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Open Access Highly Accessed Research

Multiple-center evaluation of mortality associated with acute kidney injury in critically ill patients: a competing risks analysis

Christophe Clec'h12*, Frédéric Gonzalez1, Alexandre Lautrette3, Molière Nguile-Makao2, Maïté Garrouste-Orgeas24, Samir Jamali5, Dany Golgran-Toledano6, Adrien Descorps-Declere7, Frank Chemouni1, Rebecca Hamidfar-Roy8, Elie Azoulay29 and Jean-François Timsit28

Author Affiliations

1 Medical-Surgical Intensive Care Unit, Avicenne Teaching Hospital, 125 Route de Stalingrad, F-93009 Bobigny Cedex, France

2 INSERM U823, Clinical Epidemiology of Critically Ill Patients and Airway Cancer, Albert Bonniot Institute, Rond-Point de la Chantourne, BP 217, F-38043 Grenoble, France

3 Medical Intensive Care Unit, Gabriel Montpied Teaching Hospital, 58 Boulevard Montalembert, F-63003 Clermont-Ferrand Cedex 1, France

4 Medical-Surgical Intensive Care Unit, Saint-Joseph Hospital, 185 Rue Raymond Losserand, F-75014 Paris, France

5 Medical-Surgical Intensive Care Unit, Dourdan Hospital, 2 rue du Potelet, BP 102, F-91415 Dourdan Cedex, France

6 Medical-Surgical Intensive Care Unit, Gonesse Hospital, 25 rue Pierre de Theilley, BP 30071, F-95503 Gonesse France

7 Surgical Intensive Care Unit, Antoine Béclère Teaching Hospital, 157 rue de la Porte de Trivaux, F-92141 Clamart Cedex, France

8 Medical Intensive Care Unit, Albert Michallon Teaching Hospital, BP 217, F-38043 Grenoble Cedex 09, France

9 Medical Intensive Care Unit, Saint-Louis Teaching Hospital, 1 rue Claude Vellefaux, F-75010 Paris, France

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Critical Care 2011, 15:R128  doi:10.1186/cc10241

Published: 17 May 2011

Abstract

Introduction

In this study, we aimed to assess the association between acute kidney injury (AKI) and mortality in critically ill patients using an original competing risks approach.

Methods

Unselected patients admitted between 1997 and 2009 to 13 French medical or surgical intensive care units were included in this observational cohort study. AKI was defined according to the RIFLE criteria. The following data were recorded: baseline characteristics, daily serum creatinine level, daily Sequential Organ Failure Assessment (SOFA) score, vital status at hospital discharge and length of hospital stay. Patients were classified according to the maximum RIFLE class reached during their ICU stay. The association of AKI with hospital mortality with "discharge alive" considered as a competing event was assessed according to the Fine and Gray model.

Results

Of the 8,639 study patients, 32.9% had AKI, of whom 19.1% received renal replacement therapy. Patients with AKI had higher crude mortality rates and longer lengths of hospital stay than patients without AKI. In the Fine and Gray model, independent risk factors for hospital mortality were the RIFLE classes Risk (sub-hazard ratio (SHR) 1.58 and 95% confidence interval (95% CI) 1.32 to 1.88; P < 0.0001), Injury (SHR 3.99 and 95% CI 3.43 to 4.65; P < 0.0001) and Failure (SHR 4.12 and 95% CI 3.55 to 4.79; P < 0.0001); nonrenal SOFA score (SHR 1.19 per point and 95% CI 1.18 to 1.21; P < 0.0001); McCabe class 3 (SHR 2.71 and 95% CI 2.34 to 3.15; P < 0.0001); and respiratory failure (SHR 3.08 and 95% CI 1.36 to 7.01; P < 0.01).

Conclusions

By using a competing risks approach, we confirm in this study that AKI affecting critically ill patients is associated with increased in-hospital mortality.