Systematic Review: Distribution of Age and Intervention Modalities in Therapeutic Clinical Trials for Autism Spectrum Disorder

Abstract

The prevalence of ASD remains relatively stable across the lifespan, necessitating a quantitative understanding of how intervention clinical research is applied across age groups. Here we report a systematic review of treatment studies between 2013 and 2017, enrolling 11,213 subjects with ASD in 218 studies. Individuals under 18 years old constituted the majority of studies (84%) and subjects (92%). Subjects under 18 years old were more likely to be enrolled in behavioral studies (OR (CI) = 1.34 (1.17-1.54)), and less likely to be enrolled in pharmacological (OR = 0.60 (0.52-0.69)) studies than subjects ≥ 18 years old. Identified disparities in both intervention modalities and outcome measures should serve to guide future research priorities.

Keywords: Adolescent; Adult; Autism; Clinical trial; Disparity; Systematic review.

Figure 1.

PRISMA diagram outlining disposition of studies identified by literature search. Diagram was generated using the PRISMA Flow Diagram Generator (http://prisma.thetacollaborative.ca).

Figure 2.

Histogram demonstrating the number of studies (a) and subjects (b) plotted against the mean enrolled subject age in all identified therapeutic intervention studies for individuals with ASD. Vertical dotted line is at 18 years of age. Plots demonstrating the cumulative distribution of studies by mean enrolled subject age for intervention modality subtypes (c) and primary study outcomes (d). P values are from Mann-Whitney test (c) or Kruskal-Wallis test followed by Dunn’s post-test (d).