Prognostic Significance of Serum NGAL and Troponin I against Acute Kidney Injury in Egyptian ICU Patients after Open Heart Surgery: A Pilot Study.

BACKGROUND

Acute kidney injury (AKI) is a common complication following cardiac surgery and percutaneous coronary interventions, with an estimated incidence rate around 30%, depicted by long-term intensive care unit stay and culminating renal dysfunction over time, triggering either perpetual renal damage evolving to chronic kidney disease/end-stage renal disease transitions or high vulnerability for sudden death after surgery. The classical diagnosis of AKI is based on a sharp rise in serum creatinine that takes at least 48 h to be visible and is associated with multiple nonrenal factors.

OBJECTIVE

We aimed to evaluate the predictive performance of both neutrophil gelatinase-associated lipocalin (NGAL) and Klotho for AKI in patients who underwent cardiothoracic surgery using cardiopulmonary bypass (CPB).

RESULTS

Out of the 182 patients included in the study, 65 had AKI and 117 had non-AKI according to the Kidney Disease: Improving Global Outcomes criteria relying on serum creatinine levels. Baseline serum NGAL was 103.5 ± 41.69 μg/L in the AKI group compared to 79.12 ± 48.02 μg/L in the non-AKI group ( < 0.01) and then manifested a peak-fall-rise pattern until 48 h of CPB, with a more remarkable change in the AKI than in the non-AKI group. ROC curve analysis for all measured biomarkers after 2 h of CPB showed that serum NGAL (0.819, > 75% cutoff, 83.5% accuracy) came after serum creatinine (0.864, > 140% cutoff, 85% accuracy), and troponin I was poorer than both (0.606, > 5.5% cutoff, 60% accuracy). Furthermore, multivariate analysis showed that preoperative serum NGAL, preoperative eGFR ≤60 mL/min/1.73 m, and arterial hypertension were possible risk factors for AKI with adverse outcomes.

CONCLUSIONS

Our study suggests the role of preoperative serum NGAL as a prognostic tool for renal consequences after cardiac surgery. Besides, postoperative serum NGAL is a sensitive marker for AKI, but is less specific than serum creatinine. Troponin I is considered to be a risk confirmatory tool and may help in the prediction of AKI. However, its diagnostic utility is restricted due to age-dependent cutoff values and poor standardization and harmonization because of interassay variations.