Clinical Acute Kidney Injury and Histologic Acute Tubular-Interstitial Injury and Their Prognosis in Diabetic Nephropathy

<b><i>Introduction:</i></b> Histologic acute tubular-interstitial injury (hATI) is often observed in patients with diabetic nephropathy (DN). This study aimed to determine the relationship between hATI and clinical acute kidney injury (cAKI) and evaluate significance of hATI in patients with DN. <b><i>Methods:</i></b> Patients with biopsy-proven DN through 2003–2018 in our center were selected. The prevalence of hATI and its correlations with cAKI, tubular injury biomarkers, and serum creatinine were investigated. The renal survival rates and prognostic factors were analyzed by Kaplan-Meier curve and Cox regression model, respectively. <b><i>Results:</i></b> Of 1,414 patients with DN, 70.4% were male, with a median age of 50.0 years. The incidences of cAKI and hATI were 8.6% and 57.8%, respectively. The severities of most hATI were mild (91.0%). The incidence of cAKI in those with hATI was only 12.2%. The incidences of cAKI positively correlated with the scores of hATI (Kendall <i>r</i> = 0.273, <i>p</i> &#x3c; 0.001). The presence of hATI was related to rapid creatinine rise and increased tubular injury biomarkers although without cAKI. After adjusting for significant covariates, multivariate Cox models showed that patients with hATI alone were one and a half times more likely to develop ESRD (hazard ratio [HR]: 1.46; 95% CI, 1.05–2.02) than those without hATI or cAKI, and patients with hATI plus cAKI were 3 times more likely to develop ESRD (HR: 2.96; 95% CI, 1.85–4.72). <b><i>Conclusion:</i></b> Our findings indicated that hATI was common in patients with DN where the majorities were mild hATI and without cAKI. hATI was an independent risk factor of DN progression, regardless of episodes of cAKI.