1599. AUC24 Vancomycin Bayesian-Based Dosing: Increasing Therapeutic Target Attainment with Decreased TDM Cost

BACKGROUND: Vancomycin efficacy is optimally predicted by the area under the concentration–time profile (AUC24), however, traditional AUC24-based dosing methods involve analytic PK calculations that require both peak and trough drug levels, increasing cost and time compared with trough-based dosing. Recent literature (e.g., Rybak et al 2019) suggest that Bayesian dosing tools alleviate the cost and difficulty of implementing AUC24-based dosing in order to improve patient outcomes. In this study, we compare therapeutic range attainment across 5 hospitals using trough-based dosing vs. 5 hospitals using Bayesian-supported AUC24 dosing. METHODS: De-identified data were available from 5 hospitals across the United States, EU, and Australia that used a trough-based dosing method (375 adult patients, 13,024 doses, 4,654 drug levels), and from 5 hospitals that implemented Bayesian-based AUC24 dosing (370 patients, 13,080 doses, 3,520 drug levels) using commercially available software (DoseMeRx). The proportion of doses in the therapeutic target range was determined for each hospital, and the number and cost of therapeutic drug monitoring (TDM) levels required were compared. RESULTS: In the 5 trough-based dosing hospitals, only 49.1% of doses achieved the therapeutic target of 10–20mg/L with significant variance per-hospital in the proportion of sub- and supra-therapeutic doses (range 11–35% and 14–41% respectively). Hospitals that implemented Bayesian-based AUC24 dosing successfully attained the target AUC24 (400–700mg.h/L) for 73.5% of doses, similar to a previous AUC24-based dosing intervention using increased sampling intensity (Meng et al. 2019). The number of TDM levels used for trough-based dosing was 1 per 1.34 days compared with 1 per 2.14 days in the AUC24 group (37.4% fewer levels). Bayesian-based AUC24 dosing hospitals not only avoided increased TDM costs, but counter-intuitively had decreased cost relative to the trough-based group. At a cost of $35USD per level (Meng et al. 2019), for a 500-bed hospital, this equates to savings of $60,305 per annum. CONCLUSION: This study demonstrates that implementing Bayesian-based AUC24 dosing results in improved therapeutic target attainment. TDM levels were less frequent in the Bayesian-based AUC24 dosing group, leading to decreased cost. DISCLOSURES: All authors: No reported disclosures.