Geoepidemiology of systemic vasculitis: comparison of the incidence in tworegions of Europe

Objective-The aetiopathogenesis of the primary systemic vasculitides (PSV) is unknown but includes both environmental and genetic factors. The develop ment of classification criteria/definitions for PSV allows comparison of th e epidemiology between different regions. Methods-The same methods and the American College of Rheumatology (1990) cr iteria or Chapel Hill definitions were used to compare the epidemiology of Wegener's granulomatosis, Churg-Strauss syndrome, microscopic polyangiitis, and polyarteritis nodosa in Norwich least England population 413 500) and Lugo (northwest Spain population 204 100). Patients with PSV were identifie d between 1 January 1988 and 31 December 1998. Results-Overall, the incidence of PSV in adults was almost equal in Norwich (18.9/million) and Spain (18.3/million). The incidence of Wegener's granul omatosis in Norwich (10.6/million) was greater than in Spain (4.9/million). There was a marked age-specific increase in incidence in Norwich with a pe ak age 65-74 years (52.9/million), but a virtually equal age distribution b etween ages 45 and 74 in Lugo (34.1/million). There was no significant incr ease with time in either population, or evidence of cyclical changes in inc idence. Conclusion-These data support the suggestion that environmental factors may be important in the pathogenesis of PSV.