Low levels of hemoglobin associate with critical illness and predict disease course in patients with ANCA-associated renal vasculitis.

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a small vessel vasculitis often leading to critical illness by multi-organ failure. Data for patients with specifically ANCA-associated renal vasculitis requiring intensive care unit (ICU) supportive care are limited and have mainly focused on long-term renal and overall outcome. Particularly, data on critical illness during the initial course of disease are scarce and remain poorly determined. Therefore, the purpose of this retrospective study was to identify predictors of critical illness in a cohort of patients with ANCA-associated renal vasculitis. We retrospectively included a total number of 53 cases with confirmed ANCA-associated renal vasculitis between 2015 till 2020 in a single-center cohort study. We here identified an association between low hemoglobin levels and requirement of ICU supportive care in patients with ANCA-associated renal vasculitis. Furthermore, levels of hemoglobin below 9.8 g/dL at admission independently predicted prolonged requirement of ICU supportive care in critically ill patients with ANCA-associated renal vasculitis. These findings confirm that low levels of hemoglobin negatively affect short-term outcome and could further improve our current understanding for the role of anemia in ANCA-associated renal vasculitis.