Defining and Measuring Quality of Life in Medicine

To the Editor.—Drs Leplége and Hunt ¹ assert that variability across cultures, between patients, and in the same patient over time makes efforts to define the term quality of lifeimpossible. It is an "idiosyncratic mystery." They conclude that physicians and health economists should avoid quality of life assessment. At the same time, the authors assert that quality of life is paramount to patients and is, indeed, the only concern of the patient who seeks medical care. The unwelcome conclusion is that outcomes—whether patients feel better and are able to do more, whether they are spared subsequent treatments, and whether they are glad they sought medical care—are not a part of medicine.

This argument, however, rests on a faulty assumption. Variability among patient appraisal of quality of life is limited. No one thinks severe abdominal pain is better than a runny nose, as Fanshel and Bush² long ago pointed out (even if it is difficult, as they recognized, to find a measurement unit that expresses their relative quality-of-life impact). Even cultural variation has limits. When asked about their ability to carry out common tasks of daily living, the responses of!Kung and Herero elders of southwest Africa (seminomadic pastoralists) were best understood in terms of a physical function component highly correlated with age.³ More generally, utilities elicited for health states are highly correlated across populations and across sociodemographic groups.⁴ If health state utilities do vary according to patient health status (as demonstrated for dialysis patients⁵ but not, however, for all patient groups), this variability only shows that other distinct features of patient experience must be considered by clinicians when recommending treatments or assessing outcomes. These include family support systems, willingness to adopt prosthetic technologies, and patient attachment to life.

Leplége and Hunt have exaggerated the idiosyncratic nature of health-related quality of life (HRQL) by confounding it with quality of life more generally. This distinction is critical: HRQL measures are likely to be more highly correlated with health status and more sensitive to changes in health than general quality-of-life measures. When the authors suggest that quality of life be viewed as "the best possible physical and emotional state compatible with [a patient's] medical condition," they are talking about HRQL, which is already well assessed by a variety of measurement tools. When they complain that such measures of health status do not capture other components of patient quality of life, such as the capacity to love or have "a positive approach to everyday events," they are right, but the measures also were never intended to do so.