The impact of parkinsonism on costs of care in patients with AD and dementia with Lewy bodies.

Objective: To compare the annual direct costs for patients with Alzheimer's disease (AD) and no parkinsonism (AD), patients with AD and parkinsonism (AD/P), and patients with dementia with Lewy bodies (DLB). For the entire sample, the authors examined the incremental costs associated with increasing parkinsonism.

Methods: Cross-sectional comparisons of 1 year of direct costs were done. Fifteen patients met criteria for DLB, and 133 met criteria for probable AD, of whom 39 had signs of parkinsonism and 94 did not. Patients' caregivers reported on the patient's use of health care services, receipt of unpaid care, and comorbid medical conditions. Severity of cognitive impairment and parkinsonism were determined during patient examinations. Costs were estimated by multiplying utilization data by a unit cost for each type of care. Costs were compared after adjustment for covariates using multiple regression equations.

Results: After adjusting for important covariates, patients with AD/P or DLB had significantly higher annual direct costs than patients with AD. The average adjusted increases in costs above the AD baseline costs were 7,119 dollars (AD/P) and 13,754 dollars (DLB) for formal direct costs and 7,394 dollars (AD/P) and 19,564 dollars (DLB) for total direct costs. Models for the entire sample estimated that a 1-point increase in a parkinsonism scale would result in an annual increase of 784 dollars in formal costs and 827 dollars in total costs of care.

Conclusions: Patients with Alzheimer's disease and parkinsonism or dementia with Lewy bodies have significantly higher formal and total direct costs of care than patients with Alzheimer's disease. Signs of parkinsonism in patients with degenerative dementias are significant independent predictors of costs of care.