Elsevier

Early Human Development

Volume 88, Issue 8, August 2012, Pages 637-641
Early Human Development

The long-term predictive validity of early motor development in “apparently normal” ELBW survivors

https://doi.org/10.1016/j.earlhumdev.2012.01.010Get rights and content

Abstract

Background

Within the able majority of ELBW survivors, there is a lack of identified predictors of which children will require extra support despite having escaped significant disability.

Aims

Investigate the predictive validity of early motor scores, compared to that of perinatal descriptors or early growth, on long-term motor impairment in non-disabled ELBW (< 1000 g) children.

Study design

Prospective longitudinal study.

Outcome measures

48 non-disabled ELBW children (27 male) completed the Neurosensory Motor Developmental Assessment (NSMDA) at 8 months, 2 years and 4 years post term and The Motor Assessment Battery for Children (MABC) at 11–13 years of age. Other possible predictors of long-term outcomes (gestational age, birthweight, multiple birth, head circumference measures and gender) were retrieved from the records.

Results

Early motor assessment (NSMDA score) independently predicted the MABC total score at 11–13 years of age with a positive predictive value of 87% by 4 years post term. There was increased risk of long-term motor impairment associated with male gender but the degree of prematurity, multiple birth status or early growth measures did not predict motor outcome. Postural control and sensory motor scores at 4 years post term, rather than neurological score, were associated with long-term motor outcomes for the ELBW children at 11–13 years of age.

Conclusions

Early motor scores are valid markers of long-term motor outcomes for “apparently normal” ELBW children. Early postural competence and sensory motor function are discriminating in regards to long-term motor function in neurologically normal ELBW children.

Introduction

The majority of extremely low birthweight (ELBW, < 1000 g) children are able [1], [2] but there is a high prevalence of developmental difficulties among these children [3], [4], [5]. These difficulties are associated with an increased use of support and educational services [6], [7], [8]. Perinatal variables, neuroimaging and early follow up assessment give predictive data to indicate which ELBW survivors are at risk of major disability including cerebral palsy (CP), cognitive impairment (more than 2 standard deviations below the mean on general developmental index) or uncorrectable visual or auditory impairment [1], [2], [9], [10], [11]. However, within the able majority of ELBW survivors, there is a lack of identified predictors of which children will require extra support despite having escaped major disability [12], [13].

Neither the degree of prematurity nor early cognitive testing predicts which children within non-disabled preterm groups will have poorer functional outcomes and require extra services [8], [14]. Neonatal ultrasound and magnetic resonance imaging provide evidence of white matter injuries that are associated with poorer outcomes for low birthweight children and adolescents [13], [15], [16]. However, there is still significantly increased prevalence of motor, learning and behaviour problems for preterm children compared to term born populations even in the presence of normal neonatal brain ultrasound scans [17], or if measures of central neural integrity like cognition are controlled [18], [19]. For the able majority of ELBW survivors who have escaped moderate and severe disability, early prediction of mild impairment is unclear.

A recent geographic cohort study of very preterm survivors [11] that assessed visual impairment, deafness, cerebral palsy and cognitive impairment at 2 and 8 years of age found reasonable agreement between 2 and 8 year old classifications of disability for moderate and severe disability (moderate disability: 13.4% at 2 years old, 10.7% at 8 years old; severe disability 13.9% at 2 years old, 8.6% at 8 years old) with an encouraging trend of lessening rates of moderate to severe disability over time. However early diagnosis of mild impairment had poor long-term predictive validity. Many of those children presenting with mild disability at 8 years old had not been identified at the 2 year old assessment: 38 of the 97 children considered to have nil disability at 2 years old were considered disabled at the 8 year old review [11]. As this study did not include measures of motor competence beyond the assessment of cerebral palsy, the validity of early motor assessment for timely identification of mild impairment in ELBW survivors who do not have CP still requires investigation.

The prevalence of mild motor impairment in preschool assessments of ELBW children who do not have CP [20], [21] suggest mild motor dysfunction may be a marker of those ELBW children who are likely to have ongoing developmental difficulties despite having escaped major disability. Although it is only a mild impairment, poorer motor ability in able ELBW children is associated with [3], [4], [5] and even predictive of [14], [20], [22], [23] poorer outcomes generally. This association may represent an opportunity for early identification of those “apparently normal” ELBW children who are likely to have long-term developmental difficulties. With increasing prevalence of extremely preterm birth and improved survival rates [24], the ability to predict long-term outcomes for this growing population is becoming increasingly important.

In an effort to inform improved prediction of long-term outcomes for the able majority of ELBW survivors, this study examined the predictive validity of motor assessment at 8 months, 2 years and 4 years post term as predictors of ongoing motor impairment within a non-disabled ELBW cohort. The predictive validity of early motor assessment was compared with other data normally used to predict outcomes for ELBW children including degree of prematurity, multiple birth status, head circumference and gender. As normal motor function is dependent on competence in perception, postural responses and neuromotor control, this study also investigated what specific aspects of motor development were associated with long-term motor outcomes in these children who did not have neurological disability.

Section snippets

Methods

The ELBW participants in the study group were enrolled from the total cohort born less than 1000 g between January 1992 and December 1994 at the Mater Mothers' Hospital Brisbane, Australia. Only non-disabled survivors were included in the study (disability defined as diagnosis of neurological disability at 2 years of age, more than 2 standard deviations below the mean on a General Cognitive Index at 4 years of age or uncorrectable visual or auditory impairment). One child with an amputated digit

Statistical analysis

Statistical analysis was carried out using SPSS version 14 (SPSS Inc., Chicago, USA), 5% statistical significance was assumed (two-tailed), and the distribution of variables was examined. Differences between the ELBW children who participated in the study and those of the defined cohort who did not were examined. Means and standard deviations (SD) are presented for parametric data, medians and interquartile ranges (IQR) for non-parametric data and percentages for categorical data. The

Results

Of the 105 children who met inclusion criteria, 45 children were lost to follow-up or had moved out of the study area by the 11–13 year old review while 12 children who were contacted either refused or were not available to participate within the designated testing period. The group who completed motor assessment at 11–13 years of age was compared to the group of children who did not (Table 1). The ELBW children who completed the long-term motor assessment did not differ significantly on any

Discussion

Problems of mild motor impairment were evident in these ELBW children who had escaped major disability with male gender associated with increased risk of ongoing motor difficulties. Increasing prevalence of mild motor impairment was noted in assessments of the older age groups however motor assessment as early as 8 months post term identified ELBW children who were likely to have long-term mild motor impairment despite having clinically intact neurological function. The persistence of mild motor

Conclusions

Early motor assessments are valid predictors of long-term mild impairment in “apparently normal” ELBW children. Early motor assessment is a particularly important clinical tool in identifying those children within ELBW cohorts who are likely to have extra support needs despite having escaped major disability as degree of prematurity, multiple birth factor and head circumference fail to predict mild impairment. As persistence of mild motor difficulties throughout the preschool years increases

Conflict of interest statement

None declared. The study sponsor had no involvement in the study design, in the collection, analysis and interpretation of data; in the writing of the manuscript; or in the decision to submit the manuscript for publication.

Acknowledgement

We thank the Mater Foundation for providing financial support for the study.

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