Impact of a Modified AWaRe Calculation Method on Outpatient Oral Antibiotic Use Metrics and Associated Diagnoses: A...

In this retrospective single-center study, we evaluated the impact of a modified Access, Watch, and Reserve (AWaRe) calculation method on outpatient oral antibiotic use at a 490-bed tertiary care hospital in Japan in 2025. We compared AWaRe proportions and antibiotic class-specific defined daily doses (DDDs) between the conventional and modified methods and characterized the diagnoses associated with DDD reductions attributable to the modified method. Under the modified method, long-term prescriptions of macrolides, quinolones, tetracyclines, and trimethoprim-sulfamethoxazole were converted to 14-d equivalents, and the total amount of rifaximin prescribed was set to zero. Among 2,326 outpatients who received oral antibiotics, 1,424 received at least one antibiotic affected by the modified method. The Access proportion increased from 28.1% to 46.5% (p < 0.01), whereas the Watch proportion decreased from 71.3% to 51.9% (p < 0.01). Of the DDD reductions after long-term prescription adjustment, 70.7% were associated with conditions whose long-term antibiotic treatment or prophylaxis is supported by clinical guidelines or previous studies. In conclusion, the modified AWaRe calculation method reduces the influence of rifaximin use and long-term antibiotic prescriptions on outpatient AWaRe proportions. However, diagnosis-based interpretation of reductions in DDDs, particularly for tetracyclines, requires further investigation.