Why does hearing loss matter?

Whether from a developed or underdeveloped country, chronic hearing loss in children impairs speech and language development.^{Reference Olusanya, Neumann and Saunders14} Disability and handicap results, for example through poor educational and vocational attainment. Unemployment rates are higher in deaf adults, and those that do achieve employment usually receive a lower grade than the general population.^{Reference Olusanya, Neumann and Saunders14} Children whose hearing is impaired are more prone to experiencing emotional, sexual and physical abuse, including murder.^{Reference Olusanya, Neumann and Saunders14,Reference Jones, Bellis, Wood, Hughes, McCoy and Eckley15}

The WHO estimates that unaddressed hearing loss has a global cost of 750 billion international dollars.¹² Many causes of disabling hearing loss are preventable and, owing to its negative consequences, prevention is paramount.

Hearing loss in developing countries

The prevalence of childhood disabling hearing loss is higher in developing countries.¹³ Of children aged under 15 years of age, 2.4 per cent have disabling hearing loss in South Asia, a low-income region, compared with 0.5 per cent in high-income countries.¹³ Eighty per cent of the world's deaf population receive no education. This is particularly skewed towards low- and middle-income countries, where almost no deaf people receive an education. This has devastating consequences for deaf children's futures.¹⁶

Hearing loss in children and adolescents

Sixty per cent of disabling hearing loss in children aged under 15 years is preventable. There is a disproportionately high burden in low- and middle-income countries, where 75 per cent of cases are preventable, compared with 49 per cent in high-income countries.^{Reference Graydon, Waterworth, Miller and Gunasekera11,12}

Infections are the main preventable cause.^{Reference DeAntonio, Yarzabal, Cruz, Schmidt and Kleijnen17–Reference Brophy-Williams, Jarosz, Sommer, Leach and Morris19} They occur antenatally (rubella and syphilis) or during infancy (mumps, measles and rubella). Persistent middle-ear infections cause chronic suppurative otitis media (CSOM), a condition affecting 330 million people worldwide. It is more common in low- and middle-income countries, accounting for roughly 25 per cent of the ENT workload, and is associated with higher complication rates.^{12,Reference DeAntonio, Yarzabal, Cruz, Schmidt and Kleijnen17,Reference Orji20,Reference Mushi, Mwalutende, Gilyoma, Chalya, Seni and Mirambo21}

Complications from childbirth may cause sensorineural hearing loss. This is usually secondary to cerebral damage, which may result from birth asphyxia and hyperbilirubinaemia. These complications more commonly affect premature neonates.¹²

Ototoxicity is the third main cause of hearing loss. It most commonly arises from medication use in babies or pregnant mothers.¹²

Hearing loss in adults

The difference in frequency of disabling hearing loss cases between low- or middle-income countries and high-income countries is greatest in those aged under 15 years, but adult populations differ too.

Adult disabling hearing loss is usually due to disease originating from childhood, degenerative changes and noise-induced disabling hearing loss. Many low- and middle-income countries are experiencing rapid urbanisation, and so residents are increasingly exposed to unregulated amounts of noise pollution,^{Reference Schwela, Finegold, Stewart and Griefahn22} which contributes to the high prevalence of noise-induced disabling hearing loss.^{Reference Olusanya, Neumann and Saunders14}

Minimising preventable hearing loss

As many disabling hearing loss cases in low- and middle-income countries are preventable, we can intervene in numerous ways to reduce its incidence. Self- and herd-immunity can be induced through providing childhood immunisations, particularly against measles, mumps, rubella and bacterial meningitis.^{12,Reference Olusanya, Neumann and Saunders14,Reference Brophy-Williams, Jarosz, Sommer, Leach and Morris19} Contraceptive access in low- and middle-income countries is poor. Therefore, immunising women of reproductive age against rubella, screening pregnant females for syphilis, and improving antenatal care all help to reduce neonatal disabling hearing loss.^{12,Reference Olusanya, Neumann and Saunders14,Reference Brophy-Williams, Jarosz, Sommer, Leach and Morris19}

Preventing the vertical and horizontal transmission of human immunodeficiency virus would help to reduce complications that occur secondary to CSOM (odds ratio = 4.3, 95 per cent confidence interval (CI) = 1.17–15.6; p = 0.028).^{Reference Mushi, Mwalutende, Gilyoma, Chalya, Seni and Mirambo21} Implementing newborn hearing screening programmes in low- and middle-income countries would improve the early diagnosis and treatment of sensorineural hearing loss. High-quality ENT training for professionals, accessible primary healthcare services, and up-to-date technology could prevent unsafe prescribing of ototoxic medication and allow disease to be identified at an early stage.^{Reference Smith, Huins and Bhutta18,Reference Brophy-Williams, Jarosz, Sommer, Leach and Morris19,Reference Schwela, Finegold, Stewart and Griefahn22–Reference Bhutta24} Early disease identification would reduce the prevalence of CSOM-associated complications that occur more frequently in prolonged and untreated disease (odds ratio = 1.03, 95 per cent CI = 1.007–1.05; p = 0.01).^{Reference Mushi, Mwalutende, Gilyoma, Chalya, Seni and Mirambo21}

Minimising noise exposure is essential.^{Reference Brophy-Williams, Jarosz, Sommer, Leach and Morris19,Reference Bhutta24} In the UK, the Control of Noise at Work Regulations (2005) ensure that employers reduce occupational noise to prevent it impairing their employees’ hearing.²⁵ Pressure must be put on low- and middle-income countries’ governments to create similar legislation, which is often lacking. If environments and occupations cannot be altered, personal protective equipment must be available.^{Reference Brophy-Williams, Jarosz, Sommer, Leach and Morris19}

Low- and middle-income countries carry a larger proportion of disabling hearing loss than developed countries, but the care available is minute in comparison.^{Reference Harris and Dodson26,Reference Emerson, Job and Abraham27} Although some progress has been made over the last decade to expand primary care health services in low- and middle-income countries, with a focus on educating local people in the effective management of ear diseases, accessing high-quality care remains very difficult.^{Reference Harris and Dodson26–Reference Mulwafu, Nyirenda, Fagan, Bem, Mlumbe and Chitule28}

Smoking

Over the last 10 years, tobacco use has increased by 2–3 per cent each year in India, and is expected to be responsible for 13 per cent of all deaths per year there by 2020.^{Reference Jandoo and Mehrotra42} In low- and middle-income countries, cancer of the oral cavity and throat is one of the commonest causes of death. The Aizawl district in India has the highest incidence of pharyngeal and tongue cancer in the world, affecting 11.5 and 7.6 per 100 000 population respectively.^{Reference Joshi, Dutta, Chaturvedi and Nair39}

Alcohol

In most low- and middle-income countries, alcohol is consumed infrequently but heavily.⁴³ Moderate and heavy alcohol use increases the risk of cancer, including cancer of the larynx. A systematic review demonstrated a risk-ratio of 1.44 (95 per cent CI = 1.25–1.66) for moderate consumption and 2.65 (95 per cent CI = 2.19–3.19) for heavy consumption.^{43,Reference Islami, Tramacere, Rota, Bagnardi, Fedirko and Scotti44} Through lack of education, low- and middle-income countries’ inhabitants are less aware of alcohol's negative consequences, and alcohol cessation strategies tend to fail.⁴³

Air pollution and head and neck cancer

High levels of air pollutants are associated with an increased risk of developing head and neck cancer.^{Reference Sapkota, Gajalakshmi, Jetly, Roychowdhury, Dikshit and Brennan34} Seventy-four per cent of the Indian population relies on solid fuels, greatly contrasting with that of high-income countries. For instance, in April 2017, Britain generated all electricity without using any coal.⁴⁵ The use of coal in India continues to increase, rising at a rate of 2.8 per cent each year.^{Reference Sapkota, Gajalakshmi, Jetly, Roychowdhury, Dikshit and Brennan34,Reference Penney and Cronshaw46}

A retrospective case–control study investigated exposure to air pollution from solid fuels as a risk factor for laryngeal and hypopharyngeal cancer.^{Reference Sapkota, Gajalakshmi, Jetly, Roychowdhury, Dikshit and Brennan34} Exposure to burning coal indoors for over 50 years increased the risk of developing hypopharyngeal cancer (odds ratio = 3.47, CI = 0.95–12.69) and laryngeal cancer (odds ratio = 3.65, CI = 1.11–11.93).^{Reference Sapkota, Gajalakshmi, Jetly, Roychowdhury, Dikshit and Brennan34} Other solid fuels, such as wood, increased the risk of hypopharyngeal cancer too (odds ratio = 1.62, CI = 1.14–2.32), but not in never-smokers.^{Reference Sapkota, Gajalakshmi, Jetly, Roychowdhury, Dikshit and Brennan34}

Human papillomavirus and head and neck cancer

Human papillomavirus is present in 50 per cent of squamous cell carcinomas of the head and neck, particularly affecting the tongue and tonsils.^{Reference Joshi, Dutta, Chaturvedi and Nair39} Changing oral sexual practices and the presence of high-risk HPV genotypes have increased the frequency of HPV-associated head and neck cancers in low- and middle-income countries. These particularly affect younger patients and are not sex-specific.^{Reference Joshi, Dutta, Chaturvedi and Nair39} Human papillomavirus is present in 16 per cent of oral and laryngeal cancers in high-income countries; this rate is lower than in low- and middle-income countries, especially India where prevalence ranges from 33.6 per cent to 67 per cent.^{Reference Kreimer, Clifford, Boyle and Franceschi47}

By understanding the biology of HPV-associated cancers, there is no reason to suggest that the HPV vaccine's protective properties would differ in efficacy between head and neck cancer and anogenital cancer.⁴⁸ Human papillomavirus vaccinations for genotypes 16 and 18 could prevent over 90 per cent of HPV-associated oropharyngeal cancers, supporting the argument that males should be vaccinated too, owing to their higher risk for HPV-associated head and neck cancer.^{48,Reference Bogaards, Wallinga, Brakenhoff, Meijer and Berkhof49}

Human papillomavirus vaccines are widely available in high-income and some middle-income countries. Although one of the most cost-effective methods for disease prevention, vaccines are rarely available in low-income countries.^{50,Reference Lahariya51} For vaccines to become widely available, financial subsidies must be provided. Recently, Ministries of Health and non-governmental organisations have used donated vaccinations to try and improve conditions.⁵⁰ Although a worthwhile effort, governmental and international projects are essential; otherwise, HPV-associated head and neck cancer rates are unlikely to fall.

Head and neck cancer care in developing world

Steps must be taken to both prevent and manage head and neck cancer in low- and middle-income countries. Primary preventative initiatives such as international media campaigns to raise awareness of the current head and neck cancer crisis, taxing tobacco and alcohol use, designating smoke-free areas, vaccinations, ventilation for buildings, and safe-sex programmes are essential. Secondary prevention by appropriately training professionals to manage head and neck cancers, and encouraging smoking cessation, would also be of great value.

Education and communication

Both public and healthcare staff in low- and middle-income countries are insufficiently educated in the prevention, diagnosis, treatment and rehabilitation of ENT disease. Public behaviours increase the population's risk of disease, but healthcare is insufficient in quality and quantity.⁵⁶ This is a result of poor local training and the migration of professionals.⁵⁶ Therefore, low- and middle-income countries become dependent on the importation of external practitioners who they cannot afford.⁵⁶ International bodies must help to fund training programmes for local people, as done rather successfully in Malawi by Mulwafu et al.^{Reference Mulwafu, Nyirenda, Fagan, Bem, Mlumbe and Chitule28} Being trained to deliver preventative healthcare, such as vaccinations and contraception, is paramount.

Innovative low-cost methods for training are needed. Clark et al.^{Reference Clark, Westerberg and Mitchell57} developed an Ear Trainer for low-resource settings, which recently has been validated as a realistic representation of the ear for microsurgical training. GoogleGlass is a company that has streamed live surgical operations online using a camera attached to spectacles.⁵⁸ In 2014, its first operation was live-streamed to 13 000 surgical students from 115 different countries. Students had their questions answered by the surgeon in real-time, representing a cornerstone in transnational education, and providing promise for future training in low- and middle-income countries.⁵⁹

Telemedicine, the use of electronic information and technology to provide healthcare when distance separates the patient from the professional, should be utilised as an affordable way to communicate with, and provide care to, low- and middle-income countries, which often have limited transport opportunities.^{60,Reference Combi, Pozzani and Pozzi61}

Humanitarian efforts

Although most aid is provided vertically, when trying to establish a sustainable healthcare system, horizontal aid should predominate.^{Reference Elzinga62} Financial co-operation from multiple bodies is required to establish a sustainable healthcare system in low- and middle-income countries. Independent donors, universities, ministries, and both governmental and non-governmental organisations must contribute, so that healthcare professionals can be recruited and resources made available.^{Reference De Maeseneer, van Weel, Egilman, Mfenyana, Kaufman and Sewankambo63}

Healthcare infrastructure

A sustainable healthcare system requires robust financing, a well-trained workforce who are paid adequately, an evidence-base to assist in decision-making, technology able to diagnose and treat disease, and a system to deliver medicine and technology to patients.⁵⁶ Most low- and middle-income countries’ healthcare systems underachieve in all these categories, for a variety of reasons.⁵⁶

In order to maximise the population's health for the lowest cost, most funding should target high-quality primary care service provision, with a focus on disease prevention.^{Reference Brophy-Williams, Jarosz, Sommer, Leach and Morris19,64,Reference Kaur, Clark and Lea65} This is difficult to implement, however, as privately-run services often provide treatment for established disease and thus prevention strategies are of little interest.

The role of non-governmental organisations is not simply to ‘fill gaps’ in healthcare; they can provide large-scale innovative health programmes.^{Reference Mercer, Khan, Daulatuzzaman and Reid66} But non-governmental organisations face challenges. They are dependent on donors, they usually lack a strategic plan and they often have conflicting political governance. Governments are usually focused on public popularity with short-term objectives. Along with other political motives such as pressure from big businesses (pharmaceutical, tobacco and alcohol), convincing governments to prioritise a long-term commitment towards establishing an effective disease prevention strategy is challenging.