title: Web search query volume as a measure of pharmaceutical utilization and changes in prescribing patterns.
abstract: BACKGROUND
  Monitoring prescription drug utilization is important for both drug safety and drug marketing purposes. However, access to utilization data is often expensive, limited and not timely.
  
  
  OBJECTIVE
  To demonstrate and validate the use of web search engine queries as a method for timely monitoring of drug utilization and changes in prescribing behaviors.
  
  
  METHODS
  Drug utilization time series were obtained from the Medical Expenditure Panel Survey and normalized search volume was obtained from Google Trends. Correlation between the series was estimated using a cross-correlation function. Changes in the search volume following knowledge events were detected using a cumulative sums changepoint method.
  
  
  RESULTS
  Search volume tracks closely with the utilization rates of several seasonal prescription drugs. Additionally, search volume exhibits changes following known major knowledge events, such as the publication of new information.
  
  
  CONCLUSIONS
  Search volume provides a first order approximation to pharmaceutical utilization in the community and can be used to detect changes in prescribing behavior.
authors.affiliation: Department of Pharmacy Practice and Science, University of Iowa, Iowa City, IA 52242, USA.
authors.forename: Jacob E
authors.initials: JE
authors.lastname: Simmering
authors.affiliation: Department of Pharmacy Practice and Science, University of Iowa, Iowa City, IA 52242, USA. Electronic address: linnea-polgreen@uiowa.edu.
authors.forename: Linnea A
authors.initials: LA
authors.lastname: Polgreen
authors.affiliation: Department of Internal Medicine, University of Iowa, Iowa City, IA, USA; Department of Epidemiology, University of Iowa, Iowa City, IA, USA.
authors.forename: Philip M
authors.initials: PM
authors.lastname: Polgreen
mesh_terms: D004363:Drug Utilization / Q000706:statistics & numerical data*; D006801:Humans; D020407:Internet; D010818:Practice Patterns, Physicians' / Q000706:statistics & numerical data*; D057386:Search Engine / Q000706:statistics & numerical data*
keywords: Novel data sources; Pharmacovigilance; Post-marketing surveillance