Renal survival in idiopathic membranous nephropathy: The impact of chronicity score and clinical predictors.

OBJECTIVE

Renal survival is crucial in patients with idiopathic membranous nephropathy (IMN). Our aim was to identify baseline clinical and histopathological predictors of long-term renal survival in patients with IMN.

MATERIALS AND

METHODS

In this retrospective, single-center cohort study, we reviewed 50 adults with biopsy-proven IMN (January 2009 - February 2019) who completed at least 60 months of follow-up. We recorded baseline age, sex, serum creatinine, serum albumin, 24-hour proteinuria, and the total renal chronicity score (Mayo Clinic Chronicity Score). Chronicity was classified as minimal (score 0 - 1) or non-minimal (score ≥ 2). The renal endpoint was defined as a ≥ two-fold increase in serum creatinine from baseline or the initiation of renal replacement therapy (RRT). Predictors of renal survival were assessed using univariate and multivariate Cox regression; renal survival probability was illustrated with Kaplan-Meier analysis.

RESULTS

During the 5-year follow-up, 20 out of 50 patients (40%) reached the renal endpoint. Kaplan-Meier curves demonstrated a significant divergence: only 1 out of 30 patients (3.3%) in the minimal-chronicity group progressed, while 19 out of 20 patients (95%) with non-minimal chronicity experienced either a doubling of creatinine or required RRT (log-rank p < 0.001). In univariate analysis, older age, higher serum creatinine, lower serum albumin, albumin levels below 3 g/dL, and non-minimal chronicity were associated with poor outcomes. Multivariate Cox regression confirmed three independent predictors: baseline serum creatinine (HR 2.38, 95% CI 1.37 - 4.11, p = 0.02), serum albumin (HR 0.43, 95% CI 0.23 - 0.80, p = 0.008), and non-minimal chronicity score (HR 14.4, 95% CI 3.2 - 64.6, p < 0.001).

CONCLUSION

In IMN, a high total renal chronicity score on biopsy, elevated baseline serum creatinine, and hypoalbuminemia (&lt; 3 g/dL) independently predict poor 5-year renal survival. Early recognition of non-minimal chronicity may facilitate timely therapeutic intervention and closer monitoring to mitigate progression to end-stage kidney disease.