title: Improving the measurement of self-reported medication nonadherence.
abstract: OBJECTIVE
  Medication nonadherence is a significant clinical problem in chronic disease management. Self-report measures have inadequate reliability and poor distributional properties. We demonstrate how two fundamental measurement issues have limited the usefulness of self-reported medication nonadherence measures and offer recommendations for improving measurement.
  
  
  METHODS
  We reviewed existing self-report measures of medication nonadherence in the context of hypertension, one of the most common chronic conditions in which medication nonadherence is a paramount concern. We evaluated these measures with regard to two issues: (1) conflation of causal indicators (which give rise to a latent construct) and effect indicators (which are determined by a latent construct), and (2) a lack of evidence regarding the stability of nonadherence over time.
  
  
  RESULTS
  Nonadherence measurement could be improved by using effect indicators to assess the extent of nonadherence and causal indicators to assess reasons for nonadherence. Moreover, nonadherence should be assessed longitudinally, so that recent developments in statistical modeling can illuminate the extent to which medication nonadherence is transient vs. stable.
  
  
  CONCLUSIONS
  Attention to these measurement issues can improve the assessment of self-reported nonadherence, thereby allowing more accurate conclusions to be drawn about medication-taking behavior and informing the development of improved interventions that target medication nonadherence.
authors.affiliation: Center for Health Services Research in Primary Care, Durham Veterans Affairs Medical Center, Durham, NC 27705, USA. voils001@mc.duke.edu
authors.forename: Corrine I
authors.initials: CI
authors.lastname: Voils
authors.forename: Rick H
authors.initials: RH
authors.lastname: Hoyle
authors.forename: Carolyn T
authors.initials: CT
authors.lastname: Thorpe
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Maciejewski
authors.forename: William S
authors.initials: WS
authors.lastname: Yancy
mesh_terms: D000704:Analysis of Variance; D005260:Female; D006801:Humans; D006973:Hypertension / Q000188:drug therapy* / Q000453:epidemiology / Q000523:psychology; D008297:Male; D055118:Medication Adherence / Q000523:psychology; D011594:Psychometrics; D015203:Reproducibility of Results; D018570:Risk Assessment; D011795:Surveys and Questionnaires; D014342:Truth Disclosure; D016903:Drug Monitoring