Stable incidence of primary systemic vasculitides over five years: Results from the German vasculitis resister

Objective. To register all newly diagnosed patients with primary systemic vasculitides (PSV) in a large region in northern Germany. Methods. Between January 1, 1998 and December 31, 2002 all newly diagnosed cases of PSV were identified in a large mixed rural/urban northern German region consisting of 2,777,275 habitants in a population-based prospective study. The following sources were used: departments of all hospitals, including their outpatient clinics; all departments of pathology; and the reference immunologic labs serving the catchment area. Results. During 5 years, 642 PSV patients were identified. The incidence rates for all PSV were between 40 and 54 cases per 1 million and per year. People at age 50 years and older had a 3-5-fold higher risk of developing PSV compared with those younger than 50 years. The incidence rates of antineutrophil cytoplasmic antibody (ANCA)-associated PSV (Wegener's granulomatosis [WG], microscopic polyangiitis [MPA], Churg-Strauss syndrome [CSS]) were between 9.5 and 16/million/year. WG occured 2-3 times more frequently than MPA or CSS. Conclusion. Results of a population-based vasculitis register over 5 years for the incidence of PSV among 2.78 million habitants in northern Germany revealed a stable incidence for all PSV. Compared with other European studies coming from small regions or referral centers, the incidence rates for ANCA-associated PSV were the same as in Norway, lower than those in United Kingdom, but higher than those in Spain.