Vasculitis Around the World: Epidemiologic Insights into Causality and a Need for Global Partnerships

Vasculitis is a family of rare diseases characterized by inflammation of blood vessels. Causal factors for most forms of vasculitis have not been identified. Certain forms of vasculitis are more prevalent in specific parts of the world, and clinical features of a particular type of vasculitis can vary by region. Observed geographic differences in incidence and prevalence of various forms of vasculitis and corresponding phenotypic diversities in different parts of the world suggest that epidemiological studies may generate important insights that can be leveraged to identify the causes of vasculitis. Geographic differences in incidence rates have been observed in the major forms of small and large vessel vasculitis (Figure 1). Takayasu arteritis (TA), a prototypical form of large vessel vasculitis (LVV), is more common in Japan compared to the United States and Europe. In contrast, giant cell arteritis (GCA), the other major form of LVV, is relatively uncommon in Japan compared to Europe and North America1. Incidence of antineutrophil cytoplasmic antibody (ANCA)–associated vasculitis (AAV), the prototypical form of small vessel vasculitis, also differs between Asian and Western countries. Of the 2 major forms of AAV, a higher incidence of granulomatosis with polyangiitis (GPA) has been reported in Europe and the United States compared to Japan, and a higher incidence of microscopic polyangiitis (MPA) has been reported in Japan and China compared to the United Kingdom and the United States2. Figure 1. Annual incidence of different forms of vasculitis in the United States, Europe, and Japan (per million population). A higher incidence of giant cell arteritis and granulomatosis with polyangiitis has been reported in northern regions of the world. Data are lacking from Africa, South America, and many parts of Asia. Beyond differences in incidence rates, regional differences in clinical features within a specific form of vasculitis have been … Address correspondence to Dr. P.C. Grayson, National Institutes of Health, 10 Center Drive, Building 10, 6N Rm 216G, Bethesda, Maryland 20892, USA. E-mail: peter.grayson{at}nih.gov