Developmental and Functional Outcomes at School Age of Preschool Children With Global Developmental Delay

Michael Shevell, MD; Annette Majnemer, PhD; Robert W. Platt, PhD; Richard Webster, MB, FRCP(A); Rena Birnbaum, MSc


J Child Neurol. 2005;20(8):648-654. 

In This Article


A review of the literature revealed a remarkable paucity (indeed, absence) of prospective studies characterizing the outcomes of young children diagnosed with global developmental delay. This lack of prospective data hampers our ability to accurately prognosticate developmental outcome in these children. This lack of natural history data has led some to question the predictive value of early developmental screening,[14] although such efforts are strongly encouraged by professional groups as a standard of pediatric practice.[15] In the older child (age greater than 5 years) amenable to standardized psychometric testing, it is appreciated that IQ scores are relatively stable over time.[16]

Retrospective studies have noted that older children with mental retardation were initially labeled as globally delayed. Furthermore, early developmental difficulties have been correlated with later problems in the academic setting.[17] Children with significant reading difficulties at age 7 years were found to be delayed in early neurodevelopmental milestones in the language and motor domains.[18] Similarly, early motor and cognitive delay on parental retrospective recall occurred at a higher frequency in children with significant reading problems.[19] Early developmental deficits have been documented to precede school-aged deficits in handwriting,[20] whereas early perceptual motor problems have been noted to precede poor performance on early academic mathematic concepts.[21] Thus, early delayed development can be the substrate on which later significant academic problems arise.[18] However, the actual association between early developmental delay and overall functioning at school entry has not yet been described.

Our study was designed to address these deficits. The aim was to describe the natural history of global developmental delay by delineating the developmental and functional profiles at school age in a community-derived cohort of children diagnosed with this entity. Knowledge of such outcomes will serve to improve prognostication and family counseling while also serving to direct more specific targeted intervention to minimize acquired disability. We also sought to identify possible risk factors evident at intake that can highlight subgroups of children at higher risk of later difficulties.

Our cohort of children with global developmental delay, when evaluated for their developmental profile of ability (ie, what they can do) using the Battelle Developmental Inventory, scored well below the norm across all domains assessed. Group means for the cohort were consistently more than 1.5 SD below the normative mean, with relatively little variation between the domains tested. Furthermore, a high percentage of children in the cohort (between 78% and 100%) scored below the clinically meaningful cutoff, suggesting considerable ongoing apparent and relevant developmental limitations. Nosologic stability of the original global developmental delay diagnosis was demonstrated because all but one child at follow-up fit the ongoing definition for a global delay.

Functional status, which is a measure of what a child does within the context of everyday activities pertaining to individual and social sufficiency, was also assessed. Similarly, group means were well below normative means. Relatively stronger performance in the socialization domain was noted compared with communication and especially daily living skills. Although a high percentage of children in the cohort (61-76%) scored below the clinically meaningful cutoff for this standard test, the performance profile was better than for developmental skills, suggesting that these children are able to adapt to some extent to their impairments. Presumably, this is achieved by either modifying or simplifying everyday tasks and/or by altering the environment so as to enable them to perform some activities independently.

Univariate and multivariate regression analysis was undertaken to identify possible predictor values evident at initial assessment for this later developmental and functional performance. With respect to developmental performance, the presence of any identified etiology responsible for a child's global developmental delay was predictive of poor performance on the fine motor and motor domains of the Battelle Developmental Inventory. Surprisingly, the degree of initial delay was not predictive of later developmental outcome. The degree of initial delay was noted to predict later functional performance in communication skills and overall skills, with an increasing severity correlating with later poorer functional performance.

Enhanced socioeconomic variables, specifically maternal employment and paternal postsecondary education, resulted in better Vineland Adaptive Behavior Scale communication scores. Paternal postsecondary education also improved later Vineland Adaptive Behavior Scale socialization and total scores. This suggests perhaps a mechanism for the better functional as opposed to developmental outcome. Perhaps better parental capability (ie, employment, education) reflects greater advocacy on behalf of the child, which leads to improved access to available resources to minimize disability. This provides further evidence that eventual outcome is, indeed, modifiable.

Our data suggest that children with an early diagnosis of global developmental delay have persistent significant difficulties at school age in both developmental and functional outcomes. Furthermore, this poor performance occurs across all domains of function and adaptation as well. Thus, the early involvement across different constructs and tracks of development persists over time. This widespread poor performance is clinically meaningful as manifested by the majority of children falling below widely used cutoffs and by the particularly poor functional performance related to daily living skills. Although the degree of initial delay was found to be predictive of later functional performance, a paucity of predictor variables was noted regarding developmental outcomes.

It appears from our data that the global developmental delay diagnostic construct has both nosologic and prognostic value with regard to eventual performance pattern and the persistence of meaningful difficulties in midchildhood during the early school years. Knowledge of these developmental and functional outcomes will assist the clinician in prognostication and family counseling with respect to setting realistic expectations for the child and perhaps setting objective goals for intervention.[1] The persisting difficulties highlighted suggest that a programmatic approach to the population of children with global developmental delay might be of benefit.[5] Such a programmatic approach would involve periodic systematic reassessments at key points in the lifespan to both identify ongoing difficulties (particularly those that impact on school performance) and target interventions and resource needs for children continuing to struggle. This periodic reassessment would identify those children in need of additional therapeutic intervention and guide appropriate resource allocation.[5] It is hoped that such an approach would potentiate and extend the efforts of any previously applied early intervention strategies. It has been reported that early intervention can result in significant improvements in developmental outcomes; however, these benefits diminish over time once interventions are stopped.[22] This supports the need for periodic 'injections' offered through a comprehensive programmatic approach. In this way, functional and developmental capabilities can be enhanced and, indeed, individual, familial, and societal burdens minimized.

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