Development of the Anxiety Scale for Children – ASD (ASC-ASD)

Background: Many children with ASD experience high levels of anxiety. There is a lack of suitable anxiety measures for people with ASD. Most measures have not been developed for this population. It is now generally accepted that existing anxiety measures may require adaptation to more accurately capture the varied manifestations of anxiety often associated with ASD, including anxiety related to sensory hypersensitivity, intolerance of uncertainty and ASD-specific phobias. A widely used, well validated measure of anxiety for typically developing children is the Revised Child Anxiety and Depression Scale (RCADS).

Objectives:   (i) to modify the RCADS to include items related to uncertainty, sensory anxiety and phobias; (ii) to investigate the factor structure, reliability and validity of the adapted measure with a representative sample of children and parents.

Methods: Participants were 177 children with ASD and no intellectual disability, aged 8-16 years (mean 11.1, SD=2.1) years, and their parents, recruited from a representative national research database (ASD-UK).The RCADS is a 47-item measure of anxiety and depression with six subscales: panic, separation anxiety, Obsessive Compulsive Disorder (OCD), generalised anxiety disorder (GAD), social phobia and depression. An adapted version of the RCADS was created with the addition of items relating to sensory anxiety, intolerance of uncertainty and phobias. Content validity was refined during focus groups with parents. Children completed the child version of the adapted measure and the Screen for Anxiety and Related Emotional Disorders (SCARED). Parents completed parental-report versions of the adapted measure, the SCARED and the Repetitive Behaviour Questionnaire (RBQ), Short Sensory Profile (SSP), the Strengths and Difficulties Questionnaire (SDQ), and the Child Depression Inventory (CDI-2). Parents and children completed the new measure again one month after initial administration.

Results:  The original RCADS anxiety items were analysed to determine whether the original factor structure was replicated. OCD items did not load on a distinct factor and were excluded from further analyses. The remaining 41 RCADS anxiety items were combined with the new items and further factor analyses undertaken. Items with factor loadings <.5 were excluded. Twenty four items loaded on four factors in both child- and parent- report versions: Performance Anxiety, Anxious Arousal, Separation Anxiety, and Uncertainty, forming the new measure the Anxiety Scale for Children- ASD (ASC-ASD). Internal consistency of the ASC-ASD subscales and total scores was excellent (Cronbach’s alphas ranging from .85 to .94). One month test-retest reliability was excellent for both versions (r = .84 and r =.82). Convergent validity was demonstrated with significant correlations between the ASC-ASD and SCARED, SSP, RBQ and the emotion subscale of the SDQ.  Correlations with the CDI were significant, but weaker, demonstrating divergent validity. 

Conclusions: Results provide evidence for the need to adapt anxiety measures for young people with ASD and support emerging evidence for the importance of uncertainty in the presentation of anxiety in ASD. The ASC-ASD is one of the first reliable and valid ASD specific anxiety measures which captures aspects of anxiety relevant to ASD that are absent in other measures; replication and extension is required in novel samples.