In this episode, I’ll discuss a clinical prediction model for augmented renal clearance in adult mixed critically ill patients.
Augmented or enhanced renal clearance is a phenomenon in some critically ill patients whereby their kidney function becomes supranormal. Awareness of clinicians to the possibility of augmented renal clearance in critically ill patients is growing. Augmented renal clearance is well-documented in trauma patients, especially those under the age of 50. Augmented renal clearance (ARC) of medications has been reported in 30–85% of patients in the intensive care unit, depending on patient-specific factors. A 2015 review article found that there is a clear association between ARC and subtherapeutic antibiotic concentrations as well as literature suggesting worse clinical outcomes.
Various ARC scoring systems have been studied to screen patients for augmented renal clearance.
The authors of a recent study in Critical Care Medicine sought to develop and validate a clinical prediction model for augmented renal clearance that would predict the development of ARC on the next day during a patient’s ICU stay.
This was a multi-center retrospective study. In the development phase of the study over 30,000 ICU patient-days were evaluated. The incidence of ARC was about 20% of ICU days. The authors found 6 variables that contributed to their model: day from ICU admission, age, sex, serum creatinine, trauma, and cardiac surgery.
A separate validation cohort was then tested which involved over 10,000 ICU patient-days. The validation cohort demonstrated a sensitivity and specificity of 84.1% and 76.3%, respectively. This model also demonstrated a better area under the receiver operating characteristics curve than either the ARC score or ARCTIC scoring system.
The authors have developed an online calculator that incorporates their model at arcpredictor.com.
A significant benefit of this model is that it predicts ARC on the next ICU day, which means clinicians may act in advance to adjust medication doses. Getting the dosing adjusted upfront can eliminate a period of underdosing before ARC is detected by other means. Likewise, this calculator could be used to predict the absence of ARC on the following ICU day – something that can be used to normalize medication doses that had been increased to compensate for ARC.
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