Supplementary file 1_A prevalence study of Autism Spectrum Disorder in Russia.docx

IntroductionAutism Spectrum Disorder (ASD) is a neurodevelopmental condition marked by heterogeneity in presentation. In recent decades, ASD prevalence has risen globally, yet data from non-Western and middle-income countries, including Russia, remain scarce. Thus, Russian official statistics report a prevalence of 0.41 per 1,000 (0.041%), far below global estimates of 32.2 per 1,000 (3.2%), indicating underdiagnosis. This study provides the first population-based estimate of ASD prevalence among Russian elementary school children and examines barriers to diagnosis and treatment.
MethodsThe study followed a two-phase epidemiological approach and utilized well-known instruments (SCQ, ADOS-2, ADI-R) for ASD identification. The target population included all students in grades 1–3 (n = 34,847), stratified into mainstream, special education, and resource classes. The diagnostic phase had a 25.6% participation rate. ASD prevalence was estimated using Bayesian regression correcting for screening misclassification.
ResultsThe estimated ASD prevalence was 22.2 per 1,000 children (95% CIs: 18.6–36.0), substantially exceeding what is reported based on the RF administrative data. ASD was more frequently identified in students from special education and resource classes than in general education settings. A Bayesian sensitivity analysis confirmed the robustness of prevalence estimates across plausible values for sensitivity and specificity.
DiscussionThese findings suggest that ASD prevalence in Russia is considerably underestimated via administrative data. Systemic barriers—including limited access to diagnostic services and stigma surrounding psychiatric labels—may hinder ASD identification. Addressing these challenges is essential for improving early detection and service provision in Russia and similar contexts.