Improved survival due to better renal outcomes in patients with anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV) during the years 2000 to 2015 - a Danish nationwide study

INTRODUCTION: AAV (granulomatosis with polyangiitis and microscopic polyangiitis) carry significant risk of morbidity and mortality, notwithstanding adequate treatment. It has recently been suggested that incidence rates are increasing and risk of death declining, however, contemporary large-scale descriptive studies, with appropriate follow-up, have been challenged by the rare occurrence of these diseases. Accordingly, we examined these matters by use of Danish nationwide healthcare registries.METHODS: All patients with incident AAV, regardless of primary organ manifestation and severity were included by use of ICD10 diagnostic codes (positive predictive value of \gt; 90\ and grouped in five-year intervals (P1: 2000-2004, P2: 2005-2009, P3: 2010-1015). Absolute risk ratios (ARR) adjusted for age, sex and advanced disease severity (\gt;10 days of initial hospital stay), as well as cumulative incidences were assessed based on the Aalen-Johansen estimator in R version 3.5.0.