Mortality Among Youth and Young Adults With Autism Spectrum Disorder, Intellectual Disability, or Cerebral Palsy.

Importance: Autism spectrum disorder (ASD), intellectual disability (ID), and cerebral palsy (CP) are lifelong neurodevelopmental conditions accompanied by varying impairments. US mortality data for these groups are limited. Objective: To compare mortality and causes of death among a multisite cohort identified at age 8 years with ASD, ID, or CP with the general population through youth or young adulthood. Design, Setting, and Participants: Nine US sites identified 32 787 individuals who met case definitions for ASD, ID, and/or CP at age 8 years during active population-based cross-sectional surveillance conducted biennially from 2000 through 2016 by the US Centers for Disease Control and Prevention's Autism and Developmental Disabilities Monitoring (ADDM) Network. Individuals were linked to death certificates through 2021. Cases with multiple conditions (18.9%) were included in each case group. General population data from the National Vital Statistics System were matched to ADDM Network sites and years of participation. Analyses were completed in 2024. Exposure(s): ASD, ID, or CP. Main Outcomes and Measures: Death and International Classification of Diseases, 10th revision (ICD-10) International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10) causes from death certificate linkage. Results: There were 145 deaths among 23 393 people with ASD, 285 deaths among 14 031 people with ID, and 123 deaths among 1612 people with CP. Increased mortality compared with the general population was seen for ASD (hazard ratio [HR], 1.35; 95% CI, 1.15-1.59), ID (HR, 4.35; 95% CI, 3.87-4.88), and CP (HR, 9.62; 95% CI, 8.06-11.48). Further stratified by sex and co-occurring ID, mortality for ASD was higher only for females with co-occurring ID (HR, 5.04; 95% CI,3.21-7.91) compared with females in the general population. The distribution of causes of death varied across groups. The most common underlying cause of death ICD-10 chapters were external causes of morbidity and mortality (V01-Y98) for the general population and ASD case group, and diseases of the nervous system (G00-G99) for CP and ID case groups. The only ICD-10 chapter hazard of death that was not elevated for ID and CP compared with the general population was external causes as underlying cause of death. Mortality from external causes was also not elevated as underlying or any cause of death for ASD. There were also notable subchapter mortality differences with important clinical and public health implications. Only 11% of those with ASD, 1% of those with ID, and 49% of those with CP had an ICD-10 code for the respective disability on their death certificate. Conclusions and Relevance: In this study, individuals with ASD, ID, or CP experienced higher mortality from a range of causes compared with the general population in youth and young adulthood. Mortality among these groups is difficult to ascertain using death certificates alone, since ICD-10 codes for these disabilities were rarely listed. These findings can inform public health and health care strategies to understand and prevent health disparities and excess mortality associated with developmental disabilities.