Drivers of geographic patterns in outpatient antibiotic prescribing in the United States

Antibiotic prescribing rates vary dramatically across regions in the United States, but the relative importance in prescribing practices versus per capita visit rates in driving this variation remain unclear. Quantifying their relative importance can aid in reducing antibiotic use. Using US medical claims data from 2015-2018 covering over 15 million privately insured adults, we conducted a regression analysis to estimate the relative contribution of outpatient visit rates and per-visit prescribing in explaining variation in outpatient antibiotic prescribing rates across metropolitan statistical areas. Variation in visit rates per capita explained more of the geographic variation in outpatient antibiotic prescribing rates than per-visit prescribing for conditions with high prescribing volume. Efforts to reduce antibiotic use may benefit from addressing the factors driving higher rates of outpatient visits, in addition to continued focus on stewardship. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement S.M.K received funding from NIH T32 training grant 2 T32 AI 7535-21 A1. K. I. Oliveira Roster gratefully acknowledges the support of the Sao Paulo Research Foundation (FAPESP) under grant 2021/11608-6. R.P. received funding from NIH T32 training grant T32 GM135014. This pro-ject has been funded in part by contract 200-2016-91779 from the US Centers for Disease Con-trol and Prevention to YHG. Disclaimer: The findings, conclusions, and views expressed are those of the author(s) and do not necessarily represent the official position of the Centers for Disease Control and Prevention (CDC). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Full data and code are available at: .