The prevalence of hearing impairment and associated risk factors: The beaver dam offspring study

Objective: To estimate the prevalence of hearing impairment (HI) and evaluate the cross-sectional associations of environmental and cardiovascular disease risk factors and HI in middle-aged adults. Design: Data were collected as part of the Beaver Dam Offspring Study, an epidemiological cohort study of aging. Hearing impairment was defined as a pure-tone average (0.5, 1.0, 2.0, and 4.0 kHz) greater than 25 db hearing level in either ear. Word recognition in competing message (WRCM) was measured using the Northwestern University No. 6 word list. Questionnaire information about behaviors, environmental factors, and medical history was also collected. Participants: The participants (N = 3285) were offspring of participants of the population-based Epidemiology of Hearing Loss Study and ranged in age from 21 to 84 years (mean age, 49 years). Results: The prevalence of HI was 14.1%, and the mean (SD) WRCM score was 64% (15%). In a multivariate model, after age, sex, education, and occupational noise were controlled for, a history of ear surgery (odds ratio [OR], 4.11; 95% confidence interval [CI], 2.37-7.15), a larger central retinal venular equivalent (OR, 1.77; 95% CI, 1.20-2.60 [fourth quartile vs first quartile]), and a higher hematocrit percentage (OR, 0.77; 95% CI, 0.63-0.95 [per 5%]) were independently associated with HI. Factors associated with lower WRCM scores were similar but also included mean intima-media thickness (mean difference, -0.63%; 95% CI, -1.06% to -0.19%; P = .005 [per 0.1 mm]) and statin use (mean difference, -2.09%; 95% CI, -3.58% to -0.60%; P = .005). Conclusions: Hearing impairment is a common condition in middle-aged adults. Cardiovascular disease risk factors may be important correlates of age-related auditory dysfunction.