Analysis of the prognostic risk factors of idiopathic membranous nephropathy using a new surrogate end-point

Idiopathic membranous nephropathy (IMN) is one of the most common causes of nephrotic syndrome (NS) in adults. The latest study of the chronic kidney disease-prognosis consortium showed that a 30% decrease in the estimated glomerular filtration rate (eGFR) within 2 years could cover more patients and showed a better correlation with end-stage renal disease (ESRD), as compared with serum creatinine (SCr). The aim of the present study was to analyze prognostic factors of ESRD using a 30% decrease in eGFR within 2 years as the end-point. The medical records of patients who were diagnosed as having IMN by clinical pathology between February 2011 and August 2012 and had been followed up for ≥24 months were analyzed retrospectively. A 30% decrease in eGFR or the occurrence of ESRD were the end-points. Factors affecting the prognosis were analyzed by the χ(2) test and multivariate logistic regression analysis, and the cumulative risk of risk factors was analyzed by Kaplan-Meier curve. A total of 73 patients with IMN were confirmed by clinical pathology. Blood pressure, tubulointerstitial injury area (TIA), glomerular sclerosis ratio, SCr, blood urea nitrogen, cystatin C, serum albumin and 24-h urine protein. In total, 28 patients (38.4%) reached the observation end-point. Multivariate logistic regression analysis showed that only age ≥60 years, serum albumin <25 g/l and TIA >25% were independent risk factors for predicting the occurrence of end-point events in the two groups (P<0.05), which increased the risk of the occurrence of end-point events in IMN patients by 3.471-, 3.195- and 6.724-fold, respectively. Kaplan-Meier curve showed that the occurrence of end-point events within 2 years was significantly higher in IMN patients whose age was ≥60 years, serum albumin <25 g/l and TIA >25% (log-rank P=0.004, P=0.024 and P=0.001). The results of the present study revealed that age ≥60 years, low serum albumin concentrations and severe tubulointerstitial injury are independent risk factors for the occurrence of ESRD in IMN patients.