Relationships between multiple self-reported nonadherence measures and pharmacy records

BackgroundNonadherence is a momentous problem that confounds optimal medication therapy outcomes. Measuring nonadherence presents a number of methodological conundrums. Pharmacists and other health practitioners might benefit from a simple tool for measuring adherence that correlates well with other, more systematic methods.ObjectivesTo determine (1) the concordance between monthly oral 7-day self-reported nonadherence estimates and a written 7-day self-reported estimate of nonadherence at 3 months, (2) the concordance between oral and written self-reported nonadherence measures and pharmacy records, and (3) the extent to which oral and written self-reported nonadherence measures predict current and future medication nonadherence.MethodsRecruitment involved 8 Wisconsin community pharmacies within a large managed care organization (MCO) and 63 patients with new antidepressant prescriptions. Oral and written self-report measures were modified from the Brief Medication Questionnaire. Pharmacy records were obtained from the pharmacies and MCO.ResultsOral self-reported nonadherence estimates during weeks 4, 8, and 12 were significantly correlated with written self-reported nonadherence at week 12 (P ≤ .05, week 4; P ≤ .01, week 8; and P ≤ .001, week 12). Oral self-reported nonadherence during weeks 8 and 12 was significantly correlated with and predictive of adherence measured via pharmacy records from months 1 to 6 (P ≤ .05). Oral self-reported nonadherence at week 4 was significantly correlated to nonadherence from months 1 to 6 but only predictive of future nonadherence from months 1 to 3. Written self-report of nonadherence at week 12 was significantly correlated with and predictive of nonadherence from months 1 to 6 (P ≤ .001).ConclusionsOral and written self-report measures have moderate to strong concordance with pharmacy records. Both self-report methods are significant predictors of medication nonadherence over 6 months. This study highlights the strong relationship between simple oral questions about medication use and current and future nonadherence. Such brief questions help identify sources of nonadherence and trigger appropriate interventions.