Metabolic syndrome is associated with hearing loss among a middle-aged and older Chinese population: a cross-sectional study

Cardiometabolic diseases according to the type and degree of hearing loss in noise-exposed workers

Background

This study aimed to determine the association between cardiometabolic diseases, including metabolic syndrome, hypertension, and diabetes, and the type and degree of hearing loss in noise-exposed workers.

Methods

A total of 237,028 workers underwent air conduction pure tone audiometry in 2015 to assess their health and diagnose cardiometabolic diseases. The study defined metabolic syndrome, hypertension, and diabetes using blood pressure, fasting blood sugar, cholesterol, and triglyceride levels. Mid-frequency hearing loss was defined as ≥ 30 dB at 2,000 Hz, whereas high-frequency hearing loss was ≥ 40 dB at 4,000 Hz. The average air conduction hearing thresholds at these frequencies were used to determine hearing loss degrees.

Results

The odds ratio (OR) of combined exposure to noise and night-shift work in all cardiometabolic diseases was higher than that of noise exposure alone. The risk of cardiometabolic diseases was dose-response, with higher hearing loss causing higher ORs. The ORs of hypertension compared with the normal group were 1.147 (1.098-1.198), 1.196 (1.127-1.270), and 1.212 (1.124-1.306), and those of diabetes were 1.177 (1.119-1.239), 1.234 (1.154-1.319), and 1.346 (1.241-1.459) for mild, moderate, and moderate-severe hearing loss, respectively.

Conclusions

Workers who are exposed to noise tend to demonstrate high risks of hearing loss and cardiometabolic diseases; thus, bio-monitoring of cardiometabolic diseases, as well as auditory observation, is necessary.

A bidirectional Mendelian randomisation study to evaluate the relationship between body constitution and hearing loss

Hearing loss and hearing disorders represent possible mediating pathways in the associations between noise exposures and non-auditory health outcomes. In this context, we assessed whether the noise-obesity associations should consider hearing functions as possible mediators and applied Mendelian randomisation (MR) to investigate causal relationships between body constitution and hearing impairments. We obtained genetic associations from publicly available summary statistics from genome-wide association studies in European ancestry adult populations (N= from 210,088 to 360,564) for (i) body constitution: body mass index (BMI), waist circumference (WC) and body fat percentage (BFP), and (ii) hearing loss: sensorineural hearing loss, noise-induced hearing loss, and age-related hearing impairment (ARHI). We employed colocalisation analysis to investigate the genetic associations for BMI and ARHI liability within an FTO locus. We conducted bi-directional MR for the 'forward' (from body constitution to hearing) and 'reverse' directions. We applied the random effects inverse variance-weighted method as the main MR method, with additional sensitivity analyses. Colocalisation analysis suggested that BMI and ARHI shared a causal variant at the FTO gene. We did not find robust evidence for causal associations from body constitution to hearing loss and suggested that some associations may be driven by FTO variants. In the reverse analyses, ARHI was negatively associated with BMI [effect size - 0.22 (95% CI - 0.44 to - 0.01)] and BFP [effect size - 0.23 (95% CI - 0.45 to 0.00)], supporting the notion that ARHI may diminish body constitution. Finally, our data suggest that there is no strong evidence that hearing explains the association between noise exposure and body constitution.

Associations Between Body Composition and Sensorineural Hearing Loss Among Adults Based on the UK Biobank

OBJECTIVE

To explore the association between body composition and sensorineural hearing loss (SNHL).

STUDY DESIGN

Cross-sectional study, prospective study and Mendelian randomization (MR) analyses.

SETTING

UK Biobank.

METHODS

This cross-sectional study included 147,296 adult participants with complete data on body composition and the speech-reception-threshold (SRT) test. We further conducted a prospective study with 129,905 participants without SNHL at baseline and followed up to 15 years to explore the association between body composition and new-onset SNHL. Multivariable logistic regression and Cox regression models were used. Subgroup analyses stratified by age and sex were performed. We further assessed the causal association between body composition and SNHL using two-sample MR analyses.

RESULTS

Our cross-sectional study revealed that fat percentage, especially leg (odds ratio [OR] 1.46, p = .029) and arm (OR 1.43, p = .004), were significant risk factors for SNHL. However, fat-free mass, especially in the arm (OR 0.27, p < .001) and leg (OR 0.58, p < .001) showed significant protective effects against SNHL, which was substantially consistent with the results of the prospective study. In addition, we found that young women with SNHL were more susceptible to body composition indicators. However, MR analyses revealed no evidence of significant causal association.

CONCLUSION

Fat percentage, especially in the leg and arm, was a significant risk factor for SNHL, whereas fat-free mass, especially in the leg and arm, had significant protective effects against SNHL, however, these associations may not be causal.

Impact of Low Skeletal Muscle Mass and Obesity on Hearing Loss in Asymptomatic Individuals: A Population-Based Study

The relationship between low muscle mass (LMM) with obesity and hearing loss has been poorly studied. We aimed to investigate the association of LMM and obesity on hearing loss in the general population. A total of 265,792 adults who underwent a hearing test and body composition analyses were included. Pre-sarcopenia was defined as having an appendicular muscle mass index <5.7 kg/m2 for women and <7.0 kg/m2 for men, and obesity as a body mass index ≥25 kg/m2, while pre-sarcopenic obesity was defined as the co-presence of LMM and obesity. Participants were divided into four groups according to the presence of pre-sarcopenia and/or obesity. The prevalence of hearing loss was 1.8% in the control, 2.5% in the pre-sarcopenia alone, 3.0% in the obesity alone, and 6.2% in the pre-sarcopenic obesity group (p < 0.001). Hearing Thresholds were the highest in the pre-sarcopenic obesity group compared with the other three groups. In multivariable-adjusted models, the risk of hearing loss was the highest in the pre-sarcopenic obesity group (odds ratio: 1.30 [95% confidence interval: 1.10−1.56]), followed by the obesity alone (1.20 [1.12−1.28]) and pre-sarcopenia alone (1.19 [1.06−1.34]) group compared with the control group (p < 0.001). Pre-sarcopenic obesity was independently associated with a higher prevalence of hearing loss, supporting pre-sarcopenic obesity itself as a risk for the decline in hearing function.

The influence of metabolic syndrome on age-related hearing loss from the perspective of mitochondrial dysfunction

With the increase in life expectancy in the global population, aging societies have emerged in many countries, including China. As a common sensory defect in the elderly population, the prevalence of age-related hearing loss and its influence on society are increasing yearly. Metabolic syndrome is currently one of the main health problems in the world. Many studies have demonstrated that metabolic syndrome and its components are correlated with a variety of age-related diseases of the peripheral sensory system, including age-related hearing loss. Both age-related hearing loss and metabolic syndrome are high-prevalence chronic diseases, and many people suffer from both at the same time. In recent years, more and more studies have found that mitochondrial dysfunction occurs in both metabolic syndrome and age-related hearing loss. Therefore, to better understand the impact of metabolic syndrome on age-related hearing loss from the perspective of mitochondrial dysfunction, we reviewed the literature related to the relationship between age-related hearing loss and metabolic syndrome and their components to discern the possible role of mitochondria in both conditions.

Hearing loss is associated with increased risk of incident stroke but not coronary heart disease among middle-aged and older Chinese adults: the Dongfeng-Tongji cohort study

Hearing loss has been associated with increased risk of cardiovascular disease (CVD) prevalence in cross-sectional studies. However, little is known about the prospective association between hearing loss and CVD incidence. We aimed to examine the associations of hearing loss with risk of incident CVD, coronary heart disease (CHD), and stroke in a Chinese population. We included 13,880 individuals aged 63.3 years from the Dongfeng-Tongji cohort study (2013-2018). Hearing loss was categorized into normal, mild, moderate, severe, or greater by the pure-tone average of thresholds at speech and high frequency in both ears. Cox proportional hazard models and linear regression models were used for multivariate longitudinal analyses. After multivariate adjustments, we observed suggestive dose-response associations of increased high-frequency hearing loss with elevated risk of CVD and stroke incidence. Compared with normal hearing loss at high frequency, those with moderate and severe or greater hearing loss had a 4% (95% CI: 0.92, 1.18) or 13% (95% CI: 0.98, 1.30) higher risk of CVD and 52% (95% CI: 1.06, 2.17) or 51% (95% CI: 1.03, 2.20) higher risk of stroke, while the associations were almost consistent across most subgroups. No significant associations were observed for CHD and high-frequency hearing loss, as well as CVD and speech-frequency hearing loss. In addition, higher high-frequency hearing loss was related to unfavorably altered lipid profiles and fasting glucose. Our data suggested that increased hearing loss might increase the risk of incident CVD and stroke among middle-aged and older Chinese, which was partially explained by altered CVD-related biomarkers.

Association of hearing loss with total and cause-specific mortality in US adults

We expected to explore the associations of hearing loss and hearing thresholds at different frequencies with total and cause-specific mortality. In this study, 11,732 individuals derived from the National Health and Nutrition Examination Survey (NHANES) 1999-2012 were included. Data of death was extracted from the NHANES Public-Use Linked Mortality File through December 31, 2015. Cox proportional hazards models were used to explore the associations between hearing loss, hearing thresholds at different frequencies, and total or cause-specific mortality. A total of 1,253 deaths occurred with a median follow-up of 12.15 years. A significant positive dose-response relationship between hearing loss in speech frequency and total mortality was observed, and the HRs and 95% CIs were 1.16 (0.91, 1.47), 1.54 (1.19, 2.00), and 1.85 (1.36, 2.50), respectively, for mild, moderate, and severe speech-frequency hearing loss (SFHL) with a P _trend of 0.0003. In addition, moderate (HR: 1.90, 95% CI: 1.20-3.00) and greater (3.50, 1.38-8.86) SFHL significantly elevated risk of heart disease mortality. Moreover, hearing thresholds of >25 dB at 500, 1000, or 2000 Hz were significantly associated with elevated mortality from all causes (1.40, 1.17-1.68; 1.44, 1.20-1.73; and 1.33, 1.10-1.62, respectively) and heart disease (1.89, 1.08-3.34; 1.95, 1.21-3.16; and 1.89, 1.16-3.09, respectively). Hearing loss is associated with increased risks of total mortality and heart disease mortality, especially for hearing loss at speech frequency. Preventing or inhibiting the pathogenic factors of hearing loss is important for reducing the risk of death.

Association of Metabolic Syndrome with Sensorineural Hearing Loss

The prevalence of sensorineural hearing loss has increased along with increases in life expectancy and exposure to noisy environments. Metabolic syndrome (MetS) is a cluster of co-occurring conditions that increase the risk of heart disease, stroke and type 2 diabetes, along with other conditions that affect the blood vessels. Components of MetS include insulin resistance, body weight, lipid concentration, blood pressure, and blood glucose concentration, as well as other features of insulin resistance such as microalbuminuria. MetS has become a major public health problem affecting 20–30% of the global population. This study utilized health examination to investigate whether metabolic syndrome was related to hearing loss. Methods: A total of 94,223 people who underwent health check-ups, including hearing tests, from January 2010 to December 2020 were evaluated. Subjects were divided into two groups, with and without metabolic syndrome. In addition, Scopus, Embase, PubMed, and Cochrane libraries were systematically searched, using keywords such as “hearing loss” and “metabolic syndrome”, for studies that evaluated the relationship between the two. Results: Of the 94,223 subjects, 11,414 (12.1%) had metabolic syndrome and 82,809 did not. The mean ages of subjects in the two groups were 46.1 and 43.9 years, respectively. A comparison of hearing thresholds by age in subjects with and without metabolic syndrome showed that the average pure tone hearing thresholds were significantly higher in subjects with metabolic syndrome than in subjects without it in all age groups. (p < 0.001) Rates of hearing loss in subjects with 0, 1, 2, 3, 4, and 5 of the components of metabolic syndrome were 7.9%, 12.1%, 13.8%, 13.8%, 15.5% and 16.3%, respectively, indicating a significant association between the number of components of metabolic syndrome and the rate of hearing loss (p < 0.0001). The odds ratio of hearing loss was significantly higher in subjects with four components of metabolic syndrome: waist circumference, blood pressure, and triglyceride and fasting blood sugar concentrations (p < 0.0001). Conclusions: The number of components of the metabolic syndrome is positively correlated with the rate of sensorineural hearing loss.

Sensorineural hearing loss and risk of stroke: a systematic review and meta-analysis

The aim of this systematic review and meta-analysis study was to clarify the effects of sensorineural hearing loss (SNHL) on the incidence of stroke. In line with this, PubMed, Scopus, Web of Science, and ScienceDirect databases were searched using related keywords and MeSH terms from inception to March 1, 2020. Out of the 1961 initial records, eight cohort studies comprising 4,564,202 participants were included, and their qualities were assessed using the Newcastle-Ottawa Scale (NOS). Then, the random-effects model was used to pool HR (95% CI) for risk of stroke; and heterogeneity was presented with I2 index. Subgroup analysis and publication bias tests were performed, and the pooled HR (95% CI) of stroke in SNHL was estimated as 1.31 (1.08, 1.53) for the unadjusted model and 1.33 (1.18, 1.49) for the adjusted model. Subgroup analysis indicates a significantly higher risk of stroke in patients with sudden SNHL (SSNHL) in comparison to age-related HL (ARHL) both in the unadjusted model, [HR = 1.46; 95% CI (1.08, 1.63)] versus [HR = 1.14; 95% CI (0.64, 1.65)], and in the adjusted model, [HR = 1.44; 95% CI (1.15, 1.74)] versus [HR = 1.29; 95% CI (1.24, 1.34)]. Our study showed that patients with SNHL face a higher risk of stroke than those without SNHL. It is necessary to perform hematologic and neurological examinations to help clinicians detect patients who are potentially at risk for stroke.

Obesity as a Possible Risk Factor for Pediatric Sensorineural Hearing Loss

OBJECTIVES/HYPOTHESIS

Childhood hearing loss impacts linguistic, academic, social, and psychologic development, and may have lasting implications for future workforce performance. Current evidence for obesity as a pediatric sensorineural hearing loss (SNHL) risk factor is intriguing but equivocal. We hypothesized that obesity is associated with a higher risk of SNHL. We additionally examined whether underweight is associated with a higher risk of SNHL.

STUDY DESIGN

Retrospective database review.

METHODS

A single-institution audiologic database from 2015 to 2020 was queried for audiograms with type-A tympanograms from children aged 5 to 18 years old. Comorbidities known to be associated with hearing loss were excluded. We then examined both for sub-clinical (≥15 dB) high- or low-frequency hearing loss, and for clinical (≥21 dB) hearing loss, with the aim of examining the association between obesity and SNHL. Multivariable logistic regression was performed to adjust for age, gender, diabetes mellitus, attention deficit hyperactivity disorder, and autism.

RESULTS

A total of 3,142 children were included. Obesity was not associated with risk of SNHL (adjusted OR 0.82; 95% CI: 0.60, 1.12). Underweight children had a higher risk of SNHL than normal weight children (adjusted OR 1.78; 95% CI: 1.08, 2.95). Autism was significantly associated with increased risk of sub-clinical SNHL only (adjusted OR 2.00; 95% CI 1.34, 2.98).

CONCLUSIONS

No association was found between obesity and pediatric SNHL. Underweight children may represent a higher-risk population for SNHL. There appears to be an increasing risk of SNHL as children approach adolescence. Further study of systemic risk factors for SNHL is indicated.

LEVEL OF EVIDENCE

3 Laryngoscope, 131:1416-1419, 2021.

Body mass index, waist circumference, and risk of hearing loss: a meta-analysis and systematic review of observational study

BACKGROUND

Emerging evidence implicates excess weight as a potential risk factor for hearing loss. However, this association remained inconclusive. Therefore, we aimed to systematically and quantitatively review the published observational study on the association between body mass index (BMI) or waist circumference (WC) and hearing loss.

METHODS

The odds ratios (ORs) or relative risks (RRs) with their 95% confidence intervals (CIs) were pooled under a random-effects model. Fourteen observational studies were eligible for the inclusion in the final analysis.

RESULTS

In the meta-analysis of cross-sectional studies, the ORs for prevalent hearing loss were 1.10 (95% CI 0.88, 1.38) underweight, 1.14 (95% CI 0.99, 1.32) for overweight, OR 1.40 (95% CI 1.14, 1.72) for obesity, 1.14 (95% CI 1.04, 1.24) for each 5 kg/m2 increase in BMI, and 1.22 (95% CO 0.88. 1.68) for higher WC. In the meta-analysis of longitudinal studies, the RRs were 0.96 (95% CI 0.52, 1.79) for underweight, 1.15 (95% CI 1.04, 1.27) for overweight, 1.38 (95% CI 1.07, 1.79) for obesity, 1.15 (95% CI 1.01, 1.30) for each 5 kg/m2 increase in BMI, and 1.11 (95% CI 1.01, 1.22) for higher WC.

CONCLUSIONS

In summary, our findings add weight to the evidence that elevated BMI and higher WC may be positively associated with the risk of hearing loss.

Metabolic Syndrome as a Risk Factor for Sensorineural Hearing Loss in Adult Patients with Turner Syndrome

BACKGROUND AND PURPOSE

Metabolic syndrome (MetS) is a disorder associated with an increased risk of cardiovascular disease. The frequency of each component of MetS in Turner syndrome (TS) subjects is high. An elevated incidence of hearing loss has also been reported in TS. Sensorineural hearing loss (SNHL) affects at least half of young women with TS. The association between MetS and SNHL has not been previously considered in TS. The aim of this study is to evaluate the association between these two conditions.

PATIENTS AND METHODS

Cross-sectional anthropometric, cardio-metabolic and audiological data were obtained from a cohort consisting of unrelated TS subjects (>20 years of age; n = 93). Metabolic syndrome was defined according to the International Diabetes Federation criteria. Types and severity of hearing loss were based on the American Speech Hearing Association guidelines.

RESULTS

Hearing loss was detected in 74% of ears from adult TS subjects and SNHL was observed in half of our TS subjects. The prevalence of MetS in TS subjects with or without SNHL was 64% and 11%, respectively (P < 0.05). After adjusting for age, MetS was related to a ninefold increase in the odds of SNHL. This odds increased in a stepwise manner as the number of MetS components increased.

CONCLUSION

MetS and its individual components were associated factors for SNHL in TS subjects. A reduction in the number and severity of the components of MetS might potentially contribute to decreasing the progression of SNHL at younger ages, but further studies will be needed to explain the underlying pathological mechanism connecting MetS and SNHL.

Association of metabolic syndrome with the incidence of hearing loss: A national population-based study

Background & aims

Sensorineural hearing loss (HL) is one of the most common public health problems, and its prevalence increases with increasing life expectancy. An association between HL and metabolic syndrome (MetS) is suspected. Although previous epidemiological studies have investigated the association between the two variables, there have been conflicting conclusions. Therefore, we aimed to evaluate the association between the presence of MetS—and individual components of MetS—and HL, using a longitudinal design and a large-scale population.

Methods

A total of 17,513,555 individuals who underwent national health screening between January 2009 and December 2010 were identified. Subject data from the Korean Health Insurance Review and Assessment Service were reviewed. A total of 11,457,931 subjects were ultimately included in the analysis. Baseline comorbidities were defined according to the ICD-10 code from the Korean Health Insurance Review and Assessment Service data. If the participants had an ICD-10 code for HL during the follow-up, they were defined as having incident HL. Criteria for MetS adhered to the revised National Cholesterol Education Program Adult Treatment Panel III.

Results

There were 7,574,432 subjects without MetS and 3,883,499 with MetS. The incidence of HL in subjects without MetS and with MetS was 1.3% and 1.8% at 1 year, 4.1% and 5.2% at 3 years, and 6.8% and 8.6% at 5 years, respectively (P < 0.001). However, multivariate analyses revealed a negative association. Analyses according to the components of MetS demonstrated a positive association for those associated with dyslipidemia; however, the others exhibited an inverse association with HL. We also performed analyses using 4 groups according to the presence of MetS and the components of dyslipidemia. Univariate analysis revealed a positive association between the presence of MetS and HL; however, multivariate analysis revealed a positive association between the presence of dyslipidemia components and HL, regardless of the presence of MetS.

Conclusion

Among the components of MetS, the association between low HDL or high TG levels and HL was most apparent. It is useful to evaluate each MetS component in isolation, such as the presence of low HDL or high TG levels, rather than the presence of MetS as a cluster of components.