Measurement equivalence of the Social Interaction Anxiety Scale (SIAS) and Social Phobia Scale (SPS) across individuals with social anxiety disorder from Japanese and Australian sociocultural contexts

Background
Cultural factors influence both the expression of social anxiety and the interpretation and functioning of social anxiety measures. This study aimed to test the measurement equivalence of two commonly used social anxiety measures across two sociocultural contexts using individuals with social anxiety disorder (SAD) from Australia and Japan.

Methods
Scores on the straightforwardly-worded Social Interaction Anxiety Scale (S-SIAS) and the Social Phobia Scale (SPS) from two archival datasets of individual with SAD, one from Australia (n = 201) and one from Japan (n = 295), were analysed for measurement equivalence using a multigroup confirmatory factor analysis (CFA) framework.

Results
The best-fitting factor models for the S-SIAS and SPS were not found to be measurement equivalent across the Australian and Japanese samples. Instead, only a subset of items was invariant. When this subset of invariant items was used to compare social anxiety symptoms across the Australian and Japanese samples, Japanese participants reported lower levels of fear of attracting attention, and similar levels of fear of overt evaluation, and social interaction anxiety, relative to Australian participants.

Limitations
We only analysed the measurement equivalence of two social anxiety measures using a specific operationalisation of culture. Future studies will need to examine the measurement equivalence of other measures of social anxiety across other operationalisations of culture.

Conclusions
When comparing social anxiety symptoms across Australian and Japanese cultures, only scores from measurement equivalent items of social anxiety measures should be used. Our study highlights the importance of culturally-informed assessment in SAD.