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RIFLE AKIN KDIGO Definition Staging for Acute Kidney Injury
Although the concept of acute kidney injury is easily defined, multiple operational definitions have been used over the course of years, and coming up with a universal operational definition has been more of a challenge.
Over the past 10 to 15 years, several consensus criteria for the operational definition of AKI have been developed, including the RIFLE (Risk, Injury, Failure, Loss, and End-stage) criteria developed by the Acute Dialysis Quality Initiative (ADQI) in 2004; the AKIN definition developed by the Acute Kidney Injury Network in 2007; and the Kidney Disease Improving Global Outcomes (KDIGO) definition developed by the Kidney Disease: Improving Global Outcomes Acute Kidney Injury Clinical Practice Guideline Workgroup in 2012.
All three of these consensus definitions define AKI based either on changes in serum creatinine concentration or on the presence of oliguria.
In the RIFLE criteria, AKI is defined based on at least a 50% increase in the serum creatinine concentration developing over a period of not more than 7 days or on the basis of a urine output of <0.5 mL/kg per hour for more than 6 hours.
The AKIN definition added an absolute increase in serum creatinine of at least 0.3 mg/dL to the ≥50% increase in serum creatinine, and shortened the time frame for the change in serum creatinine to 48 hours.
The KDIGO definition of AKI kept the ≥ 0.3 mg/dL increase in serum creatinine over 48 hours from the AKIN definition, but restored the time frame for the 50% relative increase in serum creatinine to 7 days, as was originally proposed in the RIFLE criteria.
Both the AKIN and KDIGO definitions retained the same urine output criteria as proposed in the original RIFLE criteria.
RIFLE AKIN KDIGO Definition Staging for Acute Kidney Injury
| Definition/Staging System | Increase in Serum Creatininea | Urine Output Criteriaa | |||
|---|---|---|---|---|---|
| RIFLE | AKIN/KDIGO | RIFLE | AKIN | KDIGO | |
| Risk | Stage 1 | ≥150% of baseline over 7 days | ≥0.3 mg/dL over baseline over 48 h; or ≥150% of baseline over 48 h | ≥0.3 mg/dL over baseline over 48 h; or ≥150% of baseline over 7 days | <0.5 mL/kg per hour for >6 h |
| Injury | Stage 2 | ≥200% of baseline | ≥200% of baseline | ≥200% of baseline | <0.5 mL/kg per hour for >12 h |
| Failure | Stage 3 | ≥300% of baseline; or ≥0.5 mg/dL to a level >4.0 mg/dL | ≥300% of baseline; or ≥0.5 mg/dL to a level >4.0 mg/dL | ≥300% of baseline; or ≥0.5 mg/dL to a level >4.0 mg/dL | <0.3 mL/kg per hour for >24 h; or Anuria for >12 h |
| Loss | Need for RRT due to AKI for >4 weeks | ||||
| End Stage | Need for RRT due to AKI for >3 months |
a Definition of AKI met by either increase in serum creatinine or urine output criteria; stage determined by highest severity of increase in serum creatinine or urine output criteria.AKI, Acute kidney injury; AKIN , Acute Kidney Injury Network; KDIGO , Kidney Disease: Improving Global Outcomes; RIFLE , Risk, Injury, Failure, Loss, End-stage; RRT , renal replacement therapy.
