Measurement techniques of quality of life in health economics

The aim of this article is to present and discuss methods used in economic evaluation of health care to measure duality of life. Broadly speaking, the quality adjustment is al ways based on a set of weights called preferences or utilities. In a specific decisional context, the simplest approach is t o identify all the health states experienced by patients and to ask subject s to reveal directly preferences for each stale. The three most widely used techniques are the rating scale and its variants, the standard gamble and the time trade-off. This direct simple approach is resource consuming and a very complex task, and the comparability of results collected from differe nt studies is limited because of great variability of methods used for desc ribing health stares, selecting subjects and applying techniques of prefere nce measurement. A recent alternative which is very attractive and is frequ ently used, is to by-pass the measurement task by using one of the pre-scor ed multi-attribute health status classification systems that exists. The cl assification is based upon a multidimensional conception of health. It allo ws us to describe an individual's or a population's health status at a give n moment and over a period of lime. The weighting function allows the diffe rent health states to be scored in relation to one another on a scale from 0 to 1. The three main available systems (Health Utilities Index, EuroQol a nd Quality of Well-Being index) are presented. Main methodological issues a ssociated with these indexes are addressed in the context of their use.