Ages and Stages Questionnaire at 3 Years for Predicting IQ at 5–6 Years

OBJECTIVES: To assess the predictive value of the 36-month Ages & Stages Questionnaire (ASQ) score for IQ score at age 5 to 6 years in the general population and to identify factors associated with IQ <85 once the ASQ score is taken into account. METHODS: Data were collected from 939 children enrolled in a population-based prospective cohort study. Developmental outcomes at 36 months were assessed via the ASQ and at 5 to 6 years via the Wechsler Preschool and Primary Scale of Intelligence. The ASQ threshold was identified via the receiver operating characteristic curve. Additional predictive factors to obtain an IQ <85 were investigated, and their interaction with ASQ score was studied. RESULTS: Sixty-nine children (7.3%) had an IQ <85. A 36-month ASQ score threshold of 270 was optimal to identify children with an IQ <85 at 5 to 6 years, with a 0.77 ± 0.11 sensitivity and 0.68 ± 0.03 specificity. Maternal educational level and occupational activity at the time of ASQ completion were associated with the risk of an IQ <85 at a given ASQ level. In the multivariate model, no interaction between the studied factors and ASQ score reached significance. CONCLUSIONS: In the general pediatric population, 36-month ASQ parental reports could be used to identify children at later risk of cognitive delay. Low maternal education level should also be considered as a major risk factor for lower IQ in preschool children regardless of ASQ score.