Appropriateness of basing vancomycin dosing on area under the concentration-time curve

Systematic Comparison of Hospital-Wide Standard and Model-Based Therapeutic Drug Monitoring of Vancomycin in Adults

We aimed to evaluate the predictive performance and predicted doses of a single-model approach or several multi-model approaches compared with the standard therapeutic drug monitoring (TDM)-based vancomycin dosing. We performed a hospital-wide monocentric retrospective study in adult patients treated with either intermittent or continuous vancomycin infusions. Each patient provided two randomly selected pairs of two consecutive vancomycin concentrations. A web-based precision dosing software, TDMx, was used to evaluate the model-based approaches. In total, 154 patients contributed 308 pairs. With standard TDM-based dosing, only 48.1% (148/308) of all of the second concentrations were within the therapeutic range. Across the model-based approaches we investigated, the mean relative bias and relative root mean square error varied from -5.36% to 3.18% and from 24.8% to 28.1%, respectively. The model averaging approach according to the squared prediction errors showed an acceptable bias and was the most precise. According to this approach, the median (interquartile range) differences between the model-predicted and prescribed doses, expressed as mg every 12 h, were 113 [-69; 427] mg, -70 [-208; 120], mg and 40 [-84; 197] mg in the case of subtherapeutic, supratherapeutic, and therapeutic exposure at the second concentration, respectively. These dose differences, along with poor target attainment, suggest a large window of opportunity for the model-based TDM compared with the standard TDM-based vancomycin dosing. Implementation studies of model-based TDM in routine care are warranted.

Evaluation of a trough-only extrapolated area under the curve vancomycin dosing method on clinical outcomes

Background Vancomycin dosing strategies targeting trough concentrations of 15-20 mg/L are no longer supported due to lack of efficacy evidence and increased risk of nephrotoxicity. Area-under-the-curve (AUC₂₄) nomograms have demonstrated adequate attainment of AUC₂₄ goals ≥ 400 mg h/L with more conservative troughs (10-15 mg/L). Objective The purpose of this study is to clinically validate a vancomycin AUC₂₄ dosing nomogram compared to conventional dosing methods with regards to therapeutic failure and rates of acute kidney injury. Setting This study was conducted at a tertiary, community, teaching hospital in the United States. Method This retrospective, cohort study compared the rates of therapeutic failures between AUC₂₄-extrapolated dosing and conventional dosing methods. Main outcome measure Primary outcome was treatment failure, defined as all-cause mortality within 30 days, persistent positive methicillin-resistant Staphylococcus aureus blood culture, or clinical failure. Rates of acute kidney injury in non-dialysis patients was a secondary endpoint. Results There were 96 participants in the extrapolated-AUC₂₄ cohort and 60 participants in the conventional cohort. Baseline characteristics were similar between cohorts. Failure rates were 11.5% (11/96) in the extrapolated-AUC₂₄ group compared to 18.3% (11/60) in the conventional group (p = 0.245). Reasons for failure were 6 deaths and 5 clinical failures in the extrapolated-AUC₂₄ cohort and 10 deaths and 1 clinical failure in the conventional group. Acute kidney injury rates were 2.7% (2/73) and 16.4% (9/55) in the extrapolated-AUC₂₄ and conventional cohorts, respectively (p = 0.009). Conclusion Extrapolated-AUC₂₄ dosing was associated with less nephrotoxicity without an increase in treatment failures for bloodstream infections compared to conventional dosing. Further investigation is warranted to determine the relationship between extrapolated-AUC₂₄ dosing and clinical failures.