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Conceptual Background and Issues in Quality of :Life Kathleen N. Lohr ~ fields as diverse as heath technology assessment, health care quality assurance, and heady services research, the hunt for reliable and valid measures of health outcomes intensified greatly in the 198Os. At the same time, the concept of health status expanded to encompass "quality of life." Neither heady status nor quality of life is a completely developed concept; neither has behind it a body of literature that fully documents the range or quality of usable measures and instruments. This is demonstrated in the existing literature, which reflects confusion over the appropn ate content of these constructs and how they should be measured. To address some of these gaps in understanding heath status and quality of life, the hnshtute of Medicine's Council on Health Care Tech- nology commissioned this monograph. It selectively surveys He quality- of-life field, offering examples of the use of these types of measures in technology assessment and related applications. Particular attention is given to their use in pharmaceutical Dials, where they have received the broadest exposure. Chapter 6 provides basic references for the technical attributes (for example, reliability, validity) of many established measures and also reviews a few less well knows measures, especially those used in cancer studies, so mat potential users wild be able to appreciate their relative advantages and limitations. The final chapter offers some recom- mendations concerning the appropriate applications of these measures and highlights areas for cooperative research
2 CONCEPTUAL BACKGROUND KW. LOHR Potential users of quality-of-life measures need to appreciate me con- ceptual complexity of this field and We great array of tools available. Misapprehension about what is being measured or poor choices among existing measures can lead users to unfortunate but avoidable mis- takes. The most important point to understand is that quality of life, health status, functional status, and similar terms are not synonymous; quality of life, In particular, is an inconsistently used concept and is iD- def~ned in the clinical or health services research literature. Furthermore, the instruments used to assess these vanables are not always interchange- able. Finally, the practical inferences one might draw from me applica- tion of these measures in clinical or biomedical research, policy research, or even clinical practice could vary cram aticaDy, depending on what one believed one was measunng. A Continuum of Health-Related Measures Some experts view these concepts as lying along a health-state condn- uum: the more restrictive He concept (such as impaillnent), for instance, the furler to the left on me continuum, arid the more global He concepts (ultimately including quality of life), the more to the nght. Concepts to the right encompass aD He domains lying to the left Others see these constructs as a set of concentric circles. Dimensions such as functional status are closer to He center and thus are more nanowly defined; quality of life is the largest circle and, again, embodies the broadest set of circumstances or attributes that may affect an individ- ual, including those in He smaller circles. Health Status The greatest confusion concerns the distinctions equivalency, He commonalities between measures related directly to individual health status and those embracing other attributes of an individual's life. Health status sometimes denoted health-related quality of lifeitself constitutes a complex, multidimensional construct. A partial list of vm- ables generally recognized in this domain includes survival and life ex- pectancy; various symptom states, such as pain; numerous physiologic states, such as blood pressure or glucose level; physical function states of
CONCEPTUAL BACKGROUND AND ISSUES 3 many sorts9 for instance, mobility and ambulation, sensory functioning, sexual functioning, or a range of capacities relating to impairment, dis- ability, and handicap; emotional and cognitive function status, such as anxiety and depression or positive weB-being; perceptions about present and future heady; and satisfaction with heals care Bohr 19881. Expert generally agree on five distinct health concepts as belonging in me do- main of health statu~physical health, mental heady, social functioning, role functioning, and general health perceptions; some add pain as a sixth key concept (Ware 1987; MosteDer et al. 19891. Health status measures differ in a number of ways. Some of these constructs (death, paint are age-old; others (modem notions of functional status, patient satisfaction with care) are quite recent. Some (death, physi- olog~c states) have been defined and can be observed and measured with considerable precision; others (emotional stability, heady perceptions) are open to substantial interpretation and are measured win less quantitative rigor. Finally, some can or must be measured by someone other than the patient, especially physiologic variables requiring laboratory or other tests; others are assessed only through direct inquiry of a patient or research study subject, primarily Hugh questionnaires. In the last two decades, numerous heady status measures of docu- mented reliability and validity have been developed (McDowell arid Newell 1987, Bohr and Ware 1987, Bohr 19891. The Sickness Impact Profile (SIP) (Bergner et al. 1981) is one well-lmown example of a general health measure. Its 12 dimensions include ambulation, mobility, body care (coDeccively considered a physical health measure), social interaction, communication, aler ness behavior, emotional behavior (col- lectively, a psychosocial measure), sleep/rest, eating, work, home man- agement, and recreation/pastimes. In this and similar instruments, He individual is asked to respond to a series of statements about specific components of health; in He case of me SIP, the person is asked to respond "yes" if the statement describes him or her 'today" and "is related to your health." Questions concem~ng activi- ties are phrased in terms of actual performance, not capacity to perform. In contrast, me General Health Ratings Index was developed as a way to ask people to evaluate Heir heady In general (Davies and Ware 1981~. This measure assesses people's views of their own poor, current, and future heath and their susceptibility to illness by asking them to respond to questions such as "Dunn" the past month, how worded or concerned about your health have you been?" or to label as true or false such state-
4 KW. LOHR meets as "When there is something going around, I usually catch it." This approach integrates He physical arid psychosocial domains tapped more specifically and direc~dy by over heath status questionnaires. Quality-of-Life Measures A fun set of qu~ibr-of-life measures would encompass not only the types of measures just mentioned but also a wide range of intemal and external amibutes of the individuad. One expert defines quality of life as "Bose aspects of life and human function consider essential for living fully" (Mor 1987~. (For He most comprehensive review of these meas- ures to date, see He volume of He Journal of Chronic Diseases edited by Katz, 1987.) These can include components of onets "environment," such as attributes of housing, neighborhood, or community that relate to comfort, safety, absence of clime, convenience of shopping or commut- ing to work, and any number of similar material factors. Other environ- mental aspects of quality of life might involve characteristics of work situations (work load, stressful job relationships). Other personal or environment attributes might be included in a comprehensive quality-of-life definition, such as educations atta~runent or opportunities, income and living standards, and similar financial, so- cial, or demographic elements. Yet others view measures of an individ- ual's ability to cope with short- or long-tenn stressed situations as an important dimension of quality of life. Notions of coping can Hen be extended to ideas of the social support network (for example, family, friends, neighbors, co-workers) and of religion and spirituality. One comprehensive listing of quality-of-life vanables used in surgical teals, for instance, notes aD of the constructs already mentioned (for both health status and quality of life), as wed as scales or measures of body image, confidence, self-image, self-esteem, and level of hope (O 'Young and McPeek 1987~. In sum, concepts of quality of life can be extraordinarily broad, and He interests of clear technology assessment strategy and communication of research results are best senred when the health status segment of tile continuum is clearly demarcated and appropriate mesons and measures am selected. ISSUES RELATING TO SELECTING HEALTH AND QUALITY- OF-LIFE MEASURES Questions about the reliability and the face, construct, and convergent/ discnminant validity of many of these measures abound, especially for
COlICE~ BACKGROUND ED ISSUES s the more diffuse or global quality~f-life ~ns~nents. S~rnilar questions can be raised about the feasibility or practicality of administration and about the need or desirability of measuring one or another domain of health or quality of life if (on Me grounds of sway resources or respondent burden) it means excluding another important, presumably similar do- main. No one answer to these problems can be given. The relevance and value of these measures are determined in large part by He goals of the technology assessments, research studies, or coccal situations in which they may be used. That decided, determining the breadth of measures to be used and selecting the actual measures depends on the quality and suitability of existing instruments forge intended purposes. Most experts concede that no single gold standard exists for assessing aD the available measures; they must be evaluated, in part, against each over and In me context of commonly accepted standards of reliability and validity. Most experts also caution, however, against the development of yet new meas- ures, precisely because many good general and specific tools do exist. With respect to the health-related quality-of-life arena, there is growing agreement Cat Be use of one good general heady measure, supplemented by diagnosis- or problem-specific insurgents, is likely to be the most efficient and rewarding assessment strategy. For the investigator and clinician interested in this field but lacking the time to review it thoroughly, much can be reamed from the successes and failures of past applications of good (or not so good) measures. In addition, information can be amassed about the documented reliability and validity of a number of measures as used for various populations and in heath care deliver settings. The remainder of this monograph (and the citations given herein) constitutes a brief overview of the uses, pitfalls, advantages, and limitations of selected health status ~ealth-sensitive quality-of-life) measures, especially In the technology assessment arena. Our aim is to illustrate and describe these measures and the related concepts so that readers can decide whether and when using these meas- ures win improve their research In medical technology assessment. REFERENCES Bergner, M., Bobbitt, R.A., Carter, W.B., and Gilson, B.S. The Sickness Impact Profile: Development and final revision of a heal stems measure. Medical Care 19~:787-805, 1981. Davies, A.R., and Ware, I.E., Jr. Measuring Health Perceptions in the Heals Insurance Expenment. R-271 1-HHS. Santa Monica, Califor- nia, The RAND CoIporation, 1981.
6 KW. LOHR Katz, S., ed. The Portugal conference: Measuring quality of life and functional status in clinical and epidemiologic research. Proceedings. Joumal of Chronic Diseases 40~6~:459-650, 1987. Lohr, K.N. Outcome measurement: Concepts and questions. Inquiry 25~:37-50, Spring 1988. Lohr, K.N., ed. Advances in health status assessment. Proceedings of a conference. Medical Care 27~3~:SI-S294 (Supplement), 1989. Lohr, K.N., and Ware, I.E., Ir., eds. Proceedings of Me advances in heals assessment conference. Journal of Chronic Diseases 40:SI-SI93 (Supplemerlt), 1987. McDowell, I., and Newell, C. Measuring Health. A Guide to Rating Scales and Questionnaires. New York, Oxford University Press, 1987. Mor, V. Cancer patients' qualibr of life over Me disease course: Lessons from Me real world. Numb of Chronic Diseases 40~61:535-544, 1987. MosteDer, F., Ware, I.E., Ir., and Levine, S. Finale panel. Comments on Me conference on advances in health status assessment. Medical Care 27~31:S282-S294 (Supplement), 1989. O'Young, I., and McPeek, B. Quality of life variables in surgical trials. Joumal of Chronic Diseases 40~61:513-522, 1987. Ware, I.E., Ir. Standards for validating heady measures: Definition and content. loumal of Chronic Diseases 40~6~:473480, 1987.
