Accuracy of vancomycin AUC values estimated with trough-only data in a veteran population

The purpose of this study was to evaluate the accuracy and precision of estimating area under the curve (AUC) values using only vancomycin trough concentrations versus both peak and trough values derived from applying 4 different volume of distribution (Vd) models in a veteran population.

This retrospective, observational study was performed from July 2021 to April 2022 using data from 5 Veterans Affairs hospitals across the US. AUC values for a total of 259 veterans were included in the analysis, with 10 excluded after pooling of data. Trough-only AUC values were calculated with 1-compartment intermittent infusion equations (Sawchuk-Zaske equations) using age- and weight-adjusted Vd values derived from an online calculator (VancoPK) or fixed Vd values specified by 3 comparator models.

The mean population peak-trough AUC was 496 (range, 266-886). Of the 4 Vd models evaluated, the VancoPK model was the most accurate and precise, yielding a mean trough-only AUC of 491, with a correlation of 0.925; the root mean square error was 41, meaning that approximately 95% of the trough-only AUCs were within 82 points of values calculated using AUC peak-trough couplets.

A trough-only AUC estimation approach has many advantages over a peak-trough approach. The equation Vd = 0.29 (age) + 0.33 (actual BW in kg) + 11 provided accurate and precise AUC estimates with trough-only data when applied to pharmacokinetic equations in a veteran population.