CHICAGO (FRONTLINE MEDICAL NEWS) – Adjustment for fluid balance increased the detection rate of acute kidney injury, more accurately staged the kidney damage, and distinguished false-positive cases in critically ill children, based on a secondary analysis of the Study of the Prediction of Acute Kidney Injury in Children Using Risk Stratification and Biomarkers (AKI-CHERUB).

Fluid overload can mask acute kidney injury (AKI) in critically ill children. “The failure to correct serum creatinine measure for fluid overload dilutes the impact of AKI on outcomes,” David T. Selewski, MD , of the University of Michigan, Ann Arbor, said at the annual meeting sponsored by the American Society for Nephrology.

The issue that AKI can be missed or misclassified was explored in a subanalysis of 184 pediatric patients (mean age, 7.7 years) in the single-center, prospective, observational AKI-CHERUB cohort. All of the children had been treated in the intensive care unit (ICU) for at least 48 hours. The hypothesis was that correcting serum creatinine for fluid balance “would reveal the true impact of AKI on outcomes,” Dr. Selewski said.

The primary outcome was ICU mortality. Secondary outcomes were length of mechanical ventilation, and length of stay in the ICU and the hospital.

The original study documented an ICU mortality rate of 7.1%. AKI was identified in 77 (41.8%) of the 184 patients. The median peak fluid overload during ICU admission was 12.9 (interquartile range, 7.4-20.8).

The serum creatinine data were corrected for fluid balance and these rates were reassessed. Following the adjustment, the rate of AKI increased from 41.8% to 53.4%, with 30 new cases identified according to standard defined criteria. The mean fluid overload was now 11.2 (interquartile range, 5.7-17.7).

In the original cohort, there were 40 cases of severe AKI (stage 2 and 3). Following the creatinine correction, 13 more cases were judged to be severe. Of these, five cases were associated with a worse outcome in terms of ICU mortality. Additionally, 10 cases that had been diagnosed as AKI were found to be false positives.

The results need to be studied in larger studies and in other populations, such as neonates, Dr. Selewski said.