Quality of life in patients with chronic obstructive pulmonary disease

Many factors influence quality-of-life impairment in chronic obstructive pulmonary disease (COPD). Reliable measurement of the impact of the disease requires standardised questionnaires, which can apply to every patient. This process is more accurately termed health status measurement. General health questionnaires may be valid in COPD, but are less sensitive to treatment than disease-specific measures. At the level of individual patients, the correlation between health status and forced expiratory volume in one second (FEV1) is weak, both between and within patients. This may be due to the weak correlation between FEV1 and exercise capacity, since the correlation between exercise and health status is consistently quite strong. Health status measures provide an overall measure of the effect of COPD on the patient; therefore, they are particularly suitable for assessing the effect of complex treatments, such as rehabilitation or pharmacological therapies that have multiple mechanisms of action. Health status measurement has demonstrated the size and duration of effect of a single COPD exacerbation and has shown that repeated exacerbations have a cumulative effect, which increases the rate of decline in health. Health status questionnaires are generally too complex to use in routine practice; however, the Medical Research Council Dyspnoea Scale provides a simple and reliable measure for assessing health impairment