Epidemiology and outcomes of acute kidney injury in critically ill surgical patients

PURPOSE: Acute kidney injury (AKI) is common in critically ill patients but is poorly defined in surgical patients. We studied AKI in a representative cohort of critically ill surgical patients.

METHODS: This was a retrospective 1-year cohort study of general surgical intensive care unit patients. Patients were identified from a prospective database, and clinical data were reviewed. Acute kidney injury events were defined by risk, injury, failure, loss, and end-stage renal classification criteria. Outcomes were inpatient and 1-year mortality, inpatient lengths of stay, and discharge renal function. Risk factors for AKI and outcomes were compared by univariate and multivariate analyses.

RESULTS: Of 624 patients, 296 (47%) developed AKI. Forty-two percent of events were present upon admission, whereas 36% occurred postoperatively. Risk, injury, failure, loss, and end-stage renal classification distributions by grade were as follows: risk, 152 (51%); injury, 69 (23%); and failure, 75 (25%). Comorbid diabetes, emergency admission, major surgery, sepsis, and illness severity were independently associated with renal dysfunction. Patients with AKI had significantly worse outcomes, including increased inpatient and 1-year mortality. Acute kidney injury starting before admission was associated with worse renal dysfunction and greater renal morbidity than de novo inpatient events.

CONCLUSIONS: Acute kidney injury is common in critically ill surgical patients and is associated with increased mortality, persisting renal impairment and greater resource use.