Evaluation of outpatient antibiotic use using AWaRe and DDD/DOT indicators: A community pharmacy-based study in Nayoro City, Japan

Abstract

Objective

This study evaluated outpatient antibiotic use in Nayoro City using the WHO AWaRe.

classification and DDD/DOT indicators. It assessed: (1) overall antibiotic use, (2) differences in Access group proportions by prescription duration, and (3) regional prescribing patterns in response to a confirmed drug shortage.

Methods

We retrospectively analyzed 32,632 outpatient prescriptions from July 2022 to March 2025. Short-term prescriptions (≤14 days) were extracted per national guidelines. Antibiotics were classified using the AWaRe framework, and DDDs were calculated. Cosine similarity assessed consistency across pharmacies. Following a cefaclor shortage in May 2024, changes in faropenem use were analyzed using Pearson's correlation, cross-correlation (CCF), vector autoregression (VAR), Welch's t-test, and interrupted time series (ITS) analysis.

Results

Short-term prescriptions comprised 81.1 % of all prescriptions. Access to antibiotics accounted for 33.2 % of all prescriptions and 27.2 % of short-term ones, considerably lower than the WHO's target of 60 %. Watch group antibiotics, especially second- and third-generation cephalosporins and fluoroquinolones, were predominantly prescribed for short-term use. Cefaclor alone represented 22.5 % of all prescriptions. After its shortage, the use of faropenem (Reserve group) significantly increased. Cosine similarity (≥0.85) confirmed consistent prescription patterns across pharmacies—antibiotic selection varied by prescription duration.

Conclusion

This study identified regional overuse of Watch antibiotics and a shift toward Reserve agents during drug shortages. Hospital formulary restrictions likely influenced citywide prescribing trends. These findings highlight the need for stable antibiotic supply chains, formulary review, and locally adapted antimicrobial stewardship strategies.