Estimated glomerular filtration rate with and without race for drug dosing: Cystatin C vs. serum creatinine

The goal of this study was to use a model kidney function clearance-dependent drug (vancomycin) to understand the gain or loss of precision in dosing with use of serum creatinine (S-cr), serum cystatin C (S-cys) and race and nonrace-based equations of the estimated glomerular filtration rate (eGFR). In this study of hospitalized patients, we compared S-cr, S-cys and their combination to estimate kidney function and vancomycin clearance. The nonrace-based S-cys eGFR model outperformed other clearance models and improved the probability of target attainment by 15%. When S-cys is not available, we show that the new 2021 CKD-EPI eGFR(cr) equation (no race factor) performs as well as the current conventional approach. This improvement in model performance does not negate the need for individualized dosing but exemplifies the need to remove race as a factor of kidney-function dose adjustment.