LONG TERM (MORE THAN 20 YEARS) CLINICAL OUTCOME OF 114 IMN PATIENTS: A SINGLE CENTRE EXPERIENCE

Introduction and Aims: Idiopathic Membranous Nephropathy (IMN) is the most common cause of Nephrotic Syndrome (NS) in adults. The natural history varies from spontaneous remission to ESRD, and it is difficult to assess the percentage of patients with these possible outcomes because most relevant studies have a short term follow-up and include both nephrotic and non-nephrotic patients. The purpose of this retrospective study was to analyse the probability of long term kidney survival in a cohort of patient with NS due to IMN. Methods: Our report includes 114 patients (M = 70, F = 44) with biopsy-proven IMN and NS at presentation. They were observed for an average of 117 months (14-330) between April 1981 and June 2008. All patients were treated with immunosuppressive therapy (80.7% Corticosteroids plus alkylating agents [Ponticelli's Schedule]; 18.4% with corticosteroids alone; 0.9% with Cyclosporin). Patients were stratified into three subgroups on the basis of response to therapy: complete responder (CR) proteinuria = 0.3 g/24h, partial responder (PR) proteinuria = 3.5 and > 0.3 g/24h, and non responder (NR) proteinuria > 3.5 g/24h and they were homogeneous for gender, age and comorbidities (Table 1). The clinical outcame was evaluated one year after the beginning of therapy. The primary end point was ESRD. Renal survival was estimated using Kaplan Meier plots, logrank test and Cox proportional-hazard models. Results: At diagnosis, CKD-EPI GFR was less than 60 ml/min in 27.2% of patients. The censored renal survival rate at the 5th, 10th, 15th and 20th year was respectively 91.7% (CI 86-97%), 83.9% (CI 76-91%), 75% (CI 66-84%) and 68.7% (CI 59-78%). The cumulative life survival at the 5th, 10th, 15th and 20th year was respectively 90%, 79%, 67% and 62%. After 12 months CR, PR, and NR occurred in 27.2%, 35.9% and 36.8 of patients, respectively. After 20 years of follow-up, ESRD occurred in 0% of CR patients, in 5% of PR and in 40% of NR patients (Fig 1). Conclusions: Our patients' characteristics, as well as the therapeutic strategies adopted at our Centre are homogeneous, and the length of our follow up is remarkable since it covers more than 20 years, unlike most works in the literature. Our data confirm that complete remission confers an excellent long term prognosis. Moreover, partial remission could be considered an excellent therapeutic goal as well, since IMN patients could avoid NS and its adverse clinical consequences