Risk Factors for Emergency Department Utilization Among Adolescents with Autism Spectrum Disorder

Background: During recent years children and adolescents with autism spectrum disorder (ASD) have be increasing their ED utilization at a higher rate compared to those without ASD. Investigation is needed into the risk factors for elevated ED utilization among adolescents diagnosed with ASD who are more vulnerable for psychiatric emergencies.

Objectives: This study mined a large, national healthcare claims database to examine healthcare utilization history of adolescents with ASD to identify risk factors for elevated ED utilization.

Methods: Using MarketScan® between 2005 and 2014, we designed a retrospective, longitudinal study to determine the risk factors associated with the ED utilization among adolescents (aged 12-21) with ASD. We identified ASD subjects as those with at least two separate diagnoses of ASD (ICD-9 codes 299.0x and 299.8x) through the entire study period. The ED utilization was summarized at the individual level on a yearly basis, with an index date of the first ED visit during that year. For a calendar year without ED visit, the index date is set to be July 1^st. Risk factors include mental health comorbidity; psychotropic medications; prior visit(s) to a psychiatrist, prior ED visit and demographic characteristics (age, sex, etc.).

Results: Our study cohort consists of 63,886 ASD patients with 181,686 person-year observations. Multivariable logistic regression analysis examining the independent effect of each factor on ED utilization found a statistically significant sex-by-age interaction effect on ED utilization (p=0.03). While female adolescents with ASD generally were more likely to visit ED than males, sex effect was significant in early and late adolescence (age 12-14: adjusted Odd Ratio 1.24; 95% confidence Interval [1.13-1.37]); 18-21: 1.26 [1.14-1.39]), but not in middle adolescence (15-17: 1.08 [0.98-1.19]). Meanwhile, the longitudinal effect of age depends on sex. For females, the odds of ED visit significantly increased when patients entered late stage adolescence (age bracket 12-21 vs. 12-14: 1.24 [1.08, 1.42], age bracket 15-17 vs. 12-14: 0.99 [0.88-1.11]). In contrast, the odds of ED visits among males increased monotonically over time. In addition, having internalizing (e.g. digression) type of mental health comorbidity alone or concurrently having externalizing comorbidity (e.g. adhd) increased the odds of ED visits significantly (concurrent: 1.27 [1.19-1.37]; internalizing only: 1.17 [1.08-1.28]; Reference: neither); but not with the externalizing comorbidity alone (1.02 [0.94, 1.10]). Clearly prescriptions of more categories of psychotropic drugs were associated with higher ED risk. Even prescriptions of just two categories of these medications significantly elevated the odds of ED visit (1.20 [1.12-1.30]). Finally, a prior ED visits was strongly associated with recurrent ED visits (9.55; [8.93-10.23]).

Conclusions: This study has reaffirmed previous work documenting higher ED utilization by adolescent females than males among adolescents with ASD. Concurrent externalizing and internalizing psychiatric comorbidities as well as internalizing conditions alone correlate to higher ED utilization. Illness severity as demonstrated by psychiatric referral and use of two or more classes of psychotropic medications also appear to mark vulnerability for ED utilization. Previous ED visits appear to correlate most strongly for future ED utilization.