The Autism Impact Measure (AIM) was designed specifically for treatment-outcome assessment in children with ASD, focusing on treatment-relevant aspects of symptom presentation and efficient detection of short-term improvement. The AIM demonstrated strong reliability and validity in initial psychometric studies. The current study evaluated the AIM's sensitivity to change across well-established treatments. The sample included 471 children with ASD (ages 2-14) participating in one of six treatments. The AIM was administered at baseline and 6-week intervals and a battery of domain-specific concurrent measures was also administered. A longitudinal repeated measures design examined the degree to which: (a) AIM domain scores changed over time in response to treatment and (b) change in AIM domains was associated with change in measures of similar constructs. Results across growth curve models indicated that AIM domains are sensitive to change in symptoms across treatment. Across all models, symptoms decreased over time, with some deceleration in rate of improvement. For all AIM domains except Repetitive Behavior, symptoms improved as a function of treatment group. Correlations of change between AIM and other measures varied across domains (from 0.01-0.43 across measures). This was the first large-scale study to systematically evaluate sensitivity to change in a measure of core ASD symptoms. The results provide support for the AIM's ability to detect short-term improvement across symptom domains and indicate that AIM domains are sensitive to change overall and as a function of different treatment conditions. The brief repeated assessment window also highlights the AIM's utility for detecting improvements across short-term treatments. Autism Res 2020, 13: 1867-1879. © 2020 International Society for Autism Research and Wiley Periodicals LLC LAY SUMMARY: Good measures are important for assessing outcomes in children with autism. However, there are few tools for tracking short-term changes in autism symptoms. This study tested a new measure, the Autism Impact Measure (AIM), in a large group of children with autism. The results showed that the AIM appears to be a valid and accurate tool for measuring autism symptoms. The AIM may be a helpful tool for researchers and clinicians interested in tracking short-term improvements in autism symptoms.
Keywords: assessment; autism spectrum disorder; autism symptoms; measurement; treatment outcome.
© 2020 International Society for Autism Research and Wiley Periodicals LLC.