Psychometric Properties of a Novel Vineland-II™ 2-Domain Composite Score to Assess Social Communication and Social Interaction in Autism Spectrum Disorder

Background: Challenges in socialization and communication are core symptoms of autism spectrum disorder (ASD) and need to be addressed by new treatments for ASD. However, there is a lack of consensus on appropriate outcome measures for evaluating core symptoms of ASD in clinical trials of new treatments.

Objectives: The Vineland Adaptive Behavior Scales, Second Edition (Vineland™-II) Socialization and Communication domain scores are both reliable and valid scales used as endpoints in ASD clinical trials. To explore the measurement properties of a novel Vineland-II 2-domain composite (2DC) score, which combines these 2 independently validated scales, we conducted a psychometric analysis of this new scale using data from the VANILLA phase 2 trial of balovaptan, a 12-week study in adult males with ASD and intelligence quotient (IQ) ≥ 70 (NCT01793441).

Methods: The Vineland-II 2DC score is calculated as the arithmetic mean of the Vineland-II Socialization and Communication domain standard scores. The measure was administered by experienced raters. Test-retest reliability was assessed using interclass correlation coefficient (ICC) in patients with no change in their clinical status at day 84 on the Clinical Global Impression–Improvement (CGI-I) scale. Sensitivity to change (baseline to day 84) was assessed by comparing mean scores on Vineland-II 2DC between subjects with CGI-I scores of “minimally improved” or better versus “no change” or worse using analysis of covariance. Convergent and discriminant validity, as well as known-group validity, were also explored with baseline Vineland-II 2DC, age, and IQ as covariates.

Results: The Vineland-II 2DC demonstrated very good test-retest reliability with an ICC of 0.83 (N = 88). The 2DC score correlated with (0.97 Pearson correlation coefficient) and demonstrated similarly robust psychometric properties to the Vineland-II Adaptive Behavior Composite score. Correlations with symptom-oriented scales that measure attributes different to those measured by Vineland-II 2DC were weak, as hypothesized. Known-group validity was strong, with significant difference in scores between Clinical Global Impression–Severity groups (nominal P < 0.05); and sensitivity to change for the Vineland-II 2DC score was significant across groups (nominal P < 0.05).

Conclusions: Challenges in socialization and communication are among the most important symptoms that need to be addressed by new treatments for ASD. However, there is a lack of validated measures of these core symptoms established in ASD clinical trials. In adults with ASD and IQ ≥ 70, the novel Vineland-II 2DC score shows evidence of reliability, validity and sensitivity to change, and enables a comprehensive assessment of socialization and communication abilities in people with ASD. These findings support the use of the Vineland-II 2DC score as an outcome measure for assessing the core deficits of socialization and communication in future ASD phase 3 clinical trials. Replication of these findings in other datasets is required to further validate the Vineland-II 2DC score.