Could the total renal chronicity score at renal biopsy and baseline creatinine be predictive of long-term renal survival in primary membranous nephropathy patients?

Objective: Renal survival is important in patients with idiopathic membranous nephropathy (IMN). In this study we investigated the factors affecting renal survival in IMN patients Methods: This retrospective single center cohort study included patients who were diagnosed with IMN by renal biopsy between January 2009 and February 2019 and had a 5-year follow-up. Age, gender, serum creatinine, serum albumin, 24-hour proteinuria of the patients at the time of renal biopsy were recorded. The total renal chronicity score was calculated from the results of renal biopsy and patients were divided into minimal and non-minimal (including mild, moderate and severe) according to the total chronicity score. Renal survival was defined as at least a two-fold increase in serum creatinine from baseline and the need for renal replacement treatment (RRT). Results: Twenty patients (40%) had doubled serum creatinine levels or needed RRT. In univariate analysis, age, serum creatinine, serum albumin, serum albumin grade (<3g/dl) and total renal chronicity grade were found to be risk factors for renal survival. Multivariate Cox regression analysis revealed that the serum creatinine level [hazard ratio (HR) 2.38, confidence interval (CI) 1.37-4.11, p=0.02], serum albumin level (HR 0.43, CI 0.23-0.8, p=0.008) and total renal chronicity score grade (HR 14.4, CI 3.2-64.6, p:<0.001) were independent risk factors for renal survival. Conclusions: Low albumin levels (especially <3g/dl), high serum creatinine levels and high total renal chronicity scores (the presence of non-minimal degree of chronic change) on renal biopsy at the time of diagnosis are predictive of poor renal survival.