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

Table 5 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 day considering only data gathered during the first three days of ICU admission

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	238
≥1 hr	18	175	0.78	0.57	0.09	0.98	1.9	< 0.001	4.5
≥2 hr	15	130	0.68	0.69	0.10	0.98	2.2	< 0.001	4.3
≥3 hr	13	91	0.56	0.78	0.13	0.97	2.6	< 0.001	4.2
≥4 hr	12	71	0.52	0.83	0.14	0.97	3.0	< 0.001	4.6
≥5 hr	7	59	0.30	0.85	0.11	0.96	2.1	0.06	2.5
≥6 hr	5	40	0.22	0.90	0.11	0.95	2.2	0.08	2.4
≥12 hr	4	8	0.17	0.98	0.33	0.96	9.0	0.002	7.4

Receiver-operator characteristic area under the curve for this comparison = 0.72 (0.61-0.83). 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