Outcome measures in the hearing aid fitting/selection process.

The World Health Organization (1980) defines health as both the absence of disease and infirmity and the presence of physical, mental, and social well-being. The latter are considered quality of life domains relevant to health care practice and research. A key issue in this era of changing health care priorities is whether a patient's health improves as a result of a given treatment with the net benefit measured using health-related quality of life assessment measures. That is, change in physical, social, mental, and functional health, is used to evaluate the human benefits and financial value of selected programs and interventions (Testa and Simonson, 1996). Corporations and consumer organizations are pressing health plans to provide them with quality of life indicators of how well patients are faring in the hands of a particular health professional, and/or health care organization. In addition to outside agencies, patients themselves are seeking assurance that the rehabilitative services they seek are both beneficial and cost-effective (Gagne et al, 1995). Interestingly, Wall Street investors as well are monitoring the quality issue and in their view “the challenge for health plans is to re-engineer the business so the product they are selling can be evaluated on a quality as opposed to a price basis,” (Freudenheim, 1996). In turn, health professionals in general and audiologists in particular, are faced with unprecedented pressures to demonstrate the efficacy of the services they are providing. A number of reliable and valid measures of health related quality of life are available to the clinician and researcher. Some of the measures are disease-specific while others are more generic. Increasingly audiologists are considering the impact of a patient's hearing impairment in a more global/generic manner with reference to its impact on the physical, psychological and social domains or dimensions of health status. This change in philosophy is manifested in the observation that more and more audiologists are beginning to assess the effectiveness of a given intervention namely hearing aids, in terms of the functional impact or more globally the impact on quality of life. In this context, the functional impact of hearing aids implies how well is this type of intervention helping a patient achieve maximum quality of life including independence in important activities of daily living (Granger, 1984). Two domains or dimensions of auditory function tend to be measured including objective health status, such as “impairment” and subjective health status such as self-perceived “disability or handicap” (Testa and Simonson, 1996). Disability/handicap measures translate the impairment dimension into an estimate of the actual impact on quality of life impact (Testa and Simonson, 1996). It is well-known that the latter perceptions of health status are affected by the level of impairment, as well as expectations regarding health, and the ability to cope with a given set of limitations. However defined, two persons with the same objective health status (e.g. impairment) may have very different perceptions of their health related quality of life (Testa and Simonson, 1996). According to the speculative model of temporally-evolving impairment, disability and handicap, individuals choose to pursue amplification because the hearing impairment has begun to interfere with quality of life (Hyde and Riko, 1994). Specifically, the impairment domain of auditory function/dysfunction appears to increase slowly over time, sometime later disability accrues relating nonlinearly to the impairment. At some unknown point in time, the individual perceives a handicap and a decision to pursue amplification ensues with differential response to intervention (Hyde and Riko, 1994). It has been suggested that in light of the above model, each of these dimensions of health status should be measured objectively and subjectively prior to and at selected intervals following the hearing aid fitting. The measurement of outcomes over time allows for the process of acclimatization to take place. Acclimatization implies an improvement in objective or subjective performance with hearing aids that cannot be attributed to the task, any procedures or training effects (Gatehouse, 1991).