Cost effectiveness of cholinesterase inhibitors in the treatment of Alzheimer's disease: a review with methodological considerations.

Cholinesterase inhibitors have been available for the treatment of Alzheimer's disease since 1993. They have significantly positive effects on cognitive functioning and other domains of functional capacity, such as activities of daily life in terms of efficacy, but the clinical value of these effects are under discussion. Cholinesterase inhibitors may also influence behavioural and psychological symptoms in Alzheimer's disease. Cholinesterase inhibitors are also regarded as rather expensive and, therefore, the question of cost effectiveness is essential. Pharmacoeconomic evaluations of cholinesterase inhibitors have so far been conducted in retrospect on efficacy data from prospective randomised clinical trials combined with economic data from other sources. There are no published specific cost-effectiveness studies of cholinesterase inhibitors which prospectively collected empirical data on costs and outcomes. There is only one published randomised clinical trial with such empirical data with a cost consequence analysis design, indicating cost neutrality. Several types of models to describe the long-term effects have been published, indicating cost effectiveness. However, due to methodological considerations, the validity of these models is difficult to judge. A research agenda for the cost effectiveness of cholinesterase inhibitors is proposed, including long-term studies with empirical data on resource use, costs and outcomes, studies on quality of life, informal care and behavioural and psychological symptoms, combination and comparative studies on mild cognitive impairment.