Comparative evaluation of open-access Bayesian calculators for vancomycin area under the concentration-time curve...

Web-based Bayesian calculators have been increasingly used for vancomycin area under the concentration-time curve (AUC) estimation. However, their performance in Asian populations remains poorly characterized. The present study evaluated freely available online Bayesian calculators for vancomycin AUC estimation using a single steady-state trough concentration in Taiwanese non-critically ill hospitalized adults and compared their estimates with AUC values derived from two steady-state concentrations using conventional first-order pharmacokinetic equations (Sawchuk-Zaske method).

This retrospective single-center study included 313 vancomycin treatment courses delivered at National Taiwan University Hospital. Three web-based calculators were evaluated: ClinCalc, VancoVanco, and Practical Antimicrobial TDM (PAT) models (PAT1998 and PAT2024, each with and without serum creatinine adjustment). All Bayesian-derived AUC estimates were generated using a single steady-state trough concentration. Agreement between Bayesian-derived AUC (bAUC) and trapezoidal-derived AUC (tAUC) was assessed using Spearman's correlation, Bland-Altman analysis, the bAUC/tAUC ratio, and clinical concordance was assessed based on AUC classification into three categories: subtherapeutic (<400 mg·h/L), therapeutic (400-600 mg·h/L), and supratherapeutic (>600 mg·h/L).

All calculators exhibited significant correlations with the tAUC (all p < 0.0001). ClinCalc consistently underestimated the tAUC and VancoVanco exhibited the greatest overestimation and the weakest correlation, and the PAT-based models demonstrated the smallest bias, with its median ratios closest to unity (0.97-1.03). In addition, PAT2024 achieved the highest clinical agreement for subtherapeutic (89%), therapeutic (83%) and supratherapeutic (94%) AUC classification. Serum creatinine adjustment had a minimal impact on PAT-based estimates.

Meaningful differences in bias, precision, and clinical agreement exist between freely available Bayesian vancomycin AUC calculators. Among all calculators examined in this study, PAT2024 achieves the most favorable performance for Taiwanese hospitalized adults, which supports population-specific model selection for AUC-guided vancomycin monitoring in clinical practice.