PhD, Faculty of Health Sciences, University of the Witwatersrand / HIV/AIDS continues to be one of the greatest health challenges which South Africa faces.
The epidemic in children is closely linked to that in women, the prevalence of which
continues to grow according to antenatal statistics from the South African Department of
Health (DOH). HIV is known to invade the central nervous system at the time of infection,
and causes widespead damage. In children, this leads to a well-researched condition
known as HIV encephalopathy, which affects all areas of neurodevelopment. The effects
of timely initiation of antiretroviral therapy on alleviating the impact of encephalopathy
have been well described.
Neurodevelopmental delay is a stage four disease indicator according to the World Health
Organisation (WHO), and therefore is a criterion for initiation of Highly Active Antiretroviral
Therapy (HAART). HAART is often only administered according to the virologic and
immunologic status of a child, as standardised neurodevelopmental assessment tools are
not widely available in South African clinics. When HAART initation is dependent on
immunologic status, it is often too late to prevent encephalopahy. To date, the only means
of prevention of this condition is early initation of HAART, which has not been widely
available in South Africa. Stringent guidelines for the commencement of this therapy
according to the WHO, and the South African Department of Health (DOH) have had to
be followed, leading to late initiation of HAART, and widespread central nervous system
encephalopathy. Studies which have been carried out in South African clinics have
demonstrated the high prevalence of this condition. Once there is evidence of
encephalopathy, children should be referred for assessments in all facets of development,
and where necessary, for rehabilitation. A standardised developmental screening tool
which is suitable for use in a developing country is therefore necessary in order to screen
for neurodevelopmental delays to allow for further assessment and referral to
rehabilitation services, as well as providing an additional assessment criterion for initiation
of HAART.
Paediatric HIV clinics in developing countries are understaffed, and children may be seen
by junior staff or screened by nurses due to the high numbers of clinic attendees. This
often results in neurodevelopment being inadequately assessed and children are
therefore not referred for intervention services. A standardised screening tool, which
The Development of a Screening Tool to Evaluate Infants who are HIV Positive
could be administered by clinic staff in order to ensure correct and timely referral of
children for further assessment and intervention is therefore necessary. This is of
importance both locally and internationally where a screening tool, which has been
developed specifically for this purpose, does not exist.
The aim of this study was therefore to evaluate the agreement between the Bayley-III
Screening Test and the Bayley Scales of Infant Development (3rd version) in a population
of HIV positive infants in order to evaluate its appropriateness for use in South Africa. The
Bayley Scales of Infant Development have long been considered the ‘gold standard’ in
infant developmental assessment, which is why this tool was chosen to evaluate the
Bayley-III Screening Test against. The developmental scores in each facet (cognitive,
motor or language) were evaluated to determine which should be included in an
assessment tool for this population. Further objectives for the study were to adapt the
screening tool to the needs of the population, or to develop a new screening tool should
the Bayley-III Screening Test not prove suitable for use in this population.
In order to meet the aims and objectives, a cross-sectional study was conducted where
112 HIV positive infants between the ages of six and eighteen months were assessed
using the Bayley-III Screening Test and the Bayley Scales of Infant Development (3rd
version) (BSID III). The infants were stratified into four age groups namely 6-8 months, 9-
12 months, 13-16 months, and 17-18 months. Children were recruited from Harriet Shezi
Children’s Clinic at Chris Hani Baragwanath Hospital in Soweto.
The agreement between the Bayley-III Screening Test and the Bayley Scales of Infant
Development (3rd version) was analysed using Kappa, for the overall group, and for each
age group. Overall agreement between the tools was as follows: K=0.58 for the Cognitive
facet, K=0.82 for the Expressive Communication facet, K=0.76 for the Receptive
Communication facet, K=0.44 for the Fine Motor facet and K=0.57 for the Gross Motor
facet. These values indicate that the Bayley-III Screening Test is therefore not
acceptable for clinical use, as excellent agreement (k≥0.75) in all facets would be
necessary for this purpose.
A new screening tool therefore had to be developed. The infant’s developmental scores
from the BSID III were analysed to determine which facets of development were most
severely affected, and therefore which facets should be included in a new screening tool.
Gross motor function was demonstrated to be the area which was most severely affected,
followed by cognitive function. A gross motor screening tool would therefore be suitable
for use in this population, as no equipment would be necessary. Gross motor
development is the most universally similar aspect of development, which is not
completely dependent on cultural or socioeconomic factors which often have an influence
on language and cognitive development.
Item selection from the BSID III was undertaken to determine which items should be
included in a brief screening tool. In each of the four age groups, item selection occurred
as follows: Two items which discriminated the At-Risk, from Emerging and Competent
groups (less than 20% in the At-Risk group, and 100% in the other groups) were selected.
Two items, which discriminated between children in the ‘Emerging’ and ‘Competent’
categories on the BSID III were selected (0-5% of children who were At-Risk obtained
credit, 30-50% of the Emerging group obtained credit, and 100% of the Competent group
obtained credit). Lastly, two items were selected which discriminated the Competent
group from the other two groups (100% or as high as possible in the Competent group,
and 0% in the other groups).
The new gross motor screening tool was assembled using the selected items, scoring
was allocated, and it was tested against the scores obtained on the Gross Motor facet of
the BSID III for the initial 112 infants. Agreement between the tools was analysed using
Kappa, and refinements were made according to the discrepancies. This was done three
times, until the Kappa value revealed excellent agreement between the tools (k = 0.87). A
panel of experts was then invited to examine the new gross motor screening tool, and to
comment on it, and further adjustments were made accordingly.
Preliminary concurrent validity testing of the new gross motor screening tool was then
carried out against the Gross Motor facet of the BSID III on 60 children, who were
recruited from the Harriet Shezi Children’s Clinic at Chris Hani Baragwanath Hospital in
Soweto. Statistical analysis revealed that the agreement between the BSID III and the
new screening tool was excellent (k=0.85). The diagnostic properties of the new gross
motor screening tool were as follows: sensitivity 97.4%, specificity 85.7%, positive
predictive value 92.7%, and negative predictive value 94.7%. These values indicate that the statistical properties of the tool are excellent, and the tool will not be predisposed to
underreferrals or over-referrals. Preliminary reliability testing was carried out on 15
children for test-retest/intrarater reliability and 15 children for interrater reliability.
Interrater, test-retest and intrarater reliability were excellent (r=1, r=0.98, r=0.98
respectively). Further testing of reliablity and validity should be undertaken in order to
establish these properties, and standardisation should also be carried out on healthy
children. Given the need for an assessment tool of this nature in South Africa and other
developing countries, and the statistical properties thus far, the tool may be used clinically
for the purposes for which it was developed.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/9392 |
| Date | 06 April 2011 |
| Creators | Hilburn, Nicole Clare |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
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