The terms “morbidity” and “mortality” are often used to define disease states. Morbidity refers to disease severity and need for medical intervention. The concept of morbidity can be applied to an individual or a population, with morbidity rates differing depending on the disease in question. “Comorbidity” refers to the presence of two or more chronic conditions affecting an individual at the same time (Boyd. Aging Clin Exp Res 2008;20:181-188http://link.springer.com/article/10.1007%2FBF03324775). Mortality, or how likely a condition is considered to be deadly, refers to the number of people who died in a given population. Health status is a consequence of the interaction between mortality and morbidity (Manton. The Milbank Memorial Fund Quarterly Health and Society 1982;60:183-244http://www.milbank.org/the-milbank-quarterly/search-archives/article/3091/changing-concepts-of-morbidity-and-mortality-in-the-elderly-population?back=/issue/1982/2). Some conditions that are widespread (high morbidity) have low mortality rates—and, indeed, the opposite is true as well. People are surviving longer, and increases in longevity are accompanied by a rise in the number of disabling conditions with which one lives. Evidence is accumulating linking hearing loss to disability, including functional limitations, physical mobility problems, and activity restrictions. Because disability is known to increase mortality risk, recent studies have explored the contribution of hearing status to mortality.
Several research groups have explored the connection among hearing loss, mobility, and mortality using large data sets. Data from one of the longitudinal studies were drawn from the Statistics Canada National Population Health Survey (NPHS) for 1994–95 through 2006–07; data from another were drawn from the Blue Mountains Hearing Study (BMHS), a population-based survey of older adults living in an Australian community; the third set of data were mined from the Health, Aging, and Body Composition study of Medicare beneficiaries residing in Pittsburgh, PA, and Memphis, TN (Genther. J Gerontol A Biol Sci Med Sci 2015;70:85-90http://biomedgerontology.oxfordjournals.org/content/70/1/85.abstract; Karpa. Ann Epidemiol 2010;20:452-459http://www.annalsofepidemiology.org/article/S1047-2797(10)00057-8/abstract; Feeny. J Clin Epidemiol 2012;65:764-777http://www.jclinepi.com/article/S0895-4356(12)00007-8/abstract). Although different statistical methods were used to model the links among hearing status, mobility, and mortality, the trends are comparable and implications for audiology considerable. In their prospective population-based study, Feeny et al. defined hearing status based on self-report of the ability to hear in one of five different situations, ranging from the ability to hear a conversation with one other person in a quiet room without a hearing aid to the inability to hear at all. Genther et al. and Karpa et al. defined hearing loss as better-ear four-frequency pure tone average poorer than 25 dBHL. Follow-up times for these prospective studies differed: five years for the cohort in the Karpa et al. study, 12 years for participants in the Feeny et al. study, and eight years for participants in the Genther et al. study.
Robust in analyses accounting for confounding factors such as age, the evidence is clear, as displayed in the table. Despite differences in geography, follow-up time, and statistical methodology, hearing loss, whether self-reported or measured audiometrically, was linked to an increasing risk of mortality. Further, whether direct or indirect, history of falls, mobility limitations, poor self-rated health, fear of falling, and slower gait speed contributed to the relationship that emerged (Li. Gait Posture 2013;38:25-29http://www.gaitposture.com/article/S0966-6362(12)00379-7/abstract). It is noteworthy that Fisher and colleagues found in their community-based Icelandic sample that walking disability, cognitive impairment, and self-reported health did not explain the impact of hearing impairment on mortality (Fisher. Age Aging 2014;43:69-76http://ageing.oxfordjournals.org/content/43/1/69.long). Whether the association with mortality is mechanistic, possibly mediated by declines in physical functioning or self-reported health status, falls, or the degree to which people are engaged in their social environments, hearing status matters (Mendes de Leon. Am J Epidemiol 2003;157:633-642http://aje.oxfordjournals.org/content/157/7/633.full.pdf).
A CALL TO ACTION
Even as a recent report by the President's Council of Advisors on Science and Technology (PCAST) attempts to diminish the role of hearing health care professionals in the management of older adults with mild to moderate hearing loss (for instance, stating that consumers should be able to self-diagnose, self-treat, and self-monitor their hearing status), I would argue that the expansion in morbidity—or increase in the absolute number of years lost to disability as life expectancy increases—is a call to action for audiologists. The PCAST report is a disruptive innovation, calling for affordable and accessible hearing health care for the millions of people with hearing loss who do not purchase hearing care solutions (bit.ly/PCAST-hearing). It is imperative that audiologists document the value and enduring quality-of-life outcomes associated with the purchase of hearing health care. Consumers are willing to pay for quality services, so value- and performance-based patient-reported outcome measures (PROMs) could be used by patients to help make informed decisions regarding choice of professional and intervention. Audiologists should incorporate one or two PROMs into their practice setting and document how hearing care solutions and rehabilitation help their patients to integrate technology into daily life, yielding improved quality of life. For example, self-rated health, a widely used PROM, is a powerful predictor of mortality and is a correlate of hearing status. Similarly, history of falls, social and emotional loneliness, depression, and low physical activity levels relate to hearing status and mortality and can be reliably quantified, reflecting the experience of the patient (Chen. J Am Geriatr Soc 2014;62:850-856http://onlinelibrary.wiley.com/doi/10.1111/jgs.12800/abstract; Mick. Otolaryngol Head Neck Surg 2014;150:378-384http://oto.sagepub.com/content/150/3/378.abstract; Pronk. Int J Audiol 2011;50:887-896http://www.tandfonline.com/doi/abs/10.3109/14992027.2011.599871?journalCode=iija20). Audiologists should use social media to underscore how hearing status and its rehabilitation are critical to enhanced quality of life, well-being, and longevity. We must be proactive and disseminate data analytics documenting how hearing health care solutions successfully mitigate the effects of hearing loss. Such information is sorely needed to underscore the critical role audiologists play in the delivery of hearing health care.