When and how to assess quality of life in chronic lung disease

Since the early 1980s there has been increasing awareness of the importance of quantifying health-related quality of life (HRQL) in patients with chronic respiratory disorders included in clinical trials. HRQL scores are clearly complementary to functional assessments, and have been shown to be better predictors of use of health resources (hospital readmissions, GP consultations exacerbations) than pulmonary function tests alone. Two types of HRQL score are available: "generic scores" cover a wide array of items and allow comparison of patients suffering from various medical conditions; they may however lack responsiveness and therefore underestimate changes in HRQL induced by a pharmacological or non-pharmacological management; "disease-specific scores" are more responsive and sensitive to changes, and thus more suitable for assessing the impact of management on HRQL. The choice of a HRQL instrument must take into account its validity, reliability, and responsiveness in the population studied; it must also be adapted to the severity of respiratory impairment, to ensure optimal discriminant potency. In clinical trials, the use of a "generic" score combined with a "disease-specific" score is recommended for optimum assessment. This is however too time-consuming for clinical practice: the use of short-time HRQL tools quantifying specific items such as resting and exertional dyspnoea, activities of daily life and emotional status appears more appropriate in this setting; furthermore, these items correlate better with HRQL scores than pulmonary function tests.