Stable incidence of systemic vasculitides in Schleswig-Holstein, Germany

Introduction: The authors present data on the incidence of primary systemic vasculitides (PSV) in the northern German state of Schleswig-Holstein from 1998 to 2005. Methods: Population-based study of all new cases of PSV from 1 January 1998 onward in a region with a population of 2.83 million. The sources of patient data were all hospital departments in the catchment area, including outpatient clinics; all departments of pathology; and the reference immunological laboratories serving the catchment area. Results: Over this eight-year period, 982 patients with newly diagnosed PSV were identified in Schleswig-Holstein, of whom 273 were diagnosed with ANCA (i.e., anti-neutrophil cytoplasmic antibody)-associated vasculitis (AAV). The incidence of all types of PSV combined was between 38 and 54 cases per million population per year. The incidence of AAV (which includes Wegener's granulomatosis [WG], microscopic polyangiitis [MPA], and Churg-Strauss syndrome [CSS]) was between 9.5 and 16 cases per million per year. WG consistently accounted for two-thirds to three-quarters of all new cases of AAV diagnosed each year. Discussion: This population-based vasculitis registry designed to capture all new cases of PSV in an eight-year period in a northern German region with 2.83 million inhabitants revealed stable incidence figures for all types of PSV and for AAV. Compared to figures obtained in other studies from small regions or referral centers, the incidence rate of WG (as an illustrative type of AAV) in this study was the same as those in Norway and Sweden, lower than that in the United Kingdom, but higher than those in Spain and in Vilnius (Lithuania). It is unclear whether these differences truly reflect a north-south gradient within Europe or are merely due to methodological differences.