Estimating the relationship between disease progression and cost of care in dementia

Background Previous studies have shown a positive relationship between disease severity and cost. Aims To explore the factors affecting time to institutionalisation and estimate the relationship between the costs of care and disease progression. Method Retrospective analysis of a longitudinal data-set for a cohort of 100 patients diagnosed with Alzheimer's disease or vascular dementia. Results Changes in both Mini-Mental State Examination (MMSE) and Barthel scores have independent and significant marginal effects on costs. Each one-point decline in the MMSE score is associated with a £56 increase in the four-monthly costs, whereas each one-point fall in the Barthel index is associated with a £586 increase in costs. Conclusions It may be inappropriate for economic models of disease progression in dementia to be based solely on measures of cognitive change. MMSE and the Barthel index are independent significant predictors of time to institutionalisation and cost of care, but changes in the Barthel index are particularly important in predicting costs outside institutional care.