Epidemiology of major chronic inflammatory immune-related skin diseases in 2019

Introduction: 'Chronic inflammatory immune-related skin disease' (ISDs) is an umbrella term grouping together heterogeneous entities characterized by chronic inflammation potentially involving the whole skin. We are not covering all ISDs in this review, but take a few as the most representative, including nonbullous and bullous diseases. The question we are aiming to address can be summarized as follows: 'despite the differences, is it possible to define some unifying epidemiologic characteristics and shared progression pathways which can guide the organization of healthcare?'Areas covered: This review covers incidence, prevalence, risk factors and prognosis of psoriasis, atopic dermatitis (AD), pemphigus and pemphigoid. Medline, Embase and the Cochrane Library were searched for papers published between January 2005 and December 2019.Expert opinion: ISDs epidemiology varies according to the ISD type, age, sex, climate, and sociodemographic variables. AD and psoriasis pose a considerable public health burden owing to their high prevalence worldwide and morbidity. Their secular trend of increasing incidence points to a role for environmental factors and gene-environment interactions. Bullous diseases are much rarer, with limited data available. Worldwide, the leading cause of skin disease disability-adjusted life-years (DALYs) is attributable to AD. Future research should focus on risk factors and prevention at the global level.