Self-Report Assessment of Hearing Aid Outcome - An Overview

Introduction

Patients have always provided clinicians with real-world outcome assessments of their hearing aids. Watson and Tolan (1949) and Davis and Silverman (1947) both address the importance of gathering information from the "patient's perspective" during the initial trial period with hearing aids in everyday listening environments. In a study of 20 hearing aid users, aided speech discrimination scores did not predict with any degree of reasonable accuracy how much benefit was obtained in everyday listening situations (Tonning, 1978). One of the conclusions of this study emphasized the need for self-report measures of outcome: "... results indicate that we need to pay attention to the patient's experience with hearing aids under everyday listening conditions in each individual case when a hearing aid is selected" (p.13).

Until quite recently, however, most real-world assessments of outcome involved informal discussions with the professional. Rather than formally measuring real-world outcomes, professionals relied on laboratory measures of fitting outcomes. These measures included speech recognition in quiet and in noise, insertion gain, and aided loudness judgments. In the past 20 years, there has been a proliferation of self-report measures of hearing aid outcome. Unfortunately, the majority of clinicians still do not routinely administer self-reports of outcome. (Lindley, 2006).

The goal of this paper is to review the history and provide a short summary of these measures so that the practicing clinician can have an easy reference to integrate these useful tools into their daily practice.

Overview and History of Self Reports

One of the first published self-reports of hearing aid outcome was the Scale of Self-Assessment of Hearing Handicap (High, Fairbanks, & Glorig, 1964). Self-report outcome measures with known psychometric properties are useful for determining the effectiveness of hearing aids. Effectiveness with amplification can be measured across several dimensions, including handicap reduction, acceptance, benefit, and satisfaction. Several different self-report measures of hearing aid outcome have been developed over the past two decades addressing each one of these dimensions. Because they comprise two of the most significant components of a patient's experience with hearing aids (Humes & Humes, 2004), only self-report measures of hearing aid benefit and satisfaction will be addressed.

Hearing aid benefit can be defined as the difference between unaided and aided performance measured either objectively or subjectively. Hearing aid benefit can be measured objectively by comparing aided and unaided measures of speech recognition ability, as one example. Hearing aid benefit can also be measured subjectively through the use of self-report measures. Because objective tests are completed using a pre-defined external standard, they are almost exclusively tests that take place within the laboratory. Therefore, self-report measures of outcome are a useful method of determining real-world benefits of hearing aid performance.

Another separate dimension of outcome is hearing aid satisfaction. Satisfaction differs from benefit in that satisfaction is not necessarily performance driven. For example, a patient can have a significant degree of benefit as measured on any aided and unaided tests, but report dissatisfaction as measured on a satisfaction scale.

An important question to address at this time is, "Why do we need self-report measures of real-world outcome?" According to Cox (2003) there are at least three reasons to use self-report measures of benefit and satisfaction. First, for largely economic reasons, health care is becoming more consumer driven. In this evolving system, the consumer decides what treatment is selected and when it is complete. The major indices of quality of service are self-report of outcome and satisfaction. Consumer-driven health care places an added emphasis on the patient's point of view. Therefore, it is critical to measure the real-world benefit and satisfaction of hearing aid use. Because today's patients are more savvy and informed, thanks in part to easily accessible information on the Internet, they want to know how much benefit they are receiving in everyday listening situations. Using a self-report of hearing aid outcome is simply the right thing to do.

A second reason why self-report measures of outcome are gaining importance is related to the fact that many of these real-world experiences simply cannot be measured effectively in laboratory conditions. The traditional hearing aid outcome measures clinicians have used in the past like speech recognition in quiet and in noise, do not capture the true experiences of hearing aid use in everyday listening situations. In order to quantify the true impact hearing loss and its associated treatment have on activity limitations, lifestyles, etc., self-report measures of outcome should be used.

Third, even when laboratory conditions are used to simulate real-world listening situations they do not always resemble the patient's impression of the actual real-life situation. According to Cox (2003), self-report outcome measures are increasing in use, because they give us a scientifically defensible way to validly measure the real-life success of the hearing aid fitting.

Finally, an evidence-based practice paradigm requires clinicians to demonstrate that their hearing aid fittings are providing benefit in real-world conditions. For this reason, self-reports of outcome are the new "gold standard" for measuring and reporting success.

Self-report measures of hearing-aid benefit and satisfaction are reviewed below. Only self-report measures of either hearing aid benefit or satisfaction that use normative data are included in this review. Many of the self-report measures of benefit and satisfaction listed here have been used in peer-reviewed research, and were found during a subsequent PubMed search.

Open Ended Self-Report Measures of Outcome

Open-ended self-report measures are those that allow the patient to nominate and target their own areas of improvement with amplification. The assumed advantage of an open-ended scale is that it can be tailored to the true communication needs of the patient.

Open-Ended Problems Questionnaire

As one of the first published open-ended self-report of outcome measures, (Barcham & Stephens, 1980) an open-ended format allows the patient to target one item for improvement with amplification. As an assessment tool it has been normed on over 500 subjects.

Client Oriented Scale of Improvement (COSI)

The Client Orient Scale of Improvement (COSI) was developed by the National Acoustic Laboratories (NAL) (Dillon, James, & Ginis, 1997). The COSI is an open-ended scale in which the patient targets up to five listening situations for improvement with amplification. The patient is able to choose up to 5 listening situation from a list of 16. The COSI was normed on 1770 adults with hearing loss in Australia. The goal of the COSI is for the patient to target up to five specific listening situations and report the degree of benefit obtained compared to that expected for the population in similar listening situations. Many hearing aid manufacturers now include the COSI in their fitting software. The COSI can be downloaded for free from the NAL web site (https://www.nal.gov.au/nal_products front page.htm).

Glasgow Hearing Aid Benefit Profile (GHABP)

The GHABP (Gatehouse, 1999) examines six dimensions of outcome including disability, handicap, hearing aid use, benefit, satisfaction, and residual disability. The GHABP consists of four predetermined and four patient-nominated items. Therefore, the GHABP could be considered a combination open-ended and closed-ended measure of outcome. The GHABP was normed on 293 adults. Based on the normative findings, it is an appropriate instrument for clinicians who want to use self-report data to measure improvement in audibility. The Hearing Aid Benefit Interview, a completely open-ended questionnaire, is the precursor to the GHABP (Gatehouse, 1994).

Closed-Ended Self-Report Measures of Outcome

Closed-ended self-report measures allow the patient to complete a self-report scale using a pre-determined list of areas of concern. The assumed advantage of the closed-ended scale is that the scores can be more readily compared to normative data. One of the disadvantages of a closed-ended measure is that individual communication preferences cannot be accounted for. In an era in which outcome measures are gaining importance (Cox, 2003), this is an important consideration. Closed-ended outcome measures, although outstanding tools for conducting clinical research, can sometimes fail to address the unique needs of all individuals seen in the clinic.

Denver Scale of Communication Function - Modified (DSCF-M)

The DSCF-M (Kaplan, Feely, & Brown, 1978) was one of the first published self-report measures. It was designed to assess 4 pre-specified aspects of communication skills in adults. Thirty-four questions covering four areas including attitude towards peers, socialization, communication, and difficult listening situations are assessed. Because the DSCF-M was normed on only 21 adult subjects, its validity has been questionable.

Profile of Hearing Aid Performance (PHAP)

The PHAP was developed by Cox and Gilmore (1990). It consists of 66 items measuring two aspects of hearing aid performance: 1) speech communication in a variety of everyday listening situations, and 2) reactions to loudness or quality of environmental sounds in seven subscales. The goal of the PHAP is to measure aided performance rather than benefit. Normative data for test-retest reliability were completed on 30 subjects.

Profile of Hearing Aid Benefit (PHAB)

The PHAB was developed (Cox, Gilmore, & Alexander, 1991) at Memphis University. It consists of 66 items in seven subscales including familiar talkers, ease of communication, reverberation, reduced cues, background noise, aversiveness of sounds, and distortion of sounds. The goal of the PHAB is to measure hearing-aid benefit (unaided vs. aided) across those seven dimensions. The PHAB has been normed on 42 hearing aid users.

Abbreviated Profile of Hearing Aid Benefit (APHAB)

In an attempt to develop a more clinic-friendly measure of outcome, the APHAB was developed (Cox & Alexander, 1995). Like the PHAB, the goal of the APHAB is to quantify the disability caused by hearing loss, and the reduction of that disability achieved with hearing aids. The APHAB uses 24 items covering 4 subscales: ease of communication, reverberation, background noise, and aversiveness to sounds. The APHAB has been normed on 128 elderly adults with mild to moderate hearing loss. The APHAB can be downloaded from the University of Memphis Hearing Aid Research Lab (HARL) web site (www.ausp.memphis.edu/harl/applications.html).

Hearing Aid Performance Inventory (HAPI)

The HAPI (Walden, Demorest, & Helper, 1984) uses 64 items based on 12 bipolar communication features (e.g., visual cues present/absent). The goal of the HAPI is to assess the effectiveness of amplification on a variety of everyday listening situation. The HAPI has been normed on 128 hearing aids users, 119 of which were men.

Hearing Performance Inventory (HPI) and Hearing Performance Inventory - Revised (HPI-R)

The HPI (Giolas, Owens, & Lamb, 1979) uses 158 items on a 4-point scale to assess hearing aid performance in everyday living. The HPI has been normed on 190 adults. The HPI-R (Lamb, Owens, & Schubert, 1983) uses 90 items to assess communication difficulties of persons with hearing loss. The HPI-R was normed on 354 adults with hearing loss.

Hearing Aid Users Questionnaire (HAUQ)

The HAUQ uses an 11-item questionnaire to assess hearing aid use, benefit, and satisfaction (Dillon, Birtles, & Lovegrove, 1999). The HAUQ uses a 4-point scoring score for each of the 11 questions. The goal of the HAUQ is to measure problems that may affect a person's ability to use and benefit from hearing aids. It has been normed on 4,421 adults with hearing loss.

Hearing Aid Needs Assessment (HANA)

The goal of the HANA (Schum, 1999) is to examine relationships between perceived communication needs with actual benefit eventually achieved with hearing aids. The HANA assesses 11 items using a 3-point rating scale per item. It has been normed on 82 adults, 25 of which were previous users of amplification.

Satisfaction with Amplification in Daily Life (SADL)

The SADL (Cox & Alexander, 1999) was designed to quantify hearing aid satisfaction using 15 items in four subscales. The four subscales consist of positive effects, service & costs, negative features, and personal image. The SADL was normed on between 126 and 225 adults, depending on the subscale, and can be downloaded from the University of Memphis HARL web site (www.ausp.memphis.edu/harl/applications.html).

Hearing Handicap Inventory for Adults (HHIA) and Hearing Handicap Inventory for the Elderly (HHIE)

The HHIA (Newman, Weinstein, Jacobson, & Hug, 1991) is a revised and updated version of the HHIE (Weinstein, Spitzer, & Ventry, 1986). The HHIA was designed to both quantify handicap and also assess benefit by measuring change in perceived handicap after the fitting of hearing aids. The 25-item HHIA has 2 subscales (emotional consequences and social and situational effects) that have been normed on 28 adults. Like the HHIA, the HHIE has 25 items with the same subscales used for the HHIA. The goal of the HHIE is to measure the perceived effects of hearing loss. Both the HHIE and the HHIA allow the patient to answer "yes", "no", or "sometimes" to all 25 items on the questionnaire. The HHIA and the HHIE both have 10-item screening versions.

Communication Profile for the Hearing Impaired (CPHI)

The goal of the CPHI (Erdman & Demorest, 1990) is to identify up to five specific areas of listening difficulty and the degree of benefit obtained compared to that expected for the population in similar situations. The CPHI is a 145-item questionnaire addressing four areas: communication performance, communication environments, communication strategies, and personal adjustment. It has been normed on 827 patients at the Walter Reed Army Medical Center.

International Outcome Inventory - Hearing Aid (IOI-HA)

Consisting of seven questions on a 5-point rating scale, the goal of the IOI-HA is to assess benefit, satisfaction, and quality-of-life changes associated with hearing aid use. The IOI-HA has been normed on 154 adults (Cox, Alexander, & Beyer, 2003). The IOI-HA was designed to be used with other self-report tools, like the APHAB. It is available in several languages, and can be downloaded from the University of Memphis HARL web site (www.ausp.memphis.edu/harl/applications.html).

MarkeTrak Satisfaction Survey

Published every four years since 1991, the MarkeTrak survey is 48-tem questionnaire with several subscales devoted to satisfaction as it relates to specific hearing aid features and specific listening environments (Kochkin, 1996). It has been extensively normed on a large cross-section of the general population.

World Health Organization Disability Assessment Schedule (WHO-DAS II)

Developed by the World Health Organization (WHO) and the National Institutes of Health (NIH) (Rehm, Ustum, & Saxema, 1990) it assesses multiple domains associated with quality of life, self-care, work activities, and other aspects of communication. The WHO-DAS II is particularly relevant to audiology because of items related to self-report of understanding and communicating in everyday listening situations. The WHO-DAS II has been used by the Veterans Administration system as a global measure of hearing aid outcome.

Hearing Aid Interview (HAI)

The HAI is a survey developed by Humes and Humes (2004) that is designed to be administered to patients over the phone. The HAI provides a brief self-report across two dimensions: satisfaction with amplification and use rate. It is scored on a 1 to 5 scale. The HAI was normed on 123 adult hearing aid users.

Speech, Spatial and Qualities of Hearing Scale (SSQ)

The SSQ is designed to measure a range of hearing disabilities across several domains, including auditory disability and handicap. There are 80 questions about auditory attention, perceptions of distance and movement, sound-source segregation, listening effort, prosody and sound quality. The SSQ is designed to be administered to patients through an interview format, similar to the COSI or GHABP) rather than self-administered. The SSQ has gained popularity recently, especially in Europe. It can downloaded at this website: www.ihr.gla.ac.uk/products/ssq.php

Practical Issues Related to the Use of Self-Report Measures

In order to make this review of self-reports more useful for the busy clinician, several commonly asked questions are posed, along with recommendations. Recommendations to each question are based on the best available clinical evidence.

When Should a Self-Report of Outcome Be Given to the Patient?

The question of exactly when a self-report of outcome should be administered to a patient is important for two reasons. One, if the self-report is completed too soon, the patient may not have had enough time to become familiar with the fundamental daily care and maintenance of the devices, like cleaning and insertion/removal into the ears. At least one study asserts that administering self-reports too soon results in artificially lower-than-expected outcomes because patients were not given ample time to learn how to use their hearing aids (Vestergaard, 2006).

On the other hand, if a clinician waits too long to conduct self-report measures, the entire fitting process is unnecessarily prolonged. Both the patient and the clinician are needlessly waiting to put closure to the fitting process. A recent evidence-based review of hearing aid acclimatization suggests that hearing aid benefit is optimized approximately thirty days post-fitting for the typical patient (Taylor, 2007). The clinical evidence suggests that self-reports of outcome should be administered about three to four weeks post-fitting.

What Self-Report Outcome Measure Should Be Used?

Due to the abundance of self-reports available to the clinician, it is difficult to know which ones work the best. When making this decision, it is important to examine exactly what dimension of real-world outcome you are trying to capture in the most time-efficient manner. Cox and Alexander (2007), in a large-scale study with several variables, examined the relationship between self-reports of outcome and personality. Analyses of the collection of outcome measures produced a set of three components that were interpreted as a Device component, a Success component, and an Acceptance component. Results suggest that personality is more closely linked to self-report of hearing aid outcome than conventional laboratory measures, such as the audiogram. Precisely how personality affects outcome should be taken into consideration when selecting a self-report questionnaire.

Future Trends and Conclusions

It is been demonstrated that overall hearing aid outcome can be represented by three separate and unique dimensions (Humes & Humes, 2004). These dimensions include hearing aid usage, aided speech recognition and benefit/satisfaction. There are many laboratory measures of hearing aid performance that can help determine these separate dimensions of outcome. Although laboratory measures do not reflect real world benefit, they certainly have their place in the clinic. (See Bray & Nilsson (2002) for a review of laboratory measures of outcome.) It is up to the clinician to use both laboratory and self-report measures to define the multiple dimensions of outcome.

Unless patients report that our efforts are helpful, it is difficult to justify that hearing aids are successful. It is widely accepted that self-reports of outcome reflect the real-world listening experiences of patients. In an evidence-based practice paradigm, the use of self-report assessments of real world outcome is the new "gold standard" and should be used to measure treatment effectiveness. As health care continues to become more consumer driven, it is imperative for audiologists to account for changes in communication as a result of using hearing aids. It is widely accepted that self-reports of hearing aid outcome reflect these changes.

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