Suitability of the <i>DSM</i> -5 social anxiety disorder severity scale for autistic adults

In autistic adults, measurement tools may not adequately differentiate between autistic characteristics and features of anxiety. This may be particularly evident in the case of social anxiety disorder; however, few measures of social anxiety disorder have been validated for autistic adults. Instead, assessments are often made using measures designed and validated for non-autistic adults. To address this, we examined the suitability of the self-report Severity Measure for Social Anxiety Disorder in 284 autistic adults. We evaluated its psychometric properties, explored a rescored version that aimed to account for autistic differences in reporting and conducted content analysis on qualitative feedback from autistic participants. Confirmatory Factor Analysis did not confirm the unidimensional structure of the Severity Measure for Social Anxiety Disorder for autistic adults and over half attributed at least one response to a factor other than social anxiety (e.g. fatigue). Exploratory Factor Analysis of a rescored version of the Severity Measure for Social Anxiety Disorder based on autistic adults' responses to reflect those just due to social anxiety, revealed that a two-factor solution was most appropriate, again suggesting social anxiety was not a solitary latent variable. Our findings recommend caution be applied when using the Severity Measure for Social Anxiety Disorder with autistic adults and our content analysis may inform more precise future measurement.Lay abstractMental health measures used with autistic adults are often only evaluated for use with non-autistic adults, which may cause inaccurate measurement. This is important when measuring social anxiety disorder as some features overlap with social characteristics of autism. This study evaluated one self-report questionnaire measure of social anxiety disorder, the Severity Measure for Social Anxiety Disorder. The Severity Measure for Social Anxiety Disorder is based upon criteria for diagnosis of social anxiety disorder, and we aimed to understand its suitability for autistic adults. The Severity Measure for Social Anxiety Disorder was completed by 284 autistic adults and 80 non-autistic adults who were then asked five follow-up questions about ambiguous questions on the Severity Measure for Social Anxiety Disorder. We found that over half our sample of autistic adults, on at least one question, attributed their answer to something other than anxiety. Furthermore, in autistic adults, one underlying construct of social anxiety did not link their answers on the Severity Measure for Social Anxiety Disorder together, suggesting the Severity Measure for Social Anxiety Disorder might not be suited to capturing social anxiety disorder in autistic adults. To improve measurement, we rescored answers where participants said their response was due to something other than social anxiety, however, the rescored Severity Measure for Social Anxiety Disorder did not only capture social anxiety in autistic adults either. Finally, we analysed the reasons other than social anxiety autistic adults said influenced their answers. We grouped their responses into 10 categories, for example, 'fatigue', 'sensory overwhelm', and 'masking'. Overall, our findings suggest caution when using the Severity Measure for Social Anxiety Disorder with autistic adults, and the categories identified may suggest how to measure social anxiety more accurately in autistic adults.