title: Pharmacy data in epidemiological studies: an easy to obtain and reliable tool.
abstract: OBJECTIVE
  The agreement between drug use measured in computerized pharmacy records and patient interviews or questionnaires is generally good. However, most investigations on this subject studied selected populations or subsets. We studied the coverage of Dutch pharmacy data for our study cohort, and the agreement between the different sources.
  
  
  METHODS
  We used the data from 8592 subjects of an on-going population-based study, focused on the impact of microalbuminuria (PREVEND). Data on drug use was collected in a questionnaire and at community pharmacies. Drug use was measured in the year preceding the questionnaire. Agreement between the sources was measured using kappa-values, sensitivity and positive predictive value.
  
  
  RESULTS
  Pharmacy data could be collected for 7568 (88%) of the study cohort. Pharmacy data and questionnaires showed good agreement for antihypertensives, lipid lowering drugs, oral antidiabetics and oral contraceptives, but poor agreement for nitrates, hormone replacement therapy and painkillers.
  
  
  CONCLUSIONS
  Pharmacy data could be collected for a large proportion of our cohort. For chronically used drugs pharmacy data generally agrees well with questionnaires. However, for drugs used for shorter periods, as needed, or also available over-the-counter, the agreement is not so good. Pharmacy data can be a valuable source of drug information in epidemiological studies.
authors.affiliation: Department of Social Pharmacy, Pharmacoepidemiology and Pharmacotherapy, Groningen University Institute for Drug Exploration (GUIDE), Groningen, The Netherlands.
authors.forename: Taco B M
authors.initials: TB
authors.lastname: Monster
authors.forename: Wilbert M T
authors.initials: WM
authors.lastname: Janssen
authors.forename: Paul E
authors.initials: PE
authors.lastname: de Jong
authors.forename: Lolkje T W
authors.initials: LT
authors.lastname: de Jong-van den Berg
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D004358:Drug Therapy / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D016347:Medical Records Systems, Computerized; D008875:Middle Aged; D009426:Netherlands; D010594:Pharmacies; D017891:Pharmacoepidemiology / Q000379:methods*; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires