title: Agreement between self-reported data on medicine use and prescription records vary according to method of analysis and therapeutic group.
abstract: OBJECTIVE
  This study compared national self-reported data on medicine use and national prescription records at the individual level.
  
  
  METHODS
  Data from the nationally representative Danish health survey conducted in 2000 (n=16,688) were linked at the individual level to national prescription records covering 1999-2000. Kappa statistics and 95% confidence intervals were calculated.
  
  
  RESULTS
  Applying the legend time method to medicine groups used mainly on a chronic basis revealed good to very good agreement between the two data sources, whereas medicines used as needed showed fair to moderate agreement. When a fixed-time window was applied for analysis, agreement was unchanged for medicines used mainly on a chronic basis, whereas agreement increased somewhat compared to the legend time method when analyzing medicines used as needed.
  
  
  CONCLUSIONS
  Agreement between national self-reported data and national prescription records differed according to method of analysis and therapeutic group. A fixed-time window is an appropriate method of analysis for most therapeutic groups.
authors.affiliation: University of Copenhagen, Faculty of Pharmaceutical Sciences, Department of Pharmacology and Pharmacotherapy, Section for Social Pharmacy, Universitetsparken 2, Copenhagen, Denmark. meretewnielsen@yahoo.dk
authors.forename: Merete Willemoes
authors.initials: MW
authors.lastname: Nielsen
authors.forename: Birthe
authors.initials: B
authors.lastname: Søndergaard
authors.forename: Mette
authors.initials: M
authors.lastname: Kjøller
authors.forename: Ebba Holme
authors.initials: EH
authors.lastname: Hansen
mesh_terms: D003625:Data Collection / Q000706:statistics & numerical data; D011307:Drug Prescriptions / Q000706:statistics & numerical data*; D004363:Drug Utilization; D006801:Humans; D004364:Pharmaceutical Preparations / Q000600:supply & distribution; D017891:Pharmacoepidemiology; D011996:Records
chemical_list: D004364:Pharmaceutical Preparations