1575. Vancomycin Loading Doses and Nephrotoxicity on Medicine Teaching Services

BACKGROUND: IDSA guidelines recommend the usage of a loading dose when using vancomycin for seriously ill patients to rapidly achieve adequate trough concentrations. While the relationship between vancomycin and nephrotoxicity is the focus of many studies, and with the strength of that relationship still debated, few studies have examined the relationship between vancomycin loading doses and nephrotoxicity. METHODS: We performed a retrospective cohort study examining vancomycin dosing for internal medicine teaching services’ patients over the 2014–15 academic year at one academic medical center. We generated a list of all hospitalized patients aged 18–85 who received vancomycin and were admitted to a teaching service. Patient data were extracted from the inpatient EMR via manual chart review. Patients were excluded if their pretreatment calculated glomerular filtration rate (GFR) was less than 50 mL/minute, if they received less than three doses of vancomycin, or if their initial dose was subtherapeutic (<10 mg/kg). Nephrotoxicity was determined by 7-day acute kidney injury (AKI) rate. Patients in the loading dose (>20 mg/kg) cohort were compared with those in the standard dose cohort (10–20 mg/kg). Our primary modeling used multi-variable logistic regression with AKI as our outcome of interest. RESULTS: 438 of the initial 804 patients were enrolled. The loading dose (n = 365, 83%) and standard dosing (n = 73, 17%) cohorts were not significantly different regarding demographics, GFR, nephrotoxic drug exposure, total vancomycin received, trough levels, or comorbidities, and were only significantly different regarding body mass index (BMI). The 7-day AKI rate was not significantly different between the two arms (6.3% in the standard dosing arm and 8.2% in the loading dose arm P = 0.6). AKI rate significantly increased in both arms in the setting of concurrent piperacillin–tazobactam and vancomycin administration (OR 2.5, P = .04). There was no association between BMI and AKI. CONCLUSION: Few studies have examined the relationship between nephrotoxicity and vancomycin loading doses. The results of this study provide evidence that the use of loading doses is not significantly associated with increased 7-day AKI rate. [Image: see text] [Image: see text] DISCLOSURES: All authors: No reported disclosures.