Update on the epidemiology, risk factors, and outcomes of systemic vasculitides.

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) and giant cell arteritis (GCA) are the most common primary systemic vasculitides of the adult population, while polymyalgia rheumatica (PMR) is a clinical syndrome often associated with GCA. Incidence and prevalence rates of AAV have been increasing in the last decades, whereas those of GCA and PMR have remained stable. The mutual interplay between environmental and genetic risk factors leading to the development of these diseases has been further analyzed in the last years. The role of infectious agents has repeatedly been studied with regard to Staphylococcus aureus, associated with relapse in granulomatosis with polyangiitis, and Herpes zoster, potentially contributing to GCA development. Remission of disease and prevention of disease-related complications are the most important outcomes for all systemic vasculitides. Although these goals are achieved in the majority of patients receiving modern therapies, the prevention of treatment-related complications, especially glucocorticoid side effects, is still an unmet need that is common to AAV, GCA, and PMR.