Background/Purpose: The experience of living with a serious illness, such as systemic sclerosis (SSc), can pose challenges for an individual’s self-concept and social roles. This can necessitate new patterns of interacting with others, which may lead to social anxiety. Research on the social impacts of SSc is limited, and there are few validated measures in this area. The Social Interactions Anxiety Scale (SIAS-6) was developed to assess social interactional anxiety, or distress experienced when interacting with others. The instrument has demonstrated good measurement properties, but has not been tested in SSc. The present study has the following two aims: 1) to assess the reliability and validity of the SIAS-6 in a sample of SSc patients, and 2) to explore whether scores can be meaningfully compared across the limited and diffuse subtypes of the disease.  

Methods: Confirmatory factor analysis (CFA) was used to evaluate the structural validity of the one factor model of the SIAS-6 in sample of patients with SSc  (N = 596; 59.1% limited, 40.9% diffuse) enrolled in the Scleroderma Patient-centered Intervention Network (SPIN) Cohort. Multiple group confirmatory factor analysis (MGCFA) was used to evaluate the comparability of the factor structures of the SIAS-6 for patients with limited and diffuse disease subtypes. The MGCFA evaluated configural invariance (i.e., baseline model fitting a one-factor solution for both groups), metric invariance (i.e., factor loadings constrained to equivalence), and factor variance invariance (i.e., factor loadings and variances constrained to equivalence) models.  Internal consistency reliability was examined via Cronbach’s coefficient alpha. Convergent validity was examined via Pearson product-moment correlations with measures of depression, body image dissatisfaction/avoidance, fear of negative evaluation, and social anxiety.

Results: Per descriptive fit indices using CFA, a one-factor model was found to fit the data (Comparative Fit Index [CFI] = 0.99, Standardized Root Mean Residual [SRMR] = 0.02, Root Mean Square Error of Approximation [RMSEA] = 0.06). The MGCFA demonstrated that the metric invariance model best fit the data (i.e., equivalent factor loadings but different variances across disease groups) based on the descriptive indices of CFI, SRMR, and RMSEA; change in CFI; and the Satorra-Bentler X² difference test. Internal consistency reliability was good for limited (α  = 0.86) and diffuse (α  = 0.92) groups. Convergent validity testing demonstrated significant, moderate to strong correlations in the expected directions with measures of depression (r = 0.48, p < .01), body image dissatisfaction, avoidance, and concerns (r = 0.51, r = 0.42, r = 0.54, respectively, all ps < .01), fear of negative evaluation (r = 0.57, p < .01), and social anxiety (r = 0.58, p < .01) in the total sample. 

Conclusion: The present study demonstrates that the SIAS-6 can be confidently used as a one-factor measure of social interaction anxiety in patients with both limited and diffuse subtypes of SSc.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/a-psychometric-analysis-of-the-social-interaction-anxiety-scale-sias-6-in-systemic-sclerosis-results-from-the-scleroderma-patient-centered-intervention-network-spin-cohort/