Table 2b. Hospital-based incidence rates of AKI before and after RIFLE/AKIN/KDIGO.

Study	Era			Country	Enrollment	Setting	Definition used	Incidence
Hou et al.22	Before			USA (Chicago)	1979	Hospitalized (single center)	Increase in serum creatinine by 0.5 mg/dl if baseline ⩽1.9 mg/dl, 1.0 mg/dl if baseline 2.0–4.9 mg/dl, and 1.5 mg/dl if baseline ⩾5 mg/dl	4.9%
Nash et al.23	RIFLE	AKIN	KDIGO	USA (Boston)	1996	Hospitalized (single center)	Increase in serum creatinine by 0.5 mg/dl if baseline ⩽1.9 mg/dl, 1.0 mg/dl if baseline 2.0–4.9 mg/dl, and 1.5 mg/dl if baseline ⩾5 mg/dl	7.2%
Liano et al.139				Spain (Madrid)	1991–1992	Hospitalized (multicenter)	Increase in serum creatinine 2 mg/dl in normal renal function or 50% increase if CKD	AKI: 209/million/year (95% CI: 195–223) ATN: 88/million/year (95% CI:79–97)
Hsu et al.9				USA (California)	1996–2003	Hospitalized (multicenter)	Increase in serum creatinine by 0.5 mg/dl if baseline⩽1.9 mg/dl, 1.0 mg/dl if baseline 2.0–4.9 mg/dl, and 1.5 mg/dl if baseline ⩾5 mg/dl	Nondialysis-requiring AKI: 3227 to 5224 per million person-years Dialysis-requiring AKI: 195 to 295 per million person-years
Liangos et al.139				USA (National Hospital Discharge Survey)	2001	Hospitalized patients (multicenter)	ICD-9-CM codes for acute renal failure	1.9%
Uchino et al.140	After			Australia (Melbourne)	2000–2002	Hospitalized (single center)	RIFLE	18%
Ali et al.141	RIFLE	AKIN	KDIGO	United Kingdom (Scotland)	2003	Hospitalized patients (multicenter)	RIFLE	1811/million/year (AKI) 336/million/year (ACRF)
Porter et al.142				United Kingdom (Nottingham)	2011–2013	Hospitalized patients (multicenter)	AKIN+RIFLE	10.7%