Variance and Dissent: Self-Reported Medication Nonadherence
- 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.
- We find the author’s responses to our initial comments very positive. Their thoughts reflect the significant amount of research that has been conducted by leading experts to date on the conceptualization, measurement, and evaluation of medication nonadherence. We appreciate the additional clarification Drs. Voils et al. have provided regarding the importance of latent variables and their relationship to cause and effect indicators in psychometric analyses.
- We appreciate the thoughtful response from Drs. Morisky and DiMatteo and are grateful for the opportunity to engage in an important discussion about the measurement of medication nonadherence with two leading experts. We agree with the authors on many issues: a short measure of nonadherence is particularly desirable for use in the clinical setting; nonadherence measures should focus on a particular disease yet encompass its various therapies; and potential reasons for nonadherence are different from the actual behavior of not taking medications.
- We agree with the authors of this important piece that many self-report measures of medication adherence have lacked adequate reliability and strong evidence of validity. Limitations in adherence measurement constitute a major problem in this important area of investigation. In a rush to document the effectiveness of their interventions, or to identify correlational or causal elements in the adherence puzzle, too many researchers have simply constructed their own adherence measures or modified existing ones, failing to apply even rudimentary techniques of psychometric analysis and measurement development.