Abstract
A retrospective data analysis using 2000-2008 three state Medicaid Analytic eXtract was conducted to examine the prevalence and association of comorbidities (psychiatric and non-psychiatric) with healthcare utilization and expenditures of fee-for-service enrolled adults (22-64 years) with and without autism spectrum disorders (International Classification of Diseases, Ninth Revision-clinical modification code: 299.xx). Autism spectrum disorder cases were 1:3 matched to no autism spectrum disorder controls by age, gender, and race using propensity scores. Study outcomes were all-cause healthcare utilization (outpatient office visits, inpatient hospitalizations, emergency room, and prescription drug use) and associated healthcare expenditures. Bivariate analyses (chi-square tests and t-tests), multinomial logistic regressions (healthcare utilization), and generalized linear models with gamma distribution (expenditures) were used. Adults with autism spectrum disorders (n = 1772) had significantly higher rates of psychiatric comorbidity (81%), epilepsy (22%), infections (22%), skin disorders (21%), and hearing impairments (18%). Adults with autism spectrum disorders had higher mean annual outpatient office visits (32(ASD) vs 8(noASD)) and prescription drug use claims (51(ASD) vs 24(noASD)) as well as higher mean annual outpatient office visits (US$4375(ASD) vs US$824(noASD)), emergency room (US$15,929(ASD) vs US$2598(noASD)), prescription drug use (US$6067(ASD) vs US$3144(noASD)), and total expenditures (US$13,700(ASD) vs US$8560(noASD)). The presence of a psychiatric and a non-psychiatric comorbidity among adults with autism spectrum disorders increased the annual total expenditures by US$4952 and US$5084, respectively.