The incremental direct costs associated with behavioral symptoms in AD

To determine the incremental costs associated with behavioral symptoms in patients with AD. A total of 128 patients with probable AD were enrolled into this study. Cognitive function and extrapyramidal features were assessed in patients with AD. Caregivers were interviewed to determine use of health care services, receipt of unpaid care, severity of behavioral symptoms (Neuropsychiatric Inventory [NPI]), and comorbid medical conditions in patients with AD. Healthcare utilization data were multiplied by unit costs to estimate direct formal costs. Unpaid caregiving hours were multiplied by an hourly wage to estimate direct informal costs. The annual incremental direct costs of additional behavioral symptoms were estimated with multiple regression equations. Annual, direct costs were significantly higher in patients with AD at or above the median score on the NPI (high NPI group), after adjusting for group differences in severity of cognitive impairment and comorbid conditions. Patients in the high NPI group had formal costs between US$3,162 and US$5,919 higher than the low NPI group and total direct costs between US$10,670 and US$16,141 higher, depending on the severity of cognitive impairments. Models for the entire sample estimated that a one-point increase in the NPI score would result in an annual increase of between US$247 and US$409 in total direct costs, depending on the value of unpaid caregiving. Behavioral symptoms in patients with AD significantly increase direct costs of care.