Reasons for hospitalization and in-hospital mortality for anti-neutrophil cytoplasmic antibody vasculitides: analysis of the National Inpatient Sample.

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a heterogeneous group of conditions resulting in frequent hospitalizations and high in-hospital mortality (IHM). Our study aimed to use the National Inpatient Sample (NIS) to determine and categorize the main reasons for hospital admission and IHM in patients with AAV. We performed a retrospective study of adult AAV hospitalizations in 2016, 2017, and 2018 in acute care hospitals across the USA conducted using the NIS database. We classified the main reasons for hospital admission and IHM into 19 different categories using the principal International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10) diagnosis. A total of 41,155 hospitalizations had either a principal or secondary ICD-10 code for AAV (GPA or MPA). Rheumatologic and respiratory diagnoses were the most common reasons for hospitalization, while infectious and respiratory diagnoses were the most common reasons for IHM. Sepsis, unspecified organism A41.9, was the most common specific principal diagnosis for hospitalized and deceased AAV patients. Our results show that the leading reasons for hospitalization and mortality for AAV patients were rheumatologic, respiratory, and infectious diagnoses. This data suggests that careful monitoring and management of infectious and pulmonary complications in AAV may improve hospital outcomes.