Published in:
Open Access 01-04-2013 | Research
Diagnostic accuracy of early urinary index changes in differentiating transient frompersistent acute kidney injury in critically ill patients: multicenter cohortstudy
Published in: Critical Care | Issue 2/2013
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Introduction
Urinary indices have limited effectiveness in separating transient acute kidneyinjury (AKI) from persistent AKI in ICU patients. Their time-course may vary withthe mechanism of AKI. The primary objective of this study was to evaluate thediagnostic value of changes over time of the usual urinary indices in separatingtransient AKI from persistent AKI.
Methods
An observational prospective multicenter study was performed in six ICUs involving244 consecutive patients, including 97 without AKI, 54 with transient AKI, and 93with persistent AKI. Urinary sodium, urea and creatinine were measured at ICUadmission (H0) and on 6-hour urine samples during the first 24 ICU hours (H6, H12,H18, and H24). Transient AKI was defined as AKI with a cause for renalhypoperfusion and reversal within 3 days.
Results
Significant increases from H0 to H24 were noted in fractional excretion of urea(median, 31% (22 to 41%) and 39% (29 to 48%) at H24, P < 0.0001),urinary urea/plasma urea ratio (15 (7 to 28) and 20 (9 to 40), P <0.0001), and urinary creatinine/plasma creatinine ratio (50 (24 to 101) and 57 (29to 104), P = 0.01). Fractional excretion of sodium did not changesignificantly during the first 24 hours in the ICU (P = 0.13). Neitherurinary index values at ICU admission nor changes in urinary indices between H0and H24 performed sufficiently well to recommend their use in clinical setting(area under the receiver-operating characteristic curve ≤0.65).
Conclusion
Although urinary indices at H24 performed slightly better than those at H0 indifferentiating transient AKI from persistent AKI, they remain insufficientlyreliable to be clinically relevant.