The Autism and Developmental Disabilities Monitoring (ADDM) Network continues to report increases in the percentage of U.S. children identified with autism spectrum disorder (ASD). Few studies, however, have examined prevalence among U.S. adults.

To use open data on ASD prevalence among fee-for-service Medicare beneficiaries, considering trends in the context of sociodemographic factors and dual enrollment in Medicaid.

Administrative prevalence estimates from the Centers for Medicare and Medicaid Services (CMS) were used to explore changes in ASD prevalence among fee-for-service Medicare beneficiaries. These rates were compared with corresponding childhood prevalence estimates from the ADDM Network.

In 2018, there were 87,108 fee-for-service Medicare beneficiaries with autism diagnoses, representing a 236.1% increase from 2008. For 8-year-old children in the ADDM Network, the 2008–2018 change was 32.41%. National ASD prevalence increased in the fee-for-service Medicare population every year from 2007 through 2018, most substantially for beneficiaries under the age of 65. While only 10 states had a prevalence at or above 1 in 1000 beneficiaries in 2007, 48 states and the District of Columbia had a prevalence above that value in 2018. Prevalence in the Medicare population also increased from 2016 to 2018, a period in which program enrollment declined.

Even more so than among children, autism prevalence increased in the fee-for-service Medicare population from 2007 through 2018. While geographic and sociodemographic differences in ASD identification existed, prevalence grew across states and most subgroups. Further research is needed to address questions involving the identification and support of autistic adults.

Adults

Autism spectrum disorder (ASD)

Medicare

Open data

Prevalence

© 2025 The Author. Published by Elsevier Inc.