The use of qualitative methods in developing the descriptive systems of preference based measures of health related quality of life for use in economic evaluation

The objective of this paper is to describe how qualitative methods can be used in the development of descriptive systems of preference based measures (PBM) of health related quality of life.

The requirements of NICE and other agencies together with increasing use of patient reported outcome measures has lead to an increase in the demand for PBM. Recently, interest has grown in developing new PBM and whilst previous research on PBM has mainly focused on the methods of valuation, research into the methods of developing descriptive systems is an emerging field.

Traditionally, descriptive systems of PBMs were developed using top down methods, where content was derived from existing measures, the literature, or health surveys. A contrasting approach is a bottom up methodology, which takes the views of patients or lay people on how their life is affected by their health. This approach generally requires the use of qualitative methods. Qualitative methods lend themselves well to the development of PBMs. They also ensure the measure has appropriate language, content validity and responsiveness to change. Whilst the use of qualitative methods in the development of non PBMs is fairly standard, their use in developing PBMs was until recently nonexistent.

In this paper, we illustrate the use of qualitative methods by presenting two case studies of recently developed PBMs; one generic and one condition specific. We outline the stages involved, discuss the strengths and weaknesses of the approach and compare with the top down approach used in the majority of PBMs to date.