High urinary excretion of kidney injury molecule-1 predicts adverse outcomes in acute kidney injury: a case control study

BACKGROUND Acute kidney injury (AKI) is a common clinical syndrome with poor prognosis. The insensitivity and non-specificity of traditional markers of renal dysfunction prevent timely estimation of the severity of renal injury, and the administration of possible therapeutic agents. Urinary kidney injury molecule-1 (uKIM-1) is a marker of epithelial injury of renal tubules. Different uKIM-1 levels are associated with various degrees of renal injury. This study sought to evaluate uKIM-1 as a predictor of renal prognosis by analyzing uKIM-1 levels in patients with AKI. METHODS A total of 258 patients were screened, 201 patients were enrolled in the study, and 17 patients were lost to follow up. Therefore, 184 AKI patients were included in this study and were classified into transient AKI and renal AKI groups according to short-term renal function recovery (48 h). Changes in renal function were observed for one year during regular follow up, and risk factors that affected renal prognosis were analyzed. RESULTS The uKIM-1 level in the renal AKI group was significantly higher than that in the transient AKI group. The receiver operating characteristic area under the curve (ROC-AUC) of uKIM-1 for the diagnosis of renal AKI was 0.691, and its sensitivity and specificity were 66.3 % and 64.7 %, respectively. The uKIM-1 level at AKI occurrence was significantly higher in the group with deterioration in renal function than in the group with stable renal function. Thus, uKIM-1 level is a prognostic factor for poor renal prognosis. ROC curve analysis demonstrated that the AUC for the prediction of renal function progression on the basis of uKIM-1 levels in patients with renal AKI and AKI was 0.680 and 0.703, respectively; the sensitivity was 78.6 % and 78.4 %, respectively; and the specificity was 57.9 % and 60.8 %, respectively. uKIM-1 > 2.37 ng/mg in patients with AKI positively correlated with poor renal prognosis. CONCLUSIONS uKIM-1 levels sensitively predict the renal prognosis of patients with AKI, and they may be used as early screening indicators for poor renal prognosis.