Urinary tract trauma as a predictor of acute kidney injury in severely injured patients: A retrospective analysis of observational studies.

Aim: The main objective of this study was to determine whether urinary trauma increases the risk of acute kidney injury (AKI) in patients with severe trauma. As a secondary objective, we assessed the reliability of neutrophil gelatinase-associated lipocalin (NGAL) in the early prediction of AKI in this patient population.

Methods: Retrospective analysis of two prospective observational studies involving 179 adult patients with severe trauma (Injury Severity Score >16). NGAL levels were measured by taking a blood sample 24 h after admission. AKI was diagnosed according to the Kidney Disease Improving Global Outcomes (KDIGO) classification.

Results: The overall incidence of AKI was 29%. Kidney or vascular injury was an independent risk factor for AKI (risk ratio [RR] = 3.1, 95% confidence interval [CI] 1.93-4.90). Trauma to urinary passages was also associated with an increased risk of AKI (RR = 4.2, 95% CI 2.70-6.46). Among patients without urinary tract injury, serum NGAL levels were significantly higher in trauma patients who developed AKI during the first 5 days in the intensive care unit (ICU) compared to patients without this organ dysfunction (214.6 µg/L [IQR 167.3] vs. 90.6 µg/L [IQR 58.4]; P<0.001). In patients with urinary tract trauma, there was no difference in the NGAL levels between the two groups (184.6 µg/L [IQR 139.9] vs. 118.3 µg/L [IQR 118.1]; P=0.216). NGAL was not a reliable predictor of AKI in patients with urinary trauma (AUC 0.660).

Conclusion: Urinary tract injury is associated with a significant increase in AKI in patients with severe trauma during the first 5 days of hospitalization in the intensive care unit. In these patients, NGAL is not a reliable predictor of the development of AKI.