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The HUI3 scoring function has strong theoretical and empirical foundations. It performs well in predicting directly measured scores. The HUI3 system provides a practical way to obtain utility scores based on community preferences.

The Health Utilities Index Mark 2 (HUI:2) is a generic multiattribute, preference-based system for assessing health-related quality of life. Health Utilities Index Mark 2 consists of two components: a seven-attribute health status classification system and a scoring formula. The seven attributes are sensation, mobility, emotion, cognition, self-care, pain, and fertility. A random sample of general population parents were interviewed to determine cardinal preferences for the health states in the system. The health states were defined as lasting for a 60-year lifetime, starting at age 10. Values were measured using visual analogue scaling. Utilities were measured using a standard gamble technique. A scoring formula is provided, based on a multiplicative multiattribute utility function from the responses of 194 subjects. The utility scores are death-anchored (death = 0.0) and form an interval scale. Health Utilities Index Mark 2 and its utility scores can be useful to other researchers in a wide variety of settings who wish to document health status and assign preference scores.

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The aim of this article is to review the concept of the qualityadjusted life-year (QALY), a widely used measure of health improvement that is used to guide health-care resource allocation decisions. The QALY was originally developed as a measure of health effectiveness for cost-effectiveness analysis, a method intended to aid decision-makers charged with allocating scarce resources across competing health-care programs [1][2][3]. We refer to this original concept of the QALY, as defined in the early literature, as the "conventional" QALY, recognizing that alternative conceptual models have been proposed, including but not limited to so-called "equity-weighted" QALYs. The US Panel on Cost-Effectiveness in Health and Medicine [4] and the National Institute of Health and Clinical Excellence (NICE) in Britain have both endorsed the conventional QALY for their "reference case," i.e., a standardized methodological approach to promote comparability in cost-effectiveness analyses of different health-care interventions.In using QALYs, we assume that a major objective of decisionmakers is to maximize health or health improvement across the population subject to resource constraints. The use of QALYs further assumes that health or health improvement can be measured or valued based on amounts of time spent in various health states. The conventional QALY is therefore a valuation of health benefit. We note, however, that decision-makers may also have other objectives such as equity, fairness, and political goals, all of which currently must be handled outside the conventional Special Issue [5] addresses some of these variations on the conventional QALY. The QALY was not initially developed to aid individual patient decision-making, although its use has sometimes been extended into clinical decision analyses for this purpose.The core concept of the conventional QALY is grounded in decision science and expected utility theory. The basic construct is that individuals move through health states over time and that each health state has a value attached to it. Health, which is what we are seeking to maximize, is defined as the value-weighted time-life-years weighted by their quality-accumulated over the relevant time horizon to yield QALYs. Health states must be valued on a scale where the value of being dead must be 0, because the absence of life is considered to be worth 0 QALYs. By convention, the upper end of the scale is defined as perfect health, with a value of 1. To permit aggregation of QALY changes, the value scale should have interval scale properties such that, for example, a gain from 0.2 to 0.4 is equally valuable as a gain from 0.6 to 0.8. States worse than dead can exist and they would have a negative value and subtract from the number of QALYs. These conditions, along with an assumption of risk neutrality over life-years, are sufficient to ensure that the QALY is a useful representation of health state preferences.