Epidemiology of psoriasis and psoriatic arthritis

Abstract

Psoriatic arthritis (PsA) is a unique type of chronic infl ammatory arthritis that occurs in association with the skin manifestations of psoriasis, commonly presenting with extra articular manifestations which includes nail involvement, enthesitis and dactilitis. It is also important to note that like rheumatoid arthritis PsA has been shown to have signifi cant cardiovascular comorbidities. Studying the epidemiology of PsA has been limited by the lack of a universally agreed classifi cation criteria. Since the introduction of the CASPAR classifi cation criteria, we are seeing a promising trend towards the acceptance of this criteria as an internationally agreed method for present and future epidemiological and research work in the fi eld of PsA. In this chapter we present the available data on the incidence and prevalence of Psoriasis, PsA and the possible associated CVD comorbidities. The data show the extent of variabilities of PsA incidence and prevalance between different ethnic and population groups. The highest reported prevalence of Psoriasis worldwide (11.8 %) came from Kazakhastan, and generally believed to be higher in populations of European ethnicity and lowest in West Africa and East Asia. The prevalance of PsA in the general population ranged from the highest reported in Italy 0.42 % to the lowest in Japan at 0.001 %. On the other hand the prevalence of PsA in Psoriasis patients increases to the range of 6–40 %. The incidence of reported cases of PsA is gradually increasing due to the improved awareness of the condition amongst primary care physicians.