Theresa H. Chisolm

The aging auditory system: anatomic and physiologic changes and implications for rehabilitation

Over the last century, research in the area of age-related hearing loss has provided a vast amount of knowledge regarding age-related effects on the anatomy and physiology of the auditory system. As we enter the new millennium, researchers are beginning to shift their attention towards developing methods of modulating the effects of age-related hearing loss and the development of efficacious intervention strategies to meet all of an individuals hearing-related rehabilitative needs. The purpose of this review is to provide a framework for considering how the biological aspects of the aging auditory system interact with the most common current therapeutic intervention for age-related hearing loss—the use of amplification—and also how the biological aspects point to other potential intervention strategies.

The WHO-DAS II: Psychometric Properties in the Measurement of Functional Health Status in Adults With Acquired Hearing Loss

The World Health Organizations (WHO) Disability Assessment Scale II (WHO-DAS II) is a generic health-status instrument firmly grounded in the WHOs International Classification of Functioning, Disability and Health (WHO-ICF). As such, it assesses functioning for six domains: communication, mobility, self-care, interpersonal, life activities, and participation. Domain scores aggregate to a total score. Because the WHO-DAS II contains questions relevant to hearing and communication, it has good face validity for use as an outcome measure for audiologic intervention. The purpose of the present study was to determine the psychometric properties of the WHO-DAS II on a sample of individuals with adult-onset hearing loss, including convergent validity, internal consistency, and test-retest stability. Convergent validity was established by examining correlations between the WHO-DAS II (domain and total scores) and the Abbreviated Profile of Hearing Aid Benefit (APHAB) and the Hearing Aid Handicap for the Elderly (HHIE), two disease-specific measures, as well as with the Short Form-36 for veterans (SF-36V), a second generic measure. Data on all four measures were collected from 380 older individuals with adult-onset hearing loss who were not hearing aid users. The results of the convergent validity analysis revealed that the WHO-DAS II communication domain score was moderately and significantly correlated with scores on the APHAB and the HHIE. WHO-DAS II interpersonal and participation domain scores and the total scores were also moderately and significantly correlated with HHIE scores. These findings support the validity of using the WHO-DAS II for assessing activity limitations and participation restrictions of adult-onset hearing loss. Several WHO-DAS II domain scores and the total score were also significantly and moderately-markedly correlated with scores from the SF-36V. These findings support the validity of the WHO-DAS II as a generic health-status instrument. Internal consistency reliability for all the domain scores was adequate for all but the interpersonal domain. Test-retest stability for all the domain scores was adequate. Critical difference values were calculated for use in clinical application of the WHO-DAS II. From these findings, we concluded that the WHO-DAS II communication, participation, and total scores can be used to examine the effects of adult-onset hearing loss on functional health status. Further work examining the utility of the WHO-DAS II as an outcome measure for hearing aid intervention is warranted.

Short- and long-term outcomes of adult audiological rehabilitation.

Objective: To examine short- and long-term subjective benefits of providing a counseling-oriented audiological rehabilitation (AR) program as an adjunct to hearing aid intervention for individuals with adult-onset hearing loss. Design: One hundred six veterans (68 men and 38 women), fit binaurally with digitally programmable analog hearing aids, participated. The Communication Profile for the Hearing Impaired (CPHI; Demorest & Erdman, 1987) was administered to all participants before hearing aid fitting. Half the patients were randomly assigned to receive hearing aids alone (i.e., control); the other patients were assigned to participate in a 4-wk group AR program in conjunction with receiving hearing aids (i.e., HA+AR). At the end of the AR program, the CPHI was again administered to all participants to assess short-term benefit and at 6 mo and 1 yr after hearing aid fitting to assess long-term benefit. Results: A separate repeated-measures version of the general linear model was used to examine short- and long-term benefits for the CPHI factor scores (communication importance, communication performance, adjustment, interaction, and reaction) and for individual importance ratings and scale scores. Hearing aid use improved both short- and long-term self-perception of communication performance, with no additional benefits from participation in the AR program. Consistent with the goals of a counseling-oriented AR program, differential short-term treatment effects were found for communication strategy usage, which led to differential short-term benefits for the interaction and reaction factors. Although failing to reach strict criteria for statistical significance, there was an observable difference in short-term outcomes between the two groups for the adjustment factor, with greater improvements occurring for the HA+AR group. Over the course of the year, benefits measured for the HA+AR group remained stable, whereas scores for the control group continued to increase, resulting in no differences in factor scores between groups at 1 yr after intervention. Conclusions: The finding of a short-term differential treatment benefit for AR in terms of interaction and reaction, and possibly for adjustment, was important, as better outcomes in these areas may be important in the decision to keep hearing aids. If this is the case, then the data support the inclusion of a counseling-oriented AR program. Differential treatment effects in interaction and reaction appeared to result from communication strategy use, indicating that the AR program is meeting many of its goals in this area. The lack of long-term differential effects appeared as the result of continued changes in adjustment, interaction, and reaction with continued hearing aid experience.

Modulation of Presbycusis: Current Status and Future Directions

Literature and ideas are reviewed concerning the modulation of presbycusis – the influence of variables that can alter the severity and/or time course of presbycusis or counteract its negative aspects. Eleven topics are identified: variables related to biological aging; genetics; noise-induced hearing loss; moderately augmented acoustic environment; neural plasticity and the central auditory system; neural plasticity and hearing aids; socioeconomic and cultural barriers to hearing aid use; lifestyle (diet, exercise, etc.); medical variables; pharmaceutical interventions for presbycusis, and cognitive variables. It is concluded that the field of otogerontology will best be served by a comprehensive, integrative interaction among basic researchers and clinical scientists who will continue to learn how the auditory problems associated with presbycusis can be intentionally modulated in beneficial ways.

The WHO-DAS II: measuring outcomes of hearing aid intervention for adults.

The World Health Organizations Disability Assessment Scale II (WHO-DAS II) is a generic health-status instrument that provides six domain scores and a total, aggregate score. Two of the domain scores, communication and participation, and the total score, have good validity, internal-consistency reliability, and test-retest stability in individuals with adult-onset hearing loss. As such, these two domain scores and the total WHO-DAS II score may be useful as generic outcome measures to assess the effectiveness of hearing aid intervention for this population. Before the use of the WHO-DAS II in hearing aid clinical trials, however, the responsiveness of the instrument and the short- and long-term outcomes to hearing aid intervention had to be determined. Responsiveness and outcomes were assessed in 380 veterans (approximately half received hearing aids and half served as controls) by examining group differences, effect-size estimates, and individual differences as a function of hearing aid intervention. For comparison, data also were obtained on two disease-specific measures, the APHAB and the HHIE. The WHO-DAS II communication domain and total scores were sufficiently responsive to hearing aid intervention for use in future studies in which group differences are to be detected. The WHO-DAS II participation domain was not sufficiently responsive to hearing aid intervention. The APHAB and HHIE, both disease-specific measures, were more sensitive to hearing aid intervention than the generic measure. The short- and long-term outcomes of hearing aid intervention were also examined in the present study. Group outcomes for hearing aid intervention can be expected to be stable for at least 6 months when measured by WHO-DAS II total score and for at least 12 months when measured by the WHO-DAS II communication domain scores. Effect-size estimates and examination of the number of individuals exhibiting change scores exceeding 90% critical differences for true changes in scores indicate that for clinical applications, disease-specific instruments are more useful than the WHO-DAS II. The findings of this study support the use of the WHO-DAS II as a generic measure in hearing aid trials research so as to allow for comparisons of health-status outcomes across different diseases or disorders.

Health-Related Quality of Life and Hearing Aids: A Tutorial

Health-related quality-of-life (HRQoL) instruments measure the impact of a disorder and treatment on several attributes that are thought to constitute the self-perceived health status of an individual. This tutorial reviews the conceptual framework of HRQoL, including the challenges associated with defining and measuring HRQoL, specifically as it applies to audiologic care. A relatively new instrument, the World Health Organization-Disability Assessment Schedule II, will be discussed as a potentially valuable instrument to measure the impact of hearing loss and hearing aid intervention on self-perceived HRQoL.

Evidence for the Use of Hearing Assistive Technology by Adults: The Role of the FM System

Hearing assistive technologies include listening, alerting, and/or signaling devices that use auditory, visual, and/or tactile modalities to augment communication and/or facilitate awareness of environmental sounds. The importance of hearing assistive technologies in the management of adults with hearing loss was recently acknowledged in an evidence-based clinical practice guideline developed by the American Academy of Audiology. Most currently available evidence for hearing assistive technology use by adults focuses on frequency-modulated (FM) technology. Previous research is reviewed that demonstrates the efficacy of FM devices for adults in terms of laboratory measures of speech understanding in noise. Also reviewed are the outcomes from field trials of FM use by community-dwelling adults, which, to date, have been disappointing. Few to no individuals, in previous studies, elected to use FM devices at the end of the trial periods. Data are presented from a 1-group pretest-posttest study examining the role of extensive counseling, coaching, and instruction on FM use by adults. In addition, the potential influence of the cost of devices to the individual was eliminated by conducting the study with veterans who were eligible to receive FM systems through the Veterans Affairs National Hearing Aid Program. Positive outcomes were obtained at the end of a 6-week trial period and were found to remain 1 year after study completion. Implications for increasing the evidence base for the use of FM devices by adults are discussed.

Computerized dynamic visual acuity with volitional head movement in patients with vestibular dysfunction.

Objectives: Patients with uncompensated vestibular dysfunction frequently report blurred vision during head movement, a symptom termed oscillopsia. One way to measure the functional deficit associated with an impaired vestibulo-ocular reflex is by comparing visual acuity from a baseline condition in which there is no head movement to visual acuity obtained during a dynamic condition with head movement. A previously described test incorporated a treadmill upon which patients walked during assessment of visual acuity. The objective of the current investigation was to evaluate an alternative method of assessing dynamic visual acuity that uses volitional head movement instead of walking on a treadmill. Methods: Fifteen participants with normal vestibular function and 16 participants with impaired vestibular function were enrolled. All participants performed the visual acuity task under baseline conditions with no movement and also under dynamic conditions that included 1) walking on a treadmill and 2) volitionally moving their head in the vertical plane. Results: No difference in performance was observed between the treadmill task and the volitional head movement task. Participants with impaired vestibular function performed more poorly under the dynamic conditions than did participants with normal vestibular function. Conclusions: The results suggest that the volitional head movement paradigm may be useful in identification of patients with functional deficits of the vestibulo-ocular reflex.

A Randomized Control Trial: Supplementing Hearing Aid Use with Listening and Communication Enhancement (LACE) Auditory Training.

Objective: To examine the effectiveness of the Listening and Communication Enhancement (LACE) program as a supplement to standard-of-care hearing aid intervention in a Veteran population. Design: A multisite randomized controlled trial was conducted to compare outcomes following standard-of-care hearing aid intervention supplemented with (1) LACE training using the 10-session DVD format, (2) LACE training using the 20-session computer-based format, (3) placebo auditory training (AT) consisting of actively listening to 10 hr of digitized books on a computer, and (4) educational counseling—the control group. The study involved 3 VA sites and enrolled 279 veterans. Both new and experienced hearing aid users participated to determine if outcomes differed as a function of hearing aid user status. Data for five behavioral and two self-report measures were collected during three research visits: baseline, immediately following the intervention period, and at 6 months postintervention. The five behavioral measures were selected to determine whether the perceptual and cognitive skills targeted in LACE training generalized to untrained tasks that required similar underlying skills. The two self-report measures were completed to determine whether the training resulted in a lessening of activity limitations and participation restrictions. Outcomes were obtained from 263 participants immediately following the intervention period and from 243 participants 6 months postintervention. Analyses of covariance comparing performance on each outcome measure separately were conducted using intervention and hearing aid user status as between-subject factors, visit as a within-subject factor, and baseline performance as a covariate. Results: No statistically significant main effects or interactions were found for the use of LACE on any outcome measure. Conclusions: Findings from this randomized controlled trial show that LACE training does not result in improved outcomes over standard-of-care hearing aid intervention alone. Potential benefits of AT may be different than those assessed by the performance and self-report measures utilized here. Individual differences not assessed in this study should be examined to evaluate whether AT with LACE has any benefits for particular individuals. Clinically, these findings suggest that audiologists may want to temper the expectations of their patients who embark on LACE training.

Utility Measures of Health-Related Quality of Life in Patients Treated for Benign Paroxysmal Positional Vertigo

Objectives: Comparing the effects of different disorders and interventions on health-related quality of life (HRQoL) is important for healthcare policy and accountability. There are two basic approaches to measure HRQoL: questionnaires derived from psychometrics and preference-based measures or utilities derived from econometrics. While disease-specific HRQoL questionnaires, such as the Dizziness Handicap Inventory (DHI), are important because they focus on the impact of a specific problem and its treatments (i.e., vestibular disorders), economic comparisons of the impacts of diseases/disorders and their treatments are typically based on utility assessment. The utility measures for audiology application (UMAA) were developed to measure utilities for various audiologic conditions using a standard computer. The purpose of this study was to determine if the UMAA provides stable, valid, and sensitive utility measures of the effects of benign paroxysmal positional vertigo (BPPV) and its treatment on HRQoL. It was hypothesized that utilities, as measured by the UMAA, would indicate improvement in HRQoL post-treatment for BPPV comparable to a disease-specific health status measure (DHI). Design: The UMAA incorporates three techniques to measure utility: rating scale, standard gamble, and time tradeoff. A utility is a cardinal measure of strength of preference and is measured on a continuum basis from 0.0 (incapacitating dizziness) to 1.0 (no dizziness). Fifty-two adults with BPPV of the posterior semicircular canal completed the UMAA and DHI before treatment and again post-treatment. A subgroup of 15 participants completed the UMAA on two occasions before treatment to assess test-retest stability and to establish critical difference values. Results: Results from this investigation demonstrate that utilities as measured through the UMAA are stable, valid, and comparable to the DHI. Post-treatment utilities were also significantly higher than pretreatment utilities, indicating that the utilities, as measured through the UMAA, are sensitive to improvement in HRQoL after BPPV treatment. Conclusions: Utilities as measured through the UMAA seem sensitive to changes in HRQoL after treatment of BPPV. Since the UMAA can be used to measure patient preference (i.e., utility), it may be useful for comparison of specific audiologic conditions, such as BPPV, to nonaudiologic conditions, such as cardiovascular disease and kidney disease.