1960. Lost in Translation: Comparing Rates of Outpatient Antibiotic Use in Three Metrics

BACKGROUND: The Centers for Disease Control and Prevention (CDC) tracks US outpatient antibiotic use in prescriptions per 1000 persons (Rx/1000), while the World Health Organization uses defined daily doses per 1000 persons (DDD/1000), which are based on average adult dose, for global surveillance. A third metric, days of therapy (DOT)/1,000 persons, has not been previously evaluated at the national level. We aim to compare time trends in outpatient oral antibiotic use as Rx/1000, DDD/1000, and DOT/1,000 in the same data to inform ongoing CDC surveillance and facilitate international comparison. METHODS: We identified dispensed outpatient oral antibiotics using pharmacy claims in 2011–2016 IBM® MarketScan® Commercial Databases for individuals <65 years old. Using enrollment data, we calculated mean annual membership with drug coverage. Annual rates of outpatient oral antibiotic use were calculated for Rx/1000, DDD/1000, and DOT/1000 persons. Prescriptions written with a ratio of DDD to days supplied >10 were considered biologically implausible and excluded from DDD calculations. We examined trends for each metric from 2011 to 2016 using negative binomial regression. RESULTS: Annual numbers of outpatient oral antibiotic prescriptions ranged from 18.6 million to 30.0 million (mean 24.3 million). Overall, Rx/1000 decreased by 7% from 892 in 2011 to 829 in 2016 (Figure 1). From 2011 to 2016, DDD/1000 increased 2% from 23.8 to 24.2 while DOT/1000 decreased 9% from 25.4 to 23.1. Significant per-year decreases were found from 2011 to 2016 for Rx/1000 (−1.1%) and for DOT/1000 (−1.6%), while no significant per-year change was seen with DDD/1000 (table). DDD/1000 underestimate use in pediatrics under the age of 10 (Figure 2). Prolonged duration is seen in adolescents and reflected by DOT/1000. CONCLUSION: Trends in DDD/1000 for population aged <65 years do not mirror trends in Rx/1000 and DOT/1000. These differences may reflect that Rx/1000 and DOT/1000 more accurately capture antibiotic prescriptions in children than DDD/1000. As DDD/1000 underestimate antibiotic use in children, DDD/1000 underestimates reduction in antibiotic use over time and may not accurately reflect changes in use over time. [Image: see text] [Image: see text] [Image: see text] DISCLOSURES: All Authors: No reported Disclosures.