Prevalence of Autism Spectrum Disorder Severity Levels From the Fifth Edition of the Diagnostic and Statistical Manual (DSM-5) in the Autism and Developmental Disabilities Monitoring Network

The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) introduced severity level specifiers for autism spectrum disorder (ASD) with minimal description of the criteria for categorizing three levels of severity (1 to 3, with 3 being the most “severe”). The objective of the analysis was to assess the prevalence of ASD severity levels using population-based surveillance data. We analyzed severity level data on children with ASD ages 4- and 8-years-old in 2018 and 2020 in the multisite Autism and Developmental Disabilities Monitoring (ADDM) Network. Prevalence of any documented severity level and of each individual level were calculated overall and by demographic characteristics. Prevalence ratios adjusted for sex, race/ethnicity, age, intellectual disability, ADDM surveillance year, and site (aPRs) and 95% confidence intervals (CIs) were used for comparisons. Less than half (40.4%) of children with documented ASD diagnoses had any severity level specified in their records, with wide variation by site (4.8%-73.2%). Severity levels were more common in records of children aged 4, in surveillance year 2020, and more often missing in non-Hispanic Black children and from records also missing information on intellectual disability (ID). Higher prevalence of more severe (level 3) ASD was observed among non-Hispanic Black children, children aged 4 years, children in 2020, and children with ID. Utilization of the DSM-5’s severity levels by community professionals varied widely, limiting their potential utility in identifying needed services and supports for children with ASD.