Product Narrative: Hearing Aids

3.1. Globally 466 million people have disabling hearing loss; this number is expected to double by 2050 due to ageing populations, and new cases of hearing loss caused by untreated ear infections, ototoxicity, and noise exposure.

Hearing loss that prevents hearing at thresholds lower than 40 decibels (d.B.) in the better hearing ear in adults and lower than 30 d.B. in the better hearing ear in children is known as disabling hearing loss.4 More than 5% of the global population—or 466 million people—have disabling hearing loss, with 34 million of these being children.5 It is the fourth leading cause of disability globally.6 Approximately 90% of people with hearing loss live in low- and middle-income countries (L.M.I.C.s) with prevalence rates almost four times that of high-income regions.7

Multiple causes for hearing loss exist, but they can primarily be placed into two categories: congenital and acquired factors. Congenital causes include genetic causes and complications due to pregnancy or childbirth such as maternal infections (especially congenital syphilis), birth asphyxia, exposure to certain drugs during pregnancy, and low birth weight or jaundice. It is estimated that five out of every 1,000 babies are born with hearing loss or acquire it soon after birth in one or both ears. Acquired causes can occur at any age and include infectious diseases, such as mumps, measles or rubella, chronic ear infections, use of ototoxic medicines (i.e. medicines known to damage cells in the ear), injury, noise exposure, and blockages in the ear canal.8 Untreated infections, ototoxicity and ear blockages are the primary factors for hearing loss in L.M.I.C.s.

The number of people with disabling hearing loss is expected to double to 900 million people by 2050,9 driven by:

POPULATION GROWTH AND AGEING. Disabling hearing loss is associated with ageing; approximately one-third of people over 65 years of age are affected by disabling hearing loss10 and as the population increases from 7.5 billion people11 in 2017 to 10 billion in 205012, the world's population over 65 years of age is expected to double to 1.5 billion.13
NOISE EXPOSURE. Noise exposure can come from occupational environments, entertainment venues, and personal listening devices. The W.H.O. estimates that 1 billion young people are at risk of hearing loss due to listening practices.
UNTREATED EAR INFECTIONS. Inability of health systems to identify and treat incident and chronic ear infections will result in an additional 16.5 million people developing hearing loss each year.14
OTOTOXICITY. Certain classes of drugs, such as some used in the treatment of neonatal infections, malaria, drug-resistant tuberculosis (T.B.) and cancers, have ototoxic side effects that can result in hearing loss (refer to Case Study 1).

CASE STUDY 1: MANAGING OTOTOXICITY IN THE T.B. TREATMENT PROGRAMME

Drug-resistant T.B. requires the use of second-line injectable anti-T.B. drugs, such as aminoglycosides and polypeptides, which are associated with hearing loss. Studies demonstrate that the frequency of ototoxicity in patients on treatment has ranged from 10 – 50%.15

To address this issue, the National Department of Health in South Africa implemented an ototoxicity management programme in 2001 with the aim to prevent ototoxicity among people taking medication for T.B. by implementing hearing screening to identify patients who need hearing aids. In 2019, the e.Moyo Foundation, in collaboration with Entheos (a U.S.-based N.G.O.) and Ndlovu Group (a South Africa based N.G.O.), set up a hearing health care pop-up clinic at a local T.B. hospital to provide hearing health services. These include: ear and hearing assessment, ear impression taking, hearing aid fitting (including free hearing aids with earmoulds), and post-hearing aid fitting and maintenance support.