27 Risk factors of augmented renal clearance in critically ill children using iohexol clearance for renal function assessment

Introduction Augmented renal clearance(ARC) of hydrophilic drugs is frequent in PICU patients and warrants adjustment of standard dosing regimens to prevent therapeutic failure. Knowledge of patient-, disease- and therapy-related factors associated with ARC, would allow to predict before the start of treatment, which patients would benefit from higher drug doses. We aimed to identify predictors of ARC in critically ill children with normal serum creatinine(Scr) using iohexol plasma clearance (CLiohexol) to quantify renal function. Methods We performed a post hoc analysis of data collected from an interventional study conducted at our academic PICU, which measured glomerular filtration rate (GFR) by CLiohexol in patients with normal Scr. ARC was defined as GFR exceeding normal values for age plus 2 standard deviations. Multivariable logistic regression analysis was performed to identify predictors of ARC. Results GFR was measured in 85 patients, median age was 16 [IQR 5;89] months, 59% had a surgical profile. Median CLiohexol was 122[IQR 75;152] ml/min/1.73m2. Fourthy patients out of 85 (47%) expressed ARC. Postoperative status was identified as independent predictor of ARC (p=0.014, OR 4.253, 95%CI 1.338–13.517). However, in patients after cardiac surgery the odds of developing ARC were significantly lower (p=0.010, OR 0.163, 95%CI 0.041 –0.644). There was a trend suggesting more ARC in male patients and in those without need for vaso-active drugs, however, this was not statistically significant. Conclusion Our findings raise clinicians’ awareness about ARC potentially being present in children after major surgery. This knowledge allows to anticipate on enhanced elimination of drugs by using empirically adjusted dosing regimens immediately from the start of treatment.