From stepping stones to milestones. Developmental assessment in infants and toddlers

Abstract

The development of most children proceeds without problems, although a small percentage experiences a developmental delay. Luckily, children with a developmental delay often benefit from early intervention. Timely identification is therefore crucial and adequate instruments measuring early child development are needed. The main aim of this dissertation is the evaluation of the suitability of instruments assessing early child development for Dutch children. One instrument that is used worldwide for extensive assessment of developmental levels of infants and toddlers is the Bayley-III. Using standardized tasks, a trained professional measures the child’s cognitive, language, and motor development. The Bayley-III is created and standardized in the US. As such, the content of the items and the test material might not be suitable for children in other countries in view of cultural differences and possible differences in developmental trajectories and pace. To develop a version of the Bayley-III that is suitable for Dutch children –the Bayley-III-NL- the item content and the testing materials were evaluated and a few small adaptations were made were necessary. Next, based on the test results of 400 Dutch children, it was concluded that the items ascended in difficulty for each subtest and that the original item sequence of the Bayley-III could be retained for the Bayley-III-NL. Finally, the scores based on Dutch norms and US norms were compared for 1912 children to study whether the Dutch norms differed from the US norms. The results showed that the Dutch norms fluctuate around the US norms on all subtests and that they significantly deviated from each other at most ages. Furthermore, using US norms resulted in an overestimation of the number of children with a developmental delay for the Gross Motor Subtests and an underestimation for most other subtests. Thus, population specific norms should be preferred over the US norms. Another instrument that was evaluated, was the Ages and Stages Questionnaire (ASQ-3) which is a screening measure answered by parents measuring the development of Problem solving, Fine motor, Gross motor, Communication, and Personal-social skills of children in the age of 1 month to 5 years. ASQ-3 results were compared to the Bayley-III-NL results for 1244 children to study whether a Dutch translation of the ASQ-3 might be adequate for use in the Netherlands . The results showed that the ASQ-3 correctly identified children who showed age appropriate functioning according to the Bayley-III-NL results. However, many children were identified as at risk for a delay by the ASQ-3, but were not delayed according to the Bayley-III-NL. For the Netherlands, it is advised to use the 18-42 months ASQ-3 age versions and to use a total ASQ-3 score instead of scores per domains. When the total score is at least 1 SD below the mean it is advised to refer a child for extensive developmental assessment. The results on the ASQ-3 showed potential for use in the Netherlands as a screening measure and future research should focus on adapting the ASQ-3 for Dutch children.