Equations to Estimate the Normalized Creatinine Generation Rate (CGRn) in 3/Week Dialysis Patients With or Without Residual Kidney Function

Objective: Normalized creatinine generation rate (CGRn) can be computed for a variety of dialysis schedules using a recently described kinetic modeling program. However, the availability of estimating equations might facilitate broader study of this metric. We developed equations to estimate CGRn based on modeling and then tested them against modeled CGRn values in the Frequent Hemodialysis Network Nocturnal Trial baseline (3/week) dataset. Design and methods: We used a what-if derivation of a previously published variable volume 2-pool creatinine kinetic model to generate predicted predialysis values of serum creatinine that would result from creatinine generation rates of 250-2000 mg/day in patients with creatinine distribution volumes of 20 to 50 L, dialyzed from 60 to 480 min per treatment three times a week. Then, in patients with residual kidney function, we calculated an anuric expected predialysis serum creatinine value before applying the same equations. We then compared estimated CGRn values as predicted by this approach with modeled values in patient data from the Frequent Hemodialysis Network Nocturnal Trial. Results: The estimating equations for CGRn yielded results similar to those obtained with formal modeling, in both anuric patients and those with residual kidney function, with mean percent error of 0.845 +/- 6.15 (SD) in anuric patients, and ?0.29 +/- 4.90 in patients with a mean creatinine clearance of 5.44 +/- 4.82 mL/min, with R-squared values of 0.96 in both anuric patients and those with residual renal clearance of creatinine. Conclusions: In patients dialyzed 3/week, CGRn can be estimated using prediction equations. Use of these equations may facilitate broader investigation of CGRn as a measure of nutritional status and outcome. (C) 2020 by the National Kidney Foundation, Inc. All rights reserved.

Automated summary

This article introduces equations for estimating normalized creatinine generation rate and demonstrates their effectiveness in predicting outcomes in patients with different levels of kidney function.