The relative effect of Alzheimer's disease and related dementias, disability, and comorbidities on cost of care for elderly persons.

OBJECTIVES: Our primary objectives were (a) to determine the relative impact of Alzheimer's disease and related dementias (ADRD), disability, and common comorbid health conditions on the cost of caring for community-dwelling elderly person and (b) to determine whether ADRD serves as an effect modifier for the effect of disability and common comorbidities on costs.
METHODS: Participants were drawn from community respondents to the 1994 National Long Term Care Survey. The authors compared total cost of caring for persons without ADRD with that of those who had moderate and severe ADRD. Using regression analysis, the author identified the adjusted effect of ADRD, limitations in activities of daily living (ADLs), and common comorbidities on total costs.
RESULTS: Persons with severe ADRD had higher median total costs ($10,234) than did persons with moderate ADRD ($4,318) and those without ADRD ($2,268, p <.001). However, disability measured by ADL limitations was a more important predictor of total cost than was ADRD status in both stratified and multivariate analyses. Comorbidities such as heart attack, stroke, and chronic obstructive pulmonary disease also increased costs. Severe ADRD was an effect modifier for ADL limitations, increasing the positive impact of disability on total costs among persons with severe ADRD, but not for comorbidities. DISCUSSION: Disability, severe ADRD, and comorbidity all had independent effects that increased total costs. Thus, any risk adjustment procedure should account for disability and comorbidity and not just ADRD status.