Development of a measure of asthma-specific quality of life among adults.

PURPOSE

A key goal in asthma treatment is improvement in quality of life (QoL), but existing measures often confound QoL with symptoms and functional impairment. The current study addresses these limitations and the need for valid patient-reported outcome measures by using state-of-the-art methods to develop an item bank assessing QoL in adults with asthma. This article describes the process for developing an initial item pool for field testing.

METHODS

Five focus group interviews were conducted with a total of 50 asthmatic adults. We used "pile sorting/binning" and "winnowing" methods to identify key QoL dimensions and develop a pool of items based on statements made in the focus group interviews. We then conducted a literature review and consulted with an expert panel to ensure that no key concepts were omitted. Finally, we conducted individual cognitive interviews to ensure that items were well understood and inform final item refinement.

RESULTS

Six hundred and sixty-one QoL statements were identified from focus group interview transcripts and subsequently used to generate a pool of 112 items in 16 different content areas.

CONCLUSIONS

Items covering a broad range of content were developed that can serve as a valid gauge of individuals' perceptions of the effects of asthma and its treatment on their lives. These items do not directly measure symptoms or functional impairment, yet they include a broader range of content than most existent measures of asthma-specific QoL.