A Novel Approach to Evaluate Antibiotic Utilization Across the Spectrum of Inpatient and Ambulatory Care and Implications for Prioritization of Antibiotic Stewardship Efforts

Background: Antibiotic overuse remains a significant problem. The objective of this study was to develop a methodology to evaluate antibiotic use across inpatient and ambulatory care sites in an integrated healthcare system to prioritize antibiotic stewardship efforts. Methods: We conducted an epidemiologic study of antibiotic use across an integrated healthcare system on 12 randomly selected days from 2017 to 2018. For inpatients and perioperative patients, administrations of antibiotics were recorded, whereas prescriptions were recorded for outpatients. Results: On the study days, 10.9% (95% confidence interval [CI], 10.6%-11.3%) of patients received antibiotics. Of all antibiotics, 54.1% were from ambulatory care (95% CI, 52.6%-55.7%), 38.0% were from the hospital (95% CI, 36.6%-39.5%), and 7.8% (95% CI, 7.1%-8.7%) were perioperative. The emergency department/urgent care centers, adult outpatient clinics, and adult non-critical care inpatient wards accounted for 26.4% (95% CI, 25.0%-27.7%), 23.8% (95% CI, 22.6%-25.2%), and 23.9% (95% CI, 22.7%-25.3%) of antibiotic use, respectively. Only 9.2% (95% CI, 8.3%-10.1%) of all antibiotics were administered in critical care units. Antibiotics with a broad spectrum of gram-negative activity accounted for 30.4% (95% CI, 29.0%-31.9%) of antibiotics. Infections of the respiratory tract were the leading indication for antibiotics. Conclusions: In an integrated healthcare system, more than half of antibiotic use occurred in the emergency department/urgent care centers and outpatient clinics. Antibiotics with a broad spectrum of gram-negative activity accounted for a large portion of antibiotic use. Analysis of antibiotic utilization across the spectrum of inpatient and ambulatory care is useful to prioritize antibiotic stewardship efforts.