The significance of foot process effacement in renal prognosis and response to treatment in IgA nephropathy

This study aimed to analyze the impact of foot process effacement (FPE) severity on prognosis and treatment response in IgA nephropathy (IgAN). 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. 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 disease progression in the severe FPE group compared to the others (log-rank P < 0.01). Multivariate Cox regression analysis further confirmed that severe FPE might be an independent risk factor for renal disease progression in IgAN (adjusted HR: 2.480, 95% CI: 1.100–5.593, P = 0.029). Subgroup analyses revealed a consistent trend of increased renal failure risk with severe FPE across clinical subgroups, with statistical significance attained in males and those aged ≤ 45 years, while interaction tests showed no significant modification by gender or age ( P > 0.05). 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. For patients with severe FPE, immunosuppressive therapy (IST) was associated with a significant improvement in treatment response, and this benefit was most evident after a treatment duration of 12 months. Severe FPE serves as an independent predictor of renal disease progression in patients with IgAN and holds significant clinical value. Not applicable.