Introduction
The word "quality" is one that is often used but not thoroughly understood. Quality can imply that a product or service possesses some positive characteristic that distinguishes it from its competitors or it can imply excellence and superiority. We can gauge the quality of an automobile, for example, by measuring the number of times it needs to be repaired. In healthcare applications, "quality of care" suggests that patients are evaluated and treated by skilled and credentialed providers in accordance with published or accepted practices that have been shown to maximize the opportunity for positive outcomes. We can determine the quality of care delivered by a particular hospital, for example, by measuring the post-surgical infection rate. "Quality of life", on the other hand, is more difficult to define and measure as it encompasses a wide range of domains that describe the human experience.
When quality of life is considered in regard to the impact of a disease, illness or injury, we are referring to an individual's health-related quality of life (HRQoL). As we spend ever-increasing sums of money on healthcare, it seems logical to study and measure the impact of treatments and interventions on HRQoL. What exactly does the money spent on healthcare buy? In an environment of limited resources, where should our healthcare dollars be spent? Is reducing blood pressure by a few mm of mercury better than reducing low density lipids by a few mg or improving speech recognition by a few percentage points? Indeed, there is a shift in society's focus away from how long one lives to how well one lives, as well as a recognition of the importance of a patient's self-perception of the impact of healthcare intervention as opposed to traditional methods of measuring treatment effectiveness. Finally, in this era of evidence-based practice, it is reasonable to expect that patients, their families, and third party payers will demand evidence that treatment improves HRQoL (Abrams & Chisolm, 2000). This article will briefly discuss the issues associated with HRQoL, its definitions, measurement, and the evidence that supports the relationship between hearing loss, audiologic intervention, and HRQoL. For a more comprehensive review of the concepts reviewed in this article, the interested reader is referred to a tutorial on HRQoL and hearing aids (Abrams, Chisolm, & McArdle, 2005).
Health-Related Quality of Life
Most of us have a pretty good idea of what constitutes a good quality of life: it is a life characterized by meaningful relationships, political freedom, economic independence, rewarding work, and rich recreational and spiritual experiences. When an illness or injury impacts on our lives, our self-perceived HRQoL undergoes a change. Croog (1993) proposes the following broad definition of HRQoL:
"Health-related quality of life can be viewed as the totality of characteristics of the way of life of an individual or group with particular reference to (1) the areas of physical health, emotional health, cognitive function, social role performance, well-being, and/or life satisfaction and (2) the objective conditions of existence, including living conditions and environmental stressors" (p. 14).
Revicki (1989) describes HRQoL more simply as a multidimensional concept that encompasses the physical, emotional, and social components associated with an illness or treatment. What, then, constitutes these multiple dimensions? Spilker (1996) identifies five major domains that generally constitute HRQoL as generally referred to by most researchers in this area. They include: physical status and functional abilities; psychological status and well being; social interactions; economic and/or vocational status and factors; and religious and/or spiritual status.
The National Institutes of Health (NIH) recognize that the general term "quality of life" encompasses cultural, psychological, interpersonal, spiritual, financial, political, temporal, and philosophical domains" (NIH, 1993). Although not all of these dimensions may be affected by disease, many influence how an individual may cope with the disease and respond to treatment (Abrams et al., 2005. Finally, a definition of HRQoL that takes into account quantity as well as quality of life is suggested by Patrick (1993): "Health-related quality of life is the value assigned to duration of life as modified by the impairments, functional states, perceptions and social opportunities influenced by disease, injury, treatment or policy" (p.82).
The Relationship between Audiologic Intervention and HRQoL
In considering the impact of hearing loss on HRQoL, it may be useful to use the World Health Organization's International Classification of Functioning, Disability and Health (World Health Organization [WHO-ICF], 2001) as a conceptual model. The WHO-ICF classified the effect of disease or disorder (and its subsequent treatment) on body structures and functions, activity, and participation. As described by Chisolm and Abrams (2007), the negative effects of adult-onset hearing loss are not limited to an impairment of body structure or function (i.e., a damaged sensory organ), but also involve activity limitations, such a reduction the ability to understand speech and, consequently, restrictions in participation in a variety of life events, ultimately leading to reductions in HRQoL.
Audiology treatment, provided through hearing aids, assistive listening devices, and/or cochlear implants, is highly successful in addressing the negative consequences of hearing disorders. This is accomplished by first reducing impairments to body function through improved audibility, which then allows for improved speech intelligibility (reduction in activity limitations), which can result in increased involvement in family and social situations (reduction in participation restrictions) and ultimate improvement is self-perceived HRQoL. Activity limitations, participation restrictions, and HRQoL can be mediated through audiologic rehabilitation programs such as those described by Wayner and Abrahamson (1996) and Chisolm, Abrams, and McArdle (2004).
How is HRQoL Measured?
Not surprisingly, measuring HRQoL is about as difficult as defining it. If we accept the premise that HRQoL assessment involves examining the degree to which an individual's health status impacts on the self-perception of daily functioning and well being, we can identify those specific measures that allow us to validly measure HRQoL. Generally speaking, HRQoL can be assessed using either generic or disease-specific instruments (NIH, 1993). Generic instruments are broad in scope and applicability. The advantage of generic measures is that they allow comparison across diseases and interventions because they do not focus on any particular disorder or treatment. The disadvantage of these measures is that they are not particularly sensitive to audiologic intervention, since few of the major generic measures, such as the Medical Outcome Survey (MOS) SF-36F (Ware & Sherbourne, 1992), contain any items that pertain to hearing loss. Disease-specific instruments on the other hand, focus on a single disease or disorder, defining its effects on daily functioning and well being (e.g. Hearing Handicap Inventory for the Elderly [HHIE], Ventry & Weinstein, 1982). The advantage of disease specific measures is that they tend to be sensitive to audiologic intervention, with the disadvantage being that they do not allow for comparisons of the effects of different disorders and interventions on HRQoL. For example, how does a 15-point decrease in the HHIE compare to a 15-point decrease in a disease-specific depression scale? In a consensus statement on HRQoL, the NIH (1993) recommended that both disease-specific and generic instruments be utilized for assessing HRQoL.
Disease-Specific HRQoL Instruments
As noted above, the HHIE is an example of commonly-used audiologic disease-specific measure. The HHIE is a 25-item instrument that measures the self-perceived psychosocial effects of a hearing loss on the older individual, with 12 items measuring the effect of hearing loss on social/situational functioning and 13 items measuring the emotional impact of the hearing loss. In addition to measuring the HRQoL effects of hearing aids, the HHIE has also been used to examine the effects of other audiologic rehabilitative intervention (Abrams, Hnath-Chisolm, Guerriero, & Ritterman, 1992; Mulrow et al., 1990, Stark & Hickson, 2004).
An example of a disease-specific instrument that incorporates a question specifically designed to assess HRQoL is the International Outcomes Inventory - Hearing Aids (IOI-HA; Cox, Hyde, & Gatehouse, 2000). The IOI-HA is relatively short and easy to administer. Each of its seven questions is designed to target a different outcome domain. These include: usage (number of hours per day of hearing aid use); benefit in terms of improvement in hearing-related activities; residual activity limitations; satisfaction; residual participation restrictions; impact on others; and, quality of life. Each item has five response choices and is scored on a scale of 1 to 5, with 1 indicating the most negative response and 5 the most positive. Psychometric data for the IOI-HA have been developed (Cox & Alexander, 2002). The IOI has also been used to assess non-hearing aid audiologic intervention. Hickson, Worrall, and Scarinci (2006) used alternative wording of the IOI (as suggested by Noble, 2002) to assess the outcomes of a community-based communication intervention for older adults and to assess the views of the participants' significant others. One question, for example, specifically asks the participants and their significant others about the effect of the program on enjoyment (i.e., quality) of life.
Generic HRQoL Instruments
As noted above, generic measures do not focus on any particular disorder or treatment, but rather on the self-perceived overall health status of the individual. Examples of generic measures are the Sickness Impact Profile (SIP; Bergner, et al., 1981), MOS SF-36, and the EQ-5D (EuroQoL Group, 1990). While some researchers argue that that generic measures can be as responsive as disease-specific measures in some settings (O'Connor, 1993; Kaplan, et al., 1989), Bess (2000) concluded that generic instruments appear to lack responsiveness to the effects of audiologic intervention for adult-onset hearing loss. Some recently-developed generic measures, however, have shown increased responsiveness to audiologic intervention.
The Psychosocial Impact of Assistive Devices Scale (PIADS) developed by Day and Jutai (1996), for example, was designed to assess how assistive devices (although not necessarily audiologic) affect subjective perceptions of psychological well-being and quality-of-life. Saunders and Jutai (2004) demonstrated that the PIADS to be sensitive to the overall psychosocial impact of hearing aid intervention in adults. Another recently-developed instrument is the World Health Organization's Disability Assessment Schedule II (WHO-DASII, World Health Organization [WHO], 1999.) The WHO-DAS II consists of 36 items organized into six domains: Communication, Mobility, Self Care, Interpersonal, Life Activities, and Participation in Society. In addition to these six domain scores, the WHO-DAS II also provides a Total Score. McArdle et al. (2005) demonstrated that the WHO-DAS II Total Score and the Communication domain score were responsive to both short-term and long-term effects of hearing aid intervention.
Preference-based HRQoL Assessment
In addition to disease-specific and generic assessments (measures also known as "profiles") preference-based methods or utilities provide an alternative and powerful method of measuring HRQoL. Utility measures are derived from economic and decision theory and refer to the preference an individual or population expresses for a particular health state (Bennett & Torrance, 1996). A utility is a cardinal measure of the strength of preference (O'Connor, 1993) and is typically measured using a scale that ranges from 0.0 (death) to 1.0 (perfect health). Utility measures are emerging as a major psychometric approach to measuring HRQoL due to its potential to compare the effect of disease and interventions on HRQoL across and within disorders (Abrams, et al., 2005).
As described by Abrams and Hnath Chisolm (2000) and Abrams et al. (2005), three methods commonly used to measure utilities have recently been used to assess HRQoL in adults with hearing loss. One method uses a rating scale (RS), also known as a "feeling thermometer" where a patient may be asked to rank her present health state on the thermometer before and after audiologic intervention to determine the extent to which our treatment has improved the patient's perceived quality of life.
Another approach to measuring utilities involves the use of the "standard gamble technique" (SG). In this approach the patient is offered a choice between two alternatives: living with health state "B" with certainty (which is presumably their present health state) or gambling on treatment "A". Treatment "A" can lead to either perfect health (or hearing) or immediate death (or deafness). The interviewer manipulates the probabilities of perfect health (hearing) and death (deafness) in choice "A" until the patient is indifferent between his present health state ("B") and choice "A". The higher the probability of death (deafness) the patient is willing to consider, the lower is the health state (or quality of life) inherent in remaining with choice "B".
The third approach is termed the "time-trade-off" (TTO) technique. In time-trade-off the patient is offered a choice between living a normal life span in his or her present health or hearing state or a shortened life span in perfect health or with perfect hearing. The interviewer reduces the life span spent in the perfect health/hearing state until the patient is indifferent between the shorter period of perfect health/hearing and the longer period in the less desirable state.
Recently, a computer-assisted program was developed to assess utilities in patients seen by the audiologist. The program is called Utility Measures for Audiology Application (UMAA) software (Roberts & Lister, 2005) and it is currently being evaluated at the VA Medical Center Bay Pines, the University of South Florida, and the American Institute for Balance. To date, data have been obtained which demonstrate significant correlations between utilities as measured with each of the three approaches (i.e., RS, SG, and TTO) and the responses of adult patients with hearing loss to the HHIE (Condill, 2006). Data also demonstrated that RS, SG, and TTO utilities were not only significantly correlated with self-report of the effects of dizziness by patients with BPPV on the Dizziness Handicap Inventory (Jacobsen & Newman, 1990), but also changed significantly as a result of treatment (Sembach, 2006). Finally, preliminary data (Fulton, personal communication) from 17 patients with tinnitus demonstrate significant correlations between RS, SG and TTO utilities and responses to the Tinnitus Handicap Inventory (Newman, Jacobson, & Spitzer, 1996).
What Does the Research Tell Us?
Just as defining and measuring HRQoL presents unique challenges, so does systematically examining the association between HRQoL and audiologic intervention. There have been a number of recent studies that have used utility measures to examine the cost-effectiveness of cochlear implants. (Summerfield, Marshall, & Davis, 1995; Wyatt, Niparko, Rothman, & deLissovoy, 1996; Evans, Seeger, & Lehnhardt, 1995). A cost-effectiveness analysis that measures the costs associated with improved HRQoL as determined by a utility measure is called a cost-utility analysis (CUA), the result of which is expressed as the cost per quality-adjusted life years (QALY) gained. In many of the cochlear implant studies, the cost per QALY for the implant was compared against those of other medical devices and interventions. For example, Evans et al. (1995) calculated a cost per QALY of $15,590 for the cochlear implant as compared to previously published costs per QALY for coronary angioplasty ($11,490), implantable defibrillator ($29,220) and knee replacement ($49,700).
Another study incorporating a generic measure of HRQoL was conducted by Joore and colleagues (2002), who demonstrated that new hearing aid users experienced less anxiety and depression following hearing aid use as measured by the EQ-5D (EuroQoL Group, 1990). Mulrow et al. (1990) also demonstrated a reduction in depression among hearing aid users as measured by the Geriatric Depression Scale (GDS; Yesavage et al., 1982-83). Furthermore, Joore et al. (2003) and Stark and Hickson (2004) showed improvements on selected domain scores of the MOS-SF36 as result of hearing aid use.
Not surprisingly, the association between HRQoL and audiologic intervention has been stronger when measured with disease-specific measures. Reductions in both emotional and social consequences of hearing loss as measured by the HHIE has been demonstrated in numerous studies (Malinoff & Weinstein, 1989; Abrams et al., 1992; Chmiel & Jerger, 1996; Stark & Hickson, 2004).
In a large, multi-site study McArdle et al. (2005) administered both generic (WHO-DASII) and disease-specific (HHIE) HRQoL measures to 380 participants randomized into experimental (immediate hearing aid treatment) and control (delayed hearing aid treatment) groups. Hearing aids were shown to improve both generic and disease-specific HRQoL although the improvement in HRQoL was stronger as measured by the disease-specific measures.
Conclusions
A recent issue of the Journal of the American Academy of Audiology published the findings of a task force charged with conducting a systematic review of research related to HRQoL benefits of amplification in adults (Chisolm et al., 2007). The conclusion of the task force was that hearing aids improve HRQoL by reducing the psychological, social, and emotional effects of sensorineural hearing loss. Compelling evidence is emerging that hearing aids and other forms of audiologic intervention are indeed having a positive impact on patient-perceived HRQoL, whether measured by generic or disease-specific instruments. It is becoming clear that our interventions are significantly minimizing the negative impact of hearing impairment on activities and participation and, consequently, on HRQoL among individuals with sensorineural hearing loss. These findings are particularly encouraging and meaningful as our society struggles to determine which health conditions and treatments merit attention for research funding and third party reimbursement.
References
Abrams, H.B., & Chisolm, T.H. (2000). Outcome measures: the audiological difference. In H. Hosford-Dunn, R. Roeser & M. Valente, (Eds.), Audiology Practice Management. (pp. 69-95). New York: Theime.
Abrams, H.B, Chisolm, T.H., & McArdle, R. (2005). Health-related quality of life and hearing aids: a tutorial. Trends in Amplification, 9, 99-109.
Abrams, H.B., Hnath-Chisolm, T., Guerreiro, S.M., & Ritterman, S. (1992). The effects of intervention strategy on self-perception of hearing handicap. Ear and Hearing, 13, 371-377.
Bennett, K.J., & Torrance, G.W. (1996). Measuring health state preferences and utilities: Rating scale, time trade-off, and standard gamble techniques. In B. Spilker (Ed.), Quality of Life and Pharmacoeconomics in Clinical Trials, Second Edition (pp. 253-265). Philadelphia: Lippincott-Raven,.
Bergner, M., Bobbitt, R.A., Carter, W.B., & Gilson, B.S. (1981). The Sickness Impact Profile: Development and final revision of a health status measure. Medical Care, 1, 787-805.
Bess, F.H. (2000). The role of generic health-related quality of life measures in establishing audiological rehabilitation outcomes. Ear and Hearing, 21, 74S-79S.
Chisolm, T.H. & Abrams, H. (2007). Measuring the Effects of Audiology Treatment on Health-Related Quality of Life. In Perspectives on Aural Rehabilitation and its Instrumentation, ASHA Special Interest Division 7, 14(1): 2-6.
Chisolm, T.H., Johnson, C.E., Danhauer, J.L., Portz, L.P., Abrams, H.B, Lesner, S., McCarthy, P.A., & Newman, C.W. (2007). A systematic review of health-related quality of life and hearing aids: final report of the American Academy of Audiology Task Force on the Health-Related Quality of Life Benefits of Amplification in Adults. Journal of the American Academy of Audiology, 18, 151-183.
Chisolm, T.H., Abrams, H., & McArdle, R. (2004). Short and long-term outcomes of adult audiological rehabilitation. Ear and Hearing, 25, 464-477.
Chmiel, R., & Jerger, J. (1996) Hearing aid use, central auditory disorder, and hearing handicap in elderly persons. Journal of the American Academy of Audiology, 7,190-202.
Condill, S. (2006). Utility measures in patients with hearing loss. Unpublished Doctor of Audiology Project, University of South Florida.
Cox R.M., Hyde, M., Gatehouse, S., Noble, W., Dillon, H., Bentler, R., Stephens, D., Arlinger, S., Beck, L., Wilkerson, D., Kramer, S., Kricos, P., Gagne, J.P., Bess, F., Hallberg, & Lillemor. (2000). Optimal outcome measures, research priorities and international cooperation. Ear and Hearing, 21, 106S-15S.
Cox, R.M. & Alexander, G.C. (2002).The International Outcome Inventory for Hearing Aids (IOI-HA): psychometric properties of the English Version. International Journal of Audiology, 41, 30-35.
Cox, R.M., Alexander, G.C., & Beyer, C.M. (2003). Norms for the International Outcome Inventory for Hearing Aids. Journal of the American Academy of Audiology, 14, 403-413.
Croog, S.H. (1993). Current issues in conceptualizing and measuring quality of life. In Quality of Life Assessment: Practice, Problems, and Promise. Proceedings of a workshop, Bethesda, MD, October, 1990.
Day, H., & Jutai, J. (1996). Measuring the psychosocial impact of assistive devices: the PIADS. Canadian Journal of Rehabilitation, 9,159-168.
EuroQoL Group (1990). EuroQoL - a new facility for the measurement of health-related quality of life. Health Policy, 16,199-208.
Evans, A.R., Seeger, T., & Lehnhardt, M. (1995). Cost-utility analysis of cochlear implants. Annals of Otology, Rhinology, & Laryngology Supplement, 166, 239-240.
Hickson, L., Worrall, L., & Scarinci, N. (2006). Measuring outcomes of a communication program for older people with hearing impairment using the International Outcome Inventory. International Journal of Audiology, 45, 238-246.
Jacobsen, G.P., & Newman, C.W. (1990). The development of the dizziness handicap inventory. Archives of Otolaryngology Head & Neck Surgery, 116(4), 424-427.
Joore, M.A., Potjewijd, J., Timmermann, A.A., & Auteunis, L.J. (2002). Response shift in the measurement of quality of life in hearing impaired adults after hearing aid fitting. Quality of Life Research, 11, 299-307.
Joore, M.A., Brunenberg, D., Chenault, M.N., & Anteunis, L.J. (2003). Societal effects of hearing aid fitting among the moderately hearing impaired. International Journal of Audiology, 42, 152-160.
Kaplan, R.M., Anderson, J.P., Wu, A.W., Mathews, W.C., Kozin, F., & Orenstein, D. (1989). The Quality of Well-Being Scale. Medical Care, 27(3), S27-S43.
Malinoff, R.L., & Weinstein, B.E. (1989). Measurement of hearing aid benefit in the elderly. Ear and Hearing, 10(6), 354-356.
McArdle, R., Chisolm, T.H., Abrams, H.B., Wilson, R.H., & Doyle, P.J. (2005). The WHO-DAS II: measuring outcomes for hearing aid intervention for adults. Trends in Amplification, 9, 127-143.
Mulrow, C.D., Aguilar, C., Endicott, J.E., Tuley, M.R., Velez, R., Charlip, W.S., Rhodes, M.C., Hill, J.A., & DeNino, L.A. (1990). Quality-of-life changes and hearing impairment: A randomized trial. Annals of Internal Medicine, 113, 188-194.
National Institutes of Health. (1993). Quality of Life Assessment: Practice, Problems, and Promise - Proceedings of a Workshop, October 15-17, 1990. Washington, DC: US Dept of Health and Human Services.
Newman, C.W., Jacobson, G.P., & Spitzer, J.B. (1996). Development of the Tinnitus Handicap Inventory. Archives of Otolaryngology, Head and Neck Surgery, 122, 143-148.
Noble, W. (2002). Extending the IOI to significant others and to non-hearing-aid-based interventions. International Journal of Audiology, 41(1), 27-29.
O'Connor, R. (1993). Issues in the measurement of health-related quality of life. Working Paper 30. NHMRC National Centre for Health Program Evaluation, Melbourne, Australia, July 1993.
Patrick, D.L. (1993). Reactions and recommendations: Quality of life in NIH-sponsored studies. In National Institutes of Health (1993). Quality of Life Assessment: Practice, Problems, and Promise. Proceedings of a workshop, Bethesda, MD, October, 1990.
Revicki, D.A. (1989). Health related quality of life in the evaluation of medical therapy for chronic illness. The Journal of Family Practice, 29(4), 377-380.
Roberts, R., & Lister, J. (2005). Utility Measures for Audiology Application (UMAA) [Computer software]. Bay Pines, FL: VA Medical Center Bay Pines.
Saunders, G.H., & Jutai, J.W. (2004). Hearing specific and generic measures of the psychosocial impact of hearing aids. Journal of the American Academy of Audiology, 15(3), 238-248.
Sembach, M. (2006). Utility measures in patients with BPPV. Unpublished Doctor of Audiology Project, University of South Florida.
Spilker, B. (1996). Introduction. In B. Spilker (Ed.), Quality of Life and Pharmacoeconomics in Clinical Trials, Second Edition (pp. 1-10). Philadelphia: Lippincott-Raven,.
Stark, P. & Hickson, L. (2004). Outcomes of hearing aid fitting for older people with hearing impairment and their significant others. International Journal of Audiology, 43, s390-398.
Summerfield, A.Q., Marshall, D.H., & Davis, A.C. (1995). Cochlear implantation: demand, costs, and utility. Annals of Otology, Rhinology, & Laryngology Supplement, 166, 245-248.
Ventry, I.M. & Weinstein, B.E. (1982). The Hearing Handicap Inventory for the Elderly: a new tool. Ear and Hearing, 3, 128-133.
Ware, J.E. & Sherbourne, C.D. (1992). The MOS 36-item Short-Form Health Survey (SF-36): I. Conceptual framework and item selection. Medical Care, 30, 473-483.
Wayner, D.S., & Abrahamson, J.E. (1996). Learning to Hear Again: An Audiology Rehabilitation Curriculum Guide. Texas: Hear Again, Inc.
World Health Organization. (1999). The World Health Organization Disability Assessment Schedule II: Field Trials Version. Geneva. World Health Organization.
World Health Organization. (2001). International Classification of Functioning, Disability and Health (ICF). Geneva, Switzerland.
Wyatt, J.R., Niparko, J.K., Rothman, M., deLissovoy, G. (1996). Cost utility of the multichannel cochlear implant in 258 deaf individuals. Laryngoscope, 106, 816-821.
Yesavage, J.A., Brink, T.L., Rose, T.L., Lum, O., Huang, V., Adey, M., & Leirer, V.O. (1982-83). Development and validation of ageriatric depression screening scale: a preliminary report. Journal of Psychiatric Research, 17, 37-49.
