Purpose: The Risk, Injury, Failure, Loss and ESRD (RIFLE) classification has been widely accepted for the definition of acute kidney injury (AKI); however, no study has described in detail the last two stages of the classification: "Loss" and "ESRD". We aim to describe and evaluate the development of "Loss" and "ESRD" in a group of critically ill patients.
Methods: We conducted a retrospective analysis of cases prospectively collected from the Acute Physiology and Chronic Health Assessment (APACHE III) database. Subjects were consecutive critically ill patients >18 years of age admitted to three ICUs of two tertiary care academic hospitals, from January 2003 through August 2006, excluding those who denied research authorization, chronic hemodialysis therapy, kidney transplant recipients, readmissions, and admissions for less than 12 h for low risk monitoring.
Results: 11,644 patients were included in the study. The median age was 66 (interquartile range, 52-76), 90% were Caucasians and 54% of the patients were male. Half of the patients developed AKI, and most of the patients were in the Risk and Injury stages. From the patients that developed AKI, a total of 1,065 (19%) patients required renal replacement therapy (RRT), 415 (39%) underwent continuous renal replacement therapy (CRRT) and 650 (61%) underwent intermittent hemodialysis. A total of 281 patients on RRT did not survive hospital discharge, 97 patients progressed to "Loss", and 282 patients progressed to "ESRD". After multivariable adjustment, the progression to "ESRD" was associated with higher baseline creatinine, odds ratio (OR) 1.19 per every increase in creatinine of 0.1 mg/dl (95% CI, 1.11-1.29) P < 0.001; and less frequent use of CRRT, OR 0.18 (95% CI, 0.11-0.29) P < 0.001.
Conclusion: In this large retrospective study we found that almost 50% developed some form of AKI as defined by the RIFLE classification. Of these, 19% required RRT, and 4.9% progressed to "ESRD". "ESRD" was more likely in patients with elevated baseline creatinine and those treated with intermittent hemodialysis.