An important outcome of any clinical intervention is the change in the subject's own perceived state of health. This can be categorized as health-related quality of life (HRQL), utility (preference-based health state), and daily life performance. 174 Swedish subjects with chronic obstructive pulmonary disease (COPD) (mean age 64.3 ± 12 years) completed five self-administered questionnaires: Short Form 36 (SF-36), St George's Respiratory Questionnaire (SGRQ), EuroQol-5D (EQ-5D), Health States-COPD (HS-COPD), and Work Productivity and Activity Impairment Questionnaire for COPD (WPAI-COPD). The subjects scored these outcomes instruments for ease of completion using a 5-point scale. The time taken to complete them was noted and the administrators' opinion of the subjects' comprehension of the questionnaires recorded using a 4-point scale.