Predisposing Factors and Outcome of Acute Kidney Injury After Blunt Trauma: A 10-Year Study.

Introduction: Acute kidney injury (AKI) indicates an impairment of the renal function following blunt trauma. It is multifactorial and associated with an increased risk of morbidity and mortality. The incidence and risk factors of AKI in young patients with trauma are not well-described. This study aimed to evaluate the incidence, clinical characteristics, and outcomes of post-traumatic AKI. We hypothesized that AKI is associated with worse outcomes in patients with trauma.

Methods: This was a retrospective study of all adult trauma patients admitted to a level 1 trauma center between 2011 and 2021. AKI was diagnosed on the basis of the Kidney Disease Improving Global Outcomes criteria. Data were collected and analyzed for patients with and without AKI using chi-square test and Student's t-test. Multivariate logistic regression analysis and Kaplan-Meier curves were performed.

Results: A total of 17,341 patients with trauma were evaluated, of which 140 (0.8%) developed AKI. Patients with AKI were older (40 ± 20 versus 32 ± 16 y), had more comorbidities, and had a higher injury severity score (ISS) and in-hospital mortality (65% versus 3.2%) than non-AKI patients. Direct trauma to the kidney was reported in only nine (6.4%) patients in the AKI group. Among patients with AKI, nonsurvivors had a higher ISS and were more likely to have hypotension, elevated serum lactate, positive troponin, and a lower platelet-to-lymphocyte ratio than survivors. Multiple logistic regression analyses showed that age, ISS, acute respiratory distress syndrome, blood transfusion, diabetes mellitus, onadmission Glasgow coma scale score, and shock index were predictors of AKI in trauma patients, whereas ISS (odds ratio (OR) = 1.05; 95% confidence interval (CI):1.003-1.100; P = 0.03), serum lactate level (OR = 1.25; 95% CI: 1.019-1.533; P = 0.03), and hypotension (OR = 3.22; 95% CI: 1.044-9.945; P = 0.04) were independent predictors of mortality in patients with posttraumatic AKI. Kaplan-Meier survival analysis showed significant differences in mortality among the three stages of AKI (P = 0.03), with the worst outcome in stage III. However, after adjusting for age, hypotension, and ISS, the Cox regression model showed that only stage I had better survival than stages II and III, whereas no survival difference was noted between stages II and III (P = 0.06).

Conclusions: AKI in young trauma patients is uncommon and associated with a prolonged hospital course and higher mortality. This study identified factors that independently predicted the development of AKI and its outcomes in patients with trauma. However, further prospective and multicenter studies are required to minimize the incidence and complications of posttraumatic AKI.