Glucocorticoid Dosing and Outcomes in ANCA-Associated Vasculitis With Kidney Involvement.

Introduction: There may be reservations about the guideline-recommended use of reduced glucocorticoid (GC) therapy in severe ANCA-associated vasculitis (AAV). We examined differences in outcomes based on oral GC use during induction therapy for AAV with kidney involvement. Methods: We conducted a single-center, retrospective cohort study (2010-2023) of patients with biopsy-proven kidney involvement from AAV. Patients were divided into eras 2020 onward (reduced-GC) versus pre-2020 (standard-GC) according to practice shift after adopting a reduced-GC regimen. The primary outcome was the composite of end-stage kidney disease (ESKD) or death within 12 months postbiopsy. Secondary outcomes included serious infection, clinical remission, and change in estimated glomerular filtration rate (eGFR). Results: There were 138 participants (mean age: 65.2 years, 46.4% female, 68.1% anti-myeloperoxidase), comprising 41 in the reduced-GC era and 97in the standard-GC era. The former group was older (70.3 vs 63.1 years) and had worse baseline kidney function (eGFR: 15.6 vs 22.6 ml/min). The reduction of cumulative GC for reduced-GC compared with the standard-GC era was 39% in the first month, 28% in the first 3 months, and 34% in the first 6 months. For reduced-GC compared with standard-GC era, there was no significant difference in ESKD or death (24.4% vs. 21.6%), serious infection (14.6% vs. 17.5%), or remission (63.4% vs. 63.9%); and both groups showed similar improvement in eGFR over 12 months. Conclusion: Reduced-GC during induction therapy in individuals with organ-threatening kidney involvement was not associated with a change in outcomes or kidney function recovery. This supports data from a large, randomized trial.