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

Christophe Clec'h , Frederic Gonzalez, Alexandre Lautrette, Moliere Nguile-Makao, Maite Garrouste-Orgeas, Samir Jamali, Dany Goldgran-Toledano, Adrien Descorps-Declere, Frank Chemouni, Rebecca Hamidfar-Roy, Elie Azoulay and Jean-Francois Timsit

Critical Care 2011, 15:R128doi:10.1186/cc10241

Introduction: 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, daily Sequential Organ Failure Assessment (SOFA) score, vital status at hospital discharge, and lengths of stays. Patients were classified according to the maximum RIFLE class reached during the ICU stay. The association of AKI with hospital mortality considering "discharge alive" as a competing event was assessed through the Fine and Gray model.

Results : Of the 8639 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 stays than patients without AKI. In the Fine and Gray model, independent risk factors for hospital mortality were: RIFLE classes Risk (sub-hazard ratio -SHR-: 1.58; 95% confidence interval -CI-: 1.32-1.88; p < 0.0001), Injury (SHR: 3.99; 95% CI: 3.43-4.65; p < 0.0001) and Failure (SHR: 4.12; 95% CI: 3.55-4.79; p < 0.0001), non-renal SOFA score (SHR: 1.19 per point; 95% CI: 1.18-1.21; p < 0.0001), class 3 of Mc Cabe (SHR: 2.71; 95% CI: 2.34-3.15; p < 0.0001), and respiratory failure (SHR: 3.08; 95% CI: 1.36-7.01; p < 0.01).

Conclusions : By using a competing risks approach, this study confirms that AKI affecting critically ill patients is associated with increased hospital mortality.

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