Prescriber-level surveillance of outpatient antimicrobial consumption to enable targeted antimicrobial stewardship: a nationwide observational study, Switzerland, 2015 to 2022

Background: In Europe and other high-income countries, antibiotics are mainly prescribed in the outpatient setting, which consists of primary, specialist and hospital-affiliated outpatient care. Established surveillance platforms report antimicrobial consumption (AMC) on aggregated levels and the contribution of the different prescriber groups is unknown. Aim: To determine the contribution of different prescribers to the overall outpatient AMC in Switzerland. Methods: We conducted a retrospective observational study using claims data from one large Swiss health insurance company, covering the period from 2015 to 2022. We analysed antibiotic prescriptions (ATC code J01) prescribed in the Swiss outpatient setting. Results were reported as defined daily doses per 1,000 inhabitants per day (DID) and weighted according to the total population of Switzerland based on census data. Results: We analysed 3,663,590 antibiotic prescriptions from 49 prescriber groups. Overall, AMC ranged from 9.12 DID (2015) to 7.99 DID (2022). General internal medicine (40.1% of all prescribed DID in 2022), hospital-affiliated outpatient care (20.6%), group practices (17.3%), paediatrics (5.4%) and gynaecology (3.7%) were the largest prescriber groups. Primary care accounted for two-thirds of the prescribed DID. Quantity and type of antibiotics prescribed varied between the prescriber groups. Broad-spectrum penicillins, tetracyclines and macrolides were the most prescribed antibiotic classes. Conclusion: Primary care contributed considerably less to AMC than anticipated, and hospital-affiliated outpatient care emerged as an important prescriber. Surveillance at the prescriber level enables the identification of prescribing patterns within all prescriber groups, offering unprecedented visibility and allowing a more targeted an