The urine output definition of acute kidney injury is too liberal

Table 7 Areas under the curve for varying durations of urine output from 1 to 6 hours

Duration of urine output (hours)	AUC (95% CI)	P value^a	Optimal threshold (ml/kg/hour)	Relative risk (95%CI)
12	0.68 (0.63 to 0.73)	0.054	0.47	2.69 (1.93 to 3.75)
11	0.68 (0.64 to 0.73)	0.095	0.48	2.53 (1.83 to 3.50)
10	0.69 (0.64 to 0.73)	0.087	0.37	2.52 (1.83 to 3.47)
9	0.69 (0.64 to 0.74)	0.2	0.34	2.94 (2.14 to 4.06)
8	0.70 (0.65 to 0.74)	0.64	0.33	3.27 (2.38 to 4.49)
7	0.70 (0.65 to 0.74)	0.76	0.31	3.39 (2.47 to 4.65)
6	0.70 (0.65 to 0.74)	1	0.31	3.68 (2.68 to 5.04)
5	0.69 (0.65 to 0.74)	0.23	0.30	3.45 (2.53 to 4.72)
4	0.71 (0.66 to 0.75)	0.47	0.23	3.61 (2.62 to 4.99)
3	0.69 (0.64 to 0.73)	0.17	0.23	3.03 (2.22 to 4.14)
2	0.66 (0.62 to 0.71)	0.036	0.19	2.68 (1.94 to 3.68)
1	0.61 (0.56 to 0.66)	0.0003	0.10	1.77 (1.27 to 2.48)

Areas under the curve (AUCs) of varying durations of urine output from 1 to 6 hours for prediction of mortality or dialysis and relative risk for those below the threshold compared with those above the threshold. Comparisons were made in reference to the AUC of average hourly urine output over 6-hour period with the DeLong method. CI, confidence interval. ^a P value for difference relative to 6-hour urine output.

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