The Development of a New Computer Adaptive Test of Medication Adherence for People with Type 2 Diabetes Mellitus: Medication Adherence Item Bank

Over 27 million Americans have type 2 diabetes mellitus (T2DM), accounting for >7.7 million hospital admissions. Social determinants of behavior, including medication adherence, play a critical role in their health outcomes. We developed a new patient-reported outcome (PRO) measure to evaluate medication adherence in people with T2DM, using established measurement development standards. An item pool was created that reflected important content related to medication adherence for people with T2DM. The item pool was then refined, using feedback from experts, a reading-level assessment (ensuring no >5th grade reading-level content was included), a translatability review (e.g., to allow future measure translation into Spanish), and feedback from T2DM patients. Next, 225 people with T2DM completed 58 self-report medication adherence items. Exploratory factor analysis supported the item pool’s essential unidimensionality. Five items were excluded due to low item-rest correlations. Confirmatory factor analysis supported retaining 27 items. All items fit the graded response model, and no items had meaningful differential item functioning for the factors age, sex, education, or socioeconomic status. The final item bank is comprised of 27 items and can be administered as a computer adaptive test or 6- item short form. Internal consistency reliability was excellent for all administration formats (α’s all ≥ .90). The new Medication Adherence item bank provides a reliable, content-relevant assessment of medication adherence for people with T2DM. It is part of the comprehensive Re-Engineered Discharge for Diabetes Computer Adaptive Test (REDD-CAT) measurement system, which is designed to capture important social determinants of behavior for people with T2DM. Work is underway to establish additional psychometric properties (e.g., test-retest reliability, validity) of this new measure. Disclosure S. Mitchell: Other Relationship; Self; See Yourself Health LLC, Speaker’s Bureau; Self; Merck Sharp & Dohme Corp. M. A. Kallen: None. A. Bragg: None. I. Moldovan: None. J. M. Howard: None. B. W. Jack: None. J. A. Miner: None. C. M. Graves: None. N. Carlozzi: None. Funding National Institute of Diabetes and Digestive and Kidney Diseases (R21DK121092)