Scientific Abstract
Background: Autism spectrum disorder (ASD) is highly heritable and prevalent condition that carries a significant clinical burden; however, it is under-recognized. The Social Responsiveness Scale (SRS-2) is a 65-item rating scale used to measure autism spectrum severity. We conducted a retrospective chart review to assess agreement between informant and self SRS-2 reports and a clinical diagnosis of ASD, hypothesizing that discordance will be present in overall impairment and symptom characterization results.
Methods: We analyzed 148 patients referred to an ASD specialty clinic with both self and informant rated versions of the SRS-2. Raw scores were calculated and used to generate T-scores for five subscales and one total scale. Spearman correlations (Spearman’s ρ) were calculated and stratified by age (<25 vs ≥25) and sex (male vs female) to examine the correlation between the self- and informant-rated SRS-2 total and subscale T-scores. Agreement of raters on the total and subscale T-scores was established by intraclass correlation coefficients (ICC).
Results: Correlations between the self- and informant-rated SRS-2 scales were all statistically significant, but low (Total: ρ=0.26, Subscales: ρ=0.19-0.50; all p<0.05). The ICCs were consistent with the Spearman correlation results, showing poor consistency between self- and informant-rated scores (Total: ICC=0.30; Subscale: ICC=0.21-0.49; all p<0.05). There was moderate overall agreement when examining impairment, with 54.1% to 72.3% of self and informant reports agreeing. The disagreement between self and informant was 39% and in more than half of cases, the difference in scoring was substantial with a T-score ≥10. As a screening tool, sensitivity and specificity for a positive self or informant SRS-2 report were 72% and 44%, respectively.
Conclusions: Our findings suggest that a screen positive for ASD on either the informant- or self- rated SRS should be clinically evaluated for ASD. The utility of the SRS-2 as a screening tool is superior when reports when reports from both self and informant are available.