Does pre-school developmental assessment agree with later intellectual assessment? A retrospective cohort study

This study sought to assess the association between early developmental assessment of toddlers with idiopathic global developmental delay (GDD) and their later intelligence test scores.

Toddlers with idiopathic GDD attending a community clinic over a 6-year period were assessed initially using the Griffiths Mental Development Scales - Extended Revised version (GMDS-ER) and later completing formal intelligence testing using the Stanford-Binet Intelligence Scale - 5th Edition (SB5) at age 4-6 years. Spearman's correlation was used to assess the association of quotient scores across the tools. The composite quotient (GQ) and the subscale quotients of GMDS-ER were correlated with the full-scale IQ (FSIQ), verbal and non-verbal IQ scores from the SB5.

Thirty of 153 children assessed at the clinic were eligible for the study. The correlation between GMDS-ER GQ and later SB5 FSIQ was strong (r = 0.86, P < 0.001). The subscales' associations were moderate to strong (0.48-0.71). Eighty-six percent (86%) of children with delay on GMDS-ER GQ were found later to be in the impaired category based on the FSIQ of the SB5.

There was a strong association between toddlers' early developmental quotients and later IQ scores for children with idiopathic GDD, though agreement between early GDD diagnoses and later intellectual disability is not absolute. Individualised care is needed around prognostic advice and recommendations to caregivers and families in the early years, so they may effectively plan for interventions, supports and later reassessment to optimise their child's development and learning.