Acute kidney injury in intensive care unit patients: a comparison between the RIFLE and the Acute Kidney Injury Network classifications

Table 1 Risk, Injury, Failure, Loss of Kidney Function, End-stage Kidney Disease classification [2]

Class	GFR criteria	Urinary output criteria
Risk	Serum creatinine × 1.5 or GFR decrease > 25%	< 0.5 ml/kg/hour × 6 hours
Injury	Serum creatinine × 2 or GFR decrease > 50%	< 0.5 ml/kg/hour × 12 hours
Failure	Serum creatinine × 3, GFR decrease > 75% or serum creatinine ≥4 mg/dl with an acute rise > 0.5 mg/dl	< 0.3 ml/kg/hour × 24 hours, or anuria × 12 hours
Loss	Persistent acute renal failure = complete loss of kidney function > 4 weeks
End-stage kidney disease	End-stage kidney disease > 3 months

For conversion of creatinine expressed in conventional units to standard units, multiply by 88.4. Patients are categorized on serum creatinine or urinary output, or both, and the criteria that lead to the worst classification are used. Glomerular filtration rate (GFR) criteria are calculated as an increase of serum creatinine above the baseline serum creatinine level. When the baseline serum creatinine is unknown and there is no past history of chronic kidney disease, serum creatinine is calculated using the Modification of Diet in Renal Disease formula for assessment of kidney function [14], assuming a GFR of 75 ml/min/1.73 m².

ISSN: 1364-8535