The utility approach to assessing health-related quality of life is the most widely used technique for
assessing preferences for health outcomes in the economic evaluation of health care. The scale for utility
scores assigns a value of 1.0 to perfect health and 0.0 to death. The utility scores are employed to weigh time
spent in each health state to estimate quality-adjusted life years (QALYs) gained, which is used as the
denominator in cost-utility analysis and cost-effectiveness analysis. Utility scores are obtained through direct
assessments using techniques such as standard gamble (SG), time-trade off (TTO), and visual analog scale
(VAS), or by using multi-attribute systems such as the Health Utilities Index (HUI) or EuroQol (EQ-5D).
According to international HE guidelines, the most preferred utility methods are SG and TTO, followed by EQ-
5D, VAS and HUI, respectively. In Thailand, the EQ-5D is the most recommended utility method because it has
acceptable feasibility and validity.

Keywords: Utility, Preference, Health-related quality of life, Quality of life weights, Quality-adjusted life years,
QALYs