Comparison of absolute serum creatinine changes versus Kidney Disease: Improving Global Outcomes consensus definitions for characterizing stages of acute kidney injury.
BACKGROUND
The Kidney Disease: Improving Global Outcomes (KDIGO) system for classification of acute kidney injury (AKI) severity utilizes a staging schema based on relative changes in serum creatinine (sCr) concentration and urine output. This study compares the in-hospital mortality associated with KDIGO-defined AKI stages and AKI stages defined by absolute sCr increases ('Delta-Creatinine').


METHODS
The study included an analysis of hospital discharge and laboratory data from an urban academic medical center over a 1-year period. Including adult in-patients undergoing two or more sCr measurements, the study classified AKI stages using the KDIGO consensus standards as well as absolute increases in sCr ('Delta-Creatinine'); Stage 0, sCr increase <0.3 mg/dL, Stage 1, sCr increase 0.3-0.69 mg/dL, Stage 2, sCr increase 0.7-1.19 mg/dL and Stage 3, sCr increase ≥1.2 mg/dL or initiation of renal replacement therapy. The Delta-Creatinine cut-points were defined to optimize discrimination of in-patient mortality between AKI stages. The associations between KDIGO and Delta-Creatinine AKI stages and in-hospital mortality were compared using the time-dependent hazard ratios (HRs) and the net reclassification improvement (NRI).


RESULTS
Of the 19 878 hospitalizations included in the analysis, the prevalence of AKI was 23.4% as defined by the KDIGO criteria. The Delta-Creatinine system discriminated the differences between adjacent AKI stages (i.e. 1 versus 0, 2 versus 1, 3 versus 3) earlier than the KDIGO system. The NRI between Delta-Creatinine and KDIGO for the prediction of mortality was 9.7% [95% confidence interval (CI) 6.2-13.2%]. Stratification by age, sex, race and history of chronic kidney disease (CKD) resulted in similar NRI values.


CONCLUSIONS
The Delta-Creatinine system, based on the absolute increases in sCr, provides a promising alternative to the KDIGO system for characterizing the severity of AKI and its associations with in-patient mortality.
Department of Emergency Medicine, University of Alabama School of Medicine, Birmingham, AL, USA. hwang@uabmc.edu
Henry E
HE
Wang
Gaurav
G
Jain
Richard J
RJ
Glassock
David G
DG
Warnock
D058186:Acute Kidney Injury / Q000097:blood / Q000175:diagnosis* / Q000401:mortality*; D000293:Adolescent; D000328:Adult; D032921:Consensus; D003404:Creatinine / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate; D017052:Hospital Mortality; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D051436:Renal Insufficiency, Chronic / Q000097:blood / Q000175:diagnosis* / Q000401:mortality*; D012307:Risk Factors; D012720:Severity of Illness Index; D015996:Survival Rate; D062606:Tertiary Care Centers; D055815:Young Adult
D003404:Creatinine
acute kidney injury; chronic kidney disease; health services; hospital mortality