When were the RIFLE (Risk, Injury, Failure, Loss, End-stage) and AKIN (Acute Kidney Injury Network) criteria published?

Publication Timeline of RIFLE and AKIN Criteria for Acute Kidney Injury

The RIFLE criteria were published in 2004, while the AKIN criteria were published in 2007. 1

RIFLE Criteria (2004)

• The RIFLE classification system (Risk, Injury, Failure, Loss of kidney function, and End-stage kidney disease) was proposed by the Acute Dialysis Quality Initiative workgroup in May 2004 2, 3
• RIFLE defined AKI as a rise in creatinine of ≥50% from baseline value and/or a fall in the glomerular filtration rate (GFR) by ≥25%, and/or a decrease in urine output below 0.5 ml/kg/h for 6 hours or more 1
• RIFLE included five categories: Risk, Injury, Failure, Loss, and End-Stage kidney disease 1
• A pediatric version (pRIFLE) was subsequently developed for use in children 1

AKIN Criteria (2007)

• The Acute Kidney Injury Network (AKIN) published their AKI classification in March 2007 2
• AKIN criteria were an evolution of the RIFLE criteria, with the Risk, Injury, and Failure stages becoming stages 1,2, and 3 1
• AKIN added a ≥0.3 mg/dl rise in creatinine within 48 hours to the definition of stage 1 AKI 1
• AKIN removed GFR criteria as markers of adult AKI 1
• AKIN eliminated the Loss and End-stage categories as they were considered outcomes rather than stages 1

Key Differences Between RIFLE and AKIN

• Time frame: RIFLE required changes within 7 days, while AKIN shortened this to 48 hours for the 0.3 mg/dl criterion 1
• Baseline requirement: AKIN stipulated that adequate fluid resuscitation should have been undertaken and urinary obstruction excluded before applying the criteria 1
• Classification structure: RIFLE used Risk/Injury/Failure/Loss/End-stage, while AKIN used Stages 1/2/3 1
• Diagnostic threshold: AKIN added the 0.3 mg/dl increase criterion based on studies showing this small rise was independently associated with increased mortality 1

Subsequent Development - KDIGO Criteria

• In 2012, the Kidney Disease Improving Global Outcomes (KDIGO) guideline merged elements from both RIFLE and AKIN criteria 1
• KDIGO maintained the 0.3 mg/dl increase within 48 hours or ≥50% increase within 7 days from AKIN 4
• KDIGO also modified criteria for stage 3 AKI to include rises in creatinine to ≥4.0 mg/dl 1

Impact of These Classification Systems

• Both RIFLE and AKIN criteria have been validated in multiple studies and are widely accepted 1
• Studies have shown that both classification systems demonstrate a progressive increase in mortality with worsening AKI stage 3
• The RIFLE criteria showed a stepwise increase in relative risk for death from Risk (RR=2.40) to Injury (RR=4.15) to Failure (RR=6.37) 3
• Even small increases in serum creatinine (≥0.3 mg/dl) are independently associated with approximately fourfold increase in hospital mortality 1

These classification systems have standardized the definition of AKI, allowing for better epidemiological comparisons across populations and over time, as well as standardization of entry criteria and endpoints in clinical trials 1.