Practitioners seeking to help children with Autism Spectrum Disorders (ASDs) have increasingly relied on evidence-based practices (EBP), or those interventions consistently supported by high quality, peer-reviewed outcome research. Several reviewers have recently developed rubrics for objectively evaluating the quality of outcome research, including specific standards for designating a practice as evidence-based. These efforts reflect a growing convergence regarding the general characteristics of high quality research and the number and quality of such studies needed to constitute EBP. Reviewers have been limited, however, to drawing broad conclusions about practices, because of the limited number of outcome studies, and the tendency for some studies to rely on broadly defined methods and measures. As a result, it is difficult for individual practitioners to translate EBPs identified thus far into specific objectives for specific individuals, and so they cannot yet take full advantage of the growing body of outcome research.
To demonstrate a two-stage process for generating individualized, evidence-based intervention goals from methodologically sound outcome research by (a) establishing whether a given program (e.g., the Picture Exchange Communication System, or PECS) is an EBP for teaching communication and related skills, and then (b) generating specific objectives reflecting consistent patterns across studies of at least adequate quality.
We conducted PSYCHLIT and PUBMED searches for outcome studies in which PECS was used to teach communication or improve related skills and behaviors among children with ASD, focusing on studies published in English in peer-reviewed journals. After rating studies according the Reichow, Volkmar, and Cicchette (2008) rubric, we first evaluated whether PECS is a broadly defined EBP. Selecting only studies of at least Adequate quality, we then summarized patterns of findings across at least two studies for a similar population as indicating: (a) Consistent evidence, when similar findings were obtained across all studies; (b) Some evidence when there was a generally positive, though not perfectly consistent, trend obtained across 3 or more studies, and; (c) Emerging evidence when findings were obtained by only one study examining a specific question.
Preliminary calculations of inter-observer agreement on the application of the Reichow rubric exceeded 80% for all components. Preliminary analyses of more than a dozen studies, including both group and single-case designs, indicated that PECS is an established EBP. Patterns of evidence were noted that potentially serve several different purposes: (a) the identification of goals addressing the acquisition of PECS itself (e.g., that PECS is initially mastered relatively quickly by most children, even those with little or no independent, functional communication skills; (b) addressing related skills (e.g., that improvements in PECS may be associated with improvements in some aspects of speech, and does not result in decreases in vocalization or speech), and; (c) helping to choose between PECS and other strategies according to other child characteristics.
These findings demonstrate a two step approach to translating outcome research into individualized, evidence-based goals. We discuss characteristics of PECS that facilitate this approach, and some of the patterns of weakness in the outcome studies reviewed.