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ObjectiveChanges in autism diagnostic criteria found in DSM-5 may affect autism spectrum disorder (ASD) prevalence, research findings, diagnostic processes, and eligibility for clinical and other services. Using our published, total-population Korean prevalence data, we compute DSM-5 ASD and social communication disorder (SCD) prevalence and compare them with DSM-IV pervasive developmental disorder (PDD) prevalence estimates. We also describe individuals previously diagnosed with DSM-IV PDD when diagnoses change with DSM-5 criteria.MethodThe target population was all children from 7 to 12 years of age in a South Korean community (N = 55,266), those in regular and special education schools, and a disability registry. We used the Autism Spectrum Screening Questionnaire for systematic, multi-informant screening. Parents of screen-positive children were offered comprehensive assessments using standardized diagnostic procedures, including the Autism Diagnostic Interview-Revised and Autism Diagnostic Observation Schedule. Best-estimate clinical diagnoses were made using DSM-IV PDD and DSM-5 ASD and SCD criteria.ResultsDSM-5 ASD estimated prevalence was 2.20% (95% confidence interval = 1.77-3.64). Combined DSM-5 ASD and SCD prevalence was virtually the same as DSM-IV PDD prevalence (2.64%). Most children with autistic disorder (99%), Asperger disorder (92%), and PDD-NOS (63%) met DSM-5 ASD criteria, whereas 1%, 8%, and 32%, respectively, met SCD criteria. All remaining children (2%) had other psychopathology, principally attention-deficit/hyperactivity disorder and anxiety disorder.ConclusionOur findings suggest that most individuals with a prior DSM-IV PDD meet DSM-5 diagnostic criteria for ASD and SCD. PDD, ASD or SCD; extant diagnostic criteria identify a large, clinically meaningful group of individuals and families who require evidence-based services.