Tonight's journal club requires knowledge of the KDIGO acute kidney injury stages. These are nearly direct translations from the previous AKI staging systems.

RIFLE: the first system. KDIGO 1, 2, 3 roughly corresponds to R, I, F. The primary difference is KDIGO categorizes people with just a 0.3mg/dL rise in Cr as AKI, RIFLE does not.
AKIN: As far as I can see AKIN 1, 2, 3 is identical to KDIGO 1, 2, 3.