The Unknown Epidemiology of Psoriasis

Abstract

Psoriasis is a chronic skin disease, with no identified etiology or cure, worldwide distribution and predominantly male. Skin diseases contribute 1.79% to the global disease burden measured in disability-adjusted life years (DALYs) placing them in the 18th position. It is the third of the skin diseases with the highest total burden.
The data to date, which include 68 articles and full reports from 20 countries, have estimated the worldwide prevalence of psoriasis to range between 0.09% and 11.4%, equivalent to at least 100 million affected individuals. In most developed countries, the prevalence is between 1.5% and 5%, with Norway being the country with the highest prevalence. The only study carried out in Portugal, was published in 1994, with a sample of 1037 participants of all ages and concluded a prevalence of psoriasis in Portugal of 1.9%.
Different methodologies, differences in the definition of prevalence, in the definition of case, in the ages of the studied populations and in the sampling techniques are observed. Available prevalence data cover only 20 countries, which means that the epidemiology of this disease elsewhere is completely unknown. There is a small proportion of studies carried out in developing countries, contributing to greater inequality in the published results.
The quality of the epidemiological data obtained is essential for a better understanding of the size and distribution of the problem, for the management of this chronic disease and for the adequate planning of healthcare.