Epidemiology and clinical outcomes of patients with idiopathic membranous glomerulonephritis at Groote Schuur Hospital over a ten year period

Includes bibliographical referencesBACKGROUND: Glomerulonephritis is a common cause of end-stage renal disease (ESRD) in developing countries. Idiopathic membranous nephropathy (IMGN) is an identified cause of nephrotic syndrome in South Africa. Early attainment of complete remission (CR) or partial remission (PR) in patients with IMGN has been shown to slow progression to ESRD. There is a dearth of outcome studies in Africa on IMGN. METHODS: This study was approved by the institution's Human Research Ethics Committee. It was a retrospective review of patients diagnosed (biopsy-proven) with IMGN at the Division of Nephrology and Hypertension, Groote Schuur Hospital, Cape Town, over a 10-year period. Secondary causes of MN were excluded in this study. Demographic, clinical, biochemical and histological records of such patients were retrieved for analysis. The trends in clinical and biochemical parameters over the course of follow-up from baseline were also determined. The primary outcome of interest was the attainment of a CR or PR at the last date of follow-up. Predictors of the composite of CR and PR at the last follow-up visit were assessed using univariate and multivariate Cox-Regression analysis. The trend in estimated glomerular filtration rate over the median duration of follow-up was evaluated as a secondary outcome. RESULTS: There were 56 patients with histologic and clinical parameters compatible with the diagnosis of IMGN. There were 26/56 females (46.4%) with an overall mean age of 41.5±14.6 years. Forty-three (43) patients had subsequent follow-up care at our centre with a median duration of follow-up of 23.0 (13.0, 48.0) months. Sixteen patients (37.2%) were treated with immunosuppression (ISP)-combination of steroids and cyclophosphamide, and 81.4% received renin-angiotensin system (RAS) blockade. There were no statistically significant differences in demographic and clinical features of patients treated with or without ISP. Trends in level of proteinuria, estimated GFR and serum albumin concentrations were also not significantly different between the two groups. Eighteen patients (41.9%) reached CR or PR at the last visit. There were also no statistically significant differences in demographic, clinical, histological, and biochemical characteristics of patients who had or had not achieved remission. The median time-to-remission of patients treated with or without ISP was similar - 48.6 and 48.7 months respectively (p=0.13) while the proportions of patients not reaching CR/PR at 1 year and 2 years were 94.6% and 80.8% respectively by Kaplan-Meier analysis. Gender, race and u se of immunosuppression did not influence remission status (log rank p>0.05). On regression analysis, the predictors of CR/PR at last follow up visit were GFR [OR 1.01 (95%CI: 1.00 - 1.02); p=0.041] and systolic BP (OR 0.97 [95%CI: 0.95 – 0.99); p=0.036]. CONCLUSION: Remission outcomes with the current immunosuppressive treatment protocol for I M G N are delayed and poor. There is a need for its re-evaluation and also for longitudinal, multicenter studies to assess the best treatment approach (-es) to IMGN in South Africa