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

Table 3 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 the next day

Longest duration of oliguria	Days with AKI-Cr next day	Days with no AKI-Cr next day	Sens.	Spec.	PPV	NPV	LR	P	RR of AKI-Cr
None	5	443
≥1 hr	18	257	0.78	0.63	0.07	0.99	2.1	< 0.0001	5.9
≥2 hr	15	194	0.65	0.72	0.07	0.98	2.4	0.0003	4.6
≥3 hr	13	125	0.57	0.82	0.09	0.98	3.2	< 0.0001	5.5
≥4 hr	12	95	0.52	0.86	0.11	0.98	3.8	< 0.0001	6.3
≥5 hr	7	75	0.30	0.89	0.09	0.98	2.8	0.01	3.4
≥6 hr	5	50	0.21	0.93	0.09	0.97	3.1	0.02	3.8
≥12 hr	4	9	0.17	0.99	0.31	0.97	13.5	0.0005	11.5

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; hr, hours; LR, likelihood ratio (positive); NPV, negative predictive value; PPV, positive predictive value; Sens, sensitivity; Spec, specificity; RR, relative risk.

ISSN: 1364-8535