Academic journal article Bulletin of the World Health Organization

Community-Based Infant Hearing Screening for Early Detection of Permanent Hearing Loss in Lagos, Nigeria: A Cross-Sectional study/Tests D'audition En Communaute Pour Les Nourrissons En Vue Du Depistage Precoce Des Hypoacousies Permanentes a Lagos, Au Nigeria : Etude transversale/Cribado Comunitario De la Audicion del Lactante Para la Deteccion Precoz De la Hipoacusia Permanente En Lagos, Nigeria: Estudio Transversal

Academic journal article Bulletin of the World Health Organization

Community-Based Infant Hearing Screening for Early Detection of Permanent Hearing Loss in Lagos, Nigeria: A Cross-Sectional study/Tests D'audition En Communaute Pour Les Nourrissons En Vue Du Depistage Precoce Des Hypoacousies Permanentes a Lagos, Au Nigeria : Etude transversale/Cribado Comunitario De la Audicion del Lactante Para la Deteccion Precoz De la Hipoacusia Permanente En Lagos, Nigeria: Estudio Transversal

Article excerpt

Introduction

WHO estimates that globally the number of people with hearing loss, defined as a loss of more than 40 dB on the hearing loss scale (> 40 dB HL), has more than doubled from 120 million in 1995 to at least 278 million in 2005, thus making this condition the most prevalent sensory deficit in the population. (1-3) Permanent hearing loss can occur at any age but about 25% of the current burden is of childhood onset. (1) Annually, up to 6 per 1000 live-born infants, or 798 000 babies worldwide, suffer permanent hearing loss at birth or within the neonatal period and at least 90% of them are in developing countries. (4)

Permanent congenital and early-onset hearing loss (PCEHL) is etiologically heterogeneous and associated with significant and irreversible deficits in linguistic, cognitive and psychosocial development. (5-9) Primary prevention through immunization, genetic counselling, and improved antenatal and perinatal care may help to address some environmental causes, such as birth trauma, infection and neonatal jaundice requiring exchange blood transfusion, but has a limited impact on genetic or hereditary etiologies, such as connexin 26, Pendred and Usher syndromes. (1,10) Moreover, effective primary prevention is rarely possible in the 38-60% of children with idiopathic PCEHL who live in developing countries. (11,12) Nonetheless, such infants can develop essential language and cognitive skills if the condition is detected early and they are provided with appropriate intervention services within the first year of life. (13-15)

In recognition of the complementary value of implementing both primary and secondary prevention measures for permanent hearing loss, the World Health Assembly passed a resolution in 1995 urging Member States to:

prepare national plans for the prevention and control of major causes of avoidable hearing loss, and for early detection in babies, toddlers and children within the framework of primary health care. (16)

Although the resolution did not propose methods of achieving the goal of early detection, universal newborn hearing screening using transient evoked otoacoustic emissions (TEOAE) and automated auditory brainstem responses (AABR) before hospital discharge has been effective in many countries. (17-19) In the absence of such objective screening, PCEHL may not be detected until the child is 2-6 years of age, when intervention outcomes may be suboptimal. (17)

Current evidence suggests that Nigeria has the highest proportion of developmentally disadvantaged children in the world, excluding those with hearing loss. (20) Nonetheless, the present standard of maternal and child health care in the country makes the primary prevention of PCEHL untenable. In addition, conventional hospital-based universal hearing screening programmes are unlikely to be effective, as the majority of births occur outside regular hospitals. (21) Routine childhood immunization programmes in developing countries often provide effective community-based platforms for attracting a significant number of babies born outside regular hospitals for new health interventions under the concept of "immunization plus". (22) Consequently, this study set out to determine the feasibility and effectiveness of community-based (i.e. non-hospital) universal infant hearing screening during bacille Calmette-Guerin (BCG) immunization for the early detection of PCEHL in Nigeria.

Methods

Location and setting

This cross-sectional study was conducted in an inner-city area of Lagos, Nigeria, with a population of 243 777. The area is served by one general, one pediatric and one maternity hospital as well as by seven health centres, all of which are state-owned, and by several private hospitals. The availability of an established audiological centre that could provide appropriate interventions for children in whom PCEHL was detected was a key factor in choosing this study location. …

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