Clinical impact of an educational antimicrobial stewardship program associated with infectious diseases consultation targeting patients with cancer: Results of a 9-year quasi-experimental study with an interrupted time-series analysis

•The addition of an ASP to IDC improved antibiotic use among cancer patients.•ID consultation alone did not have a significant impact on antibiotic use.•Implementing the ASP was necessary to reduce and improve the use of antibiotics.•These interventions were accompanied by improved outcomes of bacteremic infections.•This change in antibiotic use was safe in this cohort of immunocompromised hosts. Antibiotic stewardship programs (ASP) have already demonstrated clinical benefits. However, their effectiveness or safety in immunocompromised hosts needs to be proved. An ecologic quasi-experimental study was performed from January 2009 to June 2017 in the Oncology department of a tertiary-care hospital. A stable program of Infectious Diseases consultation (IDC) already existed at this unit, and an educational ASP was added in 2011. Its main intervention consisted of face-to-face educational interviews. Antibiotic consumption was assessed through quarterly Defined Daily Doses (DDD) per 100 occupied bed-days. Mortality was evaluated in patients with bloodstream infections through the quarterly incidence density per 1000 admissions, and the annual mortality rates at 7 and 30-days. Time-trends were analysed through segmented-regression analysis, and the impact of the ASP was assessed through before-after interrupted time-series analysis. Mortality significantly decreased throughout the study period (−13.3% annual reduction for 7-day mortality rate, p