title: Influence of provider and urgent care density across different socioeconomic strata on outpatient antibiotic prescribing in the USA.
abstract: OBJECTIVE
  Despite a strong link between antibiotic use and resistance, and highly variable antibiotic consumption rates across the USA, drivers of differences in consumption rates are not fully understood. The objective of this study was to examine how provider density affects antibiotic prescribing rates across socioeconomic groups in the USA.
  
  
  METHODS
  We aggregated data on all outpatient antibiotic prescriptions filled in retail pharmacies in the USA in 2000 and 2010 from IMS Health into 3436 geographically distinct hospital service areas and combined this with socioeconomic and structural factors that affect antibiotic prescribing from the US Census. We then used fixed-effect models to estimate the interaction between poverty and the number of physician offices per capita (i.e. physician density) and the presence of urgent care and retail clinics on antibiotic prescribing rates.
  
  
  RESULTS
  We found large geographical variation in prescribing, driven in part by the number of physician offices per capita. For an increase of one standard deviation in the number of physician offices per capita there was a 25.9% increase in prescriptions per capita. However, the determinants of the prescription rate were dependent on socioeconomic conditions. In poorer areas, clinics substitute for traditional physician offices, reducing the impact of physician density. In wealthier areas, clinics increase the effect of physician density on the prescribing rate.
  
  
  CONCLUSIONS
  In areas with higher poverty rates, access to providers drives the prescribing rate. However, in wealthier areas, where access is less of a problem, a higher density of providers and clinics increases the prescribing rate, potentially due to competition.
authors.affiliation: Department of Emergency Medicine, Johns Hopkins University, Baltimore, MD, USA Center for Disease Dynamics, Economics & Policy, Washington, DC, USA eklein@jhu.edu.
authors.forename: Eili Y
authors.initials: EY
authors.lastname: Klein
authors.affiliation: Department of Emergency Medicine, Johns Hopkins University, Baltimore, MD, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Makowsky
authors.affiliation: Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, USA.
authors.forename: Megan
authors.initials: M
authors.lastname: Orlando
authors.affiliation: Department of Emergency Medicine, Johns Hopkins University, Baltimore, MD, USA.
authors.forename: Erez
authors.initials: E
authors.lastname: Hatna
authors.affiliation: Center for Disease Dynamics, Economics & Policy, Washington, DC, USA.
authors.forename: Nikolay P
authors.initials: NP
authors.lastname: Braykov
authors.affiliation: Center for Disease Dynamics, Economics & Policy, Washington, DC, USA Princeton Environmental Institute, Princeton University, Princeton, NJ, USA.
authors.forename: Ramanan
authors.initials: R
authors.lastname: Laxminarayan
mesh_terms: D000553:Ambulatory Care / Q000379:methods*; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D011307:Drug Prescriptions / Q000706:statistics & numerical data*; D004363:Drug Utilization; D006801:Humans; D012959:Socioeconomic Factors; D014481:United States
chemical_list: D000900:Anti-Bacterial Agents
keywords: antibiotic resistance; pharmacoepidemiology; public health