Comparison of creatinine clearance estimation methods in patients with trauma

The abilities of a modified Cockcroft-Gault equation and the standard equation to estimate creatinine clearance (CLcr) in trauma patients were compared. The medical records of patients with stable renal function who had been treated for trauma and had had a 24-hour urine collection for creatinine measurement were reviewed. Creatinine concentrations in urine and serum were used to calculate the actual CLcr, which was normalized to 1.73 sq m. CLcr was estimated by the modified equation (which normalized body weight to 72 kg) and by the standard equation using ABW, IBW, and dosing body weight (DBW). Values derived with the standard equation were normalized to 1.73 sq m. The predictive performances of the modified and standard equations in estimating the actual CLcr were then compared. Fifty patients were enrolled. The standard equation using IBW or DBW produced estimates that differed significantly from the actual CLcr. The modified equation and the standard equation using ABW did not differ significantly in bias or precision, but both were significantly less biased than the standard equation using IBW or DBW. The only significant difference among equations in precision was between the modified equation (the more precise) and the standard equation using IBW. There were no clinically significant differences among methods in gentamicin dosing simulations. The modified Cockcroft-Gault equation can be used to estimate CLcr in trauma patients with stable renal function.