Quality of Life, Quantification of

The term quality of life, as used in health research and policy, refers primarily to the quantification of the cost of being in a less-than-perfect health state. Such quantification is motivated largely by economic analyses, which require comparison of all costs and benefits of a policy or situation, including not only mortality and resource costs but also morbidity. Without such quantification, it is impossible to assess the net benefits of policies that affect health or to make formal analyses comparing the costs and benefits of different treatments. Various methods exist for eliciting quality of life quantifications and calculating quality-adjusted life years (QALYs). However, all of them have major drawbacks, and thus while it is always possible to [Page 869]generate the needed numbers, it is difficult to defend them as accurate in most contexts.

Quality of life is a concept that permeates modern and ancient philosophy. It invokes two interrelated but fundamentally different meanings, creating some practical confusion. One sense of the term captures concepts related to happiness, satisfaction, and freedom from pain, while another refers to the worthiness of people's lives. In modern health science, researchers are interested in the former concerns, and particularly with assigning cardinal values to different states of well-being. However, subtle influences of the latter interpretation sometimes confuse measures and understanding.

In the post-Enlightenment world, where everyone's life is considered to have worth and everyone's wellbeing is considered a legitimate concern, there is near universal agreement that improving people's quality of life is a worthwhile endeavor. Making people happy (comfortable, functional), and not just long-lived, is seen as a goal of health care, health policy, and health research.

The motivation for quantifying quality of life in health science is largely driven by the limits of the ordinal concept—increased longevity or health or happiness is better—in economic analysis (which is the study and assessment of trade-offs) of health care. While it is straightforward to quantify the number of lives (or life years) saved for a given expenditure on mortality-reducing interventions, it is more difficult to quantify the trade-off when the benefits are a reduction in morbidity rather than mortality. Comparison of the value of interventions that reduce morbidity to those that reduce mortality, and analysis of interventions that substantially affect both, is impossible without a common metric. That metric is also useful for descriptive epidemiology and other research, apart from economic analysis.

A naive and inappropriate measure of the cost of morbidity is the loss of productivity (often measured in terms of lost wages). This implicitly invokes the ‘worthiness’ sense of quality, equating the value of someone's life to what they produce. Lost wages are often the basis of payouts from insurance contracts or policies designed to mimic insurance (e.g., the settlements paid to survivors of victims of the 9/11 attacks). Such measures have a legitimate economic basis (roughly speaking, rational insurance contracts should replace what can be replaced with money, but not pay for those things which cannot be replaced).

But they should not be mistaken for the appropriate value to incorporate into decision making. Individual productivity is a reasonable approximation for the value of someone's life in some sociopolitical systems (e.g., primitive cultures where survival of the community is in question, or modern highly communitarian systems such as fascism or communism), but in modern Western traditions, there is general agreement that someone suffering poor health causes much greater cost than merely the wages lost, as does dying prematurely.

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