Exploring the psychometric properties of the Intellectual Disability versions of the Short Warwick-Edinburgh Mental Wellbeing Scale and Kidscreen10, self-reported by adolescents with intellectual disability.

Background: There are no validated self-report measures that can be used to assess health and wellbeing in adolescents with intellectual disability (ID).

Method: The aim of this study was to explore the psychometric properties of two newly adapted self-report health-related quality of life (HRQoL) and mental wellbeing measures: the Intellectual Disability versions of the Short Warwick-Edinburgh Mental Wellbeing Scale (ID-SWEMWBS) and Kidscreen10 (ID-Kidscreen10). For this, we used data from a sample of 427 adolescents (aged 11-19) with ID recruited from special school settings.

Results: Confirmatory factor analysis (CFA) was conducted to validate the factor structure of both measures. Internal consistency was assessed using Cronbach's alpha and test-retest reliability was analysed using intra-class correlation coefficients. The internal consistency measured using Cronbach's alpha was found to be in the range of 0.70-0.78, test-retest reliabilities were expressed using intra-class correlation coefficients that were found to be high for both measures (ID-SWEMWBS, 0.758; ID-Kidscreen10, 0.723), and the CFA supported the unidimensional structure of both measures.

Conclusions: The results of this study indicate that the ID-SWEMWBS and ID-Kidscreen10 have very good psychometric properties and can be used as self-report measures to assess HRQoL and mental wellbeing in adolescents with ID.