Response shift in the measurement of quality of life in hearing impaired adults after hearing aid fitting.

Abstract

REASON FOR THE STUDY: Response shift is the change in the meaning of one's self-evaluation of a target construct, like quality of life (QOL). The objective of this study was to investigate whether response shift in the measurement of generic and specific QOL occurred in persons with a relatively mild health condition. For this purpose hearing impairment was used as a research model. Response shift effects were observed in the scores on the dimensions of hearing related QOL. In the scores on overall hearing related QOL, and in the scores on the generic control items, no response shift occurred. This study showed that response shift effects can take place in a relatively mild condition as well. The occurrence of response shift in QOL ratings over time could have large implications for the estimation of the effectiveness of medical interventions and for the use of these estimations in cost-effectiveness analyses. After a successful treatment the conventional change could be an underestimation of the effectiveness of the treatment, although it has also been argued that psychological adaptation is a welcome capacity of human beings, and that then-test changes do no justice to this capacity.