Substance Use Disorder Rates Higher in Patients with Autism Spectrum Disorder

While it is not currently known what the risk of substance use disorder (SUD) is for patients with autism spectrum disorder (ASD), new research suggests higher rates of mortality in this patient population.

A team led by, Jing-Syuan Huang, MD, Department of Psychiatry, Beitou Branch, Tri-Service General Hospital, National Defense Medical Center, examined the risk of SUD for ASD patients, while identifying the comorbidities, psychotropic agents, and mortality within this patient population.

In the retrospective, population-based, cohort, the investigators analyzed the data of 1.9 million participants from the Taiwan National Health Insurance Research Database between 2000-2015.

The study included patients who attended at least 3 outpatient visits within a one-year period for symptomatic ASD, determined by the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnostic codes.

The researchers excluded patients diagnosed with ASD prior to 2000, diagnosed with SUD before the first visit for ASD, and individuals with missing data.

The investigators then matched patients with ASD with non-ASD controls by age, sex, and index date in a 1:4 ratio and calculated adjusted hazard ratios (aHRs) with 95% confidence intervals (CI) for SUD, including alcohol use disorder (AUD) and drug use disorder (DUD). They also calculated the risk of mortality.

Study Results

Overall, the research team identified 6599 patients with ASD with a mean age of 11.9 years old, 77.2% of which were male. The mean follow-up period was 8.1 years and the median follow-up period was 4.3 years. The study also included 26,396 controls.

In a multivariable-adjusted analysis, the aHR was 2.33 (95% CI, 1.89-2.87) for SUD, 2.07 (95% CI, 1.60-2.63) for AUD, and 3.00 (95% CI, 2.15-4.58) for DUD. These figures were significantly higher in the ASD than it was in the control group.

The aHRs for SUD in different ASD subgroups with 1 psychotropic agent was 0.60 (95% CI, 0.43-0.66) and 0.37 (95% CI, 0.28-0.49) for multiple psychotropic agents. These figures were also significantly lower than the aHRs for those in the ASD subgroup with no psychotropic agents.

Comparing Patient Subgroups

When comparing patients with ASD with non-ASD individuals with the same comorbidities, the investigators found higher aHRs for SUD among patients with ASD (range, 1.17-2.55).

In addition, the ASD subgroup not receiving any psychotropic agents had an aHR of 6.39 (95% CI, 5.11-7.87) for SUD when they had a comorbid tic disorder, as well as aHRs of 5.48 (95% CI, 5.12-5.70) for AUD and 5.42 (95% CI, 5.12-5.80) for DUD when they had comorbid impulse control disorder.

The mortality rate was also significantly higher in patients with ASD and concomitant SUD than it was in the control group without SUD (aHR, 3.17; 95% CI, 2.69-3.89).

Ultimately, the data sheds light on the risk of substance use disorder in an ASD patient population.

“These findings suggest that patients with ASD are vulnerable to the development of SUD. Comorbid ASD and SUD were associated with an increase in mortality risk,” the authors wrote.

The study, “Risk of Substance Use Disorder and Its Associations With Comorbidities and Psychotropic Agents in Patients With Autism,” was published online in JAMA Pediatrics.