A study to evaluate the performance of black South African urban infants on the Bayley Scales of Infant Development III
Date
2012-01-25
Authors
Rademeyer, Vanessa Kathleen May
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Abstract
South Africa (SA) needs a suitable tool to evaluate child development as no such tool
exists at present. Well known standardised tests are designed in First World Countries but
pose problems when used on different populations. The Bayley Scales of Infant
Development, a tool designed and normed in the United States of America (USA) is
considered to be the gold standard in infant assessment. The revised and updated, 3rd
edition was published in 2006. No studies have been done on its use on populations other
than the USA. The USA and SA populations are very different and therefore may
perform differently on developmental tests since previous research has shown that
African infants perform better than USA infants.
The main aim of this study was to use the Bayley Scales of Infant and Toddler
Development III (Bayley-III) to evaluate the performance of a cohort of black urban
African infants in South Africa, in an effort to determine whether it is a suitable tool for
use on this population. The Hypothesis was that SA and USA children perform similarly
on the test. Other objectives included assessing whether gender or anthropometric
indicators influence performance.
The revised 3rd edition of the Bayley Scales of Infant Development (Bayley-III) was
used to assess the performance of 122 black African infants at several urban clinics in
Gauteng, South Africa. The sample consisted of infants falling into four age categories; 3,
6, 9 and 12 months. SA scores were compared to USA norms. Scores were compared across age groups, subtests and sex. Height, weight and head circumference was also
measured, converted into z-scores and correlated with test scores.
Overall the SA mean score was 103.4, which is statistically significantly higher
(p=0.0007) than the USA mean of 100.For subtests, the mean score was 99.7 for the
cognitive, 106.8 for the language and 103.5 for the motor subtests as opposed to 100 for
the USA. Therefore the results of this study showed that SA scores were statistically
significantly higher than the USA norms. Gender differences in scores for specific
subtests were found, indicating that girls and boys perform differently developmentally at
different ages. However this analysis was at subgroup level with individually small
numbers and further research is required to investigate this. Anthropometric indicators
such as height, weight and head circumference were found to have no significant
association with scores on the test, indicating that growth had no effect on development
in this population
Although the overall SA mean (103. 4) was statistically significantly higher than the USA
mean (100), clinically the difference is small when one considers the variability of
development. Developmental milestones can be reached within a range of months and
can vary considerably. The Bayley-III is therefore a suitable tool to use on this
population. More research is recommended to assess a larger more diverse group,
including all age groups for which the Bayley-III caters, as well as on all population
groups in SA.