Oliguria as predictive biomarker of acute kidney injury in critically ill patients

Table 4 Relation between length of longest episode of oliguria during an ICU day at risk (patient day without a diagnosis of RIFLE I[Cr]) and AKI-Cr in the next two days

Longest duration of oliguria	Days with AKI-Cr next 2 days	Days with no AKI-Cr next 2 days	Sens.	Spec.	PPV	NPV	LR	P	RR of AKI
None	9	439
≥1 hr	26	249	0.74	0.63	0.09	0.98	2.1	< 0.001	4.7
≥2 hr	22	187	0.62	0.72	0.10	0.97	2.3	< 0.001	4.2
≥3 hr	18	120	0.51	0.83	0.13	0.97	2.9	< 0.001	4.5
≥4 hr	17	90	0.49	0.87	0.16	0.97	3.7	< 0.001	5.4
≥5 hr	10	72	0.29	0.90	0.12	0.96	2.7	0.004	3.1
≥6 hr	6	49	0.17	0.93	0.11	0.96	2.4	0.04	2.5
≥12 hr	4	9	0.11	0.99	0.31	0.96	8.7	0.002	7.0

Receiver-operator characteristic area under the curve for this comparison = 0.72 (0.63-0.81). P-values refer to Fisher's exact test for presence or absence of stated degree of oliguria and AKI outcome.
AKI-Cr, acute kidney injury defined by changes in serum creatinine; LR, likelihood ratio (positive); NPV, negative predictive value; PPV, positive predictive value; Sens, sensitivity; Spec, specificity; RR, relative risk.

ISSN: 1364-8535