Objectives To assess the incidence of ANCA-associated vasculitides (AAV) in a stable population by registering all newly diagnosed patients in a large region in Northern Germany. To investigate the epidemiology and pattern of AAV over seventeen years in a prospective study.
Methods Between 1/1/98 and 31/12/14 all newly diagnosed cases of AAV (Granulomatosis with polyangiitis (GPA), microscopic polyangitis (MPA), eosinophilic granulomatosis with polyangitis (EGPA)) as defined by the Chapel Hill Consensus Conference 1992 were identified in a large mixed rural/urban northern German region consisting of 2,83 million habitants in a population-based prospective study. The following sources were explored on a regular basis: (a) departments of all hospitals, including their outpatient clinics; (b) all departments of pathology, and (c) the reference immunological laboratories serving the catchment area. All cases were re-evaluated by the authors.
Results Within the observation period of seventeen years 551 patients were identified as having a new diagnosis of AAV in the catchment area, the incidence rate was 12 (range 8 -16)/million/year. GPA represents 70% of the AAV with an incidence rate of 7.9 (range 6–12)/million/year (95% CI 1;11 - 5;19), MPA with an incidence rate of 2.4 (range 1–5)/million/year (CI 0;3 – 1;9) and EGPA 1.1 (range 0–2)/million/year (CI 0;4).
Incidence rates of GPA were on average three times higher than those of MPA and seven times higher than CSS. The incidence rates were stable between 1998 and 2014, our observations did not reveal significant differences. Gender differences were not observed. People diagnosed with MPA were on average 66.4 years old.
Conclusions Results of our unique population based vasculitis register over seventeen years assessing the incidence of AAV in a region of 2.83 million habitants in northern Germany demonstrate stable incidence rates for AAV. Variances between years have been observed, but no pattern or periodicity. Compared to other studies investigating small regions or referral centers the incidence rates for AAV were comparable to the incidence rates observed in Norway, Sweden and the United States, lower than those in United Kingdom, but higher than in Spain and Vilnius. The incidence rates of MPA are significantly higher in Japan, whereas GPA and CSS have rarely been diagnosed.
Disclosure of Interest None declared