Development of an Item Pool for a Needs-Based Measure of Quality of Life of Carers of a Family Member with Dementia

Abstract

Background and Objectives: This paper describes the development of an item pool for a needs-based self-report outcome measure of the impact of caring for a relative, friend or neighbour with dementia on carer quality of life. The aims are to give a detailed account of the steps involved and describe the resulting item pool. Methods: Seven steps were followed: generation of an initial item set drawing on 42 needs-led interviews with carers; a content and face validity check; assessment of psychometric potential; testing of response formats; pre-testing through cognitive interviews with 22 carers; administration rehearsal with two carers; and final review. Results: An initial set of 99 items was refined to a pool of 70 to be answered using a binary response format. Items were excluded due to overlap with others, ceiling effects, ambiguity, dependency on function of the person with dementia or two-part phrasing. Items retained covered a breadth of areas of impact of caring and were understandable and acceptable to respondents. Conclusions: The resulting dementia carer-specific item pool reflects the accounts of a diverse sample of those who provide care for a person with dementia, allowing them to define the nature of the impact on their lives and resulting in a valid, acceptable set of items.