Honoring Deaf History Month: a conversation with researcher Lydia Haile about IHME’s hearing loss study

Deaf and hard-of-hearing people are everywhere, in every era, socioeconomic status, and age group. An IHME study based on the 2019 Global Burden of Disease (GBD) study found that in 2019, nearly 1.6 billion people globally were living with hearing loss. That’s 1 in 5 people in the world. Of those, 403 million people (nearly 30%) had hearing loss that was moderate or higher in severity after adjusting for hearing aid use, which means that when these people talked with friends in quiet places or on the telephone, they did so with difficulty – if at all. After low back pain and migraines, hearing loss is the third highest cause of years lived with disability (YLDs), and it’s the highest cause of YLDs among sensory disorders.  

The GBD study, by nature, considers hearing loss and deafness as a disability. But hearing loss and deafness is not a uniform or tragic experience, as Through Deaf Eyes, a documentary on Deaf history that’s part of Gallaudet University’s “Deaf Eyes” project, attests. I can attest to this, too—I’ve been hard of hearing since childhood and have had mixed success with using hearing aids, but I have never experienced hearing loss as disabling. How might we value the richness of Deaf culture and the hard-of-hearing experience while also conducting studies that identify and quantify who it affects and where they need more support across the globe? In honor of Deaf History Month, I asked Lydia Haile, a former IHME fellow and lead author of IHME’s study on hearing loss prevalence, to explore how researchers walk this fine line and help us put IHME’s March 2021 paper in perspective. 

First things first, why do so many people suffer from hearing loss? 

The hair cells in our ears are critical to processing and transmitting sounds, and they naturally degrade as we age. As people continue to live longer and longer, we’re going to see populations where a lot of older people are experiencing that natural breakdown. Noise exposure is another leading cause because it can hasten hair cell degradation, leading to hearing loss at earlier ages. Some people experience hearing loss due to genetic factors. People also experience it because of infections like otitis media (an infection of the middle ear) or because they used certain medications.  

Why should we be concerned about hearing loss? 

I think we should be concerned in terms of making sure that people have access to the resources they need to be able to communicate with other people in their community, forge social ties, and feel connected. Research indicates that people who experience hearing loss can be at greater risk of experiencing social isolation. It can be a risk factor for other conditions, too, like dementia. 

But I want to be careful in framing hearing loss as an objectively burdensome condition. Many people who have hearing loss don’t experience their condition in that way, and describing hearing loss as disabling can be seen as insulting to certain groups. It’s less that the experience of not being able to hear certain sounds is inherently bad for your health, and more about what that means for how that individual is able to navigate society. Assistive technologies, hearing aids, sign language, and other communication aids can help make sure that people with hearing loss have the resources that they need. The key issue is communication. 

Some deaf or hard-of-hearing people don’t experience their condition as disabling, or they don’t identify as disabled. In the study, hearing loss is mostly described in terms of its disabling effects, perhaps by necessity because the nature of the GBD study is to measure health loss and determine years of life lived with disability. How do we square that diversity of experience and perception with the ways that hearing loss is categorized and described in the GBD study? 

There’s a lot to be said about how disability is really dependent on social context. An individual who is hard of hearing may not see that condition as limiting them in any way. It’s really more about whether their environment is accommodating their needs.  

When you’re working in the epidemiology and public health space – and particularly if you’re trying to quantify how much a certain condition impacts day-to-day activities – it’s a challenge to factor in the nuance of individual experience, and to do so in a sensitive way that doesn’t presume there is normative state of health or that, if a person hasn’t achieved that normative state, their quality of life is lesser-than. When you assign a value to an individual’s life quantitatively, as the GBD study does, those metrics are loaded and come with certain assumptions that we need to be clear about when discussing and interpreting results.  

The concept of disability is a loaded assumption to place on how people are navigating their day-to-day lives, so I think that, rather than using language that is othering and marginalizes people for having different abilities, we should be careful about addressing the specific needs that people with hearing loss may have – like access to sign language and assistive technologies. There’s certainly a long way to go in that regard with public health. But I do think that there are a lot of people who experience these conditions who are really bringing conversation there.  

When it comes to hearing loss and deafness, what is the GBD study great at describing, and what is beyond its scope? 

GBD is great at taking data on hearing loss prevalence from heterogeneous sources and making that information interpretable and useful to other researchers, policymakers, and health care providers. Otherwise, it is really difficult to gauge how high the prevalence of hearing loss is in a certain country and how that may compare to another country. The data, science, and modeling can clarify what services are needed in that country. For example, the estimates can help uncover where there is need for more audiologists and hearing specialists, or if the level of hearing health care provision is sufficient for a population. That information can be used as a call to action to divert resources to areas where prevalence is high or there is a large unmet need for services.  

In addition to that, the disability-adjusted life years (DALYs) metric can be useful in terms of how it has brought non-communicable diseases and conditions to the forefront in a way that they weren’t historically. For example, DALYs can show that hearing loss is the sensory disorder that causes the most “health loss” globally. With the DALY, we’re able to bring attention to conditions that aren’t commonly thought about when we discuss global health but are just as important. By modeling plausible estimates of prevalence, the GBD study can show how hearing loss and other non-communicable diseases and conditions are affecting a lot of people – not just in the high-income world, but globally.  

The limitations of GBD’s estimation of hearing loss might be that there is only so much information we can obtain from global sources on the underlying factors of hearing loss. So many factors can be associated with hearing loss in a population, and often it’s difficult to obtain that information from survey sources. Models are only as good or as useful as their underlying data. And given the status of data collection on hearing loss problems and the functional limitation associated with hearing loss, I think that it can be difficult to create useful estimates with sparse datasets. 

I will say that with the advance of different diagnostic methods like telehealth, we may see more data from unconventional sources in the future. You can only get granular, useful, and predictive models if you have granular, comparable, and clinically relevant data – which can be challenging given the data collection landscape. 

Did anything surprise you in your March 2021 study? 

We forecasted that 2.5 billion people will experience hearing loss by 2050. That’s a large number! There has been a lot of talk about whether – as time goes on and populations age – there will be enough health care workers to address the needs of those with hearing loss and other conditions. Given the dearth of audiologists and other hearing health care providers that we currently have globally, I think that figure is tough to look at unless there’s a large change in the staffing around audiology and other hearing healthcare services. 

What do you consider the most important findings of that study? 

I think the big takeaway that one in five people experience hearing loss is really important. This is a very common condition or shared experience. As an individual in this world, hearing or not, I’m hoping that means we can all be more conscientious of certain norms that we have in our day-to-day lives. For example, I’m seeing more and more individuals in my generation taking sign language courses to be able to communicate with somebody who primarily uses sign language. Many people experience hearing loss, and there are steps that we can take as individuals moving in the world to make the world easier to navigate for deaf and hard-of-hearing people. 

There’s this perception that hearing loss is mostly something older individuals experience in what’s termed “the West” or higher-income countries. This study shows that isn’t necessarily the case. There are so many people experiencing hearing loss in all corners of the world in different age groups who need resources just as much as older people. It’s a challenge for lower- and middle-income countries as well, particularly where need is quite high and access to assistive technologies and health care providers is quite low. 

The study also found a large, unmet need for hearing health care services, whether that be a hearing aid, a cochlear implant, assistive technologies, or connection to sign language courses and things along these lines. I think that’s really the huge takeaway. There are things that we can do as individuals, as researchers, or as policymakers to allocate resources to programs that improve access to hearing health care.