Table 1.

Diagnosis and staging criteria for AKI of RIFLE, AKIN, KDIGO, and CK definitions based on serum creatinine

ClassificationDefinition for AKIStageSerum Creatinine Criteria for AKI Staginga
RIFLEIncrease in SCr ≥50% within 7 dRiskTo ≥1.5 times baseline
InjuryTo ≥2 times baseline
FailureTo ≥3 times baseline or ≥0.5 mg/dl increase to at least 4.0 mg/dl
AKINIncrease in SCr ≥0.3 mg/dl or ≥50% within 48 h1Increase of ≥0.3 mg/dl or to 1.5–1.9 times baseline
2To 2–2.9 times baseline
3To ≥3 times baseline or ≥0.5 mg/dl increase to at least 4.0 mg/dl or initiation of RRT
KDIGOIncrease in SCr ≥0.3 mg/dl within 48 h or ≥50% within 7 d1Increase in SCr ≥0.3 mg/dl within 48 h or to 1.5–1.9 times baseline
2To 2.0–2.9 times baseline
3To 3.0 times baseline or to at least 4.0 mg/dl or initiation of RRT
CKIncrease in SCr ≥0.3 mg/dl within 24 h or ≥0.5 mg/dl within 48 h1Increase in SCr ≥0.3 mg/dl within 24 h or ≥0.5 mg/dl within 48 h
2Increase in SCr ≥0.5 mg/dl within 24 h or ≥1.0 mg/dl within 48 h
3Increase in SCr ≥1.0 mg/dl within 24 h or ≥1.5 mg/dl within 48 h
  • For patients meeting diagnosis criteria for AKI according to RIFLE, AKIN, or KDIGO, the stages based on percentage increase were determined by the ratio of peak SCr value obtained during hospitalization to baseline. RIFLE, Risk Injury Failure Loss ESRD; AKIN, Acute Kidney Injury Network; KDIGO, Kidney Disease Improving Global Outcomes; CK, creatinine kinetics; SCr, serum creatinine; RRT, renal replacement therapy.

  • a Urine output was not used, because records of hourly urine output were not available in the majority of patients.