Epidemiology of AKI in the ICU.

Up to a little while ago there was no uniform definition for acute kidney injury (AKI). Recently, the Acute Dialysis Quality Initiative proposed the RIFLE consensus classification for AKI. This classification was adapted and modified by the Acute Kidney Injury Network into the AKI staging system. This classification defines 3 stages of severity of AKI, including less severe AKI. The incidence of AKI in ICU patients is increasing; severe AKI, treated by renal replacement therapy (RRT), has now an incidence comparable to that of acute lung injury/acute respiratory distress syndrome (ALI/ARDS), and less severe AKI has an incidence comparable to that of sepsis. The prognosis of patients with AKI treated with RRT is still dim, with mortality rates between 50% and 60%. It is important to know that AKI is not only a consequence of severe disease, but also contributes to its worse outcome. Severe AKI, and less severe AKI, as defined by the AKI classification, have an independent association with mortality.