The Significance of Foot Process Effacement in Renal Prognosis and Response to Treatment in IgA Nephropathy

Objectives This study aimed to analyze the impact of foot process effacement (FPE) severity on prognosis and treatment response in IgA nephropathy (IgAN). Methods In this retrospective study, 1,506 patients with biopsy-proven IgAN were categorized by FPE severity and followed for ≥12 months. The Kaplan-Meier survival and Cox regression analysis were performed to explore the relationship between FPE and adverse renal outcomes. The concordance index (C-index), the area under the receiver operating characteristic (ROC) curve (AUC), and the calibration curve were used to evaluate the nomogram model. Results A total of 1506 patients were included in this study and categorized into three groups according to the degree of FPE. Patients in the severe FPE group exhibited more severe clinical and pathological manifestations. Kaplan-Meier analysis revealed a significantly higher risk of renal failure in the severe FPE group compared to the others (log-rank P < 0.01). Multivariate Cox regression analysis further confirmed that FPE might be an independent risk factor for renal prognosis in IgAN (adjusted HR: 3.688, 95% CI: 1.548 - 8.784, P = 0.009). Subgroup analysis suggested that FPE level warranted particular attention in male patients aged ≤45 years. The FPE-incorporated nomogram showed excellent predictive performance for 3-, 5-, and 8-year end-stage renal disease (ESRD) risks(C-index=0.93; AUCs=0.958, 0.964, 0.892) and was well-calibrated. Furthermore, we found that FPE severity is an important factor influencing the treatment response, and immunosuppressive therapy (IST) can overcome this influence. For patients with severe FPE, IST is an essential intervention measure, and the recommended treatment duration is no less than 12 months. Conclusions FPE serves as an independent predictor of renal progression in patients with IgAN and holds significant clinical value.