To compare the associations between dependence and clinical measures of cognition, function and behaviour and total care cost using data from a longitudinal study in Alzheimer's disease (AD).

Longitudinal, observational study.

Community-dwelling subjects.

Male and female subjects between 50 and 85 years of age with mild to moderate AD.

None.

Subject dependence was assessed using the Dependence Scale (DS), cognition (ADAS-Cog, MMSE), function (DAD), behaviour (NPI) and resource utilization with the Resource Utilization in Dementia Questionnaire.

The repeated measures models confirmed a significant association between the DS and total care cost indicating an increase in cost with increasing dependence. A 1-unit increase in DS score was associated with a 28.60% increase in total care cost. Model 2 indicated that a one point change in MMSE, DAD and NPI is associated with 5.29%, 2.32% and 1.71% increase in total cost, respectively. Model 3 indicated that a one point change in ADAS-Cog, DAD and NPI is associated with a 1.74%, 2.42%and 1.62% increase in total cost, respectively.

Strategies which prevent deterioration in clinical measures or delay dependence should result in total cost savings. The quantitative relationships observed should assist in the economic assessment of interventions which effect cognition, function, behaviour and dependence.