Efficiency of a Long-term Infectious Diseases Consultation and Antimicrobial Stewardship Program at a Japanese Cancer Center: An Interrupted Time-Series Analysis.

Background: Patients with cancer are particularly susceptible to developing drug-resistant organisms due to the high frequency of infections during cancer treatment and the use of broad-spectrum antimicrobial agents. Therefore, patients with cancer are ideal candidates for an antimicrobial stewardship program (ASP); however, no established ASPs specifically target these patients. In this study, we evaluated the effect of a 46-month ASP intervention and infectious diseases consultation using a unique antimicrobial quality measure. Methods: Our single-center, retrospective, observational study was conducted from 1 April 2018 to 31 January 2024 and evaluated 2 phases: preintervention (antimicrobial notification by the infection control team) and postintervention (implementation of ASP and establishment of the infectious diseases consultation service). Results: The days of therapy (DOT) for 3 intravenous carbapenems significantly decreased, and the DOT of narrow-spectrum antimicrobials significantly increased after the intervention. A significant reduction was observed in the length of hospital stay, with no change in the incidence of hospital-acquired resistant microorganisms. All-cause in-hospital mortality rates and the 30-day mortality rate among patients with bacteremia episodes were numerically reduced, although not significantly, compared to the preintervention period. The rate of appropriate use of antimicrobial agents increased significantly during the late postintervention period (1 April 2021 to 31 January 2024). Conclusions: Our intervention was associated with the promotion of appropriate use of antimicrobial agents and a reduction in the length of hospital stay. These findings can help establish safer cancer treatments and improve patient prognosis.