Impact of decreasing vancomycin exposure on acute kidney injury in stem cell transplant recipients

Objective: To evaluate the change in vancomycin days of therapy (DOT) and vancomycin-associated acute kidney injury (AKI) after an antimicrobial stewardship program (ASP) intervention to decrease vancomycin use in stable patients after hematopoietic stem cell transplantation (HSCT). Design: Retrospective cohort study and quasi-experimental interrupted time series analysis. Change in unit-level vancomycin DOT per 1,000 inpatient days after the intervention was assessed using segmented Poisson regression. Subject-specific risk of vancomycin-associated AKI was evaluated using a random intercept logistic regression model with mediation analysis. Setting: HSCT unit at a single quaternary-care pediatric hospital. Participants: Inpatients aged 3 months and older who underwent HSCT between January 1, 2015, and March 31, 2019 (27 months before and after the intervention) who received any dose of vancomycin. Intervention: An ASP intervention in April 2017 creating a new practice guideline to decrease prolonged (>72 hours) vancomycin courses for stable HSCT patients with febrile neutropenia. Results: Overall, 439 vancomycin exposures (234 before the intervention and 205 after the intervention) occurring across 300 transplants and 259 subjects were included. The mean vancomycin DOT was 307 per 1,000 inpatient days (95% confidence interval [CI], 272-342) and decreased after the intervention to 207 per 1,000 inpatient days (95% CI, 173-240). In multivariable analyses, the odds of AKI in the postintervention period were 37% lower than in the preintervention period (adjusted OR, 0.63; 95% CI, 0.42-0.95; P =.0268); 56% of the excess risk was mediated by vancomycin DOT. Conclusions: An ASP intervention successfully decreased vancomycin use after HSCT and resulted in a decrease in AKI. Reducing empiric antibiotic exposure for stable patients after HSCT can improve clinical outcomes.