Development and Initial Evaluation of the Anxiety Scale for Autism-Adults.

BACKGROUND

Anxiety is highly prevalent in autistic adults and can cause a significant impact on functioning and quality of life. There are no existing measures of anxiety designed and validated specifically for autistic adults. In this study, we aimed to adapt an existing anxiety measure designed for autistic children, in collaboration with autistic adults and other professionals, to make it suitable for use for autistic adults and to examine the measurement properties of the newly designed measure.

METHODS

Through consultation with autistic adults and professionals working with autistic people, we developed a preliminary self-report anxiety measure. Five hundred fifty-one autistic adults completed the measure and another measure of anxiety and depression (the Hospital Anxiety and Depression Scale). Participants completed measures again after 1 month to determine test/retest reliability. We split the sample to enable exploratory and confirmatory factor analyses to be undertaken on different samples. We conducted internal consistency and convergent and divergent validity analyses. We completed receiver operator curve (ROC) analyses to investigate sensitivity and specificity and identify an indicative clinical cutoff.

RESULTS

Our findings indicate that the Anxiety Scale for Autism-Adults (ASA-A) has promising psychometric properties. Factor analysis indicated that a bifactor solution with orthogonal general and specific factors was an adequate fit and that minimal measurement bias would occur if the scale were treated as unidimensional, so the total score could be used as a valid measure of anxiety. We identified a General Anxiety factor and three group factors (Social Anxiety, Uncertainty, and Anxious Arousal). ROC analysis indicated a score of 28 could be considered an indicative clinical cutoff.

CONCLUSION

The ASA-A is the first self-report anxiety questionnaire specifically developed and validated for autistic adults. Preliminary evaluation of the measurement properties indicates that the scale will be a useful tool in research and clinical contexts.

LAY SUMMARY

Autistic adults commonly experience anxiety, which can have a huge impact on their quality of life. One way of identifying anxiety is by using questionnaires. Research shows that anxiety may be experienced differently by autistic people, and so, questionnaires that have been created for neurotypical adults may not be suitable for autistic adults. At present, there are no anxiety measures that have been adapted specifically for autistic adults. Our team previously created an anxiety questionnaire for autistic children-the Anxiety Scale for Children-Autism Spectrum Disorder (ASC-ASD). We aimed to adapt this questionnaire to make it suitable for autistic adults. We met with autistic people and professionals, and asked them how to change the ASC-ASD to make it suitable for measuring anxiety in autistic adults. We discussed whether the questions were appropriate for adults, if the questions were worded clearly, and if anything was missing. We then created the Anxiety Scale for Autism-Adults (ASA-A). Once the questionnaire was created, 551 autistic adults with anxiety completed it. We used this information to test whether the questionnaire was a good way of measuring anxiety. We also tested the questionnaire subscales, which were as follows: Anxious Arousal, Social Anxiety, and Uncertainty. We found that the questionnaire is useful in giving a total score for anxiety, and we found that a score of 28 indicated anxiety that was likely to have an impact on someone's daily life. Each subscale was also found to be useful for providing a "profile" of anxiety. These findings suggest that the ASA-A is a good way of measuring anxiety in autistic adults. This is the first anxiety measure to be developed for autistic adults. This study is the first step toward testing out the usefulness of the measure. We hope that our questionnaire can be further tested and that in the future it will help to identify anxiety experienced by autistic adults more accurately. This would mean that the results of future studies are more likely to be valid, which should help improve what we know about the anxiety autistic people experience. We used another anxiety measure to measure anxiety levels when testing what the cutoff score should be on our measure. A clinical interview may have been a more accurate way, and should be done in the future to check that the cutoff of 28 on the ASA-A is still appropriate for identifying anxiety in autistic adults.We recruited autistic adults from a database of people who are interested in taking part in research. This helped us to get enough people to test the questionnaire, but we cannot tell how well these results apply to all autistic people. Testing the questionnaire with other autistic people, including those who may need some assistance with reading or who may need someone else to complete it on their behalf will let us know. The final questionnaire, the ASA-A, has been shown to accurately measure anxiety in autistic adults who do not have an intellectual disability. The questionnaire will be helpful in both clinical and research services.