Epidemiology of large-vessel vasculidities.

The systemic vasculitides are multisystem disorders characterised by the inflammation of blood vessels and tissue necrosis. Classified by the size of the vessels affected, the large vessel vasculitides include giant cell arteritis (GCA) and Takayasu's arteritis (TA). These are anatomically, epidemiologically and clinically distinct conditions. They are often associated with considerable morbidity and mortality. The classification of vasculitis has been an area of controversy for many years and current classification criteria remain suboptimal. Although intensive efforts are under way to improve them, a further understanding of the aetiology and pathogenesis of these diseases is required to develop more sensitive and specific diagnostic tests. These efforts, however, have been hampered by the low prevalence of these diseases. The establishment of national and international registries is encouraged to enhance valuable data collection. These are anatomically, epidemiologically and clinically distinct conditions. This article summarises the current classification systems for systemic vasculitis and their limitations. We also review the presently known epidemiology, risk factors and morbidity and mortality associated with GCA and TA.