Link Between Hearing Loss And Premature Death

A recent study links hearing loss with an increased risk for mortality before the age of 75 due to cardiovascular disease. Researchers at the Robert N. Butler Columbia Aging Center at Columbia University Mailman School of Public Health found that mortality among those with hearing loss is elevated, particularly among men and women younger than age 75 and those who are divorced or separated. However, mortality risk was diminished in adults with a well-hearing partner.

This is the first study to investigate the combined effects of hearing loss with partnership, parental status, and increased mortality risk. The findings are published in the journal Social Science and Medicine. "Old age greatly increases the risk for hearing loss," says Vegard Skirbekk, Ph.D., Columbia Aging Center faculty member and professor of Population and Family Health at the Mailman School of Public Health. "Therefore, as the population ages, we are seeing increasing numbers of people with hearing loss. At the same time, there are greater numbers of adults living without a partner - putting people with hearing loss at an increased risk for death."

Deaths related to cancer and injuries or as a result of injuries were not affected by hearing loss, although accident-related mortality was higher among the hearing impaired who lacked partners or children. "This may be due to a greater fatality from traffic-related incidents, for instance, as family members otherwise may have helped to prevent many of these deaths through warnings or preventive action," said Bo Engdahl of the Norwegian Institute of Public Health, and first author. Hearing loss is the fourth leading cause of disability. Strongly age dependent, it increases from approximately one percent among those aged 40 to 44 up to 50 percent in women and 62 percent in men aged 80 to 84.

Several Explanations

The researchers analyzed data from 50,462 adults enrolled in the Nord-Trøndelag Hearing Loss Study from 1996 to 1998. They used the Norwegian Cause of Death Registry to identify deaths until 2016. Data on marital status and number of children was obtained from the National Population Registry. The researchers also categorized smoking frequency, alcohol use, and physical activity. There are several explanations for the association between hearing loss and mortality, according to Engdahl and Skirbekk,

Families may be more likely to stay supportive and present even during spells of poor health compared to friends or those with weaker ties, which may reduce some of the mortality risk associated with functional impairments. Having a partner could allow someone with hearing loss to be socially active to a greater extent, as the spouse may provide support, take initiative, and help them overcome thresholds for socializing with others. A spouse could also encourage the use of technical support, such as hearing aids, and assist in consulting health services when necessary.

Being in a relationship may also serve as a buffer against detrimental economic consequences of hearing loss. "It is well known that rapid population-level aging is likely to result in a greater prevalence of hearing impairment, and that a loss of hearing can raise mortality risks. However there has not yet been much focus on how these effects relate to ongoing changes in family dynamics. Our findings verify that excess mortality among the hearing impaired can be particularly high among individuals with certain family constellations, such as men who are divorced or women who do not have children," Skirbekk said. "When governments develop plans to lower the incidence of hearing impairment, they may want to consider the family dimension when designing intervention and social and health support systems."

Untreated Hearing Loss And Higher Health Care Costs

Older adults with untreated hearing loss incur substantially higher total health care costs compared to those who don’t have hearing loss - an average of 46 percent, totaling $22,434 per person over a decade, says a study led by researchers at the Johns Hopkins Bloomberg School of Public Health. This is one of the largest studies to look at this issue, following many individuals for a full 10 years.

The differences between the two groups were evident as early as two years after diagnosis. Compared to the patients without hearing loss, patients with the condition generated nearly 26 percent more in total health care costs within two years, a gap that widened to 46 percent by 10 years, amounting to $22,434 per individual - $20,403 incurred by the health plan, $2,030 by the individual in out-of-pocket costs. The study did not include patients with hearing loss who had evidence of hearing aid use. The findings - published in JAMA Otolaryngology-Head and Neck Surgery - add to a growing body of research from Johns Hopkins and elsewhere showing the detriments of untreated hearing loss, which include a higher risk of dementia and cognitive decline, falls, depression and lower quality of life. In a companion paper published in the same issue, a study led by Bloomberg School researchers suggests a link between untreated hearing loss and significantly greater morbidity, affirming early studies. 

Hearing loss affects 38 million Americans, a number that’s expected to double by 2060, with current aging population trends. An estimated one in three people in the United States between ages 65 and 74 currently has hearing loss, and two-thirds of adults age 70 and older have a clinically significant hearing loss. It’s unclear how hearing loss has translated into longitudinal trends of health care utilization and costs, particularly for those whose hearing loss remains untreated, says study lead Nicholas S. Reed, AuD, a member of the core faculty of the Cochlear Center for Hearing and Public Health at the Bloomberg School and an instructor of audiology in the Department of Otolaryngology-Head and Neck Surgery at the Johns Hopkins University School of Medicine.

To investigate these questions, Reed and his colleagues mined information from the OptumLabs Data Warehouse, a large de-identified health care dataset including administrative claims from 1999 to 2016 for people enrolled in large private U.S. health plans and Medicare Advantage plans. The researchers used diagnosis codes to identify more than 77,000 patients with likely age-related untreated hearing loss, excluding those whose claims data indicated they used a hearing aid or whose hearing loss was secondary to a medical condition or toxic agent such as chemotherapy. 

The research team then matched each of these patients with other patients in the claims database on more than 25 factors including demographic characteristics, baseline health conditions and measures of health care utilization, such as inpatient hospitalizations and readmissions within 30 days, emergency department visits, days with at least one outpatient visit and health care costs. The researchers analyzed health care cost and utilization outcomes and trends at two, five and 10-year follow-up points.  At the 10-year mark, patients with untreated hearing loss experienced about 50 percent more hospital stays, had about a 44 percent higher risk for hospital readmission within 30 days, were 17 percent more likely to have an emergency department visit and had about 52 more outpatient visits compared to those without hearing loss. 

A Call To Action

When the researchers calculated how much of the extra $22,434 in total health care costs were likely due solely to hearing loss-related services, the total was only about $600 over 10 years. The study results do not indicate exactly why untreated hearing loss drives up health care utilization. Reed and his colleagues have a few ideas. One of them is hearing loss relationships with other serious health issues. In the companion paper, using the same OptumLabs dataset, Jennifer A. Deal, Ph.D., assistant scientist in the Bloomberg School’s Department of Epidemiology, and her colleagues show that untreated hearing loss is independently associated with significantly greater morbidity.

For example, compared to those without hearing loss, those with untreated hearing loss had 3.2 more dementia diagnoses, 3.6 more falls and 6.9 more depression diagnoses per 100 people over 10 years. Over 10 years, those with untreated hearing loss had an estimated 50 percent greater risk of dementia, 40 percent greater risk of depression, and almost 30 percent higher risk for falls compared to those without hearing loss.  “We don’t yet know if treating hearing loss could help prevent these problems,” Deal says. “But it’s important for us to figure out, because over two-thirds of adults age 70 years and older have clinically significant hearing loss that may impact everyday quality of life. We need to better understand these relationships to determine if treatment for hearing loss could potentially reduce risk and help maintain health in older adults.”

Deal also noted that the depression finding is important. “There aren’t a lot of studies using objectively measured hearing loss showing this association, even though it seems pretty intuitive,” she says.  Another possibility for the link between hearing loss and greater health care cost and utilization is that hearing loss might hamper patient-provider communication, says Reed, one of the paper’s co-authors. Patients who cannot hear their doctors may have trouble communicating their symptoms, participating in conversations to develop a recommended plan for their health or following discharge instructions - key elements in participating in their own care.

To help improve communication for patients with hearing loss at Johns Hopkins Bayview Medical Center, Reed and others developed a multi-element pilot program to provide extra training to doctors, improve signage or provide hearing amplification devices. The researchers are currently collecting outcomes data associated with these interventions to determine whether they result in better care. Across the United States, adults with hearing loss will be able to access hearing amplification devices more easily in 2020, when a federal law authorizing certain types of over-the-counter hearing aids will go into effect. “Knowing that untreated hearing loss dramatically drives up health care utilization and costs will hopefully be a call to action among health systems and insurers to find ways to better serve these patients,” says Reed.

Clinical Communication Breakdown     

It was not uncommon for older adults to report mishearing a physician or nurse in a primary care or hospital setting, according to another study published by JAMA Otolaryngology-Head & Neck Surgery. The prevalence of medical errors is higher among older patients. Failures in clinical communication are considered to be the leading cause of medical errors. A previous study reported that improved communication between the medical teams and families could have prevented 36 percent of medical errors. Colm M. P. O'Tuathaigh, B.A., Ph.D., of University College Cork, Cork, Ireland and colleagues conducted an analysis of interview data collected in 100 adults 60 years and older to examine communication breakdown in hospital and primary care settings among adults reporting hearing loss.

Of these adults, 57 reported some degree of hearing loss and 26 used a hearing aid device. Of the 100 adults, 43 reported having misheard a physician, nurse or both in a primary care or hospital setting. When asked to elaborate on the context of mishearing in a clinical setting, the scenarios included general mishearing, consultation content, physician-patient or nurse-patient communication breakdown, hospital setting and use of language. "This qualitative analysis confirms that age-related hearing loss has a negative effect on clinical communication across both hospital and primary care clinical settings," the authors write. "We recommend that content-related and setting-related factors identified as barriers to communication in adults with hearing impairment be incorporated within a patient-centered approach to clinical communication with this patient population."

Key Deafness Mechanism Identified

The basic outlines of human hearing have been known for years. Sensory cells in the inner ear turn sound waves into the electrical signals that the brain understands as sound. But the molecular details have remained elusive. Research from the University of Maryland School of Medicine (UM SOM), identified a crucial protein in this translation process.

The findings were published in Nature Communications. The study is the first to illuminate in detail how a particular protein, which is known as CIB2, allows hearing to work. "We are very excited by these results," said the senior author of the study, Zubair Ahmed, professor in the Department of Otorhinolaryngology-Head and Neck Surgery at UM SOM. "This tells us something new about the fundamental biology of how hearing works on a molecular level."

CIB2, which is short for calcium and integrin-binding protein 2, is essential for the structure of stereocilia, the structures at the top of the sensory hair cells in the inner ear. Stereocilia are extremely small - less than a half a micrometer in diameter - which is about the wavelength of a visible light. Each ear contains 18,000 hair cells that do not divide or regenerate. Dr. Ahmed and his colleague Saima Riazuddin, professor in the Department of Otorhinolaryngology-Head and Neck Surgery at UM SOM, along with their collaborators, discovered five years ago that CIB2 was involved in hearing. Since then, they have studied this protein in flies, mice, zebrafish and humans. The study was the first to explain the mechanism behind CIB2 in hearing.

A Big Step

In this study, they genetically engineered mice without CIB2, as well as mice in which a human CIB2 gene mutation had been inserted. The researchers found that the human mutation affects the ability of the CIB2 protein to interact with two other proteins, TMC1 and TMC2, which are crucial in the process of converting sound to electrical signals. This process is known as mechanotransduction. People with this mutation cannot turn soundwaves into signals that the brain can interpret, and so are deaf. When the researchers inserted the human CIB2 mutation into the mouse, they found that the mice were deaf. "This is a big step in determining the identity of key components of the molecular machinery that converts sound waves into electrical signals in the inner ear," said the study's co-senior author, Gregory Frolenkov, of the Department of Physiology at the University of Kentucky.

Dr. Ahmed and his colleagues are now looking for other molecules beyond CIB2 that play a key role in the process. In addition, they are exploring potential therapies for CIB2-related hearing problems. In mice, they are using the gene editing tool CRISPR to modify dysfunctional CIB2 genes. They suspect that if this modification occurs in the first few weeks after birth, these mice, which are born deaf, will be able to hear. The scientists are also experimenting with gene therapy, using a harmless virus to deliver a normal copy of the normal CIB2 gene to baby mice that have the mutated version. Dr. Ahmed says the early results of these experiments are intriguing. Nearly 40 million Americans suffer from some level of hearing loss. This includes around 74,000 children with profound, early-onset deafness. At least 50 percent of these deafness cases are due to genetic causes.

It is not clear how common CIB2 mutations are in the U.S. population or how large a role these mutations play in deafness in humans worldwide. In his research on a group of families in Pakistan that have a higher risk of deafness, Dr. Ahmed has found that about eight to nine percent seem to have mutations in CIB2. Overall, he says, the gene could play a role in tens of thousands of cases of deafness, and perhaps many more than that. He is also studying CIB2 among the general population. It may be that some versions of the gene also play a role in deafness caused by environmental conditions, creating a predisposition to hearing loss.


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