Pulmonary rehabilitation in chronic respiratory insufficiency. 7. Health-related quality of life among patients with chronic obstructive pulmonary disease.

Abstract

Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality in industrialised nations. It is essen-tially incurable and, for many, inexorably pro-gressive; health care providers spend much effort trying to minimise patients' symptoms and to improve their ability to function in day-to-day life. While improved survival time is an important aim of treatment, there is growing recognition that improving the quantity of an individual's life may not be the only goal; for some, improving the quality of life may be far more important. Since reducing symptoms, increasing function, and improving the quality of life are central therapeutic goals for patients with COPD, as for many chronic diseases, it is important for researchers and clinicians to develop a common understanding of what is meant by these phrases and how these con-cepts can be measured. In the past 10 years there has been an increasing body of literature on measurement of quality of life in patients with COPD and, more recently, on the efficacy of therapeutic agents based on quality of life measures. Stud-ies measuring the quality of life in these patients appeared in the mid 1980s'4 when quality of life measures were used to assess continuous oxygen therapy,' intermittent pos-itive pressure breathing,6 and, more recently, in the assessment of theophylline,7 inhaled bronchodilators,8 home respiratory nursing care,9 and pulmonary rehabilitation pro-grammes.'0 As this trend continues it is im-portant for clinicians to understand and assess these measures to help decide whether a new treatment is valuable. We will review quality of life measures in patients with COPD with the emphasis on issues important to the clinician who seeks an understanding of quality of life measures as they are used in therapeutic trials. Definition and relevance of health related quality of life TERMS AND DEFINITIONS The term "quality of life" is widely used in clinical research and clinical care, but rarely defined. In its broadest definition the quality of an individual's life is strongly influenced by factors that health care does not directly affect, including financial status, housing, employ-ment, and social support. Consequently many researchers favour the more restrictive terms "health-related quality of life" (HRQL) or "functional status" to mean the quality of life as it is affected by health status. Functional status connotes a stronger basis in ability to perform the tasks of daily life, while HRQL connotes a more subjective experience of the impact of health on the quality of one's life. Since COPD is a disease often affecting older, retired persons, the mechanics of task per-formance may be less important than the abil-ity to enjoy life. We have therefore chosen to use the term HRQL. In general HRQL measures the impact of an individual's health on his or her ability to perform and enjoy the activities of daily life. HRQL instruments vary from disease-specific measures of a single (usually crucial) symptom such as dyspnoea,3 to a generic global assess-ment of many facets which may include emo-tional functioning (mood changes and other psychiatric symptoms), social role functioning (employment, home management, and social or family relationships), activities of daily liv-ing (self-care skills and mobility), and the ability to enjoy activities (hobbies and