Measurement of clinical-effect: utility.

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.