Quality of life: some theoretical issues.

The concept "quality of life" is becoming increasingly popular in both the medical and general press. However, from a literature survey of approximately 100 scientific publications in which this concept was used, it appeared that rarely is a definition of this term given. Therefore, it seems useful to formulate several guiding principles: (1) "Quality of life" apparently is too vague a concept. It seems more sensible to isolate a number of relevant factors and to choose the best operational definition possible. The following factors may be considered: daily activity, pattern of complaints, subjective feeling of well-being, and sexual behavior. Based upon these factors one composite score of psychological and social consequences should be developed, analogous to an IQ test. (2) The patient is the sole authority concerning questions on "quality of life." (3) The concept "quality of life" should indicate more than a person's momentary well being, since this is dependent on mood, physiologic state, accidental events, etc. It is not the situation at one specific point which should be considered but the situation over a certain period. (4) Questions concerning "quality of life" should be put relatively. For example, does a person have more or less complaints during one period as compared to another? A second possibility is to compare a person's answers to those of a carefully chosen control group. It is essential to keep in mind that these psychologic measures are descriptive; they indicate how patients feel during a certain period concerning the above-mentioned areas and are definitely not normative in the sense of stating what is or is not desirable.