World J Nephrol Urol

World Journal of Nephrology and Urology, ISSN 1927-1239 print, 1927-1247 online, Open Access

Article copyright, the authors; Journal compilation copyright, World J Nephrol Urol and Elmer Press Inc

Journal website http://www.wjnu.org

Original Article

Volume 3, Number 1, March 2014, pages 18-24

The Duration of Postoperative Acute Kidney Injury Predicts In-Hospital Mortality in Surgical Patients

Figures

Figure 1. Cumulative survival rate for 504 postoperative patients based on their AKI stages using RIFLE criteria. The overall in-hospital survival rates were significantly different among four groups (P < 0.001 by log-rank test).

Figure 2. Cumulative survival rate for 504 surgical patients based on their duration of AKI during admission. The overall in-hospital survival rates were significantly different among four groups (P < 0.001 by log-rank test).

Tables

**Table 1.** Definition of RIFLE Classification
Category	GFR criteria	UO criteria
SCr: serum creatinine; GFR: glomerular filtration rate; ESRD: end stage renal disease; UO: urine output.
Risk	Increase in SCr ≥ 1.5 × baseline or decrease in GFR ≥ 25%	UO < 0.5 mL/kg/h × 6 h
Injury	Increase in SCr ≥ 2.0 × baseline or decrease in GFR ≥ 50%	UO < 0.5 mL/kg/h × 12 h
Failure	Increase in SCr ≥ 3.0 × baseline or SCr ≥ 4.0 mg/dL or decrease in GFR ≥ 75%	UO < 0.3 mL/kg/h × 24 h or anuria × 12 h
Loss	Complete loss of kidney function ≥ 4 weeks
ESRD	End-stage renal disease (≥ 3 months)

**Table 2.** Hazard Ratios for In-Hospital Mortality According to Duration of AKI
Parameter	β coefficient	SE	Hazard ratio	95% CI	P value
AKI: acute kidney injury; CI: confidence interval; SE: standard error. *Adjusted for age, gender, need for ventilator, APACHE II, SOFA, SAPS, MODS, surgery category, underlying diseases, emergent operation, the use of vasoactive drugs, source and severity of sepsis, baseline renal function, peak RIFLE classification (RIFLE max).
Unadjusted
Non-AKI	-	-	1 (reference)	1 (reference)	1 (reference)
First tertile	0.639	0.281	1.891	1.090 - 3.278	0.023*
Second tertile	1.225	0.251	3.405	2.081 - 5.571	< 0.001***
Third tertile	1.001	0.250	2.721	1.668 - 4.439	< 0.001***
Adjusted*
Non-AKI	-	-	1 (reference)	1 (reference)	(reference)
First tertile	0.490	0.383	1.632	0.771 - 3.455	0.201
Second tertile	1.084	0.364	2.956	1.448 - 6.035	0.010*
Third tertile	0.794	0.364	2.212	1.083 - 4.516	0.040*