Instruments assessing anxiety in adults with intellectual disabilities: A systematic review

BackgroundIn the last decades several instruments measuring anxiety in adults with intellectual disabilities have been developed.AimTo give an overview of the characteristics and psychometric properties of self-report and informant-report instruments measuring anxiety in this group.MethodSystematic review of the literature.ResultsSeventeen studies studying 14 different instruments were found. Methodological quality as measured with the Quality Assessment of Diagnostic Accuracy Studies checklist was insufficient for four studies, sufficient for seven, and good for six. For self-report, the Glasgow Anxiety Scale for people with a learning disability appears most promising, with good internal consistency (a = 0.96), high test–retest reliability (r = 0.95), sensitivity (100%) and specificity (100%). For informant-report, the general anxiety subscale of the Anxiety, Depression and Mood Scale may be promising, with good internal consistency (a = 0.83 and a = 0.84) and excellent test–retest reliability (ICC = 0.78 and ICC = 0.92), but poor interrater reliability (ICC = 0.39).ConclusionsTwo instruments appear promising. However, these instruments have only been studied once or twice, whereas the methodological quality of these studies was varying.

Research highlights
► The Glasgow Anxiety Scale is the most promising self-report instrument.
► For informant-report, the Anxiety, Depression and Mood Scale appears most promising.
► Over the years, the methodological quality of studies improved.
► For most measures of anxiety, reliability and validity are insufficiently studied.
► Reliability and validity of existing measures of anxiety should be further studied.