Better together? Reducing vancomycin use and acute kidney injury with a blended AUC and trough‐based dosing guideline

Abstract Background Vancomycin guidelines recommend area‐under‐the‐curve (AUC) therapeutic monitoring for patients with severe methicillin‐resistant Staphylococcus aureus (MRSA) infections. No recommendations exist for patients with non‐severe staphylococcal infections or those with other Gram‐positive infections. AUC‐based vancomycin dosing can be resource‐intensive and may not be necessary for all patients. Methods New institutional guidelines for vancomycin dosing were implemented across an eight‐hospital health system in 2023. The new guidelines recommended either AUC or trough‐based dosing depending on the severity of the infection and the likelihood of MRSA. Adult patient encounters with at least one vancomycin administration were compared retrospectively 6 months pre‐implementation and 6 months post‐implementation. Cumulative vancomycin dose, administrations, and serum levels were assessed. The rate of acute kidney injury (AKI) was compared in a subgroup of patient encounters with four or more administrations. Pharmacist time saved using a blended approach compared to a uniform AUC dosing guideline was estimated based on the number of patients receiving trough‐based dosing in the post‐implementation group. Results A total of 8155 patient encounters were included in the analysis (3916 pre‐implementation, 4239 post‐implementation). The primary outcome of median cumulative vancomycin dose (mg) was 500 mg lower in the post‐implementation group (3000 mg pre‐implementation vs 2500 mg post‐implementation, Odds ratio [OR] 0.94 95% confidence interval [CI] 0.90–0.97, p < 0.001). Patients in the post‐implementation group were significantly less likely to have vancomycin serum levels drawn (OR 0.86; 95% CI 0.78, 0.96, p = 0.005). A subgroup of patient encounters receiving four or more vancomycin administrations included 2483 patient encounters (1251 pre‐implementation, 1232 post‐implementation). AKI occurred in 120 (9.6%) cases pre‐implementation and 89 (7.2%) cases post‐implementation. The risk of AKI was significantly lower post‐implementation (OR 0.73; 95% CI 0.55, 0.98, p = 0.038). Estimated pharmacist time saved was between 2229 to 5201 min, equating to an estimated $16,851.24 to $39,319.56 saved over 6 months, with blended vancomycin dosing. Conclusion In this large multi‐hospital cohort, the implementation of a blended dosing method using a majority of AUC‐based dosing reduced cumulative vancomycin doses, serum levels, and AKI. Including trough recommendations for patients with less severe infections and non‐MRSA, Gram‐positive pathogens may have saved significant pharmacist time and associated costs compared to a uniform AUC dosing policy. This study further highlights the sizeable amount of unnecessary vancomycin use with a corresponding low incidence of severe MRSA infections.