Medico

Available online http://ccforum.com/content/12/4/R110

Research
Vol 12 No 4

Open Access

Acute kidney injury in intensive care unit patients: a comparison between the RIFLE and the Acute Kidney Injury Network classifications
José António Lopes1, Paulo Fernandes1, Sofia Jorge1, Sara Gonçalves1, António Alvarez2, Zélia Costa e Silva2, Carlos França2 and Mateus Martins Prata1
1Department2Department

of Nephrology and Renal Transplantation, Hospital de Santa Maria, Av. Prof. Egas Moniz, Lisboa 1649-035, Portugal of Intensive Medicine, Hospital de Santa Maria, Av. Prof. Egas Moniz, Lisboa 1649-035, Portugal

Corresponding author: José António Lopes, jalopes93@hotmail.com Received: 8 Jun 2008 Revisions requested: 25 Jul 2008 Revisions received: 29 Jul 2008 Accepted: 28 Aug 2008Published: 28 Aug 2008 Critical Care 2008, 12:R110 (doi:10.1186/cc6997) This article is online at: http://ccforum.com/content/12/4/R110 © 2008 Lopes et al.; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction inany medium, provided the original work is properly cited.

Abstract
Introduction Whether discernible advantages in terms of sensitivity and specificity exist with Acute Kidney Injury Network (AKIN) criteria versus Risk, Injury, Failure, Loss of Kidney Function, End-stage Kidney Disease (RIFLE) criteria is currently unknown. We evaluated the incidence of acute kidney injury and compared theability of the maximum RIFLE and of the maximum AKIN within intensive care unit hospitalization in predicting inhospital mortality of critically ill patients. Methods Patients admitted to the Department of Intensive Medicine of our hospital between January 2003 and December 2006 were retrospectively evaluated. Chronic kidney disease patients undergoing dialysis or renal transplant patients wereexcluded from the analysis. Results In total, 662 patients (mean age, 58.6 ± 19.2 years; 392 males) were evaluated. AKIN criteria allowed the identification of more patients as having acute kidney injury (50.4% versus 43.8%, P = 0.018) and classified more patients with Stage 1 (risk in RIFLE) (21.1% versus 14.7%, P = 0.003), but no differences were observed for Stage 2 (injury in RIFLE) (10.1% versus11%, P = 0.655) and for Stage 3 (failure in RIFLE) (19.2% versus 18.1%, P = 0.672). Mortality was significantly higher for acute kidney injury defined by any of the RIFLE criteria (41.3% versus 11%, P < 0.0001; odds ratio = 2.78, 95% confidence interval = 1.74 to 4.45, P < 0.0001) or of the AKIN criteria (39.8% versus 8.5%, P < 0.0001; odds ratio = 3.59, 95% confidence interval = 2.14 to 6.01, P <0.0001). The area under the receiver operator characteristic curve for inhospital mortality was 0.733 for RIFLE criteria (P < 0.0001) and was 0.750 for AKIN criteria (P < 0.0001). There were no statistical differences in mortality by the acute kidney injury definition/classification criteria (P = 0.72). Conclusions Although AKIN criteria could improve the sensitivity of the acute kidney injurydiagnosis, it does not seem to improve on the ability of the RIFLE criteria in predicting inhospital mortality of critically ill patients.

Introduction
Multiple definitions have until recently been used for acute kidney injury (AKI), and therefore the wide variation in definitions has made it difficult to compare results across studies and populations [1]. Recently, however, the Acute DialysisOutcome Initiative group proposed a classification for AKI – the Risk, Injury, Failure, Loss of Kidney Function, and End-stage Kidney Disease (RIFLE) classification – in order to have a uniform standard for diagnosing and classifying AKI [2]. The standard defines three grades of severity – risk (Class R),

injury (Class I) and failure (Class F) – and two outcome classes – loss of kidney function...