255. RENAL INVOLVEMENT IN EGPA: A MULTICENTRE RETROSPECTIVE STUDY OF 63 CASES

Abstract

INTRODUCTION: Eosinophilic Granulomatosis with Poly-Angiitis (EGPA) is a systemic small-vessel vasculitis characterized by severe asthma, hypereosinophilia and frequent positivity of ANCAs. In contrast to GPA or MPA, renal involvement is rare and described in fewer than 20% of patients METHODS: Retrospective multicente study including patients fullfilling the 1990 ACR criteria for EGPA or the modified criteria used in the MIRRA trial, with biopsyproven nephropathy RESULTS: Sixty-three patients were included in the study. The M/F ratio was 36/27 and the median age at EGPA diagnosis was 60 years. Renal disease was present at vasculitis diagnosis in 86% of cases. ANCA was positive in 53 cases (84%), with MPO-ANCA in 46/53 (87%). Median eosinophil count at diagnosis was 3650/mm3. All patients had asthma, whereas 48 (76%) presented with general symptoms, 33 (52%) arthralgia/myalgia, 44 (70%) sinusitis and 22 (35%) nose polyps. Peripheral neuropathy was present in 46%of cases,myocarditis in 14%, alveolar hemorrhage in 18%. The most common renal presentation was acute renal failure, present in 47 (75%) and requiring acute dialysis in 5 cases. Mean serum creatinine at diagnosis was 252 μmol/l, proteinuria was almost constant, with nephrotic syndrome in 7 cases. Renal biopsy revealed pauci-immune necrotizing glomerulonephritis (GN) in 50 cases (79%), membranous nephropathy in 6 (10%), membranoproliferative GN in 1. Pure acute interstitial nephritis was found in 6 cases (10%), but important interstitial inflammation was observed in 62% of all biopsies, with granuloma in 4 cases. Nonnecrotizing GN was observed only among ANCA-negative patients. Most patients received induction therapy with steroids, cyclosphamide (n=40), rituximab (n=7) and/or plasma exchange (n=6), followed by maintenance immunosuppression with azathioprine (n=28), rituximab (n=9), calcineurin inhibitors (n=5), MMF or MTX (n=6). After a median follow-up of 51 months, 58 patients were alive, 9 were on chronic dialysis and 2 had undergone kidney transplantation. Poor renal outcome was associated with high initial creatinine and positive ANCA serology. Renal function was available for 52 patients : median creatinine was 115 μmol/L. Vasculitis was in remission in 37 cases (61%), refractory in 2, steroid-dependent in 19 (19%), with a median prednisone dose of 5 mg/day CONCLUSIONS: Renal involvement in EGPA is rare but usually present at vasculitis diagnosis. The most frequent presentation is rapidly progressive renal failure due to necrotizing GN, but other nephropathies can be observed, such as membranous GN or pure interstitial nephritis.