Agreement between one-point and two-point sampling for vancomycin AUC estimation at follow-up TDM using the Yasuhara...

Two-point sampling (peak and trough concentrations) is considered the most accurate method for estimating the area under the concentration-time curve (AUC) of vancomycin (VCM). However, one-point sampling (trough concentration alone) can reduce the burden of therapeutic drug monitoring (TDM). Although the agreement between one-point and two-point AUC estimates during follow-up TDM has been evaluated using the Oda model, its applicability to the Yasuhara model remains unclear. Therefore, this study evaluated this agreement using the Yasuhara model.

This multicenter, retrospective, observational study included patients from nine institutions who received VCM between September 2020 and December 2023 and underwent two-point sampling during both initial and follow-up TDM. The AUC values were estimated using the Yasuhara model. Factors associated with an AUC discrepancy of ≥10% were evaluated using univariate and multivariable analyses. In addition, patients with AUC discrepancies were descriptively characterized.

Among 256 patients, the one-point and two-point AUC estimates were strongly correlated (r = 0.982, p < 0.001), and eight patients (3.1%) exhibited an AUC discrepancy. Age ≤60 years (p = 0.050) and BMI ≥25 kg/m² (p = 0.049) were associated with an AUC discrepancy in the univariate analysis but not in multivariable analysis. Patients with an AUC discrepancy commonly had hypoalbuminemia, heart failure, or ICU admission.

During follow-up TDM using the Yasuhara model, one-point AUC estimates differed by <10% from two-point sampling in 96.9% of patients. When an appropriate regimen is established based on initial TDM, one-point sampling may provide AUC estimates in agreement with two-point sampling.