Performance of different body weights in the Cockcroft-Gault equation in critically ill patients with and without augmented renal clearance: A multicenter cohort

Study objective: The primary objective was to evaluate the performance of the Cockcroft-Gault (CG) equation with different body weights (BWs) compared to a measured creatinine clearance (mCrCl) in an intensive care unit (ICU) population with and without augmented renal clearance (ARC). Design: Multicenter, retrospective cohort. Setting: Two ICUs in the United States and four ICUs from a previous international observational analysis. Patients: Adult ICU patients admitted from January 1, 2010 to July 30, 2020 with at least one mCrCl collected within the initial 10 days of hospitalization were eligible for inclusion. Measurements and main results: The primary outcome was the performance of the CG equation in ARC (mCrCl & GE;130 ml/min/1.73 m(2)) and non-ARC (mCrCl < 130 ml/min/1.73 m(2)) patients. Correlation was analyzed by Pearson's correlation coefficient, bias by mean difference, and accuracy by the percentage of patients within 30% of the mCrCl. A total of 383 patients were included, which provided 1708 mCrCl values. The majority were male (n = 239, 62%), median age of 55 years [IQR 40-65] with a surgical diagnosis (n = 239, 77%). ARC was identified in 229 (60%) patients. The ARC group had lower Scr values (0.6 [0.5-0.7] vs. 0.7 [0.6-0.9] mg/dl, p < 0.001) and higher mCrCl (172.8 (SD 39.1) vs. 89.9 mL/min/1.73 m(2) (SD 25.4), p < 0.001) compared with the non-ARC group, respectively. Among non-ARC patients there was a moderate correlation (r = 0.33-0.39), moderate accuracy (range 48-58%), and low bias (range of -12.9 to 17.1) among the different BW estimations with the adjusted BW having the better performance. Among ARC patients there was low correlation (r = 0.24-0.28), low to moderate accuracy (range 38-70%), and high bias (range of -58.5 to -21.6). Conclusions: The CG-adjusted BW had the best performance in the non-ARC patients, while CG performed poorly with any BW in ARC patients. Although the CG equation remains the standard equation for estimating CrCl in the ICU setting, a new, validated equation is needed for patients with ARC.

Automated summary

This study evaluated the performance of the CG equation in estimating creatinine clearance in different body weights among ICU patients. The results showed that CG performed moderately well in non-augmented renal clearance (ARC) patients, but poorly in ARC patients. Therefore, a new, validated equation is needed for estimating creatinine clearance in ARC patients.