RAADS-R-BR Screen: Evidence of validity for an instrument to screen the autism spectrum in adults in Brazil

Purpose This study evaluated the validity and reliability of the Brazilian Screen Version of the Ritvo Autism and Asperger Diagnostic Scale-Revised (RAADS-R-BR), comparing the original instrument's response categories with a version adapted to the Brazilian context. Methods A total of 627 participants aged 16 to 66 took part, divided into autistic (N = 352) and non-autistic (N = 275) groups, with 72.28% self-identified as female. The adequacy of the factor structure was assessed via Confirmatory Factor Analysis (CFA), and sensitivity and specificity were examined through ROC Curve analysis. Results The bifactor Screen model with modified response categories demonstrated excellent fit [χ²(169) = 318.443, p < 0.001, χ²/df = 1.884, CFI = 0.956, TLI = 0.950, SRMR = 0.081, RMSEA = 0.058 (90% CI = 0.048–0.067)], with significant factor loadings (λ>|0.30|, p < 0.05) and high internal reliability (≥ 0.80). Conclusion The ROC Curve indicated 90.1% sensitivity and 87.9% specificity, showing that the RAADS-R-BR Screen version presents suitable psychometric parameters for the Brazilian context.