The Acute Dialysis Quality Initiative group has proposed the RIFLE (Risk–Injury–Failure–Loss–End-stage renal disease) classification to assess acute kidney injury (AKI). We sought to evaluate the incidence of AKI in critically ill patients according to the RIFLE classification and the correlation between RIFLE class and hospital mortality.

We performed a retrospective cohort study applying the RIFLE classification on 1,138 patients admitted to the ICU during a 2-year period.

According to the RIFLE classification, 376 patients (33%) had AKI during their ICU stay. When assessing the maximum RIFLE class, 209 (18.3%) patients were classified Risk, 63 (5.5%) as Injury and 104 (6.3%) as Failure. Female (OR = 1.53; 95% CI = 1.18 to 1.98; P = 0.001), nonsurgical admission (OR = 1.32; 95% CI = 1.01 to 1.70; P = 0.039), APACHE II on admission above 25 (OR = 1.99; 95% CI = 1.06 to 3.76; P = 0.033), sepsis on admission (OR = 2.20; 95% CI = 1.01 to 4.79; P = 0.046) and chronic organ dysfunction (OR = 1.65; 95% CI = 1.09 to 2.50; P = 0.017) were independent risk factors for AKI. Patients with progressive RIFLE classification had increased hospital mortality, with Risk 13.9%, Injury 22.2% and Failure 47%, as compared with 7.9% (P < 0.001) among patients without AKI. Furthermore, the RIFLE class Failure was an independent predictor of 3-month hospital mortality (OR = 2.37; 95% CI = 1.23 to 4.54; P = 0.009) in addition to organ failure on admission (OR = 4.60; 95% CI = 2.31 to 9.18; P < 0.001), use of vasopressor (OR = 2.34; 95% CI = 1.09 to 5.00; P = 0.028), and APACHE II score on admission (OR = 1.160; 95% CI = 1.11 to 1.21; P < 0.001).

Patients with increasing RIFLE classification had significant elevated hospital mortality. Maximum RIFLE class Failure was independently associated with 3-month hospital mortality.