External Validation for Acute Kidney Injury Severity Scores: A Multicenter Retrospective Study in 14 Japanese ICUs

Abstract

Background/Aims: Acute kidney injury (AKI) is associated with high mortality. Multiple AKI severity scores have been derived to predict patient outcome. We externally validated new AKI severity scores using the Japanese Society for Physicians and Trainees in Intensive Care (JSEPTIC) database. Methods: New AKI severity scores published in the 21st century (Mehta, Stuivenberg Hospital Acute Renal Failure (SHARF) II, Program to Improve Care in Acute Renal Disease (PICARD), Vellore and Demirjian), Liano, Simplified Acute Physiology Score (SAPS) II and lactate were compared using the JSEPTIC database that collected retrospectively 343 patients with AKI who required continuous renal replacement therapy (CRRT) in 14 intensive care units. Accuracy of the severity scores was assessed by the area under the receiver-operator characteristic curve (AUROC, discrimination) and Hosmer-Lemeshow test (H-L test, calibration). Results: The median age was 69 years and 65.8% were male. The median SAPS II score was 53 and the hospital mortality was 58.6%. The AUROC curves revealed low discrimination ability of the new AKI severity scores (Mehta 0.65, SHARF II 0.64, PICARD 0.64, Vellore 0.64, Demirjian 0.69), similar to Liano 0.67, SAPS II 0.67 and lactate 0.64. The H-L test also demonstrated that all assessed scores except for Liano had significantly low calibration ability. Conclusions: Using a multicenter database of AKI patients requiring CRRT, this study externally validated new AKI severity scores. While the Demirjian's score and Liano's score showed a better performance, further research will be required to confirm these findings.