Measurement and utilization of healthy life expectancy: conceptual issues.

The periodic calculation of healthy life expectancies permits the evaluation of the impact of new health policies at a given moment, as well as the assessment of trends under changing health conditions. In spite of their apparent simplicity, the results obtained will have to be interpreted by experts. Useful reference values can be provided by international comparisons. However, several choices remain to be made, such as (i) the types of morbidity and disability data to be associated with mortality data; (ii) the multiple indicators available; (iii) the type of observations to be recorded, i.e., "abilities" or "performances"; (iv) whether or not the recovery of lost functions should be considered; (v) the mode of computation, i.e., life expectancy before the first morbid event or global healthy life expectancy; and (vi) the determination of thresholds based on either relative or absolute criteria.