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.

Objectives: Antibiotic stewardship programs (ASP) have already demonstrated clinical benefits. However, their effectiveness or safety in immunocompromised hosts needs to be proved.

Methods: 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.

Results: Mortality significantly decreased throughout the study period (-13.3% annual reduction for 7-day mortality rate, p < 0.01; -8.1% annual reduction for 30-day mortality, p = 0.03), parallel to a reduction in antibiotic consumption (quarterly reduction -0.4%, p = 0.01), especially for broader-spectrum antibiotics. The before-after study settled a significant inflexion point on the ASP implementation for the reduction of antibiotic consumption (change in level 0.95 DDD, p = 0.71; change in slope -1.98 DDD per quarter, p < 0.01). The decreasing trend for mortality before the ASP also continued after its implementation.

Conclusions: The combination of an ASP with IDC improved antibiotic use among patients with cancer, and was accompanied by a reduction of mortality of bacteraemic infections. Implementation of the ASP was necessary to effectively change antibiotic use.