Cost of dementia: impact of disease progression estimated in longitudinal data

Several studies have shown that health care costs are higher for demented than for non-demented persons and that health care costs are higher for more severe demented persons than less severe demented persons. However, most studies report on cross-sectional study designs, and thus fail to examine the influence of disease progression on changes in health care costs to individual persons. The objective of this study was, using longitudinal data, to examine changes in total health care costs with disease progression in demented persons.

We assumed that disease progression could be characterised by transitions between different states of dementia which reflected the degree to which the disease progressed over time. Then, changes in health care costs were regressed on a set of explanatory variables including disease progression. A total of 465 demented and non-demented persons were interviewed twice. The time between interviews was about three years. Before each interview, the participant was examined for dementia and classified by type of dementia (Alzheimer's disease, vascular or other types of dementia) and degree of dementia (very mild, mild, moderate, severe).

The results of this longitudinal study confirmed that health care costs increased over time for non-demented as well as for demented persons and that health care costs increased with disease progression. In particular, the health care costs increased when the disease had progressed into the severe state of the dementia. Also, decline in functional abilities was an important factor for explaining changes in health care costs.