Hearing loss and hearing gained: the prevalence of hearing loss and efficacy of hearing aid donation in the Philippines

The limited data available on the prevalence of hearing loss in low and middle income countries indicate that it is highly prevalent and associated with a high burden of disease, such as delayed speech and language development, social isolation, and decreased educational and vocational attainment. This, coupled with a high rate of economic hardship and lack of public health services, suggest that there is a vast unmet need for hearing healthcare services. Philanthropic hearing aid donation programs attempt to bridge this gap, however, no research on the effectiveness of philanthropic hearing aid donation programs exists in the literature. This is partly because few locally translated and normed hearing aid outcome measures exist in many of these countries. In a series of four papers focussed on the Philippines, this thesis investigates; the prevalence of hearing loss in adults and children, the effectiveness of a hearing aid donation program, and the psychometric properties of two translated outcome measures - the hearing handicap inventory short-form for adults and the elderly (HHIA-S and HHIE-S), and the international outcomes inventory for hearing aids (IOI-HA). Results show a high prevalence of hearing loss, compared with high income countries, and regional neighbours. In mild-severely impaired adults, the HHIA-S and HHIE-S showed psychometric properties similar to previous reports; but were insensitive to profound loss. The IOI-HA also showed psychometric properties in line with previous reports, however there was a lack of correlation to objective measures of hearing aid fitting. Additionally, the majority of donated hearing aids were broken or significantly under-fit six months after fitting. These findings highlight the high burden of disease of hearing loss in the Philippines, limitations of hearing aid donation programs, and limitations of outcome measures when applied in such populations.