Development of a preference-weighted health status classification system in France: the Health Utilities Index 3

The Health Utilities Index is a generic multiattribute preference-based system for assessing health-related quality of life, devised by Torrance et al. It is being used in cost-effectiveness evaluations in North America and in international multicentre studies but was not available in France. Following adaptation of the HUI3 classification in France, the purpose of the reported investigation was to derive French preference weights. This article provides a reminder of the theoretical foundations used to model the multiattribute utility function. Within this framework, a multiattribute multiplicative aggregate utility function was constructed in accordance with the explicitly decomposed approach. The study took place in June 1999 over a sample of 365 persons from the French general population, aged between 20 and 65, and not suffering from any chronic or incapacitating illness. The recruitment procedure was based upon a random selection of individuals, using the phone book. Interviews took place in the homes of the interviewees. The methods of revelation (VAS and SG) were applied by setting the value of the best possible state of the HUI3 a priori at 1, and leaving a choice between two states (worst possible state, death) for 0. The aggregated individuals (person-mean and median) were calculated and the multiplicative utility functions constructed. A comparison of the calculated utilities with the observed ones provides a primary indicator of the validity of the person-mean or median functions constructed. The slight absolute differences obtained between observed and calculated utilities and the low RMSE scores lead us towards a favourable conclusion.