How many people have Psoriasis?
Prevalence = the number of cases at any one time.
Incidence = the number of new cases. This gives and indication of whether the number of people with the disease is increasing or decreasing.
The prevalence of psoriasis in the UK is approximately 2.4% of the adult population. It is difficult to estimate the prevalence of psoriasis in many countries because there are so many differences in the way that each country records and generates its figures. For example, there are differences in the accessibility and quality of dermatology services, how data is collected, and methods used to diagnose psoriasis. To confuse things a bit more, several key discrepancies exist between how each study is carried out, the methods used and the analysis of data for example, which means that it can be difficult to compare results between countries.
Despite the challenges above regarding the lack of consistent material, reasonable estimates on the prevalence of psoriasis can be made. This has produced some interesting trends in the prevalence and incidence of psoriasis around the world. It is important to note that data is not available from all countries.
The prevalence of psoriasis in adults is estimated to range between 0.27% and 11.4%. The reasons for the variation in incidence include; the age of the population, sex, location, ethnicity, genetic, environmental factors and possibly other factors such as income.
So, who cares about the incidence of psoriasis worldwide, and why is this relevant to you?
Well, investigations into the prevalence of a disease, such as Psoriasis help identify factors that contribute to the overall risk of that disease. For example, studies help to identify potential lifestyle and nutritional factors that influence the risk of psoriasis.
The graph below has been extracted from an article in the British Medical Association (BMJ) that assessed the epidemiology of psoriasis. The graph below (Figure 1) shows the prevalence of psoriasis in each country.
The data suggest that the prevalence of psoriasis is higher in higher-income countries, such as the countries in Europe, North America and Australasia. This information helps to identify factors in these countries that may contribute to the risk of psoriasis. Ultimately, this helps to identify lifestyle, nutritional and behavioural factors that can be used to reduce the risk of disease.
Figure 1: The Global Prevalence of Psoriasis
Figure 2: Lifetime (physician or dermatologist diagnosed) prevalence of psoriasis in adults by country. [Parisi BMJ (2020)]
Figure 2 show as silimar pattern to Figure 1. The prevalence of psoriasis is higher in Europe, North America and Australisia
- Rosa Parisi, Deborah P.M. Symmons2,3, Christopher E.M. Griffiths4, Darren M. Ashcroft1 (2013) Global Epidemiology of Psoriasis: A Systematic Review of Incidence and Prevalence Journal of Investigative Dermatology (2013) 133, 377–385; doi:10.1038/jid.2012.339 (on behalf of the Identification and Management of Psoriasis and Associated ComorbidiTy (IMPACT) project team)
- Parisi R, Iskandar I, Kontopantelis E, Augustinn E, et al. (2020) on behalf of the Global Psoriasis Atlas. National, regional, and worldwide epidemiology of psoriasis: a systematic analysis and modelling study. BMJ;369:m1590 | doi: 10.1136/bmj.m15902
- I Iskandar iD ,1,2 R. Parisi iD ,2,3 C.E.M. Griffiths,2,4 and D.M. Ashcroft1,2 on behalf of the Global Psoriasis. Atlas Systematic review examining changes over time and variation in the incidence and prevalence of psoriasis by age and gender British Journal of Dermatology (2021) 184, pp243–258