Study finds connection between hearing impairment and heart failure risk

Hearing loss is linked to a heightened risk of developing heart failure, with the psychological distress caused by the impairment taking a key role in the observed association, finds a large long term study, published online in the journal Heart.

Hearing loss is increasingly common, particularly as people age, while the prevalence of heart failure is also on the rise, affecting around 64 million people worldwide, note the researchers.

While impaired hearing is associated with an increased risk of cardiovascular disease, principally, it is thought, as a result of the resulting social detachment, no study has comprehensively examined the association between objectively measured hearing ability and the risk of developing heart failure.

In a bid to plug this knowledge gap, the researchers mined the data of 164,431 participants from the UK Biobank, 4369 of whom wore hearing aids. None had heart failure to begin with. The average age of participants was 56, and 89,818 (around 55%) were women.

Their hearing ability was objectively measured using the validated Digit Triplets Test and the speech-reception-threshold (SRT). Participants (160,062) who didn't wear hearing aids were categorised into three groups according to their performance on the DTT: normal (140,839; 88%); insufficient (16,759;10.5%); and poor (2464; 1.5%).

Comprehensive background information on current health, lifestyle, and psychosocial factors was collected via questionnaires. 

Social isolation was assessed using a composite definition in the UK Biobank derived from scores (1-3) for the number of people living in the household, frequency of friend or family visits, and leisure or social activities. Those with a score of 2 or 3 were classified as socially isolated.

Psychological distress was assessed using a four-item version of the Patient Health Questionnaire (PHQ-4), with a score ranging from 0 to 12. Neuroticism, a depression-related personality trait, was assessed using 12 questions from the Eysenck Personality Questionnaire-Revised Short Form.

The development of heart failure among those who were not genetically predisposed to the condition was identified through medical records and death certificates during an average follow up of 11½ years.

During this period, 4449 (nearly 3%) of the participants developed heart failure. SRT levels were significantly positively associated with the risk of developing the condition in participants who didn't wear hearing aids. 

Compared with those with normal hearing, the adjusted heightened risks of developing heart failure were 15% and 28%, respectively, for insufficient and poor hearing, and 26% for hearing aid use. 

The associations between SRT levels and heart failure risk were stronger in those without coronary heart disease or stroke at the start of the study.

SRT levels were significantly positively associated with social isolation, psychological distress, and neuroticism among those who didn't wear hearing aids. And these factors had a substantial role in the observed associations in participants who didn't wear hearing aids, accounting for 3%, 17%, and 3%, respectively, of the heightened risk of heart failure development. 

When the scores for social isolation, psychological distress, and neuroticism were combined among those who had full data on these factors, the total mediating effect was just over 9%. 

This was less than the sum of the mediating effects of each individual factor, which amounted to 19.5%, suggesting overlap and interaction between these three factors, say the researchers.

This is an observational study, and as such, can't establish cause and effect. And data on hearing were collected only at the start of the study, while the participants in the current study were mainly of European descent and healthier than the UK general population, they acknowledge.

But there are plausible biological explanations for their findings, they say. "The rich distribution of capillaries in the…cochlea and the high metabolic demand of the inner ear may render these regions more sensitive to systemic vascular disorders rather than just local circulatory issues," they suggest. 

"Therefore, hearing impairment may reflect vascular health and serve as an early and sensitive predictor of cardiovascular disease, including [heart failure]," they add.

"Of note, both the participants who used hearing aids and those with poor hearing had a similarly significant increase in the risk of incident [heart failure], suggesting that while hearing aids can improve auditory function, they may not address the underlying vascular issues that contribute to the risk of [heart failure]," they continue.

And they explain: "Because hearing problems can lead to difficulties in speech comprehension and poor engagement in social activities, people with hearing impairment are more likely to experience social isolation, psychological distress, anxiety and depression than people without hearing impairment. 

"These psychological factors may increase the activity of the sympathetic nervous system and the hypothalamic-pituitary adrenal axis, and enhance inflammation and oxidative stress, thereby accelerating atherosclerosis, increasing peripheral stress, and promoting the development of cardiac remodelling."

The findings highlight the importance of integrating hearing health assessments into broader cardiovascular risk evaluation frameworks, they conclude. And strengthening psychological intervention in people with hearing impairment may be key to curbing the risk of heart failure, they suggest.