Three Definitions for Incidence and Staging of AKI in Children

2Clinical Journal of the American Society of Nephrology. 2015;10(4):554-561.

Application of three definitions of acute kidney injury (AKI) resulted in differences in incidence and staging in AKI in children in an observational, electronic medical record(EMR)–enabled study conducted by Scott M. Sutherland, MD, and colleagues.

There are several standardized definitions for AKI, but no consensus about which to use in children. The three standard definitions are the Pediatric RIFLE (pRIFLE), AKIN Network (AKIN), and kidney Disease Improving Global Outcomes (KDIGO) criteria. IN this study, the researchers applied the three criteria to an anonymized cohort of 14,795 hospitalizations at the Lucile Packard Children’s Hospital between 2006 and 2010 extracted from the EMR to compare the incidence of AKI and outcomes in intensive care unit (ICU) and non-ICU pediatric populations.

AKI and Aki severity stage were defined using the three criteria according to creatinine change (urine output change criteria were not used). The researchers calculated AKI incidence and each AKI stage for each classification. All-cause, in-hospital mortality and total hospital length-of-stay were compared at each subsequent AKI stage by Fisher exact and Kolmogorov-Smirnov tests, respectively.

Across the cohort, the incidences of AKI were 51.1% (pRIFLE), 37.3% (AKIN), and 40.3% (KDIGO). Across all definitions, mortality was higher among patients with AKI (pRIFLE, 2.3%; AKIN, 2.7%; KDIGO, 2.5%; P<.001 vs no AKI.

Within the ICU, pRIFLE, AKIN, and KDIGO demonstrated progressively higher mortality at each AKI severity stage. Outside the ICU, there was no association of AKI with mortality with any definition. Both in and outside the ICU, there was an association with a significantly higher length of stay at each AKI severity stage across the three definitions (P<.001). There were differences in diagnosis and staging in the three definitions; staging agreement ranged from 76.7% to 92.5%.

“Application of the three definitions let to differences in Aki incidence and staging, Aki was associated with greater mortality and LOS in the ICU and greater LOS outside the ICU. All three definitions demonstrated excellent interstage discrimination. While each definition offers advantages, these results underscore the need to adopt a single, universal Aki definition,” the researchers concluded.