Fatigue, a symptom associated with many chronic conditions and prevalent in older adults, is highly debilitating and a common complaint of individuals seen in primary health care.1 Because it is multidimensional and subjective, however, it is difficult to both define and quantify. From a psychological perspective, fatigue can be defined as a state of weariness related to reduced motivation.2 It is considered a response to internal and external demands that exceed the psychological and material resources necessary to respond or cope.
Mood states associated with subjective fatigue include depression, anger, confusion, tension, and reduced vigor. Because it tends to compromise one's focus and attention, fatigue can interfere with the ability to participate in social activities (social integration),3 as well as affect the quality of one's social interactions.4
Because of the prevalence of fatigue in primary care and its detrimental effects on well-being, investigators continue to explore potentially treatable sources of fatigue.1,51,5 Persons with hearing loss often report that they become fatigued when attempting to communicate in suboptimal listening environments, leading them to “tune out” of the conversation, likely because maintaining optimal understanding in a degraded listening environment requires a great deal of listening effort and allocation of cognitive resources.6 Recently, Hornsby and Kipp reported the results of their investigation into the extent to which hearing loss is a driver of fatigue in older adults. Their findings are of considerable clinical importance.7
MEASUREMENTS OF SUBJECTIVE FATIGUE
Hornsby and Kipp's study involved116 adults ranging in age from 55 to 94 years. The majority of participants presented with sensorineural hearing loss that was overwhelmingly mild to moderate in degree, with a mean better-ear pure tone audiometry (PTA) of 39 decibels hearing loss (dBHL). Psychosocial hearing difficulties (PHDs) were quantified using responses to the Hearing Handicap Inventory for the Elderly/Adults (HHIE/A).8 Subjective fatigue was quantified using items extracted from the Profile of Mood States (POMS), which taps into each of the moods associated with fatigue.9 Additional dimensions of fatigue were assessed using the Multidimensional Fatigue Symptom Inventory—Short Form (MFSI-SF).10
Participants who sought help for hearing difficulties were more likely to report vigor deficits (low energy) and more fatigue than similarly aged individuals in the general population on whom responses to the POMS were normed.7
The effects of degree of hearing loss on fatigue and vigor were in sharp contrast to the perceived psychosocial effects of hearing loss. Whereas the degree of hearing loss (i.e., better-ear PTA of 1000, 2000, and 4000 Hz, or 2000, 3000, and 4000 Hz) was not significantly associated with subjective ratings of each of the domains of fatigue or vigor, PHDs quantified using the HHIE/A were strongly associated with general, physical, emotional and mental fatigue, as well as with vigor.
Interestingly, after controlling for degree of hearing loss, age, and gender, a linear relationship between HHIE/A emotional subscale scores and scores on the subjective MSFI-SF fatigue scale (general, physical, emotional fatigue) emerged. In contrast, the relationship among emotional subscale scores on the HHIE/A, mental fatigue, and vigor as measured using the MFSI-SF was nonlinear—HHIE/A scores greater than or equal to 28 percent yielded a very large increase in both mental fatigue and vigor deficit ratings.7 Similarly, high social subscale score ratings (≥26%) on the HHIE/A were associated with a dramatic increase in vigor deficit, general and emotional fatigue ratings on the MFSI-SF, and total HHIE/A scores greater than or equal to 54 percent were associated with dramatically higher total scores on the MFSI-SF.
OBJECTIVE AND SUBJECTIVE RESULTS MAY VARY
These results confirm that the psychosocial stress associated with hearing difficulties is debilitating—but they also highlight a most important consideration of which clinicians should be mindful. Objectively measured hearing (i.e., impairment data) and self-reported PHDs measure different domains of function and have different correlates. The latter cannot be predicted from the former, especially because the aging process is highly individualized and the ways in which aging affects individuals and their organ systems vary considerably.11,1211,12
Whereas the prevalence of hearing impairment is close to 80 percent among persons 80 years of age and older, the prevalence of self-reported hearing difficulties is 59 percent among persons 85 years of age and older. Similarly, the prevalence of self-reported PHDs increases with severity of hearing loss, with close to 50 percent of older adults with moderate hearing loss experiencing significant handicap (HHIE/A score > 42%) versus 77 percent of elderly persons with moderate to severe hearing loss. 11,1211,12
These findings regarding the perception of hearing difficulties as they relate to fatigue and vigor underscore the importance of gathering both sets of data points—hearing impairment and PHDs—when evaluating hearing status of older adults.7 As shown in Table 1, the “health correlates” of impairment data differ from the “patient-reported well-being correlates” of PHDs. For example, probable cognitive impairment at baseline is associated with both poorer initial hearing levels and faster rates of change in four-frequency PTA; cognitive impairment is associated with lower hearing levels and faster declines in peripheral hearing ability; incidence of cognitive impairment is associated with poorer hearing levels; and hearing loss is independently associated with incident all-cause dementia.13-1513-1513-15 Furthermore, hearing impairment is associated with all-cause mortality via mediating factors that include poor self-rated health, cognitive impairment, and disability in walking.16 Hearing impairment is also associated with balance function, incidence of falls, fear of falling, physical activity levels, and increased medical expenditures.17,1817,18
In contrast, PHDs correlate more strongly with depression and subjective and objective social isolation than do measures of hearing impairment.11,1211,12 Self-perceived hearing handicap, rather than uncorrected hearing impairment, is inversely associated with quality of life among older adults.19 Furthermore, self-perceived PHDs (as measured with the HHIE/A), not measured hearing impairment, has a significant impact on a greater number of domains measured by the 36-item Short Form Health Survey (SF-36), including the physical composite scale, role limitation due to physical problems, general health, bodily pain, and social function domains.19 Finally, it is well established that self-perceived impact of a health condition (e.g., PHDs) is more closely associated with help-seeking behaviors than hearing impairment, and self-reported hearing difficulties are robust predictors of intervention uptake and outcomes.20
THE BOTTOM LINE
Speech understanding is taxing in challenging listening situations, especially when one or more processing mechanisms is compromised.21 Communication difficulties in suboptimal environments are associated with numerous subjective problems, including increased mental effort and fatigue.7,217,21 The findings of Hornby and Kipp suggest that self-reporting of PHDs correlates more strongly with subjective health measures than with objective health measures (Table).7 Whereas self-report ratings reflect the integrated perception of biological, social, and psychological dimensions of health, hearing impairment measures reflect the medical dimensions of health.22 In fact, about 12 percent of adults with normal audiograms self-report PHDs, confirming that factors beyond sound audibility are likely at play.23 In light of the fact that a major goal of audiologic testing and hearing healthcare interventions is to address challenges in daily living and to recommend treatments that will buffer the stress and fatigue associated with communicating in suboptimal listening environments, it is incumbent on audiologists to include both measures in their hearing test batteries.21