Protocol for a systematic review exploring the psychometric properties of self-report health-related quality of life and subjective wellbeing measures used by adolescents with intellectual disabilities.

BACKGROUND: Whilst there are studies that have systematically reviewed the psychometric properties of quality of life measures for children and young people with intellectual disabilities, these narrowly focus on disease or health conditions. The objective of this planned systematic review is therefore to collate, summarise, and critically appraise the psychometric properties of self-report health-related quality of life (HRQoL) and subjective wellbeing measures used by adolescents (aged 11-16) with an intellectual disability. METHODS: We designed and registered a study protocol for a systematic review of studies which explores the psychometric properties of self-report HRQoL and subjective wellbeing measures used by adolescents with intellectual disabilities. Electronic databases including PsycINFO, CINAHL, MEDLINE, and ERIC will be searched using predefined search terms to identify relevant studies. Quantitative and mixed-methods studies, and studies published in peer-reviewed journals or grey literature, will be included. Review papers, editorials, and case studies will be excluded. Eligible studies should identify self-report measures which assess HRQoL and subjective wellbeing among adolescents with intellectual disabilities. The methodological quality of the included studies will be assessed by applying the COSMIN Risk of Bias checklist. The quality of the evidence (i.e. the total body of evidence used for the overall ratings on each psychometric property of an instrument) will be evaluated in accordance with the modified GRADE guidelines. DISCUSSION: This systematic review will be among the first to systematically explore the psychometric properties of self-report HRQoL and subjective wellbeing measures used by adolescents with intellectual disabilities. By providing evidence-based knowledge about measures being used in HRQoL and subjective wellbeing research amongst this population, and more importantly how reliable and valid these measures are, the most suitable for use will be identified. Our findings will be of potential interest to clinicians, researchers, and service providers who need information about the methodological quality and the characteristics of measures to make informed decisions about the most reliable and valid tool for a specific purpose. The findings from this study will contribute to the knowledge surrounding available and appropriate measures to use for measuring HRQoL and subjective wellbeing of adolescents with intellectual disabilities, which are necessary to inform intervention development and future health policy. SYSTEMATIC REVIEW REGISTRATION: The protocol has been registered at the International Prospective Register of Systematic Reviews (PROSPERO). The registration number is CRD42021231697