The impact of age on cost-effectiveness ratios and its control in decision making.

Throughout Europe and in a number of other industrialized countries, the coming decades have been predicted to feature an increase in the proportion of patients who are elderly. This has led to considerable concern with respect to financing the health care system and has also increased the concerns about the efficiency of health care. Integrating ageing and efficiency issues, this paper examines the effects of age on the cost-effectiveness of medical interventions and its impact on decision making. First, at the clinical level, the relation between age and the cost-effectiveness of medical interventions is analysed. Second, at the population level, a framework is presented which allows researchers and decision makers to assess the impact of these effects on the decision-making process. It is shown that the allocation of health care resources at the macro-level is seriously impaired when age is ignored as a variable in cost-effectiveness analysis. Because clinical trials typically employ 'young' populations, when the data are extrapolated to the whole population the attractiveness of medical interventions in terms of cost-effectiveness may be considerably overestimated. Furthermore, the cost-effectiveness ratio may vary across countries or over time as a result of demographic or epidemiological variation. Economic evaluators should describe the impact of age, which should then be considered by decision makers to control for age effects.