Acute Kidney Injury: Controversies Revisited

Table 1

RIFLE and AKIN classification [1, 25].

RIFLE			AKIN
Category	Creatinine/GFR	Urine output (UO)	Stage	Creatinine	Urine output (UO)
Risk	Cr increase by x1.5 times or GFR decrease by ≥25%	UO ≤ 0.5 mL/kg/hr for 6 hrs	Stage 1	Cr increase by x1.5 times or ≥ 26 μmol/L	UO ≤ 0.5 mL/kg/hr for 6 hrs
Injury	Cr increase by x2 times or GFR decrease by ≥50%	UO ≤ 0.5 mL/kg/hr for 12 hrs	Stage 2	Cr increase by x2	UO ≤ 0.5 mL/kg/hr for 12 hrs
Failure	Cr increase by x3 times or GFR decrease by ≥75% or; Cr ≥ 354 μmol/L (with acute rise ≥ 44 μmol/L)	UO ≤ 0.3 mL/kg/hr for 24 hrs or anuria for 12hrs	Stage 3	Cr increase by x3 or Cr ≥ 354 μmol/L (with acute rise 44 μmol/L) or RRT^1	UO ≤ 0.3 mL/kg/hr for 24 hrs or anuria for 12 hrs
Loss (outcome)	Persistent ARF = complete loss of renal function > 4 weeks (but ≤3 months)	N/A	Nil
ESRD (outcome)	Complete loss of renal function > 3 months	N/A	Nil

RRT: renal replacement therapy.
¹Patients requiring RRT are automatically considered stage 3 AKIN regardless of stage at time of RRT initiation.