Developing a quality-of-life questionnaire for patients with respiratory illness.

In this short report, the construction of a disease-specific quality-of-life questionnaire for patients with asthma and chronic obstructive pulmonary disease (COPD) is described. Some psychometric aspects are also discussed. We listed 221 items relating to several domains of quality-of-life, and asked 204 patients to indicate, on a seven-point Likert-scale, how much of a problem each item had been during the last year. After item selection, a quality-of-life scale was constructed, consisting of 55 items divided into 7 subscales. The reliability estimates vary from 0.68 to 0.89, and can be considered as quite satisfactory. Results concerning construct validity are promising; there is a strong relationship between the Quality-of-life subscales and several indicators of illness severity. Further research is called for to validate the questionnaire.