Vancomycin area under the curve/minimum inhibitory concentration and trough level concordance-evaluation on an urban health unit.

Abstract

A vancomycin AUC/MIC (area under the curve/minimum inhibitory concentration) of 400-600 mg•h/L is associated with improved clinical outcomes for the treatment of methicillin resistant Staphylococcus aureus (MRSA) infections. Currently, there are still limited studies evaluating the relationship between vancomycin trough and AUC. To evaluate the correlation between vancomycin trough and AUC/MIC and determine if trough-guided monitoring is an adequate predictor of AUC/MIC in the Urban Health population at St Paul's Hospital. This was a retrospective chart review of 29 patients from November 2019 to February 2021. Patient demographics and laboratory data were collected from electronic medical records. The two-level equation-based approach was used to calculate AUC/MIC. The proportion of AUC/MIC values within target (400-600 mg•h/L) despite subtherapeutic troughs, and the proportion of AUC/MIC values supratherapeutic when trough is within target (15-20 mg/L) were the primary endpoints. Fifty-seven sets of levels were collected and 75% of vancomycin troughs and AUC24 were found to be discordant. When trough was 10-14.9 mg/L, AUC24 was > 400 mg•h/L in 94% of cases and when trough was 15-20 mg/L, AUC24 was > 600 mg•h/L in 69% of cases. There was a moderate correlation between vancomycin trough and AUC24h (R 2 = 0.57; p < 0.001). A vancomycin trough between 15 and 20 mg/L may result in an AUC/MIC greater than necessary for clinical efficacy. Considering these findings and the practical concerns of AUC-guided monitoring, a modest reduction in target troughs to prevent vancomycin toxicity warrants clinical consideration and further evaluation.