Cost comparison of AUC:MIC- versus trough-based vancomycin monitoring for MRSA bacteremia

It is anticipated that the updated vancomycin monitoring guidelines will reconsider area under the concentration-time curve to minimum inhibitory concentration ratio (AUC:MIC)-based monitoring instead of trough-based monitoring for methicillin-resistant Staphylococcus aureus (MRSA) infections. The AUC:MIC can be estimated using 2 steady-state serum concentrations and first-order pharmacokinetic equations or Bayesian modeling. The cost of AUC:MIC-based monitoring compared with trough-based monitoring is unknown and has been cited as a potential barrier to implementing this monitoring method. The objective of this study was to compare the total vancomycin drug and monitoring cost for patients with MRSA bacteremia who received AUC:MIC- or trough-based monitoring.

This was a single-center, retrospective cohort study.

This study included patients who were treated for MRSA bacteremia between May 1, 2013 and December 31, 2018, with an 8-month washout period between trough and AUC:MIC-based monitoring at our institution.

The primary outcome was the aggregate cost of vancomycin therapy, which included the cost associated with sample collection (i.e., supply cost and nursing time), sample analysis (i.e., assay cost and laboratory technician time), result interpretation (i.e., pharmacist time), and drug cost (i.e., cost of total administered vancomycin dose) during the hospital stay.

A total of 52 patients met inclusion criteria with 26 patients in each group. The median (interquartile range) total vancomycin drug and monitoring cost was $338.14 ($235.07-$601.05) for the AUC:MIC-based group compared with $316.79 ($253.36-$520.96) for the trough-based group (P = 0.687).

Vancomycin monitoring using 2 steady-state serum concentrations and first-order pharmacokinetic equations to calculate AUC:MIC was no more costly than a trough-based approach in patients with MRSA bacteremia at our institution.