Worldwide it is estimated that 200 million children under 5 years of age do not reach their developmental potential annually [1
]. Nearly 80% of children with disabilities live in low- and middle-income countries [2
]. Known risk factors that are associated with poor developmental outcomes include nutritional stunting, inadequate cognitive stimulation, and lead exposure [4
]. Furthermore, previous studies in Africa reveal that delayed achievement of developmental milestones can be predicted by identifying stunting in high risk populations [5
Children who experience poor nutrition early in life are more likely to have growth stunting [8
]. In turn, stunting in children is also known to cause persistent cognitive deficits [10
]. Also, the burden of nutritional deficiencies falls heavily on low and middle-income regions; as approximately 90% of individuals with undernutrition live in developing countries [11
]. In Uganda, it is estimated that undernutrition contributes to 40% of the child mortality rate for those 5 years of age and younger [12
The association of environmental lead exposure and poor neurocognitive outcomes is also well established [13
]. Even chronic, low-level lead exposure can lead to lower IQ scores, deficits in attention, and slowed growth in children [14
]. The highest risks of lead exposure in Africa include deteriorated house paint, leaded gasoline, mining operations, polluted waters, contaminated foods, and cosmetics [15
]. Young children are particularly vulnerable to the neurotoxic effects of lead due to the higher frequency of hand-to-mouth behaviors and rapid changes in brain development [16
]. One study in Kampala, Uganda found that approximately 20 percent of 4–8 year-old school children have blood lead levels above 7.15 μg/dL [17
Child development screening is limited or non-existent in many low- and middle-income countries [18
]. In these countries, there has been a marked decline in child mortality in recent years, but the prevalence of children living with neurodevelopmental disabilities continues to rise [18
]. Children in East Africa do not routinely receive pediatric well care visits and most children with developmental disabilities are not identified until school age [19
]. Some comprehensive developmental measures, such as the Mullen or the Bayley Scales of Development, have previously been utilized in high-risk global populations, but these can be time-intensive and require additional training to administer [21
It is uncertain whether developmental screening tools standardized in Western industrialized nations are valid across cultures. Western developmental milestone tools adapted for use in African settings tend to be more reliable for gross motor items, compared to social and language development [23
]. There are emerging developmental assessment tools that have been designed for use in low- and middle-income countries, however, many of these are tools are limited to children under 3 years of age. For example, the Caregiver-Reported Early Developmental Instruments (CREDI) measure of child development is a brief tool of early developmental progress in children of 0–35 months, though for study purposes, a longer version is recommended [24
]. The Kilifi Developmental Inventory has been previously validated to assess psychomotor functioning of children in Kenya for ages 6–35 months [25
]. The Guide for Monitoring Child Development is a clinician-caregiver interview designed in Turkey, which has been used to detect early developmental difficulties for children less than two years [26
]. The Developmental Milestones Checklist is a 66-item caregiver interview designed in Kenya to assess motor, language, and social development of children aged 3–24 months [27
]. Additionally, the Malawi Developmental Assessment Tool is a culturally relevant developmental assessment tool for use in rural Africa for children aged 0–6 years, however, it can be lengthy to administer with 136 items across four developmental domains and requires the use of specific objects or props for administration [28
To date, no studies have been conducted on adapted developmental screening instruments that are easily administered in clinical or community settings and are appropriate for high-risk populations aged 6–59 months in East Africa. To begin to answer these questions, we implemented an adapted developmental screening tool to determine if known neurodevelopmental risk factors, specifically lead exposure and undernutriton as assessed by nutritional stunting, are associated with delayed developmental milestones. We piloted the screening tool as part of a larger survey on environmental heavy metal exposure among children living in the Katanga urban settlement [29
]. We hypothesized that elevated blood lead levels and growth stunting would be positively associated with delayed developmental outcomes for chronological age.
We applied an adapted and easily administered screening tool designed to identify developmental milestones of children living in the Katanga urban settlement in Kampala, Uganda. This screening tool identified 14% of children in the study as having potential developmental delays. Comparatively, in the United States, approximately 15% of children between the ages of 3 years and 17 years have a developmental disability [35
]. Contrary to our hypotheses, children’s developmental outcomes were not predicted by their blood lead levels or by height-for-age Z-score less than 2 standard deviations below the reference mean, which are two known correlates of developmental delays. However, there may be other correlates associated with delayed developmental milestones on this screening tool that have yet to be analyzed and the results may vary with a larger sample size. Another implication of these findings is that this screening tool may not have sufficient sensitivity and specificity to accurately detect true developmental delays in this population. Possible explanations for this include cultural and linguistic discrepancies between the screener and its target population.
We adapted the tool from widely used developmental screeners in the United States, including the Child Development Inventory (CDI). Similar tools have previously been adapted for use in East Africa as a low cost option for developmental screening, however these are typically time-consuming and require significant cultural modifications related to wording [36
]. Our results also show that there are potential limitations of using developmental tools from wealthy Westernized nations in low- and middle-income countries. The populations of low- and middle-income countries may have lower parental education and health literacy, as well as differences in family structure. For instance, in East Africa, where extended families often live in shared homes with other families, there tends to be more emphasis on social and emotional security than structured cognitive activities, and young children often spend more time interacting with older children than with adults [36
]. Given these unique social contexts, developmental screening tools created for Western cultures, may not capture normative development patterns specific to East Africa.
A limitation of this study is the small convenience sample of caregiver volunteers and the subsequent limited generalizability to other populations in East Africa. Other significant limitations include: reliance on caregiver-reported milestones and no requirement for primary caregiver participation in the study; the fact that we did not collect a concurrent gold-standard measure of child development with which to determine criterion validity of the screener; the lack of cognitive interviews with study participants to ensure the screeners’ contextual and cultural relevance; and the lack of inter-rater reliability for the study coordinators who administered the screener. Though the two local study coordinators who administered the items on the screening tool by verbal interview were fluent in both Luganda and English, possible communication issues or varying levels of comprehension should be considered, particularly given the wide range in educational backgrounds of the caregivers. Future studies of developmental screening in this population should correlate findings of the developmental screening tool with additional measures of neurodevelopmental risk factors, such as maternal and child health concerns. It was not possible at the time of this study inception to complete a prospective design with the primary outcome measure of developmental skills assessment given that this study was completed as part of a secondary data analysis to a larger cross-sectional study on blood levels of heavy metals in children. Future research should be completed on this screening tool with a prospective study design, controlling for moderators, such as stunting and elevated lead levels, along with a comparison gold-standard developmental assessment to better determine its validity prior to widespread use in community settings.
To meet the need for accurate, brief, culturally appropriate methods to universally screen children’s development in high-risk global populations, more culturally flexible, validated screening tools are needed. These efforts should be paired with a focus on promoting therapeutic interventions for East African children. Addressing undernutrition, maximizing cognitive stimulation, and establishing community-based therapy efforts are effective, low-cost strategies that are likely to enhance child development [26
]. These efforts could be initiated by maximizing existing resources and networks, such as educating parents and community health workers on how to promote improved developmental outcomes for all children.