Cost of illness of Alzheimer's disease: How useful are current estimates?

Purpose: The goal of this literature review was to determine the validity and policy relevance of recent estimates from many countries of Alzheimer's disease (AD) costs. Design and Methods: We searched Medline and other databases for English-language peer-reviewed journals on total,. direct, indirect, and per case cost of AD that used 1985-2000 data. We adjusted costs of U.S. studies for inflation. We adjusted non-U.S. studies by that country's medical cost inflation rate and purchasing power parity (PPP). Results: Of 71 studies identified, 21 met all criteria for inclusion. Annual inflation adjusted U.S. total costs of AD varied from $5.6 billion to $88.3 billion. AD total per case (direct and indirect) costs varied from $1,500 to $91,000; indirect/family costs varied from $3,700 to $21,000. Among non-U.S. studies, AD annual adjusted per case costs varied from PPP $2,300 to PPP $30,000. Cost variation was due to diverse study methods, data sources, services included, and lack of clear differentiation between cost of AD and cost of caring for people with AD. Implications: The cost of AD is high, although reliable estimates are not available. Costs are likely to rise given expected demographic shifts in all countries. The widely variable cost estimates call into question the real costs of Alzheimer's disease and their applicability to policy initiatives.