The epidemiology of antineutrophil cytoplasmic antibody-associated vasculitis in northwestern Turkey.

Epidemiological data about antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is very limited. Until now, there has been no study about the epidemiology of AAV in Turkey. In this study, we evaluated the frequency of AAV in the northeastern part of Turkey. The general clinical features of patients diagnosed with AAV at our center within the last 10 years (2004-2014) were retrospectively recorded down. The incidence rates and the prevalence per 1,000,000 population aged ≥16 years were calculated. In addition, we evaluated the clinical features and survival rates of AAV patients. There were 30 patients with granulomatous polyangiitis (GPA), 15 with microscopic polyangiitis (MPA), and 5 with eosinophilic polyangiitis (EGPA). The overall prevalence of AAV in our region was 69.3/1,000,000 in individuals ≥16 years. Males had a similar prevalence (73.2/1,000,000) with females (65.4/1,000,000). The mean annual incidence rate was 8.1/million for all AAV. The annual incidence of AAV in females was 6.9/million; in males, it was 9.2/million. The annual incidence for GPA was calculated as 4.8/1,000,000, the incidence for MPA was 2.4/1,000,000, and the incidence for CSS was 0.8/1,000,000. Ten-year survival of patients with AAV was 65.3 %. The only independent poor prognostic factor in Cox's multivariate analysis was advanced age at the time of diagnosis (OR 7.5, 95 % CI 10.6-526, p = 0.043). The frequency of all AAV in northwestern Turkey was similar to that in southern Europe; however, it was lower than the frequency in Northern Europe.