Using a definition of hearing loss adjudicated by the World Health Organization (24
), we estimated that 63.1% (95% CI: 57.4–68.8) of adults aged 70 years and older in the U.S. population are affected by hearing loss. Age, sex, and race were the principal factors associated with hearing loss, with black individuals having a hearing loss prevalence two thirds of that of white individuals in both crude and age-standardized estimates. Among individuals with hearing loss, only 19.1% reported using a hearing aid.
Our estimates of hearing loss prevalence in older adults differ somewhat from results observed in other studies. Prevalence rates reported have been 29% (>26 dB in the standard PTA in the better ear, participants >60 years), 73% (>25 dB in the speech frequency PTA in the worse ear, participants >70 years), and 60% (>25 dB in the standard PTA in the worse ear, participants 73–84 years) in the Framingham (19
), Beaver Dam (17
), and HealthABC (18
) studies, respectively. Using similar definitions of hearing loss, prevalence from the current NHANES study would be 45%, 75%, and 61%, respectively. However, comparing prevalence estimates across different studies is difficult even when applying the same definition of hearing loss given the different demographic characteristics across cohorts particularly with regard to age and race. For example, both the Framingham cohort and Beaver Dam cohorts included few black individuals, but the HealthABC cohort included 36.3% black individuals. Age distributions and ranges also varied across these study cohorts. A strength of our study is that by applying the NHANES sample weights, our reported prevalence rates are generalizable to the entire civilian noninstitutionalized U.S. population.
Consistent with other studies, we found that age, sex, and black race were associated with hearing loss (17
). Increasing age was associated with hearing loss across all frequency definitions of PTA but with greater hearing loss changes seen at the higher frequencies. Sex differences were also most apparent at higher frequencies consistent with other prior studies (18
). Similarly, we found that black race was strongly associated with lower odds of hearing loss across all frequency definitions of PTA but with greater protective associations seen at higher frequency ranges.
The association of black race with lower odds of hearing loss has been well described in both epidemiological (18
) and in clinical research studies (32
). Current hypotheses focus on the possible protective effect of melanin in the stria vascularis (33
), but experimental animal studies studying skin pigmentation and hearing loss have been inconclusive (34
). There have not been any studies examining whether residual confounding associated with racial disparities or a potential genetic etiology could explain the protective association of black race with hearing loss. However, the role of residual confounding associated with racial disparities (e.g. higher risk of poverty, hypertensive disease in blacks) would likely bias our results toward an underestimate of the protective effect of hearing loss observed in blacks rather than toward the null hypothesis.
We did not observe significant associations of hearing loss with other cardiovascular risk factors (hypertension, smoking, diabetes, stroke) even when multiple different frequency ranges of hearing loss were considered, and hearing loss was used as a continuous variable (providing for more statistical power). Results from other large representative cohorts of older adults have also demonstrated equivocal results with regard to these risk factors (18
). For example, diabetes mellitus was found to be positively associated with hearing loss in the HealthABC study (18
) but not in the Framingham (36
) and Beaver Dam studies (37
). One likely explanation for these inconsistent results is that cardiovascular risk factors are only weakly associated with hearing loss, and their effects may be masked by stronger risk factors (eg, age) particularly in cohorts comprising older adults.
Among older adults with hearing loss, we estimate that approximately one fifth use a hearing aid, and this estimate is consistent with other national estimates of hearing aid use (19
). Rates of hearing aid use differed substantially by hearing loss severity with only 3% of individuals with mild hearing loss reporting hearing aid use versus 41% in those with moderate or worse hearing loss. Interestingly, rates of hearing aid use in the United Kingdom where bilateral hearing aids are covered by the National Health Service are not higher (40
), which suggests that access and affordability are not the only issues that limit hearing health care. These observations are likely indicative of general perceptions that undervalue the potential impact of hearing loss on health and functioning in aging.
There are limitations to our study. Approximately 13% of older adults who underwent the medical examination did not complete audiometric testing, and these individuals were generally older. Our prevalence estimates may, therefore, underestimate the true population prevalence of hearing loss. Our relatively modest cohort size also limited our statistical power to detect weaker associations or to explore potential interactions between race, sex, and other covariates.
Our results demonstrate that hearing loss is highly prevalent in older adults and that the nonmodifiable risk factors of age, sex, and race are the strongest determinants of hearing loss status. Although preventative strategies focused on noise exposure and other medical risk factors remain important, increasing emphasis needs to be placed on determining the genetic, epidemiological, and pathophysiological basis for the strong protective association conferred by black race. Other research focusing on clinical trials should further examine whether aural rehabilitative strategies, particularly among individuals with mild hearing loss where hearing aids are seldom used, can potentially mitigate the adverse health and functional effects associated with hearing loss in older adults.