Q

QALY

Acronym for quality-adjusted life-year.

Acronym for quality of life. Qualitative Analysis

This term is used in two distinct senses. The first refers straightforwardly to any kind of analysis that focuses on the direction of causation or change (for example, positive/negative, better/worse) or their relative size, not their absolute magnitude. The second kind refers to a kind of empirical investigation in which hypotheses may not be clearly formed or intended to be tested but which is designed to generate data from which hypotheses might be invented in inferential ways. Open-ended questionnaires used in surveys of individuals having particular characteristics of a priori interest are an example of a qualitative method of this second kind. Cf. Quantitative Analysis. See Qualitative Study.

Qualitative Effect

The sign (positive or negative) of the effect of one variable on another. The magnitude of the effect is quantitative rather than qualitative.

Qualitative Study

A methodological approach to the understanding of social phenomena that is largely exploratory and interpretive and intended to be a means through which general (usually social scientific) presumptions or high-level general theorizing may be crafted into more specific hypotheses and theories. It produces findings not usually arrived at by means of statistical procedures or

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other quantitative techniques, and includes in-depth (often deliberately unstructured) interviews, observations and participant observation.

Quality-adjusted Life-expectancy

Life-expectancy using quality-adjusted life-years rather than years of life. Quality-adjusted Life-year

The quality-adjusted life-year (QALY) is a generic measure of health-related quality of life that takes into account both the quantity and the quality of life generated by interventions. The invention and further development of the QALY was a response to the treatment of health outcomes solely in terms of survival without any weight being given to the quality of the additional years of life. A year of perfect health is scaled to be 'worth' 1 and a year of less than perfect health 'worth' less than 1. Death is commonly indicated by 0, though in some situations there may be states regarded as worse than death and which would have negative numbers attached to them. Thus an intervention which results in a patient living for an additional five years rather than dying within one year, but where quality of life fell from 1 to 0.6 generates 5 years' extra life with a quality of 0.6 (= 3.0) less 1 year of reduced quality (1 - 0.6) (=0.4), so the (net) QALYs generated by the intervention are 3.0 - 0.4 (=2.6).

The status of the QALY has been the subject of some debate and not a little confusion. Is it a measure of preference for health states? Is it a measure of health outcome that is independent of health states? Is it a utility measure of someone's preferences (the fact that its construction may entail the use of utility theory does not imply that it is)? Is it cardinal or ordinal? Is it consistent with the conventions of welfare economics or is it inescapably a part of extra-welfarism? What value-judgments does it embody and what is their acceptability? What empirical forms of it exist and how do they differ?

Seen as a measure of preference, the QALY is generated using expected utility theory and, in particular, the technique known as the standard gamble. This interpretation therefore rests on the applicability of the axioms of expected utility theory with the independence axiom being extended to entail that, when constructing QALYs from characteristics (like 'painfulness' or 'physical mobility'), the (dis)utility from any one is independent of the others. That is, the preferences are assumed to be additively separable. Further assumptions of this approach are that subjects' preferences have a constant proportional time trade-off (that is, they must be willing to sacrifice a con-

286 Quality of Life stant proportion of future years of life for a given QALY gain) and that a person values health outcomes independently of knowing them ahead of time, including even the extreme outcomes of death and full health. It may seem odd that people are required to be unconcerned about not knowing whether they will live or die but expected utility theory requires people to value each outcome as though it were certain. These assumptions generate a form of cardinal utility measure that is on an interval scale. The scale alone does not permit interpersonal comparisons of the sort 'Individual A is twice as ill as individual B'.

The extra-welfarist interpretation of QALYs is that they are socially chosen cardinal indicators of health or health gain that are interval or ratio scales, depending on their method of construction. This is tantamount to saying that the social welfare function is separable into different types of measure, some of which may be utility measures but one of which is, in any event, health or health gain. On this interpretation, interpersonal comparisons can be explicitly made, as can (at least in principle) whole distributions of health (or health gain), thus enabling the question of equity to be addressed directly. This has given rise to various proposals for weighting QALYs according to who gets them (for example, old v. young, male v. female, married v. single), how many you already have (relatively well v. relatively sick), and how many you have already had (a lifetime of chronic disability v. a recently acquired disability). See Assessment Quality of Life, Disability-adjusted Life-year, EQ-5D, EuroQol, Health Gain, Health Status, Health Utilities Index, Healthy Year Equivalents, SF-6D, SF-8, SF-12, SF-36.

Quality of Life

An index of the quality of a year of life, usually measured by a utility number that has been constructed in a fashion described under utility and embodying the value judgments of selected judges. See Assessment Quality of Life, Disability-adjusted Life-year, EQ-5D, EuroQol, Health Gain, Health Status, Health Utilities Index, Healthy Year Equivalents, Quality-adjusted Life-year.

Quality of Well-being Scale

The QWB is a generic preference-weighted measure combining three scales of functioning with a measure of symptoms and problems on a scale of 0 (death) to 1.0 (full health). This measure is then weighted according to population-based preference weights and combined with expected life-years to generate quality-adjusted life-year. Cf. Assessment Quality of Life, Dis-

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ability-adjusted Life-year, EQ-5D, EuroQol, Health Gain, Health Status, Health Utilities Index, Healthy Year Equivalents.

Quantile

When a continuous variable is split for convenience into equal-sized chunks of data the cut-off points between them are called quantiles. Thus, if there are four such groups (quartiles), each containing 25 per cent of the data, there are three such cut-off points, the central one being the median. Common divisions are tertiles (three groups), quartiles (four), quintiles (five), deciles (ten), centiles (or percentiles) (one hundred).

Quantitative Analysis

An analysis dealing in measured quantities of entities. Cf. Qualitative Analysis. Quartile

When a continuous variable is split for convenience into four equal-sized chunks of data the cut-off points between them are called quartiles. See

Quantile.

Quasi-experimental Research

Comparative research in which the assignment of subjects to comparator groups is not random or a control group is not used.

Quasi-market

Same as internal market.

Queue

Queues seem endemic in health care. Most of them are not the standing-inline type, a major opportunity cost of which for the person waiting is the time not available for alternative uses. Queues mostly represent the postponement

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of care (including diagnostic care), whose consequences can vary from the non-existent (as when restoration to health occurs through natural processes) to the catastrophic (as when a fatal condition goes undiagnosed). In most Western countries with waiting lists, people are mainly waiting for elective surgery. In welfare terms, what probably matters more than the numbers waiting is the time spent waiting and the hazards to which that might expose the waiter: for example, someone waiting for a hip replacement steadily loses muscle strength and becomes more vulnerable to falls, while a large number of waiting people may wait for trivial periods of time.

QuickDASH

The QuickDASH is a shortened version of the DASH Outcome Measure. Instead of 30 items, the QuickDASH uses 11 items to measure physical function and symptoms in persons with any or multiple musculoskeletal disorders of the arms, shoulders and hands. Its website is http://www.dash.iwh. on.ca/quickdash.htm. Cf. Disabilities of the Arm, Shoulder and Hand.

Quintile

When a continuous variable is split for convenience into five equal-sized chunks of data the cut-off points between them are called quintiles. See

Quantile.

Quota Sample

A sample chosen in such a way that the proportion of subjects possessing a certain characteristic is the same as in the population from which the sample comes.

Acronym for quality of well-being.

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