A Systematic Review of Communication Interventions for Minimally Verbal Children with Autism Spectrum Disorder

Background: Language difficulties commonly co-occur with autism spectrum disorders (ASD) and it is estimated 25-30% of children with ASD fail to develop functional language, or are minimally verbal. The ability to communicate effectively is an essential life skill and difficulties communicating can have a range of adverse sequelae including poorer academic achievement, behaviour difficulties and reduced quality of life. Historically, most studies have investigated communication interventions for verbal children with ASD. We cannot assume the same interventions will work for minimally verbal children. To date, there has been no systematic review to determine the most effective intervention for minimally verbal children.

Objectives: To evaluate the effectiveness of communication interventions for children with ASD who are minimally verbal.

Methods: Fourteen databases were searched to identify relevant studies. Inclusion criteria were: children with ASD < 12 years of age who were minimally verbal (less than 30 functional words/unable to use speech alone to communicate); diagnosed using standard diagnostic assessments and/or criteria (e.g. Diagnostic Statistical Manual for Mental Disorders or International Classification of Diseases) and cognitive level > 12 months. Interventions included randomised controlled trials (RCTs) that used communication-focused interventions and aimed to improve spoken communication or non-verbal communication. Primary outcomes were spoken communication (e.g. direct assessments, parent-completed tools, language samples) and non-verbal communication/augmentative communication (e.g. number of key word signs, number of initiations on an augmentative communication device). Risk of bias of included studies was assessed along with the overall quality of the body of evidence.

Results: Of 5233 studies identified, nine were randomised trials that focused on communication interventions for children with ASD who were minimally verbal. Seven of these compared 2 different interventions but only 2 studies with 153 participants compared an intervention to a control group and thereby met inclusion criteria. One study investigated a Picture Exchange Communication System (PECS) intervention administered by school teachers and the other a parent-mediated Focused Playtime Intervention (FPI). Age at baseline ranged from 4 to 11 years. Outcomes were standardised language scores and the PECS study also included frequency of initiations, speech and PECS use. Children enrolled in the PECS intervention were significantly more likely to use verbal initiations and PECS symbols immediately after intervention, however gains were not maintained 10 months later. PECS did not improve frequency of speech or language ability. There was no significant treatment effect for the FPI on expressive language, however, baseline expressive language (<11.3 months age equivalent) moderated a significant medium-large treatment effect. Both studies had high or unclear risk of bias in at least 4/7 risk of bias categories. The overall quality of the evidence was rated poor.

Conclusions: Across all outcomes, data are insufficient to show whether communication interventions (specifically, PECS and FPI) are effective in increasing verbal and non-verbal communication in minimally verbal children with ASD. Future studies that compare two treatments and include a control group will allow us to better understand treatment effects in the context of spontaneous maturation and will allow further comparison of different treatments and investigation of moderators.