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Variation between Clinician and Parent Report Outcomes Following a Trial of Pivotal Response Treatment
Assessment of autism spectrum disorder (ASD) symptom severity is an area of great clinical importance. Reliable measures of ASD symptom severity and change in symptom severity over time are necessary to quantify treatment response, yet there is no strong consensus in the literature of the best way to measure change in symptom severity (Bolte & Diehl, 2013). Two common methods of assessing change in symptom severity are parent-reported questionnaires and clinician-administered assessments. However, the literature is mixed as to the relationship between parent and clinician reports of ASD symptom severity as measures of treatment response (Stone, Hoffman, Levis & Ousley, 1994; Murray, Mayes & Smith, 2011).
Objectives:
The present study aimed to explore agreement between parent and clinician report of ASD symptom severity before and after Pivotal Response Treatment (PRT).
Methods:
The study sample consisted of 41 children ages 4-9 who were diagnosed with ASD. Participants received 16 weeks of PRT. All participants received a diagnostic and clinical characterization battery before and after treatment. Measures administered at pre-PRT and post-PRT included the Autism Diagnostic Observation Schedule (ADOS) and Social Responsiveness Scale – II Parent Report Form (SRS-II). Paired-samples t-tests were used to examine change in measures of ASD symptom severity. Pearson correlations were then used to examine the association between parent-rated and clinician-rated measures of symptom severity.
Results:
Paired-samples t-tests confirmed our previous findings of improvement in ASD symptom severity as reported by parents on the SRS-II (pre-PRT t-score M=73.95, post-PRT t-score M=68.32,p<.001) and as reported by clinicians on the ADOS Calibrated Severity Score (CSS; pre-PRT M=7.65, post-PRT M=6.90, p=.037). Pearson correlations between the change in SRS-II and the change in ADOS CSS revealed no correlation in symptom change on the two measures (r =-.115,p=.503). Furthermore, there was no significant correlation between the SRS-II and the ADOS CSS at pre-treatment or post-treatment time points (pre-PRT r=-.220,p=.185, post-PRT r=.109, p=.505). Additional Pearson correlations were run between all ADOS and SRS-II subscales, and no significant correlations were found. When controlling for gender, age, and IQ, partial correlations between the change in SRS-II and ADOS CSS remained insignificant.
Conclusions:
As a group, children improved in social communication skills following PRT; however, there was heterogeneity in treatment response. Improvement as measured by the ADOS did not relate to improvement as reported by parents on the SRS-II. This indicates that although PRT facilitated social communication skills in the sample as a whole, it may have an effect in heterogenous ways at the individual level. The ADOS tends to assess core social communication skills as well as understanding and insight, whereas the SRS-II measures skills related to social communication in naturalistic contexts. These results underscore the need for collecting outcome information from multiple informants across a variety of settings to obtain an accurate understanding of treatment response. Future studies should examine the relationship between other measures of treatment response and consider additional methods of quantifying social communication change.