Before the 1970s, quality of life received little attention in the medical or public health literature, but since then the situation has been reversed. Despite its widespread use, the term "quality of life" has different meanings to different people. For some researchers and clinicians, quality of life means almost anything beyond information about death and death rates. For others quality of life is an umbrella concept that refers to all aspects of a person's life, including physical health; psychological well-being; social well-being; financial well-being; family relationships; friendships; work; leisure; and the like. In contrast, some approaches to quality of life emphasize the social and psychological aspects of life, and contrast quality of life with quality of care.
Variation is also found in measurement strategies. Some scholars believe that quality of life can be measured by objective parameters. For example, the quality of life in a city is sometimes measured by a summary of characteristics such as the schools, the cultural offerings, the aesthetic properties, the climate, the health care system, the employment possibilities, and so on. By the same token, characteristics of a person, such as income, health status, mental health status, disease profiles, educational level, and housing situation can be summed to create an overall quality-of-life measure. Others view the objective parameters that are often associated with quality of life to be indicators, whereas the actual quality of life can only be measured by a subjective appraisal made by the individual living the life. If one believes that quality of life is inherently subjective, it is then possible to test indicators by the extent to which they predict the quality of life reported by groups of people.
Why is quality of life of interest for public health? First, a good or a poor quality of life is, in some ways, the ultimate marker of the success of preventive health practices and of health care. Second, many health care regimens often seem to detract from quality of life, at least in the short run. As individuals, with the help of their physicians, make decisions about treatment choices, they may take quality of life into account, and may seek information about the likely effects on the quality of their life. Third, and related to the previous point, recent rhetoric pits quantity of life against quality of life, especially in terms of end-of-life treatments; the argument is sometimes made that some treatments are inadvisable because the quality of life likely to result for the extra time gained is too poor. Thus, quality of life has come to be seen as a gold standard for weighing the benefits and costs of life-extending treatments. Finally, in some circumstances, people are asked to change their life circumstances, perhaps forever, for the sake of their health status and care. Relocation to a nursing home would be an example of such a dramatic change. In that situation, it is incumbent on those who plan, fund, and license nursing homes to have some way of assuring that the quality of life, in so far as it is influenced by the facility, is of an acceptable standard.
In health care, the term "health-related quality of life" (HRQL) is often used. This approach narrows consideration to those aspects of quality of life that are deemed to be affected positively or negatively by medical or health care intervention. Another important distinction is between a general HRQL measure (e.g., one that asks about quality of life affected by health) in contrast to a disease-specific HRQL measure. A disease-specific approach may pose questions in relation to the effects of a particular disease (e.g., cancer, arthritis, heart disease) and its treatment with items such as "have you experienced reduction in social activities because of your condition." Other tools are comprised of objective items (for example, agree-disagree items) that are thought to be particularly relevant to the particular disease. A generic HRQL measure may simply be a general measure that attempts to tap health status using the full range of the World Health Organization's definition of health: "physical, psychological, and social well-being."
Subjective judgments of quality of life, though logically the best single source of information, are prone to be influenced by a number of factors. First, expectations influence appraised quality of life, so that an individual may become used to circumstances that could objectively be considered substandard. (This criticism also applies to measures of satisfaction.) Second, individuals may feel constrained because of courtesy or intimidation from actually expressing their views. The intimidation is more likely if the person is in vulnerable health and perceives himself or herself as dependent on care providers, a circumstance that is common for nursing home residents. Finally, lifelong personality traits may influence perceived quality of life.
Personality is generally classified according to five traits (each of which can be seen in their expression or their opposites): neuroticism, extroversion, agreeableness, conscientiousness, and openness. Although little large-scale psychological or sociological research has been done to link subjective quality-of-life results to personality, anthropologists have observed patterns that suggest underlying personality is very much related to how individuals view the quality of their life.
MEASURES OF QUALITY OF LIFE
Examples of some general HRQL measures in widespread use include the Sickness Impact Profile (SIP), which was developed by Bergner and colleagues in the 1970s, and the Medical Outcomes Studies (MOS) Short Form, known as the SF-36, developed by John Ware and colleagues. The SIP, which was developed in the 1970s, contains 136 items that tap twelve categories of wellbeing: sleep and rest, eating, work, home management, recreation and pastimes, ambulation, mobility, body care and movement, social interaction, alertness behavior, emotional behavior, and communication. As its name suggests the SF-36 contains thirty-six questions and generates scores in eight categories: physical functioning, role limitations due to physical problems, social functioning, bodily pain, general mental health, role limitations due to emotional problems, vitality, and general health perceptions; an SF-12 is also available that provides summary scores for physical and mental functioning.
The best known approach specifically for elderly people is the Multi-level Assessment Instrument (MIA), developed by Lawton and colleagues; this is a 152-item battery that generates scores in seven areas: physical health, cognition, activities of daily living, time use, social relations and interactions, personal adjustment, and perceived environment. More recently, Kane and colleagues have been conducting research to develop a self-report measure of the psychosocial aspects of quality of life for nursing home residents: Their eleven domains include comfort, functional competence, autonomy, dignity, individuality, privacy, relationships, meaningful activity, sense of security and safety, enjoyment, and spiritual well-being.
The Quality of Well-being (QWB) Scale, developed by Kaplan and colleagues, differs from the approaches so far described because it defines quality on twenty-four functional states on a scale ranging from 0 for death to 1 for perfect health. The scoring weights were developed based on preferences that individuals assign to the various states.
USING QUALITY OF LIFE FOR RESOURCE ALLOCATION
Some policy analysts recommend using information about quality of life under certain conditions to make decisions about the relative value of health expenditures. The term "quality-adjusted life year" (QALY) is used for approaches that try to combine the effect an intervention will have both on prolonging life and the quality of that life. For example, it would be assumed that extending life for a year for someone in a coma is not as worthwhile as adding a year of vigorous function. The QWB scale described above lends itself to a QALY approach.
Technical and ethical questions arise in applying QALY. Among the former are issues of whether those who rate the conditions have sufficient understanding to apply the judgments. It is widely known that people who do not have a particular condition devalue life with that condition more than those who actually experience the disease or health state. It is also likely that there are cultural and social class differences in how various states are valued. In a well-publicized project, the Medicaid program in the state of Oregon ambitiously applied a QALY approach to Medicaid expenditures for a wide range of conditions. A series of town meetings and phone surveys elicited public opinion about the value attached to the conditions and was combined with physicians' estimations of the magnitude and duration of effects of medical interventions. These were combined with cost information to generate a rank-ordered list of priorities. This procedure yielded results that gave a higher priority to treatment of some common conditions than to much more severe but treatable conditions affecting fewer people.
The most serious criticism of QALY measures is that, as they have been developed and applied, they seem to discount the value of the lives of people with disabilities and very elderly people. If the upper boundary of quality of life is having no functional limits, then certainly quality of life for older people is deflated. An approach called "active life expectancy" developed by gerontologists has this problem: Once the individual is dependent, he or she has no more years of active life expectancy left under the measure.
PROXY EVALUATIONS OF QUALITY OF LIFE
Even if subjective appraisal is treated as a gold standard, some people will simply be unable to communicate about the quality of their lives, and alternative sources of information must be sought. This will be particularly true of people with severe cognitive impairments such as Alzheimer's disease, or people who suffer the communication and motor problems associated with stroke (which could prevent both written or oral administration of a questionnaire). It is, of course, also true of very young children, including newborn children with disabilities that are believed to severely compromise the quality of their current and expected future lives. The hospice movement has stimulated interest in appraising quality of life at the time of death, yet many people cannot be effectively queried on the subject in the last few days of life.
Under these circumstances, the choices of information sources seem to be limited to three: family members, health professionals or paid caregivers of various types, and/or direct observations of the person, from which inferences about his or her quality of life are drawn. All of these approaches have been applied with and for people with Alzheimer's disease. Some of the work in this regard was stimulated by the growth of special care units (SCUs) for Alzheimer's disease in nursing homes, and the resulting need to determine whether residents experienced a different quality of life on those specialized units than in the general population. The direct observations include repeated systematic observation of the individual's facial expression and body language for signs of positive or negative emotion. Similar multifaceted approaches have been developed for adults with intellectual impairments due to developmental disability. However, caution is recommended in resorting to proxy informants too quickly or widely. Many seniors with Alzheimer's disease and younger people with mental retardation are, nevertheless, capable of evaluating many aspects of their lives. Moreover, when it has been possible to get information from both the person most concerned and other informants, a growing body of studies show that family members and professionals may rate quality of life differently from the ratings of those living the life.
The growing attention to quality of life and the desire to minimize the negative effects of disease and health care on this quality reflects the highest of public health aspirations. The science of measuring quality-of-life outcomes is still under development and a matter of some controversy. Also at issue is the extent to which public health measures and health care provision can and should attempt to influence quality of life broadly, and whose values should inform the definitions of quality.
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