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Abstract

Introduction: Acute kidney injury (AKI) is associated with mortality in the pediatric intensive care unit (ICU), but it is unclear whether it has an independent effect on mortality in the setting of pediatric multiple organ dysfunction. Methods: AKI was determined using the serum creatinine RIFLE criteria in all patients 1 month to 21 years without chronic kidney disease admitted to a large pediatric ICU from 3/2003 to 3/2012. Patients had a daily non-renal organ dysfunction (OD) score calculated from the cardiovascular, respiratory, hematological and hepatic components of the Pediatric Logistic Organ Dysfunction score. Maximum possible score was 41. Patients were stratified into 4 subgroups based on the maximum score achieved during the first week of ICU stay: No OD (score of 0), mild OD (1 to 10), moderate OD (11 to 20), and severe OD (more than 20). Within each subgroup, we compared outcomes based on the presence or absence of AKI. The primary outcome was 28-day mortality. Secondary outcomes were number of non-renal OD-free days during the first week and ICU length of stay (LOS). P values were based on Yates-corrected Chi-squared and Mann-Whitney U tests. Results: We identified 8260 ICU admissions with 815 cases of AKI during the first week of ICU stay (9.7%). Patients with no non-renal OD (n=2124) had a mortality of 3.1% when AKI was present vs. 0.1% without AKI (odds ratio [OR] 33.2, 95% confidence interval [CI] 5.76–191.34); with mild OD (n=3072): 13.8% mortality with AKI vs. 1.4% without AKI (OR 11.6, CI 6.98–16.13); with moderate OD (n=2649): 25.3% with AKI vs. 5.2% without AKI (OR 6.1, CI 4.56–8.28); and with severe OD (n=415): 55.1% with AKI vs. 26.8% without AKI (OR 3.36, CI 2.22–5.06), all p values were <0.001. Patients with AKI also had fewer non-renal OD-free days (0 vs. 5 days, p<0.001) and longer ICU LOS (6.8 vs. 3.0 days, p<0.001). Conclusions: AKI is independently associated with mortality regardless of the severity of other OD. AKI is also associated with fewer non-renal OD-free days and a longer ICU LOS after controlling for baseline OD severity. This supports the hypothesis that AKI may exacerbate other OD and has an independent association with death in the pediatric ICU.