Days of Antibiotic Spectrum Coverage (DASC) and Oral Antimicrobial-Use Trends at a Community Pharmacy in Japan: A 2018–2023 Retrospective Observational Study

Abstract

Objective: The high frequency of prescribing oral antimicrobial agents, such as third-generation cephalosporins, macrolides, and fluoroquinolones, in local clinics is a major issue that can lead to the emergence of antimicrobial-resistant bacteria in the community. Hospitals have recently adopted the days of antibiotic spectrum coverage (DASC), which considers the antibacterial spectrum as a novel indicator of appropriate antimicrobial use. Although it has been used in inpatient settings, its applicability in community pharmacy settings remains unclear. Materials and Methods: The aim of this study was to determine whether the DASC is a valuable indicator of appropriate antimicrobial use in community pharmacies. We tabulated the use of antimicrobials dispensed at one of our pharmacies in Tokyo from 1 January 2018, to 31 December 2023. The DASC/100 prescriptions were calculated using the Antibiotic Spectrum Coverage score, which quantifies the extent of antimicrobial activity against key organisms. Higher scores indicate broader-spectrum agents, whereas lower scores indicate narrower-spectrum agents. Additionally, the days of therapy (DOT) value was calculated, along with the DOT/100 prescriptions, based on the dispensed prescriptions. Subgroup analyses were conducted for pediatric children aged < 6 years and the elderly (≥65 years). Results: The DASC/DOT was used to assess the appropriate use of antimicrobials. The DOT/100 and DASC/100 prescriptions in 2021–2023 were 50.1% and 51.5% lower, respectively, than those before 2020 (p < 0.05). During the same period, the DASC/DOT decreased by 0.7%, indicating that, despite the decrease in the number of antimicrobial prescriptions, the antimicrobial spectrum did not become narrower. In children < 6 years of age, DOT and DASC values declined significantly, possibly indicating a decrease in the number of antibiotic prescriptions for viral upper respiratory tract infections. In the elderly (≥65 years), the DASC/DOT remained relatively high, indicating their continued reliance on broad-spectrum agents, such as fluoroquinolones and macrolides. Conclusions: This study demonstrates the feasibility and benefits of the DASC/DOT as a spectrum-based indicator for appropriate antimicrobial use in community pharmacies. Therefore, the DASC/DOT serves as a practical and spectrum-sensitive indicator of outpatient antimicrobial use to guide antimicrobial stewardship in community settings. Furthermore, age-specific analyses highlighted the importance of targeted interventions to promote the judicious use of broad-spectrum antimicrobials, particularly among the elderly (≥65 years old).