Validating a Self-Reported Medication Nonadherence Measure in the Context of Multiple Chronic Diseases and Routes of Medication Administration Among Patients with Type 2 Diabetes.

Introduction: Patients with diabetes may take oral and injectable medications and often have comorbid chronic diseases. It is unclear whether to assess nonadherence for oral and injectable medications separately or combined and for comorbid conditions separately or combined. Research Design and Methods: We conducted two cognitive interview studies among patients with type 2 diabetes who were prescribed medications for oral or injectable diabetes medications (Study 1) or at least one diabetes, blood pressure, and cholesterol medication (Study 2). Participants completed the two-domain DOSE-Nonadherence measure, which assesses extent of nonadherence and reasons for nonadherence. We asked about interpretation of instructions and items, recall period, ability to respond accurately with separate versus combined versions, and comprehensiveness of reasons for nonadherence to injectable medications. Results: Based on Study 1 (n=14), nonadherence to injectable and oral medications should be assessed separately. Participants believe they can respond accurately to 7-day recall period for daily medications and a one-month recall period for weekly injectable medications. New reasons for nonadherence to injectable medications were perceived as relevant. Based on Study 2 (n-12), nonadherence to medications for diabetes, blood pressure, and cholesterol should be assessed separately. Conclusion: Although separate versions increase response time, it may improve accuracy. Responses to the measure can facilitate conversations about nonadherence between providers and patients to inform clinical decision-making.