The authors have declared that no competing interests exist.
Conceived and designed the experiments: BG PM. Performed the experiments: BG PM JS SRL GB CMM. Analyzed the data: GB. Contributed reagents/materials/analysis tools: PM BG GB. Wrote the paper: BG PM SRL.
Although concurrent vision and hearing loss are common in older adults, population-based data on their relationship with mortality is limited. This cohort study investigated the association between objectively measured dual sensory impairment (DSI) with mortality risk over 10 years. 2812 Blue Mountains Eye Study participants aged 55 years and older at baseline were included for analyses. Visual impairment was defined as visual acuity less than 20/40 (better eye), and hearing impairment as average pure-tone air conduction threshold greater than 25 dB HL (500–4000 Hz, better ear). Ten-year all-cause mortality was confirmed using the Australian National Death Index. After ten years, 64% and 11% of participants with DSI and no sensory loss, respectively, had died. After multivariable adjustment, participants with DSI (presenting visual impairment and hearing impairment) compared to those with no sensory impairment at baseline, had 62% increased risk of all-cause mortality, hazard ratio, HR, 1.62 (95% confidence intervals, CI, 1.16–2.26). This association was more marked in those with both moderate-severe hearing loss (>40 dB HL) and presenting visual impairment, HR 1.84 (95% CI 1.19–2.86). Participants with either presenting visual impairment only or hearing impairment only, did not have an increased risk of mortality, HR 1.05 (95% CI 0.61–1.80) and HR 1.24 (95% CI 0.99–1.54), respectively. Concurrent best-corrected visual impairment and moderate-severe hearing loss was more strongly associated with mortality 10 years later, HR 2.19 (95% CI 1.20–4.03). Objectively measured DSI was an independent predictor of total mortality in older adults. DSI was associated with a risk of death greater than that of either vision loss only or hearing loss alone.
Impaired vision and hearing are common among older adults
There are also prospective data to suggest that vision loss was associated with a greater mortality risk in older adults
There is a lack of population-based studies that have examined the association between the presence of objectively measured hearing and vision impairment, i.e. dual sensory impairment (DSI) and mortality risk. In the US National Health and Nutrition Examination Survey of 5444 adults aged 55–74 years, clinically confirmed DSI, however, was not found to be associated with an increased risk of mortality
In the present study, we aimed to address previous gaps in knowledge, by examining the association between clinically confirmed DSI with 10-year mortality risk in a large cohort of adults aged 55 years and older, after adjusting for potential confounders such as self-rated health, walking disability and cognitive impairment, in addition to traditional mortality risk markers.
The BMES is a population-based cohort study of common eye diseases and other health outcomes in a suburban Australian population located west of Sydney. Study methods and procedures have been described elsewhere
Pure-tone audiometry at both visits was performed by audiologists in sound-treated booths, using TDH-39 earphones and Madsen OB822 audiometers (Madsen Electronics, Denmark). Sound-proof rooms were set-up according to International Standards Organization protocol 8253-2. Bilateral hearing impairment was determined as the pure-tone average of audiometric hearing thresholds at 500, 1000, 2000, and 4000 Hz (PTA0.5–4 kHz) in the better ear, defining any hearing loss as PTA0.5–4 kHz >25 dB HL; mild hearing loss as PTA0.5–4 kHz >25–40 dB HL; and moderate to severe hearing loss as PTA0.5–4 kHz >40 dB HL.
Monocular distance logMAR (logarithm of the minimum angle of resolution) visual acuity was measured with forced-choice procedures using the retroilluminated chart with automatic calibration to 85 cd/m2 (Vectorvision CSV-100 TM; Vectorvision Inc, Dayton, Ohio) according to the Early Treatment Diabetic Retinopathy Study protocol
To identify and confirm persons who died after BMES-2, demographic information including surname, first and second names, sex and date of birth of the examined participants were cross-matched with Australian National Death Index (NDI) data for deaths, to December 2007. A probabilistic record linkage package was used, adopting a multiple pass procedure in which both data sets were grouped based on different characteristics (e.g., date of birth, name, sex) each time. Matches were divided into exact and non-exact. All non-exact matched records were examined manually and accepted if there was only one non-exact matched characteristic that was not critical. Information provided by family members during follow-up was also included if the participant was reported to have died on or before December 2007. The
A face-to-face interview with trained interviewers was conducted, and comprehensive data including information about medical history, hearing, demographic factors, socio-economic characteristics, lifestyle and health risk behaviour such as exercise, and smoking, were obtained from all participants. The medical history included cardiovascular or other systemic disease and associated risk factors, and medications used. A past history of angina, diabetes, myocardial infarction, and stroke was determined by responses to a question: “Has a doctor advised you that you have any of the following conditions?” Cognitive decline was assessed using the mini mental state examination (MMSE) questionnaire
Classification of hypertension was based on the 2003 World Health Organization/International Society of Hypertension guidelines
SAS statistical software (SAS Institute, Cary NC) version 9.1 was used for analyses. The association between single sensory impairment and DSI with mortality was examined using Cox regression models to estimate hazard ratios (HR) and 95% confidence intervals (CI). Multivariable regression models were first adjusted for age (entered as a continuous variable) and sex, and then further adjusted for confounders that were found to be significantly associated with mortality i.e. body mass index, systolic blood pressure, current smoking status, poor self-rated health, walking disability, presence of hypertension and/or diabetes, history of cancer, angina, stroke and/or acute myocardial infarction and cognitive impairment. We estimated the proportion surviving using the Kaplan Meier method. Kaplan-Meier survival curves are generated from the fitted Cox model using mean covariate values of age and sex.
Dual sensory impairment |
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Mortality risk marker | No(n = 1865) | Yes(n = 947) | p-value |
Age, |
64.2 (7.8) | 73.7 (8.4) | <0.0001 |
Male | 745 (40.0) | 471 (49.7) | <0.0001 |
Current smoker | 187 (10.1) | 86 (9.1) | 0.43 |
Poor self-rated health | 313 (16.9) | 223 (23.7) | <0.0001 |
Body mass index, |
27.9 (4.7) | 27.2 (4.7) | 0.0004 |
Systolic bloodpressure, |
144.2 (21.0) | 150.9 (22.3) | <0.0001 |
Walking disability | 54 (2.9) | 140 (14.8) | <0.0001 |
Diabetes | 161 (8.6) | 128 (13.5) | <0.0001 |
Hypertension |
1377 (74.0) | 781 (82.6) | <0.0001 |
Stroke | 52 (2.8) | 67 (7.1) | <0.0001 |
Angina | 141 (7.6) | 150 (16.1) | <0.0001 |
Acute myocardial infarction | 108 (5.8) | 102 (11.0) | <0.0001 |
Cancer | 208 (11.2) | 106 (11.3) | 0.94 |
Cognitive impairment |
20 (1.1) | 59 (6.2) | <0.0001 |
Data are presented as mean (SD) and n (%), unless otherwise specified.
Any hearing loss (>25 dB HL) and best-corrected visual impairment (<20/40).
Hypertension Stage I –140/90–160/100; Stage II - >160/100 or treated.
Cognitive impairment defined as mini-mental state examination score ≤24.
Hazard ratio (95% confidence interval) | ||||||
Visual impairment (<20/40) | Hearing impairment (dB HL) | no. of deaths (%) | Model 1 |
Model 2 |
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No visual impairment | ≤25 (No hearing loss) | 196 (10.9) | 1.0 (reference) | 1.0 (reference) | ||
>25 (Any hearing loss) | 240 (30.2) | 1.35 (1.10–1.65) | 1.24 (0.99–1.54) | |||
>25-≤40 (Mild hearing loss) | 153 (27.4) | 1.33 (1.06–1.65) | 1.27 (1.01–1.61) | |||
>40 (Moderate-severe hearing loss) | 87 (37.0) | 1.39 (1.06–1.83) | 1.16 (0.87–1.56) | |||
Presenting | ≤25 (No hearing loss) | 20 (25.6) | 1.43 (0.90–1.65) | 1.05 (0.61–1.80) | ||
>25 (Any hearing loss) | 83 (63.9) | 2.27 (1.70–3.05) | 1.62 (1.16–2.26) | |||
>25-≤40 (Mild hearing loss) | 44 (59.5) | 2.10 (1.47–2.99) | 1.46 (0.98–2.16) | |||
>40 (Moderate-severe hearing loss) | 39 (69.6) | 2.53 (1.74–3.68) | 1.84 (1.19–2.86) |
Adjusted for age and sex.
Further adjusted for body mass index, systolic blood pressure, current smoking status, poor self-rated health, walking disability, presence of hypertension and/or diabetes, history of cancer, angina, stroke and/or acute myocardial infarction and cognitive impairment.
Non-significant associations were observed between concurrent presenting visual impairment and hearing impairment at baseline with 10-year cause-specific mortality, after multivariable adjustment: coronary heart disease mortality - HR 1.47 (95% CI 0.83–2.58); stroke mortality - HR 1.05 (0.50–2.22); and cancer mortality – HR 1.79 (95% CI 0.99–3.23).
We also assessed the risk of mortality in participants with best-corrected visual impairment (bilateral) and hearing impairment (
Hazard ratio (95% confidence interval) | ||||||
Visual impairment (<20/40) | Hearing impairment (dB HL) | no. of deaths (%) | Model 1 |
Model 2 |
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No visual impairment | ≤25 (No hearing loss) | 208 (11.2) | 1.0 (reference) | 1.0 (reference) | ||
>25 (Any hearing loss) | 290 (32.9) | 1.41 (1.16–1.71) | 1.29 (1.04–1.59) | |||
>25-≤40 (Mild hearing loss) | 180 (29.6) | 1.38 (1.12–1.71) | 1.32 (1.06–1.66) | |||
>40 (Moderate-severe hearing loss) | 110 (40.3) | 1.46 (1.14–1.89) | 1.22 (0.92–1.61) | |||
Best corrected | ≤25 (No hearing loss) | 8 (40.0) | 2.07 (1.01–4.22) | 1.80 (0.79–4.12) | ||
>25 (Any hearing loss) | 34 (75.6) | 2.60 (1.74–3.90) | 1.59 (1.00–2.52) | |||
>25–≤40 (Mild hearing loss) | 17 (68.0) | 2.17 (1.28–3.67) | 1.20 (0.65–2.22) | |||
>40 (Moderate-severe hearing loss) | 17 (85.0) | 3.32 (1.95–5.63) | 2.19 (1.20–4.03) |
Adjusted for age and sex.
Further adjusted for body mass index, systolic blood pressure, current smoking status, poor self-rated health, walking disability, presence of hypertension and/or diabetes, history of cancer, angina, stroke and/or acute myocardial infarction and cognitive impairment.
To our best knowledge, this is the first population-based study to demonstrate that older adults with objectively measured DSI are at an increased risk of death from all causes compared to those without any sensory loss or a single sensory impairment. Specifically, participants with both presenting visual impairment (better eye) and bilateral hearing impairment at baseline had a 62% increased risk of dying 10 years later, independent of age, sex, self-rated health and the presence of known mortality markers. This association with mortality was more marked among older adults with concurrent moderate to severe hearing loss and any presenting or best-corrected vision loss.
Older adults in the BMES with clinically confirmed DSI compared to their counterparts without DSI had a 62% increased risk of total mortality. This finding is relatively similar to the HRs reported in a U.S. study: among men (HR 1.23 [95% CI 1.04–1.46]) and women (HR 1.63 [95% CI 1.37–1.93])
We documented a gradient effect from the severity of DSI on mortality risk. Specifically, participants with concurrent moderate to severe hearing loss (>40 dB HL) and any visual impairment (<20/40) had a higher risk of dying 10 years later, than those with mild hearing loss (<25–40 dB HL) and any vision loss (particularly those with best-corrected visual impairment). This finding concurs with the US study by Lee et al.
It is hypothesized that the increased risk of mortality observed in persons with DSI is mediated by factors known to increase the risk of hearing and visual impairment in older adults (e.g., cardiovascular disease, hypertension and diabetes)
Alternatively, it is speculated that presence of DSI could be a marker for frailty (e.g., handgrip strength, peak expiratory flow), illness or possibly accelerated aging processes
As sensory problems are common experiences within older age groups, they are often overlooked or dismissed
The strengths of this study include the use of a representative cohort with a relatively high participation rate, the use of standardized audiometric and vision testing, with measures of sensory function at more than one point in time
In summary, we found that the presence of DSI independently predicted an increased risk of mortality in older adults. These findings emphasize to clinicians the importance of recognizing that older adults with concurrent vision and hearing loss are at an increased risk of mortality compared to their non-impaired counterparts or those with only a single sensory impairment. Public health strategies to encourage earlier identification of older adults with DSI and their appropriate referral to rehabilitative services and support could improve life expectancy in this vulnerable population.