IFTA as a predictor of renal outcome in patients with malignant hypertension-related TMA: a multicentric cohort study

Background: Interstitial fibrosis and tubular atrophy (IFTA) are common pathological findings in patients with malignant hypertension (mHTN)-related thrombotic microangiopathy (TMA), but their predictive value for renal outcomes in this population remains unclear. Aim: To evaluate the prognostic value of IFTA in renal outcomes of these patients. Design and Setting：This multicenter cohort study included patients with mHTN-related TMA confirmed by renal biopsy from seven Chinese hospitals (2008 to 2024). Methods: Kaplan-Meier (KM) analysis and Cox proportional hazards models assessed the associations between IFTA severity and renal outcomes. The primary outcome was renal replacement therapy (RRT) dependence, and the secondary outcome was renal function recovery. Results: 465 patients were included in this study. During a median follow-up of 24 months, RRT dependence occurred in 182 patients and 226 patients experienced renal function recovery. KM analysis showed significant differences in the cumulative probability of RRT dependence and renal function recovery among the IFTA groups (log-rank p <0.001). Cox regression models showed a hazard ratio of 2.29 (95% CI: 1.59-3.28) and 8.00 (95% CI: 5.36-11.95) for RRT dependence in sever and extremely sever IFTA groups compared to mild/moderate IFTA group, even after adjusting for the potential confounding factors. Extremely severe IFTA negatively impacted renal function recovery in unadjusted analysis, but this significance disappeared after adjusting for global glomerulosclerosis. Conclusions: IFTA may serve as a valuable and independent predictor of renal outcomes in patients with mHTN-related TMA, guiding clinical decision-making.