POS0859 EARLY RESOLUTION OF URINARY CELLULAR CASTS PREDICTS GOOD RENAL FUNCTION IN ANCA-ASSOCIATED GLOMERULONEPHRITIS
Authors: K. Hiramoto, H. Hanaoka, S. Saito, Y. Kaneko
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> Although the prognosis of anti-neutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis has been improved due to recent advances in diagnosis and treatment, its renal outcome is still poor. In spite of previous studies that investigated a number of prognostic factors in patients with ANCA-associated glomerulonephritis, prognostic value of focusing on urinary cellular casts after induction therapy has been little elucidated. <h3>Objectives:</h3> To clarify clinical usefulness of monitoring urinary cellular casts after induction therapy in patients with ANCA-associated glomerulonephritis. <h3>Methods:</h3> Consecutive patients with newly diagnosed, biopsy-proven ANCA-associated glomerulonephritis from 2009 to 2022 in our hospital were included. Urinary casts were monitored longitudinally, and patients were classified into two groups according to the timing of complete resolution of urinary cellular casts after initiation of induction therapy. Clinical characteristics at induction therapy initiation, renal histology, and renal function at one year after induction therapy were evaluated. <h3>Results:</h3> Twenty-two patients with untreated, biopsy-proven ANCA-associated glomerulonephritis (6 granulomatosis with polyangiitis and 16 microscopic polyangiitis) were included in the analysis. The mean age was 71 years, and 13 (59%) were female. The mean eGFR at baseline was 45.8 ml/min/1.73m<sup>2</sup>, with urinary cellular casts detected in all patients before induction therapy. All patients were treated with prednisolone with the mean initial dose of 49.5 mg/day, in combination with cyclophosphamide in 16 patients (73%) and rituximab in four patients (18%). All casts disappeared in 12 patients (55%) one month after induction therapy and in 20 patients (91%) three month after induction therapy. Dividing patients into two groups according to the resolution of urinary casts in one month, no significant difference was found in clinical characteristics and laboratory data including the positivity of MPO-ANCA (91.7 vs 90.0%, p=1.00), eGFR levels at baseline (57 vs 30 ml/min/1.73m<sup>2</sup>, p=0.11), the prednisolone dose used for induction therapy (50 vs 55 mg/day, p=0.17), and cyclophosphamide use (75 vs 70%, p=1.00) between the resolution and non-resolution group, although baseline urinary protein levels were significantly higher in the non-resolution group (0.4 vs 1.1 g/day, p=0.02). Regarding with renal pathological findings, proportion of interstitial fibrosis and tubular atrophy were significantly higher in the non-resolution group (5 vs 40%, p&lt;0.01), whereas that of cellular crescents did not show significant difference (10 vs 23%, p=0.08). At one year, eGFR was significantly higher in the resolution group than in the non-early resolution group (59 vs 46 ml/min/1.73m<sup>2</sup>, p=0.02). <h3>Conclusion:</h3> Resolution of urinary cellular casts at one month after induction therapy predicts good renal function at one year in patients with new-onset ANCA-associated glomerulonephritis. <h3>REFERENCES:</h3> <b>NIL.</b> <h3>Acknowledgements:</h3> <b>NIL.</b> <h3>Disclosure of Interests:</h3> <b>None declared.</b>