Feasibility and utility of the days of antibiotic spectrum coverage (DASC) in national antimicrobial use surveillance in Japan.

Objective: Days of antibiotic spectrum coverage (DASC) is a novel metric that incorporates the antibiotic spectrum into consumption metrics, addressing the limitations of traditional metrics such as days of therapy (DOT). This study aimed to evaluate the feasibility of integrating DASC into the Japan Surveillance for Infection Prevention and Healthcare Epidemiology (J-SIPHE) system. Design: Retrospective observational study. Setting: Hospitals voluntarily participating in J-SIPHE. Participants: Inpatients from 1,833 hospitals between January 2019 and December 2022. Methods: Antibiotic use was assessed using DOT, DASC, and DASC/DOT. Antibiotic spectrum coverage scores were assigned based on published data or expert consensus. Annual trends were assessed using median values, and hospital-level variation was explored by hospital size. Proportional use of antibiotic classes by DOT and DASC was compared using 2022 data. Results: As the number of hospitals participating in J-SIPHE increased over time-particularly small and medium-sized hospitals-median DOT and DASC per 1,000 patient-days declined by 21.2% and 19.1%, respectively, from 2019 to 2022, while DASC/DOT remained stable. In 2022, proportional use of antibiotic classes varied by hospital size, and rankings differed when comparing DOT- and DASC-based measures. Broad-spectrum agents such as carbapenems and fluoroquinolones ranked higher by DASC than DOT. Hospital-level distributions of DOT and DASC/DOT showed substantial variation across hospital sizes. Conclusions: Integration of DASC metrics into national surveillance is feasible. DASC and DASC/DOT complement DOT by incorporating spectrum breadth, providing more comprehensive insight into antimicrobial use patterns and supporting stewardship benchmarking and intervention planning.