-SDI regions. Regionally, Central Sub-Saharan Africa (EAPC, -0.57; 95% CI: -0.67 to -0.48) and Eastern Sub-Saharan Africa (EAPC, -0.36; 95% CI, -0.38 to -0.34) had the largest decrease in ASIR of psoriasis from 1990 to 2019. Nationally, increases in the ASIR of psoriasis was observed only in Japan (EAPC, 0.04; 95% CI: 0.02 to 0.05).Globally, the incidence of psoriasis showed an increasing trend, but the ASIR of psoriasis decreased significantly from 1990 to 2019. Only Japan showed an unfavourable increasing trend.