[Health-related quality of life informative measure of outcome in clinical trials. Practical examples: asthma/chronic obstructive lung disease].

Methods for measuring health-related quality of life have been developed and proven valid during the past two decades. It was accomplished through international collaborations between clinicians and method experts. Standardized questionnaires, self-administered by patients, include key domains such as symptoms, functional limitations and well-being from a physical, mental and social perspective. The commonly used instruments are adapted and validated for Swedish conditions. Clinical trials can be powered also according to these outcome measures, as they show documented responsiveness to important changes in patients' everyday functioning and well-being. Patient-reported outcome of treatment efficacy is nowadays adequately standardized for scientific reviews according to the conventional criteria of evidence based medicine. Most importantly, health-related quality of life measures will provide new information of clinical value as demonstrated here in the example of asthma/chronic obstructive pulmonary disease. Thus, outcome can be better assessed by changes in the total burden of disease and its consequences than in terms of pulmonary function tests or biochemical markers.