Antibiotic Overuse for Never-Appropriate Acute Respiratory Tract Infections Among Older Adults Presenting to United States Emergency Departments, 2013-2025: Interrupted Time Series Analysis Across National Stewardship Milestones

Abstract

Background: Antibiotic overuse for acute respiratory tract infections (ARTIs) remains common in emergency departments (EDs), but national trends among older adults are not well described. Methods: We conducted a retrospective cohort study of US ED encounters in Epic Cosmos (January 2013-December 2025) among adults aged 65 years or older with never-appropriate ARTI diagnoses. Monthly antibiotic overuse (ED administration and/or discharge prescription) was evaluated with segmented regression around Centers for Disease Control and Prevention (CDC) Core Elements (November 2016), The Joint Commission (TJC) ambulatory stewardship standard (January 2020), COVID-19 onset (March 2020), and Centers for Medicare & Medicaid Services (CMS) interpretive guidance (July 2022). Results: Among 838,929 encounters, antibiotic overuse occurred in 38.5%. In the primary model, estimated 12-month changes were -5.0 percentage points (95% CI, -7.1 to -3.0; P <.001) around the CDC milestone and -15.7 percentage points (95% CI, -31.3 to -0.1; P =.049) around TJC. Estimates around COVID-19 and CMS were less stable. Discussion: Declines were most consistent around the CDC milestone; later estimates were limited by closely spaced interruptions and pandemic disruption. Conclusions: ED-focused outpatient stewardship remains needed for older adults with never-appropriate ARTIs.