Supplementary Material for: Early Renal Recovery after the First Flare of Pauci-Immune Glomerulonephritis

<b><i>Introduction:</i></b> Renal involvement is a severe manifestation of antineutrophil cytoplasmic antibody-associated vasculitis. Patients often progress to end-stage renal disease. The potential for renal recovery after the first flare has seldom been studied. Our objectives were to describe the evolution of the estimated glomerular filtration rate (eGFR) and identify factors associated with the change in the eGFR between diagnosis and the follow-up at 3 months (ΔeGFR^M0–M3). <b><i>Methods:</i></b> This was a retrospective study over the period 2003–2018 of incident patients in the Nord-Pas-de-Calais (France). The primary outcome was the ΔeGFR^M0–M3. <b><i>Results:</i></b> One hundred and seventy-seven patients were included. The eGFR at 3 months was significantly higher than at diagnosis (mean ± standard deviation, 40 ± 24 vs. 28 ± 26 mL/min/1.73 m², <i>p</i> &lt; 0.001), with a ΔeGFR^M0–M3 of 12 ± 19 mL/min/1.73 m². The eGFR at 12 months was higher than at 3 months (44 ± 13 vs. 40 ± 24 mL/min/1.73 m², <i>p</i> = 0.003). The factors significantly associated with the ΔeGFR^M0–M3 in multivariate analysis were the percentage of cellular crescents and neurological involvement. The mean increase in the eGFR was 2.90 ± 0.06 mL/min/1.73 m² for every 10-point gain in the percentage of cellular crescents. <b><i>Conclusions:</i></b> Early renal recovery after the first flare of pauci-immune glomerulonephritis occurred mainly in the first 3 months of treatment. The percentage of cellular crescents was the main independent predictor of early renal recovery.