1328. Vancomycin exposure and utilization following implementation of an AUC-guided monitoring guideline in children

BACKGROUND: The 2009 guideline for vancomycin (VAN) monitoring recommended trough (TR) of 15-20 mg/L to correlate with AUC/MIC ≥ 400. Studies have suggested attainment of target AUC/MIC ratio with TR 7-11 mg/L in most children. Prior to 2018, TR 15-20 mg/L was the primary target for VAN therapeutic monitoring at CHOC Children’s. Beginning in 2018, a clinical guideline was implemented which recommend targeting AUC/MIC of 400-600 or TR of 7-15 mg/L. Our objectives are to evaluate differences in VAN utilization, exposure, nephrotoxicity and cost savings between pre (Pre-guideline, pG) and post implementation (Post-guideline, PG) of a VAN monitoring guideline at CHOC Children’s. METHODS: Retrospective chart review of patients prescribed VAN between Jan 2016 – Jun 2017 (pG) and Jan 2018 – Jun 2019 (PG). Primary objectives evaluated differences in pharmacokinetic (PK), AUC and rate of nephrotoxicity in patients 3 months to < 18 years who received VAN ≥ 24 hour with ≥ 1 TR. Secondary objectives assessed differences in overall VAN utilization following guideline implementation. RESULTS: Seventy patients were included in the PK analysis, 35 in pG and 35 in the PG group. Median age, weight, gender, baseline creatinine, concurrent nephrotoxic agents were similar. There were no differences in duration of therapy or starting doses (mg/kg/day) between the two groups. The highest daily dose (mg/kg) and AUC (mg*h/L) attained was significantly higher in pG compared to PG group (74.9 vs. 59.9, p = 0.002 and 647 vs. 469, p < 0.0001), respectively. Changes in AUC from the initial regimen to the highest adjusted regimen was also higher in pG group (532 vs. 647, p = 0.0008) while there was no difference in PG group (459 vs. 469, p = 0.647). More patients experienced nephrotoxicity in pG compared to PG (11.4% (4/35) vs. 0 (0/35), p = 0.039). Logistic regression analysis identified AUC 800-900 as a significant risk for nephrotoxicity. Compared to pG, PG resulted in a net reduction in VAN utilization of 19.7 DOT per 1000 patient days, savings of $100,150 and 738 fewer levels drawn. CONCLUSION: In line with the 2020 consensus guideline recommendation for AUC-based VAN monitoring, our study found AUC-guided VAN monitoring in children resulted in less exposure, utilization, and nephrotoxicity. DISCLOSURES: All Authors: No reported disclosures