Background/Purpose: Antineutrophil cytoplasmic antibody (ANCA)–associated vasculitis is a heterogeneous group of rare autoimmune disorders that cause inflammation of blood vessels with various manifestations. Our study compares the differences in clinical outcomes in patients with the three main ANCA–associated vasculitis, granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA).

Methods: We analyzed data of patients hospitalized with a primary or secondary diagnosis of ANCA-vasculitis admitted in United States hospitals from 2017 to 2021 using the National Inpatient Sample (NIS) data. The NIS database is the largest publicly available database of patients hospitalized in the United States.

Results: There were 77,100 patients with a diagnosis of ANCA-associated vasculitis with a mean age of 61.3 years. Of this, 56965 (73.9%) had GPA, 11020 (14.3%) MPA, and 9115 (11.8%) EGPA. In the bivariate analysis, MPA patients had more kidney, heart, and lung complications and worse outcomes compared to GPA and EGPA patients. MPA patients when compared to GPA and EGPA patients were more likely to have acute kidney injury (47.9% vs. 30.2% vs. 21.2%), end-stage renal disease (31.2% vs. 24.2% vs. 3.5%), acute myocardial infarction (5.1% vs. 4.1% vs. 4.1%), congestive heart failure (31.3% vs. 24.9% vs. 23.3%), pulmonary hypertension (9.7% vs. 6.5% vs. 5.3%) and interstitial lung disease (11.9% vs. 4.6% vs. 4.5%), all with p< 0.001. There was no difference in the prevalence of ischemic stroke between the MPA, GPA, and EGPA (p=0.88). In the multivariate analysis with GPA as the reference group, there was no difference in in-hospital all-cause mortality between GPA and MPA patients (aOR 0.98, 95% CI 0.89-1.08). However, EGPA patients had lower mortality than GPA patients (aOR 0.67, 95% CI 0.58-0.77).

Conclusion: GPA is the most common type of ANCA vasculitis in hospitalized patients in the US. Kidney involvement, interstitial lung disease, and acute myocardial infarction appear to be more common in MPA than other ANCA vasculitis. However, MPA patients did not have worse in-patient all-cause mortality than GPA patients. EGPA patients appear to have the best in-hospital prognosis.

Table 1: Comparing various demographics and complications in different types of ANCA-associated vasculitis.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/anca-associated-vasculitis-does-the-type-matter/