The consequences of childhood hearing impairment are often overlooked, according to a Viewpoint published in this week’s edition of The Lancet.
Dr Bolajoko Olusanya, of the Institute of Child Health, University College London, UK, and Professor Valerie Newton, University of Manchester, UK, reviewed disease control priorities published in a World Bank report – "The Global Burden of Disease Study" (GBDS) – and subsequent Global Burden of Disease Initiative" (GBDI) which followed it.
Among other things the GBDS report sets out cost-effective interventions for international resource mobilisation and allocation to the developing world.
They found that although the figures in the report included adult-onset hearing impairment, they excluded permanent childhood impairment and all other child-onset hearing impairment in the calculations of the burden, financial and social, of this disability worldwide.
The degrees of hearing impairment and its related consequences range from mild dysfunction in language learning for children with a small (16-25 decibel) loss to complete social isolation for those with a hearing loss of 90db or more.
Of 120 million babies born per year in the developing world, an estimated 718,000 will have permanent bilateral hearing impairment as infants. Failure to detect and effectively manage permanent hearing loss in the first year of life has been associated with substantial and irreversible deficits in speech, linguistic and cognitive development.
GBDS justified the exclusion of childhood-onset hearing impairment on the grounds that it was already accounted for as being caused by congenital conditions, infectious diseases or injuries. But evidence suggests that a substantial portion of children have hearing impairment of unknown causation.
National health systems in many developing countries are too weak to bear the added burden of non-fatal but disabling disorders without external technical and financial support.
The authors conclude: "Although some limitations of the GBDI have been identified by the inequitable treatment of some important diseases, it is still a valuable foundation for improvement of the health of the underserved – and one for which further refinements can be introduced, especially for disorders such as permanent hearing impairment in early childhood that are not presently or adequately addressed."
Journal
The Lancet