Clinical determinants and outcomes associated with the development of acute kidney injury in critically ill patients: a Brazilian retrospective cohort study

BackgroundAcute kidney injury (AKI) is a common complication in intensive care unit (ICU) patients and associates with significant morbidity and mortality. Understanding region-specific risk factors is crucial for early identification and management, especially in resource-limited settings. This study aimed to identify characteristics, risk factors, and outcomes related to AKI in critically ill patients from a center in Northeast Brazil. MethodsRetrospective cohort study that used secondary data of adult ICU patients admitted to a medium-sized hospital in Brazil between August 2015 and April 2024. Patients with pre-existing chronic kidney disease or AKI at admission were excluded. Demographic and clinical variables, documented comorbidities, clinical and laboratory data in the first 6 hours of admission, and adverse events during hospitalization were collected. To evaluate risk factors, the variables were included in a multivariable Cox regression model, while to assess complications, a univariable model was employed. Bayesian network modeling was applied to infer causal relations between the presence of AKI and the statistically significant risk factors. Kaplan-Meier curves were used to evaluate survival and length of stay. ResultsOf 5,416 patients analyzed, 369 (6.81%) developed AKI during their ICU stay. Independent risk factors for AKI included advanced age (adjusted Hazard Ratio [aHR] 1.01 per increase in 1 year of age; 95% CI: 1.00-1.02; p=0.008), chronic liver failure (aHR 10.02; 95% CI: 4.91-20.41; p<0.001), arterial hypertension (aHR 1.29; 95% CI: 1.00-1.66; p=0.048), higher heart rate at admission (aHR 1.01 per bpm; 95% CI: 1.00-1.01; p=0.004), and reduced level of consciousness (aHR 1.67 per point decrease in Glasgow Coma Scale; 95% CI: 1.34-2.07; p<0.001). Underweight patients had a lower risk of AKI compared to those with normal weight (aHR 0.59; 95% CI: 0.38-0.91; p=0.017). AKI was associated with higher mortality (37.13% vs. 10.54%; p<0.001) and longer hospital stay (median 16 vs. 10 days; p<0.001). ConclusionsAge, chronic liver failure, arterial hypertension, higher heart rate, and reduced level of consciousness at admission are independent risk factors for AKI development. AKI was associated with poorer outcomes, highlighting the need for early identification and targeted interventions in this population.