Abstract
BackgroundAlthough serum cystatin C (sCysC), urinary N-acetyl-β-d-glucosaminidase (uNAG), and urinary albumin/creatinine ratio (uACR) are clinically available, their optimal combination for acute kidney injury (AKI) detection and prognosis prediction remains unclear. We aimed to assess the discriminative abilities of these biomarkers and their possible combinations for AKI detection and intensive care unit (ICU) mortality prediction in critically ill adults.MethodsA multicenter, prospective observational study was conducted in mixed medical-surgical ICUs at three tertiary care hospitals. One thousand eighty-four adult critically ill patients admitted to the ICUs were studied. We assessed the use of individual biomarkers (sCysC, uNAG, and uACR) measured at ICU admission and their combinations with regard to AKI detection and prognosis prediction.ResultsAUC-ROCs for sCysC, uNAG, and uACR were calculated for total AKI (0.738, 0.650, and 0.683, respectively), severe AKI (0.839, 0.706, and 0.771, respectively), and ICU mortality (0.727, 0.793, and 0.777, respectively). The panel of sCysC plus uNAG detected total and severe AKI with significantly higher accuracy than either individual biomarkers or the other two panels (uNAG plus uACR or sCysC plus uACR). For detecting total AKI, severe AKI, and ICU mortality at ICU admission, this panel yielded AUC-ROCs of 0.756, 0.863, and 0.811, respectively; positive predictive values of 0.71, 0.31, and 0.17, respectively; and negative predictive values of 0.81, 0.97, and 0.98, respectively. Moreover, this panel significantly contributed to the accuracy of the clinical models for AKI detection and ICU mortality prediction, as measured by the AUC-ROC, continuous net reclassification index, and incremental discrimination improvement index. The comparable performance of this panel was further confirmed with bootstrap internal validation.ConclusionsThe combination of a functional marker (sCysC) and a tubular damage marker (uNAG) revealed significantly superior discriminative performance for AKI detection and yielded additional prognostic information on ICU mortality.
Highlights
Serum cystatin C, urinary N-acetyl-β-D-glucosaminidase, and urinary albumin/creatinine ratio are clinically available, their optimal combination for acute kidney injury (AKI) detection and prognosis prediction remains unclear
Patient characteristics Of the 1162 consecutive adult patients screened for inclusion in the study, 78 (6.7%) were excluded for the following reasons: refusal to consent (n = 15), nephrectomy (n = 3), kidney transplant (n = 3), missing admission data (n = 34), end-stage renal disease (ESRD), or undergoing renal replacement therapy (RRT) before intensive care unit (ICU) admission (n = 23)
Patients with AKI had a higher concentration of serum creatinine (sCr) and higher Acute Physiology and Chronic Health Evaluation (APACHE) II scores at ICU admission, Table 1 Baseline characteristics and outcomes
Summary
Serum cystatin C (sCysC), urinary N-acetyl-β-D-glucosaminidase (uNAG), and urinary albumin/creatinine ratio (uACR) are clinically available, their optimal combination for acute kidney injury (AKI) detection and prognosis prediction remains unclear. Serum cystatin C (sCysC) and urinary albumin/creatinine ratio (uACR) are glomerular filtration biomarkers for AKI, whereas urinary N-acetyl-β-D-glucosaminidase (uNAG) is a tubular damage biomarker [8, 10] These biomarkers are clinically available in European, North American, and Asian centers. Because its large size precludes its glomerular filtration, uNAG is a quite sensitive marker that reflects renal tubule damage [12, 13] It manifested well as an early damage biomarker of AKI and could predict poor outcomes [12, 14]. We conducted a large, prospective, multicenter observational study in adult general intensive care units (ICUs) to assess the performance of these individual biomarkers and their possible combinations at ICU admission with respect to AKI detection and prognosis prediction
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