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Autism Spectrum Disorder: Mortality and Healthcare Implications from the National Mortality Files
Autism spectrum disorder (ASD) is a pervasive developmental disorder that globally impacts functioning, and its prevalence is increasing among children (Bukstein & Cornelius, 2006; Baxter et al., 2015). The prevalence of ASD in adults is also increasing as these diagnosed children grow up, yet there is limited information on ASD beyond childhood. The limited literature suggests a poor prognosis for adults with ASD, citing high levels of disability, poor health, low likelihood of independent functioning, and increased mortality risk (Modre et al., 2012). Previous large cohort studies on mortality risk for ASD adults have been largely focused outside of the United States, and more research is needed to determine specific causes of early mortality risk in the ASD population (Hirvikoski et al., 2016). Quantifying frequently occurring, potentially preventable causes of death in the ASD population is imperative to increasing awareness for families, care-takers, policy-makers, and practitioners.
Objectives:
The purpose of this presentation is to describe underlying causes of death for ASD individuals compared to individuals with intellectual disability (ID) and to the general population. A secondary purpose is to quantify mortality rates by age, race/ethnicity, and gender to identify vulnerable sub-populations.
Methods:
This study used national Multiple Cause-of-Death Mortality Data for years 2011-2013. These data sets are created using information from death certificates provided to the National Vital Statistics System (NVSS). The International Classification of Diseases, Tenth Revision (ICD-10) was used to code underlying causes of death. The multiple cause of death codes are classified by NVSS to identify the underlying cause of death from up to 20 multiple causes of death listed. Using ICD-10 codes, individuals with ASD and ID were identified, and cross-tabulations were run to: (1) compare ASD deaths to the ID and typical populations, and (2) compare mortality rates among sub-populations of the ASD group.
Results:
Preliminary analyses of 2011 mortality files, presented in Tables 1 and 2 attached, show 3.3% of deaths in the typical population occur before age 30, compared with 41.1% in the ASD population and 7.8% in the ID population. For the typical under 30 population, 15.5% of deaths are due to non-motor vehicle accidents, compared with 24.5% for ASD, and 2.7% ID. The ASD population under 30 also has a greater proportion of deaths (15.1%) due to ischemic or other heart disease than the typical (4.0%) or ID (1.7%) populations.
Conclusions:
Describing causes of death for the ASD population is a crucial first step in eliminating premature mortality for this group. Results show that deaths in the ASD population are to a disproportionate number of young people under age 30, which could be a reflection of the lower prevalence of ASD among older cohorts. Further, ASD individuals appear to be at increased risk of early mortality due to non-motor vehicle accidents and ischemic heart disease compared with the typical and ID populations. Analyses of the 2011 mortality files are complete, and these analyses will be replicated for 2012 and 2013 in order to substantiate these findings.