A Synthesis Review of Interventional Outcomes In Autism Spectrum Disorder

Background:  The impact of autism spectrum disorder (ASD) is substantial. The need for resources is often daily and across the lifespan, with implications for personal development, family life, school and vocational involvement, community engagement, funding; mental health, and diagnostic, developmental, rehabilitation and other services.  The mix of needed resources varies as symptoms and outcomes range widely.  Several systematic reviews have evaluated the impact of early intervention on children’s outcomes.  These reviews suggest that therapy increases positive outcomes, yet there continues to be a lack of consensus regarding best treatment, particularly over the lifespan.

Objectives:  To address this uncertainty within existing evidence, this study examined interventional outcomes for children and adults with ASD.  The project is a synthesis review of relevant intervention studies, and the development of an evidence-informed framework mapping case characteristics and needs with potential interventional approach.  It brings a unique focus relative to recent reviews (e.g., National Standards Report) in seeking to identify specific outcomes relative to intervention type and case-based manifestation of autism symptoms. 

Methods:  The study is guided by Campbell collaboration specifications for quantitative, qualitative and mixed method systematic review.  Study inclusion reflects a multi-stage process comprising: (1) initial electronic database searching for studies with definable autism intervention and outcome data; (2) strict screening for inclusion/exclusion criteria, evaluation design, sample description, contextual elements (e.g., ASD severity), findings and methodological rigor; and (3) data extraction and systematic review.

Results:  Initial screening of the literature (to November 2010) yielded 22,878 studies.  However, after the articles were reviewed for redundancy, methodology and verification of an ASD focus, 4,130 articles remained.  This database represents the following interventional approaches:  (1) Behavioural (n= 3,341 articles); (2) Social (n= 1,811); (3) Pharmacological (n= 1,768); (4) Communication/Language (n= 1,347); (5) Academic (n= 727); (6) Non-Conventional (n= 698); (7) Sensory (n= 586); (8) Developmental (n= 229); and (9) Diet (n= 192). Some articles addressed more than one approach and age group. Articles addressed ages: 0 to 4 years (n= 1,981); 5 to 12 years (n= 6,077); 13 to 17 years (n= 1,700), and 18 years and over (n= 941).  This preliminary description of the types of interventions covered will be followed by a focused review and synthesis of treatments by intervention approach and age group.

Conclusions:  Behavioral, social and pharmacological approaches in ASD have most frequently been evaluated.  On balance, the provision of intervention is preferable to non-intervention.  There are notably fewer studies addressing interventions for older adolescent and adults with the most evidence for children ages 5 to 12 years old. It is still difficult to contrast the effectiveness of interventional approaches given varying metrics, sample characteristics, outcomes and methodological rigor within primary studies.  Well-designed comparative studies are needed in contrasting varying approaches across ASD population subtypes.