Wellbeing can be understood as how people feel and function, both on a personal and social level, and how they evaluate their lives as a whole (New Economic Foundation, 2012). The concept of wellbeing has been defined and operationalised in many ways and tends to encompass both objective (e.g., income, education, and health) and subjective (e.g., happiness, perception of quality of life and life satisfaction) aspects of a person's life (Statham & Chase 2010). According to the World Health Organisation (WHO, 2021), health is a state of complete physical, mental, and social wellbeing, not merely the absence of disease or infirmity. The WHO definition links health explicitly with wellbeing and conceptualises health as a human right requiring physical and social resources to achieve and maintain. In recent years, the concept of children’s wellbeing has become firmly embedded in discourse and policy in the academic, government and public sectors in countries across the world (e.g., Statham & Chase 2010). Since the publication of UNICEF’s Report Card 7 (2007) entitled ‘Child poverty in perspective: An overview of child wellbeing in rich countries’ children’s wellbeing has been put firmly on the agenda in many countries around the world (UNICEF, 2007).
Wellbeing is a particularly important concept for children and young people with intellectual disabilities (ID). An ID is a disability characterised by significant limitations in both intellectual functioning and in adaptive behaviour, as expressed in conceptual, social, and practical adaptive skills (AAIDD, 2010). It is a generalised disorder, which encompasses a wide array of cognitive and behavioural deficiencies; and affects the individuals in all areas of life (AAIDD, 2010). The severity of ID is classified into four types, based on an intelligence quotient (IQ) test, namely mild, moderate, severe, and profound ID (AAIDD 2010). Children and adolescents with an ID are more likely to experience diminished wellness as they age, as well as having an increasing number of chronic conditions and lower socioeconomic status than their non-disabled peers (Menear et al., 2015).
Whilst there is a wide range of research examining adolescent’s health and wellbeing, few of these studies include children and young people with ID (Boström & Broberg, 2018; Davidson et al., 2017). Current large-scale global studies of wellbeing such as the WHO Health Behaviour of School-aged Children (HBSC) and Children’s Worlds do not include children who experience ID. This is of particular concern given that individuals with ID tend to experience poorer health, as well as score lower on a number of health and wellbeing indicators in comparison to their typically developed peers (Emerson, 2011). Many health and wellbeing measures are usually administered by survey and are not accessible to youth with ID. This population may have difficulty understanding the format and complexity of questions and response scales used in questionnaires designed for same-age peers (Boström et al., 2016; Davidson et al., 2017), as intellectual impairment is often associated with difficulties in communication (Shevell, 2008), working memory (Lifshitz et al., 2011) and self-insight (Jahoda et al., 2010), all of which are required to respond effectively to questionnaires. In 2011, Scott and colleagues carried out a pilot study including children (aged 11–17 years) with ID/Special Educational Needs in the WHO HBSC Questionnaire. Using the standard protocol, just over half of the children were able to ‘complete’ the survey questionnaire, however a high proportion of their responses proved to be uncodable (Scott et al., 2011).
Children and young people with ID have traditionally been assessed via proxy reports completed by parents, teachers, or carers as it is assumed that these young persons do not have the capacity to self-report on these domains (Shevell, 2008). Thus, a notable limitation is that a third party is reporting on the wellbeing of the person with an ID (Hayes et al., 2013). More broadly, since measuring health and wellbeing involves a subjective perspective, the use of proxy-reports to determine health and wellbeing has been questioned, and it has been concluded that self-reports cannot simply be replaced by proxy-reports (Verdugo et al., 2005). It is now appreciated that the young person’s view should, where possible, be sought directly rather than being inferred from proxy-reports. However, proxy-reports should not necessarily be discarded, but rather employed as an additional source of information to an individual’s health and wellbeing (Clark et al., 2015; Egilson et al., 2017; Knüppel et al., 2018), as proxy-reports can be useful when used in addition to child self-reports to assess multiple perspectives (Davidson et al., 2017).
Authors repeatedly note the under-representation of young people with ID in health and wellbeing surveys (Hicks et al., 2011; Selwn & Riley, 2015). A report from the Children’s Worlds survey highlights the exclusion of marginalised children, including those in special educational needs settings, and suggests that there is a real need for ways to be found to “include these children in research on children’s lives and wellbeing” (Rees and Main 2015:16). Research has demonstrated that many children with ID do have the capacity to respond to self-report questionnaires (Douma et al., 2006; Emerson et al., 2005) and that adaptations such as pictorial representations and limited forced choice options can strengthen their validity (Hartley and MacLean, 2006). Thus, there has been an emphasis on finding alternative and more accessible ways to enable this population to complete questionnaires independently, reliably, and confidentially (Boström & Eriksson, 2015; Boström at el., 2016). Increasing attention has been paid to the involvement of children and young people with ID in the design of wellbeing measures and capturing their views on what wellbeing means to them and what is important to their quality of life (Hicks et al., 2011). For example, Boström and colleagues (2016) developed the Wellbeing in Special Education Questionnaire (WellSEQ) in cooperation with 113 students (aged 12–16) and teachers in special educational needs settings for children with cognitive disabilities (Boström et al., 2016). Both students and teachers participated in the process of cooperative inquiry (Frauenberger et al., 2011) designing and developing the research instruments in three workshops using different methods (brainstorming, sketching, paper-prototyping, focus group, direct observations, and existing system analysis) (Boström & Eriksson, 2015; Boström et al., 2016). The WellSEQ is specifically tailored to measure self-rated mental and ill health, peer relations and school and family environment in adolescents with mild or moderate intellectual and developmental disability and is administered via an interactive touch-based application for tablet PCs (Boström et al., 2016). The standard method for collecting reliable self-reports from persons with ID has consisted of structured interviews (e.g., Emerson, 2005; Haynes et al., 2013), but because this is a highly time-consuming procedure, there has been a shift of focus to design questionnaires specifically for this population. As a result, in the past decade, and in line with the trend of stimulating participatory research in people with IDs, there seems to be an increase in studies using self-reports to assess the health and wellbeing of adolescents with ID.
Researchers have starting to address the dearth of instruments suitable for measuring health and wellbeing with adolescents in the ID population. Whilst there are studies (e.g., Carlon et al., 2010; Jardine et al., 2014; Morris et al., 2014; Solans et al., 2008) that have systematically reviewed the psychometric properties of QoL measures for children and young people with ID, these narrowly focus on disease or health conditions (Davidson et al., 2017). Therefore, an up-to-date systematic review is warranted to summarize and appraise the psychometric properties of health and wellbeing measures focused on adolescents with ID as they are useful in selecting a measure that is fit for purpose (Mason at al., 2018; Scholtes et al., 2011). This review will provide evidence-based knowledge regarding what measures are being used in health and wellbeing research amongst this population, and more importantly how reliable and valid these measures are. The most suitable health and wellbeing measures for use amongst adolescents with ID will be identified, and recommendations will be gathered to determine their reliability (i.e., to identify what works). This is urgently needed as clinicians, researchers and service providers require 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 (Kipfer and Pihet, 2019). It is expected that this systematic review will assist in informing choice when selecting an instrument for the measurement of health and wellbeing with this population. It will contribute to the knowledge surrounding available and appropriate measures to use for measuring the health and wellbeing of adolescents with ID, which are necessary to inform intervention development and future health policy.
The aim of this systematic review is to collate, summarise and critically appraise the psychometric properties of health and wellbeing measures used with children and young people (aged 11–16) with ID. The proposed systematic review will answer the following questions:
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What measures are being/have been used to assess health and wellbeing of adolescents with ID?
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What is the methodological quality of these health and wellbeing measures for use with adolescents with ID?
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What measures work best for assessing health and wellbeing of adolescents with ID?