Development and initial psychometric properties of the Warwick-Edinburgh Mental Wellbeing Scale-Intellectual Disability version.

ABSTRACT

BACKGROUND: The Warwick-Edinburgh Mental Wellbeing Scale (WEMWBS; Tennant et al., 2007) is yet to be validated in the intellectual disability (ID) population. The aim of this study was to report the development process and assess the psychometric properties of a newly adapted version of the WEMWBS and the Short WEMWBS for individuals with mild to moderate IDs (WEMWBS-ID/SWEMWBS-ID). METHOD: The WEMWBS item wordings and response options were revised by clinicians and researchers expert in the field of ID, and a visual aid was added to the scale. The adapted version was reviewed by 10 individuals with IDs. The measure was administered by researchers online using screenshare, to individuals aged 16+ years with mild to moderate IDs. Data from three UK samples were collated to evaluate the WEMWBS-ID (n = 96). A subsample (n = 22) completed the measure again 1 to 2 weeks later to assess test-retest reliability, and 95 participants additionally completed an adapted version of the adapted Rosenberg Self-Esteem Scale to examine convergent validity. Additional data from a Canadian sample (n = 27) were used to evaluate the SWEMWBS-ID (n = 123). RESULTS: The WEMWBS-ID demonstrated good internal consistency (ω = 0.77-0.87), excellent test-retest reliability [intraclass correlation coefficient (ICC) = .88] and good convergent validity with the self-esteem scale (r = .48-.60) across samples. A confirmatory factor analysis for a single factor model demonstrated an adequate fit. The SWEMWBS-ID showed poor to good internal consistency (ω = 0.36-0.74), moderate test-retest reliability (ICC = .67) and good convergent validity (r = .48-.60) across samples, and a confirmatory factor analysis indicated good model fit for a single factor structure. CONCLUSIONS: The WEMWBS-ID and short version demonstrated promising psychometric properties, when administered virtually by a researcher. Further exploration of the scales with larger, representative samples is warranted.