Using the ADOS Severity Metric to Evaluate the Trajectory of Students with ASD In a Large Public School District

Background:  

Though intended as a categorical diagnostic tool, there is an increasing trend in autism research to use the Autism Diagnostic Observation Schedule (Lord et. al 2000) as a severity and outcome measure. In response to the growing need for a measure that would allow for longitudinal comparisons of symptom severity within the same individual, Gotham et al. (2009) developed a severity metric, allowing for across-module and cross-age comparisons. To date, however, this severity metric has been used only for long-term comparisons, not for periods of time generally used to test interventions. If the metric is sensitive to change over relatively short periods of time, such as an academic year, it would have important implications for its use as an outcome measure in intervention studies. 

Objectives:  

To examine the utility of the ADOS severity metric as a measure of trajectory of students with ASD in a large public school district. 

Methods:  

The sample included 225 students from 49 kindergarten-through-second-grade autism support classrooms in a large, urban school district who were participating in a study of a classroom-based autism intervention. Students were assessed at the beginning and of the academic year using the ADOS Modules 1-3, depending on their language ability. Trajectories of the group were calculated using the ADOS severity metric. Growth mixture modeling was used to examine whether children could be empirically classified by their change in ADOS score. These groups were then compared based on their change in other outcome measures used in the study. 

Results:  Analyses are ongoing and will be completed by the time of the conference. Preliminary results suggest that children vary greatly in their change in ADOS score over the course of the academic year. Changes in scores correlated moderately with other outcome measures.

Conclusions:  

Preliminary results suggest that the ADOS severity metric may be a useful tool in evaluating intervention outcomes.