From variability to value: Advancing vancomycin therapeutic drug monitoring toward decision-grade practice through...

Persistent inter-laboratory variability in vancomycin therapeutic drug monitoring (TDM) continues to challenge the reliability of exposure-guided dosing despite advances in analytical methods and external quality assessment (EQA).

Building on recent longitudinal evidence demonstrating sustained variability across analytical platforms, this correspondence proposes a practical framework for translating EQA findings into decision-grade laboratory practice. The framework emphasizes three complementary components: (1) transparent reporting of commutability characteristics and limitations of EQA materials, (2) uncertainty-aware interpretation of results in relation to clinically relevant decision thresholds, and (3) standardized reporting of traceability and analytical descriptors to improve interoperability and cross-site comparability. Together, these measures extend EQA beyond retrospective performance assessment toward supporting clinically meaningful interpretation of laboratory results.

Integrating commutability-informed EQA with uncertainty-aware reporting and harmonized reporting standards can strengthen the clinical utility of vancomycin TDM. This decision-oriented approach has the potential to enhance reproducibility, improve confidence in exposure-guided dosing, facilitate harmonization across laboratories, and reinforce antimicrobial stewardship through more reliable therapeutic decision-making.