Abstract

Abstract Evidence suggests core autism trait consistency in older children, but development of these traits is variable in early childhood. The Social Responsiveness Scale (SRS) measures autism‐related traits and broader autism phenotype, with two age‐dependent forms in childhood (preschool, 2.5–4.5 years; school age, 4–18 years). Score consistency has been observed within forms, though reliability across forms has not been evaluated. Using data from the Environmental Influences on Child Health Outcomes (ECHO) program ( n = 853), preschool, and school‐age SRS scores were collected via maternal report when children were an average of 3.0 and 5.8 years, respectively. We compared reproducibility of SRS total scores ( T ‐scores) and agreement above a clinically meaningful cutoff ( T ‐scores ≥ 60) and examined predictors of discordance in cutoff scores across forms. Participant scores across forms were similar (mean difference: 3.3 points; standard deviation: 7), though preschool scores were on average lower than school‐age scores. Most children (88%) were classified below the cutoff on both forms, and overall concordance was high (92%). However, discordance was higher in cohorts following younger siblings of autistic children (16%). Proportions of children with an autism diagnoses were also higher among those with discordant scores (27%) than among those with concordant scores (4%). Our findings indicate SRS scores are broadly reproducible across preschool and school‐age forms, particularly for capturing broader, nonclinical traits, but also suggest that greater variability of autism‐related traits in preschool‐age children may reduce reliability with later school‐age scores for those in the clinical range.