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

OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.