To the Editor
Hearing impairment (HI) is prevalent,1 treatable, and may be a risk factor for disability and falls in older adults.2,3 We tested the hypothesis that peripheral audiometric HI is cross-sectionally associated with poorer physical function and falls in 250 men and women from Washington County, Maryland (mean age 77 years).
METHODS
Study population
We used data from a hearing pilot study in the Atherosclerosis Risk in Communities (ARIC) Study.4 Our analytic sample consisted of 250 participants with complete exposure, physical function and covariate data. Four additional participants were missing falls data.
Outcome measures
The Short Physical Performance Battery (SPPB) is an objective, performance-based test of lower extremity function composed of 3 tests: chair stands, standing balance and 4-meter walk.5 Grip strength was measured with a hand held dynamometer. Six-month falls were assessed via self-report.
Hearing impairment
Air conduction hearing threshold levels for the frequencies of 0.5, 1 , 2 and 4 kHz were obtained by pure tone audiometry in a sound attenuating booth and averaged for the better-hearing ear to yield a pure tone average (PTA) in decibels hearing level (dB HL). HI was defined as PTA>25 dB HL.
Statistical analysis
Associations between physical function and HI were modeled using linear (continuous outcomes) and logistic (binary outcomes, including falls) regression. Because of the ceiling effect, we modeled the association between HI and total SPPB score with tobit regression. Because age distributions differed substantially by HI status (Table 1), analyses were repeated excluding participants aged > 81 years. Covariate adjustments are detailed in Table 1.
Table 1.
Participant Characteristics and Multivariable-Adjusted Differences in Physical Function and Log Odds of Falls by Hearing Impairment (HI) Status, Atherosclerosis Risk in Communities Study, 2013, N=250
| Descriptive Statistics | ||||
|---|---|---|---|---|
| Characteristic | Total (N=250) | No HI (N=72) | HI (N=178) | P-valuea |
| Age (years), mean (±SD) | 77 (5) | 74 (4) | 78 (5) | <0.0001 |
| Age category (years), N(%) | ||||
| ≤ 70 | 42 (17) | 18 (25) | 24 (13) | <0.0001 |
| 71-75 | 71 (28) | 29 (40) | 42 (24) | |
| 76-80 | 66 (26) | 19 (26) | 47 (26) | |
| > 80 | 71 (28) | 6 (8) | 65 (37) | |
| ≤ High school education, N(%) | 146 (58) | 41 (57) | 105 (59) | 0.766 |
| Male sex, N(%) | 97 (39) | 16 (22) | 81 (46) | 0.001 |
| Ever smoker, N(%) | 122 (49) | 33 (46) | 89 (50) | 0.551 |
| BMI category, N(%) | ||||
| Normal weight (<25 kg/m2) | 70 (28) | 14 (19) | 56 (39) | 0.131 |
| Overweight (25-30 kg/m2) | 99 (40) | 30 (42) | 69 (39) | |
| Obese (≥ 30 kg/m2) | 81 (32) | 28 (39) | 53 (30) | |
| Diabetes,b N(%) | 85 (34) | 19 (26) | 66 (37) | 0.106 |
| Hypertension,c N(%) | 184 (74) | 52 (72) | 132 (74) | 0.753 |
| Coronary Heart Disease, N(%) | 51 (20) | 10 (14) | 41 (23) | 0.104 |
| CNS Altering Medication Use, N(%) | 21 (8) | 5 (7) | 16 (9) | 0.598 |
| Pure tone average (dB), mean (± SD) | 35 (15) | 18 (6) | 42 (12) | -- |
| SPPB total score, median (25th, 75th percentiles) | 10 (8, 11) | 11 (9, 12) | 10 (8, 11) | 0.0004 |
| SPPB Components | ||||
| Time to complete 5 chair stands (s), median (25th, 75th percentiles) | 13 (11, 15) | 12 (10, 14) | 13 (11, 16) | 0.015 |
| Unable to hold tandem balance for 10 s, N(%) | 88 (35) | 18 (25) | 70 (39) | 0.032 |
| Time to complete 4 meter walk (s), median (25th, 75th percentiles) | 4.4 (3.9, 5.2) | 4.3 (3.7, 4.9) | 4.5 (3.9, 5.4) | 0.015 |
| Grip strengthd (kg), mean (± SD) | 26 (9) | 25 (9) | 27 (9) | 0.064 |
| 1 or more falls in the past 6 months, N(%) | 40 (16) | 10 (14) | 30 (17) | 0.556 |
| >1 fall in the past 6 months, N(%) | 14 (6) | 2 (3) | 12 (7) | 0.220 |
| Multivariable-adjustede Analyses In the Full Analytic Sample (N=250) | ||||
| Outcome Measure | Measure of Association | No HI (N=72) | HI (N=178) | P-value |
| SPPB | ||||
| Total Scoref | Difference | Referent | -0.77 (-1.50, -0.05) | 0.037 |
| Components | ||||
| Chair Stands (speed)f, h | Difference | Referent | -0.04 (-0.08, -0.01) | 0.031 |
| Balanceg | Odds Ratio | Referent | 1.35 (0.66, 2.75) | 0.407 |
| 4-m walk (speed)f, i | Difference | Referent | -0.04 (-0.09, 0.02) | 0.166 |
| Grip Strengthf | Difference | Referent | 1.72 (-0.01, 3.44) | 0.051 |
| 1 or more falls in the past 6 monthsg | Odds Ratio | Referent | 1.3 (0.5, 3.1) | 0.614 |
| Multivariable-adjustede Analyses in Participants ≤ 81 years (N=193) | ||||
| Measure of Association | No HI (N=70) | HI (N=123) | P-value | |
| SPPB | ||||
| Total Scoref | Difference | Referent | -0.65 (-1.36, 0.07) | 0.076 |
| Components | ||||
| Chair Stands (speed)f, h | Difference | Referent | -0.04 (-0.07, 0,00) | 0.045 |
| Balanceg | Odds Ratio | Referent | 1.41 (0.67, 2.96) | 0.371 |
| 4-m walk (speed)f, i | Difference | Referent | -0.04 (-0.10, 0.02) | 0.197 |
| Grip Strengthf | Difference | Referent | 1.77 (0.08, 3.46) | 0.041 |
| 1 or more falls in the past 6 months | Odds Ratio | Referent | 1.32 (0.49, 3.55) | 0.581 |
Abbreviations: BMI, body mass index; CNS, central nervous system; SPPB, Short Physical Performance Battery; SD, standard deviation
P-value for continuous variables from a oneway analysis of variance (ANOVA) test or Kruskall-Wallis test comparing mean/median cognitive test scores by HI, respectively. P-values for categorical variables from Pearson’s chi2 test.
Diabetes defined as a fasting blood glucose level ≥ 126 mg/dL, non-fasting glucose ≥ 200 mg/dL, by physician diagnosis of diabetes as self-reported by the participant, or by medication use for diabetes.
Hypertension considered present if diastolic blood pressure ≥ 90 mmHg, systolic blood pressure ≥ 140 mmHg, or by antihypertensive medication use.
The average of 2 grip strength trials was used for analysis.
Models were adjusted for age (linear and quadratic terms), education (≤ high school vs. > high school), sex, smoking status, hypertension, diabetes, and CHD. Models estimating the association between HI and falls also adjusted for use of CNS-altering medications in the past 4 weeks and grip strength.
Difference in outcome by HI status estimated using linear regression.
Odds ratio comparing participants with and without HI estimated using logistic regression.
To account for non-normality, time to complete 5 chair stands was transformed to chair standing speed (chair stands/second) by dividing 5 chair stands by the time to completion of the task.
To account for non-normality, time to walk 4 meters was transformed to 4-meter walking speed (in meters/second) by dividing 4 meters by the average (of the 2 trials) time to complete the task in seconds.
RESULTS
178 (71%) participants had HI. Participants with HI were older and more likely to be male (Table 1).
In multivariable-adjusted analyses, HI was associated with a moderate difference in SPPB scores;6 the difference comparing participants with and without HI was -0.77 points (95% CI: -1.50, -0.05). Participants with HI were slower to complete 5 chair stands (difference: -0.04 stands/second, 95% CI: -0.08, -0.01); no differences in performance were observed for balance or walking speed. Participants with HI had greater grip strength than participants without HI (difference = 1.72, 95% CI: -0.01, 3.44) (Table 1).
Of 246 participants, 40 (16%) reported falling at least once in the past 6 months, and 14 (6%) reported > 1 fall (Table 1). Confidence intervals in multivariable-adjusted analyses were wide; the estimated association between HI and 1 or more falls was OR= 1.3 (95% CI: 0.5, 3.1) (Table 1).
Results were similar when restricting to participants ≤ 81 years (Table 1). The difference in SPPB score comparing participants with and without HI was -0.65 points (95% CI: -1.36, 0.07, p=0.08).
Conclusions
In this pilot study of 250 older, white participants, mild to moderate peripheral audiometric HI was independently associated with poorer lower extremity function. Few studies have assessed the association between HI and performance-based measures of physical function. Our results are consistent with previous reports of associations between HI and lower SPPB scores.2,7
Contrary to our a priori hypothesis, HI was associated with greater grip strength. Men are more likely than women to have HI. However, in exploratory sex-stratified analyses, HI was statistically significantly associated with greater grip strength in women (difference by HI status: 1.83 (95% CI: 0.02, 3.6), p=0.05). This finding may be due to chance. Alternatively, post hoc, it may be that persons with HI are more likely to compensate for possible balance concerns through the use of handrails or other assistive devices that may possibly increase hand strength.
Because of the small number of falls, our ability to detect a statistically significant difference in falls by HI status was limited, as well as our ability to adjust for covariates. Previous studies with larger sample sizes have documented that HI is associated with falls.3,8
Causal mechanisms that could explain observed associations between HI and poorer physical function include mediation through increased cognitive load and poorer cognitive function9 or reduced awareness of the auditory environment.10 Additional limitations of our study is that we are unable to rule out that observed associations are due to a common pathology affecting both the peripheral auditory and vestibular systems (vestibular measures were not included in ARIC) or due to residual confounding from a generalized process that could affect both physical and sensory function (e.g., mitochondrial dysfunction, microvascular disease).
Declines in physical function predict incident disability and mortality and negatively impact quality of life in older adults. Longitudinal studies are needed to determine if HI is associated with incident physical function decline in older adults in order to inform possible interventions and strategies for prevention.
Acknowledgments
The Atherosclerosis Risk in Communities Study is carried out as a collaborative study supported by National Heart, Lung, and Blood Institute contracts (HHSN268201100005C, HHSN268201100006C, HHSN268201100007C, HHSN268201100008C, HHSN268201100009C, HHSN268201100010C, HHSN268201100011C, and HHSN268201100012C). Neurocognitive data is collected by U01 HL096812, HL096814, HL096899, HL096902, HL096917 with previous brain MRI examinations funded by R01-HL70825. Collection of pilot audiometric data was supported by NIDCD K23DC011279 and the Eleanor Schwartz Charitable Foundation. The authors thank the staff and participants of the ARIC study for their important contributions.
Sponsor’s Role: None
Footnotes
Author Contributions: All authors meet the criteria for authorship stated in the Uniform Requirements for Manuscripts Submitted to Biomedical Journals. Jennifer A. Deal designed the study’s analytic strategy, conducted the statistical analysis, interpreted the data and drafted the manuscript. A. Richey Sharrett contributed to the design of the study, helped to design the study’s analytic strategy, and assisted with the interpretation of the results and the revision of the manuscript. Karen Bandeen-Roche contributed to the study design, helped to design the study’s analytic strategy, and assisted with the interpretation of the results and the revision of the manuscript. Stephen B. Kritchevsky contributed to the design of the study, helped to design the study’s analytic strategy, and helped to revise the manuscript. Lisa A. Pompeii contributed to the design of the study, assisted with the interpretation of the results and helped to revise the manuscript. B. Gwen Windham contributed to the design of the study, assisted with the interpretation of the results and helped to revise the manuscript. Frank R. Lin designed the pilot study, helped to design the study’s analytic strategy, and assisted with the interpretation of the results and the revision of the manuscript.
Conflict of Interest: The authors declare no competing interests.
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