Audiological profile of deaf and hard-of-hearing children under six years old in the "HI HOPES cohort" in South Africa (2006-2011)

BACKGROUND

This study concerns deaf children under six years in the South African HI HOPES Cohort.

OBJECTIVE

To examine their audiological profile, aetiological risk factors for infant hearing loss as well as the relationship between identification, amplification and socio-economic influences.

DESIGN

Using a cohort design, secondary data analysis of a pre-existing dataset demonstrated adequate representation of South African demographic characteristics.

STUDY SAMPLE

A total of 532 deaf and hard-of-hearing infants enrolled in the HI HOPES early intervention programme in three provinces (2006-2011).

RESULTS

The median age of identification of children with bilateral hearing loss (n = 502) was 24.0 months (IQR = 12-36 months). Infants with aetiological risk factors were identified later than those without risk factors, and the latest age of identification (28.5 months) was for those with three aetiological risk factors (n = 42). The median age of amplification was 32 months with 102 children eligible for amplification at 31.1 months still unamplified. Early identification did not imply early amplification, and the more economically advantaged a Province the smaller the gap between ages of identification and amplification.

CONCLUSIONS

In a field with little population-level evidence, the size, and representativeness of this dataset makes a significant contribution to our understanding of infant hearing loss in South Africa.

Diagnostic hearing testing of infants aged 0-36 months in 3 South African provinces - Comparison of audiology records to HPCSA guidelines

INTRODUCTION

Within the Early Hearing Detection and Intervention (EHDI) pathway, which includes the processes of screening, diagnosis and intervention for paediatric hearing loss, paediatric diagnostic audiology involves a battery of specific tests and procedures. International studies have highlighted a golden standard for diagnosis of paediatric hearing loss as based on the Joint Committee of Infant Hearing (2007) diagnostic guidelines, closely resembling the HPCSA diagnostic guidelines. There are limited South African studies on the processes and protocols followed in diagnostic paediatric audiology.

OBJECTIVES

This study aims to provide a comparison for how the tests used for diagnosis of paediatric hearing loss in South Africa (within both the public and private healthcare sectors) compare to the HPCSA recommended diagnostic guidelines.

METHODS

A retrospective record review of paediatric clients with hearing loss (recruited through nonprobability convenience sampling) was conducted. This study is part of a longitudinal study of 711 deaf or hard of hearing children referred to the HI HOPES early intervention programme from September 2006 to December 2011. Diagnostic data from audiology reports of 117 children between 0 and 36 months were coded and analysed.

RESULTS

Large variation was found in the tests included in the diagnostic audiology reports. For 22 children (19%) a comprehensive test battery was used. Health Professions Council of South Africa (HPCSA) recommended guidelines for diagnostic testing were not followed in any of the records analysed. Components of the HPCSA recommended test battery most frequently omitted was bone conduction testing. For both electrophysiology and behavioural testing, there was limited frequency specificity information. This exclusion of information is evidence of deficiencies in data recording and management, as well as having an effect on accuracy of classification of degree and type of hearing loss.

CONCLUSION

There are gaps in age-appropriate assessment protocols, which will have an effect on accurate differential diagnosis of paediatric hearing loss. Reasons for not including all testing components of the HPCSA recommended guidelines, as well as the possibility of developing guidelines more relevant to a developing world context, should be explored. There might be a need for. The impact of South African specific factors that have an effect on provision of accurate paediatric diagnostic audiology services should be determined.

The HI HOPES data set of deaf children under the age of 6 in South Africa: maternal suspicion, age of identification and newborn hearing screening

Background

Identification of deafness before 3 months of age substantially improves the socio-linguistic and cognitive development of deaf children. Existing studies demonstrating the feasibility of newborn hearing screening in South Africa have used small samples unrepresentative of general population characteristics. This study establishes the characteristics of the largest data set of deaf infants and their families in South Africa on which there is baseline and longitudinal data (n = 532); explores its representativeness in terms of socio-demographic features and reports on access to and quality of newborn hearing screening within the sample. It examines specifically the relationship between age of maternal suspicion of childhood deafness and age of identification of deafness by cohort characteristics.

Methods

Secondary analysis, using descriptive and inferential statistics, of a pre-existing longitudinal data set (n = 532) of deaf infants under 6 years of age, and their families, collected as routine monitoring of the HI HOPES (HH) early intervention programme.

Results

The HH cohort is representative in terms of racial profile and private/public health care use but displays slightly higher level of maternal education and slightly lower socio-economic status than national comparators. 102 out of 532 infants had undergone newborn hearing screening, resulting in 29 true positives, 15 of whom would have met the criteria for targeted screening. Later onset deafness does not account for the 73 false negatives. The median age of maternal suspicion (n = 247) of infant deafness was 18 months; the median age of identification of 28 months. Age of identification was unrelated to private/public health care status. The median delay between age of suspicion and age of identification was significantly longer in the public sector (7 m; IQR 0–15 m) compared to the private sector (2 m; IQR 0–8.5 m) (p = 0.035). Age of suspicion was unrelated to level of maternal education. Earlier age of suspicion did not predict earlier identification.

Conclusion

Targeted screening as timely response to maternal suspicion offers a viable means to reduce substantially the age of identification of deafness in South Africa until implementation of newborn hearing screening on a population-wide basis can be justified.

Early hearing detection and intervention in South Africa

Early hearing detection and intervention programs have become the standard of care to ensure optimal outcomes for infants with hearing loss, their families and society at large. The overwhelming majority of infants with congenital or early-onset permanent bilateral hearing loss are however born in developing countries like South Africa where services are scarce and awareness poor. Despite its comparatively well-developed economic and reasonably developed health care infrastructure in sub-Saharan Africa, limited information on infant hearing loss and the status of early hearing detection and intervention has been available for South Africa. Recently however, an increasing number of initiatives and reports have highlighted the extent of infant hearing loss and the status of identification and intervention services offered in the country. This report provides a review of the available evidence on infant hearing loss and the status of current early hearing detection and intervention services in South Africa.

EHDI Africa: advocating for infants with hearing loss in Africa

Children with hearing loss who happen to reside in Africa deserve the chance to develop according to their potential as much as their peers living in more affluent regions. This leaves a moral obligation to pursue ways of initiating, developing,and growing early hearing detection and intervention services in Africa. For these reasons, the first EHDI Africa international conference was held in Johannesburg, South Africa, in 2007 (13-14 August). The theme was 'Building bridges in Africa: Early childhood development for children with hearing loss'. This special issue contains several reports from the EHDI Africa conference.