Estimating measured creatinine clearance for critically ill trauma patients with presumed normal kidney function

Area of Science:

• Nephrology
• Critical Care Medicine
• Trauma Surgery

Background:

• Accurate estimation of kidney function is crucial for managing critically ill trauma patients.
• Traditional equations like Cockcroft-Gault (CG) and CKD-EPI may not perform optimally in this population.
• Augmented renal clearance (ARC) is common in trauma patients and can affect drug dosing and outcomes.

Purpose of the Study:

• To evaluate the predictive performance of the CG and 2021 CKD-EPI equations for estimating kidney function in critically ill trauma patients.
• To compare the accuracy of these equations in patients with and without augmented renal clearance (ARC).

Main Methods:

• Retrospective analysis of adult trauma patients with 24-hour urine collection for measured creatinine clearance (mCrCl).
• Inclusion criteria: presumed normal kidney function, mCrCl within 4-14 days post-admission.
• Exclusion criteria: serum creatinine >1.5 mg/dL, requirement for dialysis.

Main Results:

• Both CG and CKD-EPI equations significantly underpredicted mCrCl in the overall cohort (P < 0.001).
• Underprediction persisted in patients with ARC (mCrCl >129 mL/min/1.73m²), with median estimates of 160 mL/min (CG) and 147 mL/min (CKD-EPI).
• The CKD-EPI equation demonstrated superior precision compared to CG in patients without ARC (P < 0.003).

Conclusions:

• Standard equations for estimating kidney function, including CG and CKD-EPI, demonstrate bias towards underestimation in critically ill trauma patients.
• This underestimation is particularly pronounced in patients exhibiting augmented renal clearance (ARC).
• Clinical use of these equations in trauma patients requires careful consideration due to potential inaccuracies, especially in those with ARC.