Measurement tools for behaviours that challenge and behavioural function in people with intellectual disability: A systematic review and meta-analysis of internal consistency, inter-rater reliability, and test-retest reliability.

Behaviours that challenge (BtC) are common in people with intellectual disability (ID) and associated with negative long-term outcomes. Reliable characterisation of BtC and behavioural function is integral to person-centred interventions. This systematic review and meta-analytic study quantitatively synthesised the evidence-base for the internal consistency, inter-rater reliability, and test-retest reliability of measures of BtC and behavioural function in people with ID (PROSPERO: CRD42021239042). Web of Science, Embase, PsycINFO and MEDLINE were searched from inception to March 2024. Retrieved records (n = 3691) were screened independently to identify studies assessing eligible measurement properties in people with ID. Data extracted from 83 studies, across 29 measures, were synthesised in a series of random-effects meta-analyses. Subgroup analyses assessed the influence of methodological quality and study-level characteristics on pooled estimates. COSMIN criteria were used to evaluate the measurement properties of each measure. Pooled estimates ranged across measures: internal consistency (0.41-0.97), inter-rater reliability (0.29-0.93) and test-retest reliability (0.52-0.98). The quantity and quality of evidence varied substantially across measures; evidence was frequently unavailable or limited to a single study. Based on current evidence, candidate measures with the most evidence for internal consistency and reliability are discussed; however, continued assessment of measurement properties in ID populations is a key priority.

Development and psychometric properties of the Clinical Anxiety Scale for People with Intellectual Disabilities (ClASP-ID).

BACKGROUND: There is a critical need for the development of dependable and valid anxiety assessment tools suitable for people with moderate to severe intellectual disabilities, particularly those who speak few or no words. Distinguishing anxiety from distress caused by physical discomfort (pain) or characteristics associated with autism, prevalent in this population, necessitates specialised assessment tools. This study (a) developed a parent-report anxiety questionnaire tailored for individuals with severe to moderate intellectual disabilities, potentially with a co-diagnosis of autism, and (b) evaluated the psychometric attributes of this novel measure. METHODS: A comprehensive approach involving literature reviews, inspection of existing tools, and interviews with clinicians and parents guided the creation of the Clinical Anxiety Scale for People with Intellectual Disabilities. The tool was completed by parents or caregivers (N = 311) reporting on individuals aged 4 or older with intellectual disabilities. RESULTS: Exploratory factor analysis indicated a four-factor structure encompassing anxiety, pain, low energy/withdrawal, and consolability. The anxiety factor explained the most variance in scores (26.3%). The anxiety, pain, low energy/withdrawal subscales demonstrated robust internal consistency (α = 0.81-0.92), and convergent, divergent, and discriminant validity. Robustness of these subscales was further evidenced by test-retest reliability (ICC = 0.79-0.88) and inter-rater reliability (ICC = 0.64-0.71). Subgroup analyses consistently demonstrated strong psychometric properties among individuals diagnosed with non-syndromic autism (N = 98), children (N = 135), adults (N = 175), and across diverse communication abilities within the sample. Moreover, individuals diagnosed with both autism and anxiety exhibited significantly higher scores on the anxiety subscale compared to those without an anxiety diagnosis, while showing no difference in autism characteristic scores. CONCLUSIONS: The findings indicate that the Clinical Anxiety Scale for People with Intellectual Disabilities is a promising measure for use across diverse diagnostic groups, varying communication abilities, and with people with moderate to severe intellectual disabilities.