Relationship between Podocyte Injury and Renal Outcomes in Patients with Acute Kidney Injury: A Report from a Retrospective Study in China

INTRODUCTION: Podocyte injury has been proven to be a major cause for poor renal outcomes after acute kidney injury (AKI). However, clinical trial data are still limited. This study aimed to explore the clinical correlations between podocyte injury and renal outcomes in hospitalized AKI patients. METHOD: This retrospective study analyzed data on 52 AKI patients who were histologically diagnosed with acute tubular necrosis or acute interstitial nephritis from six centers throughout China between January 2012 and June 2023. Patients were classified into two groups based on the degree of foot process fusion: ≤50% (mild podocyte injury group) and >50% (severe podocyte injury group). The outcomes were post-AKI new-onset proteinuria and incident CKD. RESULTS: Among 52 AKI patients (14 male; median age, 49 [30, 56] years), 28 (53.8%) had mild podocyte injury; 24 (46.2%) had severe podocyte injury. After 12-month follow-up, 16 (57.1%) had post-AKI new-onset proteinuria, and 5 (17.9%) had post-AKI incident CKD in mild podocyte injury group. Twenty (83.3%) had post-AKI new-onset proteinuria, and 14 (58.3%) had post-AKI incident CKD in severe podocyte injury group. Patients with more severe foot process fusion exhibited significantly higher incidences of post-AKI new-onset proteinuria (83.3% vs. 57.1%, p = 0.041) and incident CKD (58.3% vs. 17.9%, p = 0.003) at 12 months following AKI. The degree of foot process fusion (95% CI 1.013∼3.88, p = 0.048) and proteinuria at 3 months (95% CI 1.309∼5.443, p = 0.015) were identified as independent risk factors for post-AKI new-onset proteinuria at 12 months. The degree of foot process fusion (95% CI 1.026∼14.196, p = 0.048), and the presence of partial renal pathological features, including tubular atrophy (95% CI 1.012∼5.958, p = 0.030), interstitial inflammation (95% CI 1.005∼6.846, p = 0.039), interstitial fibrosis (95% CI 1.110∼6.075, p = 0.043) were independent risk factors for post-AKI incident CKD at 12 months. Kaplan-Meier analysis shows severe podocyte injury group had worst renal survival, including post-AKI new-onset proteinuria (p = 0.0066) and incident CKD (p = 0.0455). CONCLUSION: The degree of podocyte injury is an independent risk factor for post-AKI new-onset proteinuria and incident CKD in patients, and patients with more severe podocyte injury exhibit a higher incidence of post-AKI new-onset proteinuria and incident CKD.