title: Using an index-based approach to assess the population-level appropriateness of empirical antibiotic therapy.
abstract: OBJECTIVE
  The population-level appropriateness of empirical antibiotic therapy can be conventionally measured by ascertainment of treatment coverage. This method involves a complex resource-intensive case-by-case assessment of the prescribed antibiotic treatment and the resistance of the causative microorganism. We aimed to develop an alternative approach based, instead, on the use of routinely available surveillance data.
  
  
  METHODS
  We calculated a drug effectiveness index by combining three simple aggregated metrics: relative frequency of aetiological agents, level of resistance and relative frequency of antibiotic use. To evaluate the applicability of our approach, we used this metric to estimate the population-level appropriateness of guideline-compliant and non-guideline-compliant empirical treatment regimens in the context of the Dutch national guidelines for complicated urinary tract infections.
  
  
  RESULTS
  The drug effectiveness index agrees within 5% with results obtained with the conventional approach based on a case-by-case ascertainment of treatment coverage. Additionally, we estimated that the appropriateness of 2008 antibiotic prescribing regimens would have declined by up to 4% by year 2011 in the Netherlands due to the emergence and expansion of antibiotic resistance.
  
  
  CONCLUSIONS
  The index-based framework can be an alternative approach to the estimation of point values and counterfactual trends in population-level empirical treatment appropriateness. In resource-constrained settings, where empirical prescribing is most prevalent and comprehensive studies to directly measure appropriateness may not be a practical proposition, an index-based approach could provide useful information to aid in the development and monitoring of antibiotic prescription guidelines.
authors.affiliation: Department of Medical Microbiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands m.ciccolini@umcg.nl.
authors.forename: M
authors.initials: M
authors.lastname: Ciccolini
authors.affiliation: Division of Infectious Diseases, Department of Internal Medicine, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: V
authors.initials: V
authors.lastname: Spoorenberg
authors.affiliation: Division of Infectious Diseases, Department of Internal Medicine, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: S E
authors.initials: SE
authors.lastname: Geerlings
authors.affiliation: Division of Infectious Diseases, Department of Internal Medicine, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: J M
authors.initials: JM
authors.lastname: Prins
authors.affiliation: Department of Medical Microbiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
authors.forename: H
authors.initials: H
authors.lastname: Grundmann
mesh_terms: D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D001424:Bacterial Infections / Q000188:drug therapy* / Q000382:microbiology; D024881:Drug Resistance, Bacterial; D004358:Drug Therapy / Q000379:methods; D017408:Guidelines as Topic; D006801:Humans; D009426:Netherlands; D014552:Urinary Tract Infections / Q000188:drug therapy* / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents
keywords: antimicrobial resistance; prescription guidelines; surveillance