title: Validity assessment of self-reported medication use by comparing to pharmacy insurance claims.
abstract: OBJECTIVE
  In Japan, an annual health check-up and health promotion guidance programme was established in 2008 in accordance with the Act on Assurance of Medical Care for the Elderly. A self-reported questionnaire on medication use is a required item in this programme and has been used widely, but its validity has not been assessed. The aim of this study was to evaluate the validity of this questionnaire by comparing self-reported usage to pharmacy insurance claims.
  
  
  METHODS
  This is a population-based validation study. Self-reported medication use for hypertension, diabetes and dyslipidaemia is the evaluated measurement. Data on pharmacy insurance claims are used as a reference standard.
  
  
  METHODS
  Participants were 54,712 beneficiaries of the National Health Insurance of Chiba City.
  
  
  METHODS
  Sensitivity, specificity and κ statistics of the self-reported medication-use questionnaire for predicting actual prescriptions during 1 month (that of the check-up) and 3 months (that of the check-up and the previous 2 months) were calculated.
  
  
  RESULTS
  Sensitivity and specificity scores of questionnaire data for predicting insurance claims covering 3 months were, respectively, 92.4% (95% CI 91.9 to 92.8) and 86.4% (95% CI 86.0 to 86.7) for hypertension, 82.6% (95% CI 81.1 to 84.0) and 98.5% (95% CI 98.4 to 98.6) for diabetes, and 86.2% (95% CI 85.5 to 86.8) and 91.0% (95% CI 90.8 to 91.3) for dyslipidaemia. Corresponding κ statistics were 70.9% (95% CI 70.1 to 71.7), 77.1% (95% CI 76.2 to 77.9) and 69.8% (95% CI 68.9 to 70.6). The specificity was significantly higher for questionnaire data covering 3 months compared with data covering 1 month for all 3 conditions.
  
  
  CONCLUSIONS
  Self-reported questionnaire data on medication use had sufficiently high validity for further analyses. Item responses showed close agreement with actual prescriptions, particularly those covering 3 months.
authors.affiliation: Department of Public Health, Chiba University, Chiba, Japan.
authors.forename: Misuzu
authors.initials: M
authors.lastname: Fujita
authors.affiliation: Department of Global Clinical Research, Chiba University, Chiba, Japan Chiba University Hospital, Clinical Research Center, Chiba, Japan.
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Sato
authors.affiliation: Department of Global Clinical Research, Chiba University, Chiba, Japan Chiba University Hospital, Clinical Research Center, Chiba, Japan.
authors.forename: Kengo
authors.identifier: http://orcid.org/0000-0003-4529-9045
authors.initials: K
authors.lastname: Nagashima
authors.affiliation: Chiba University Hospital, Clinical Research Center, Chiba, Japan.
authors.forename: Sho
authors.initials: S
authors.lastname: Takahashi
authors.affiliation: Department of Public Health, Chiba University, Chiba, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Hata
mesh_terms: D000328:Adult; D000368:Aged; D003920:Diabetes Mellitus / Q000188:drug therapy*; D050171:Dyslipidemias / Q000188:drug therapy*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000188:drug therapy*; D007344:Insurance Claim Reporting; D007348:Insurance, Health; D007564:Japan; D008297:Male; D008875:Middle Aged; D010604:Pharmacy; D055656:Prescriptions; D057566:Self Report; D011795:Surveys and Questionnaires / Q000592:standards*
keywords: EPIDEMIOLOGY; MEDICAL HISTORY