RESUMO
INTRODUCTION: The prevalence of Autism Spectrum Disorder has increased, varying between 0.5 and 1% around the world. The prevalence of ASD in Chile is unknown. OBJECTIVE: To estimate the prevalence of ASD in two urban communes of Santiago, Chile. SUBJECTS AND METHOD: Cross-sectional epidemiological study. 272 children aged between 18-30 months who attended well-child visits at two Family Health Centers in two urban communes of Santiago participated. Consecutive sampling was used and chil dren who were already being monitored by neurology were excluded. Screening was performed using the Modified Checklist for Autism in Toddlers (M-CHAT). Those children with altered M-CHAT were evaluated by a pediatric neurologist at the San Borja Arriarán Clinical Hospital and diagnosed with ASD according to clinical criteria. The Autism Diagnostic Observation Schedule - Second Ver sion (ADOS-2) was used as a diagnostic complement. The prevalence of ASD was estimated with a 95% confidence interval. RESULTS: 44 children had altered M-CHAT; 5 of them were clinically diagno sed with ASD. A 1.95% prevalence of ASD (95% CI 0.81-4.63) was obtained, with a sex distribution of 4 boys per 1 girl. CONCLUSIONS: This study is the first estimate of ASD prevalence in two communes of Santiago, Chile. A high prevalence of this condition was observed, which highlights the need for obtaining resources for an early multidisciplinary approach for these patients.