Cognitive and psychiatric predictors of medical treatment adherence among older adults in primary care clinics

OBJECTIVES: Medical treatment non-adherence among older adults is common and represents a significant public health care concern. Treatment non-adherence has been associated with a number of factors in older adults; however few studies have delineated the role of cognition and psychiatric status. PARTICIPANTS: Data were collected from 212 ethnically diverse older primary care patients as part of a larger study. MEASUREMENTS: Cognitive status was evaluated with the Mattis Dementia Rating scale (DRS). Psychiatric status was evaluated using the Geriatric Depression Scale (GDS) and the Beck Anxiety Inventory (BAI). Treatment adherence was assessed by the total number of missed healthcare appointments and by physician and patient ratings. Physician ratings of patients' understanding of medical instructions were also obtained. DESIGN: A series of multiple regression analyses were conducted to determine cognitive and psychiatric predictors for each measure of treatment adherence. RESULTS: GDS and DRS memory scores were both independent predictors of the total number of missed medical appointments, F(7,55) = 2.34, p = 0.038. GDS score was also shown to be a significant predictor of physician ratings of patients' understanding of medical instructions, F(7,33) = 0.89, p = 0.031. Neither cognitive performance nor psychiatric status was associated with patient or physician ratings of treatment adherence. CONCLUSIONS: Measures of cognitive functioning and depression severity were supported as predictors of objective measures of treatment adherence but they were not associated with physician or patient ratings of adherence. Patient depression may influence physician ratings of patients' comprehension of medical instructions.