Serum creatinine as stratified in the RIFLE score for acute kidney injury is associated with mortality and length of stay for children in the pediatric intensive care unit

OBJECTIVE: To evaluate the ability of the RIFLE criteria to characterize acute kidney injury in critically ill children. DESIGN: Retrospective analysis of prospectively collected clinical data. SETTING: Multidisciplinary, tertiary care, 20-bed pediatric intensive care unit. PATIENTS: All 3396 admissions between July 2003 and March 2007. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: A RIFLE score was calculated for each patient based on percent change of serum creatinine from baseline (risk = serum creatinine x1.5; injury = serum creatinine x2; failure = serum creatinine x3). Primary outcome measures were mortality and intensive care unit length of stay. Logistic and linear regressions were performed to control for potential confounders and determine the association between RIFLE score and mortality and length of stay, respectively.One hundred ninety-four (5.7%) patients had some degree of acute kidney injury at the time of admission, and 339 (10%) patients had acute kidney injury develop during the pediatric intensive care unit course. Almost half of all patients with acute kidney injury had their maximum RIFLE score within 24 hrs of intensive care unit admission, and approximately 75% achieved their maximum RIFLE score by the seventh intensive care unit day. After regression analysis, any acute kidney injury on admission and any development of or worsening of acute kidney injury during the pediatric intensive care unit stay were independently associated with increased mortality, with the odds of mortality increasing with each grade increase in RIFLE score (p < .01). Patients with acute kidney injury at the time of admission had a length of stay twice that of those with normal renal function, and those who had any acute kidney injury develop during the pediatric intensive care unit course had a four-fold increase in pediatric intensive care unit length of stay. Also, other than being admitted with RIFLE risk score, an independent relationship between any acute kidney injury at the time of pediatric intensive care unit admission, any acute kidney injury present during the pediatric intensive care unit course, or any worsening RIFLE scores during the pediatric intensive care unit course and increased pediatric intensive care unit length of stay were identified after controlling for the same high-risk covariates (p < .01). CONCLUSIONS: RIFLE criteria serves well to describe acute kidney injury in critically ill pediatric patients.