A comparison of acute kidney injury classification systems in sepsis.

Background: Since 2004, various criteria have been proposed to define and stage acute kidney injury (AKI). Nevertheless, fixed criteria for assessing severe sepsis-related AKI have not yet been established.

Objectives: To assess the ability of the different AKI classification methods to predict mortality in a cohort of patients with sepsis.

Methods: A prospective study of patients>18 years with septic shock admitted to the intensive care unit (ICU) of our hospital from April 2008 to September 2010 was conducted. Plasma creatinine levels were measured daily in the ICU. Patients were classified retrospectively according to RIFLE, AKIN, KDIGO and creatinine kinetics (CK) criteria.

Results: The AKI rate according to the different criteria was 74.3% for RIFLE, 81.7% for AKIN, 81.7% for KDIGO and 77.5% for CK. AKI staging by RIFLE (OR 1.452, P=.003), AKIN (OR 1.349, P=.028) and KDIGO criteria (OR 1.452, P=.006), but not CK criteria (OR 1.188, P=.148) were independently related to in-hospital mortality.

Conclusions: A high rate of patients with severe sepsis developed AKI, which can be classified according to different criteria. Each stage defined by RIFLE, AKIN and KDIGO related to a higher risk of in-hospital mortality. In contrast, the new CK criteria did not relate to higher mortality in patients with severe sepsis and this classification should not be used in these patients without further studies assessing its suitability.