Confirmatory factor analysis of an identity questionnaire Among autistic adolescents and young adults

Challenges during the transition to adulthood affect how adolescents and young adults (AYA) with autism integrate their autism diagnoses into their self-concept. A positive autism identity is crucial for their psychological and social well-being. This study examined the suitability of the Illness Identity Questionnaire (IIQ) for assessing autism identity by assessing its construct validity and internal consistency among 102 autistic AYA (12-25 years). Participants completed the IIQ, which measures four illness identity dimensions: rejection, engulfment, acceptance, and enrichment. We conducted confirmatory factor analysis (CFA) to evaluate the IIQ's factor structure and McDonald's omega coefficients for internal consistency. The CFA demonstrated a good fit between the theoretical model and data, χ²(242) = 257.12, p = .241, comparative-fit index [CFI] = .98, goodness-of-fit index [GFI] = .84, root-mean-square error of approximation [RMSEA] = .02, standardized root-mean-square residual [SRMR] = .09. Internal consistency was high across all dimensions (ω = .85-.90). Acceptance was significantly higher than rejection, engulfment, and enrichment, indicating more adaptive identity integration. The findings support the IIQ as a robust tool for assessing autism identity in AYA. The higher acceptance scores align with previous findings indicating more positive than negative feelings towards autism identity. However, the presence of rejection and engulfment underscores the need to promote more positive perceptions of autism identity. The IIQ offers valuable insights into how autistic AYA integrate their diagnoses into their self-concept. A positive autism identity is essential for improving psychological and social outcomes, making the IIQ valuable for researchers and clinicians.