Risk, Injury, Failure, Loss, End-stage kidney disease (RIFLE) Classification in this study is based on serum creatinine values and renal replacement therapy, i.e. ignoring criteria based on urine output, as fulfilment of urine output criteria cannot be determined from the data collected in the study.
RIFLE comprises five categories: Risk (R), Injury (I), Failure (F), Loss (L), End-stage kidney disease (E) (worst outcome). R, I and F are based on increase in serum creatinine. L and E are based on administration of renal replacement therapy.