Health Literacy, Processing Capacity, Illness Knowledge, and Actionable Memory for Medication Taking in Type 2 Diabetes: Cross-Sectional Analysis

Background: Patient knowledge about the purpose of medications is crucial to ensure safe and correct use, so it is an important index of adherence in patients with chronic illness. Objective: We examined how health literacy and its components (processing capacity and knowledge about illness) influence memory for medication purposes. Design: We conducted a cross-sectional study to examine memory for medication purposes in relation to health literacy, processing capacity, and illness knowledge among patients with diabetes in outpatient clinics. Participants: Six hundred seventy-four adults who were diagnosed with type II diabetes mellitus, age 40 years or older, taking 5 or more current medications, native speakers of English, and with glycosylated hemoglobin (HbA1c) of 6.0 or more, were recruited to the study. Main Measures: We included measures of processing capacity, illness knowledge, health literacy, and actionable memory for medication taking (memory for medication purpose). Key Results: Results suggested an association between health literacy and both processing capacity and health knowledge, with some evidence that knowledge can compensate for limited processing capacity in order to maintain health literacy. Furthermore, health literacy was associated with memory for medication purposes, with processing capacity and health knowledge partly mediating this association. This pattern of results supports the process-knowledge model of health literacy. Conclusions: Our findings establish the role of health literacy in medication taking, in relation to broader cognitive abilities and knowledge. Implications for improving the learning of medication purpose among diverse older adults with chronic illness are discussed. Trial Registration: NIH trial registry number: NCT01296633.