Carotid atherosclerotic burden and hearing function across auditory frequencies in a low-income rural Chinese population: a population-based cross-sectional study

Background Hearing impairment and carotid atherosclerosis are common in aging populations and share vascular risk factors, but whether carotid atherosclerotic burden is independently associated with hearing across auditory frequencies is uncertain, particularly in disadvantaged rural Asian populations. We examined these associations in a low-income rural Chinese population. Methods In this population-based cross-sectional study, adults aged ≥45 years underwent pure-tone audiometry and carotid ultrasonography. The primary outcome was bilateral overall pure-tone average (PTA) at 0.5–4 kHz; low-, mid-, and high-frequency PTAs were secondary outcomes. Exposures were mean carotid intima-media thickness (cIMT), plaque presence, plaque number, and total plaque area (TPA). Linear and logistic regression models were sequentially adjusted for demographic, behavioral, and cardiometabolic factors. Additional analyses addressed nonlinear age effects, effect modification by age and sex, ipsilateral versus contralateral carotid–ear associations, and continuous plaque burden. Results Among 1,933 participants (mean age, 60.8 ± 9.2 years; 37.5% men), 54.7% had no plaque, 25.5% a single plaque, and 19.8% multiple plaques. Overall PTA rose from 29.5 dB HL without plaque to 30.6 and 33.0 dB HL with single and multiple plaques, and hearing-impairment prevalence from 52.7% to 60.2% and 65.3% (both P < 0.001). These gradients were largely attenuated after adjustment for age and sex and changed little with further adjustment. In the fully adjusted model, multiple plaques were not associated with overall PTA ( β = 0.70 dB; 95% CI, −0.67 to 2.06), and neither cIMT nor plaque presence was associated with overall or frequency-specific PTA. Findings were robust to nonlinear age modeling, with no effect modification by age or sex and no stronger ipsilateral carotid–ear association. Among plaque-positive participants, each 1-SD increase in log-transformed TPA was associated with a 0.88-dB higher mid-frequency PTA (95% CI, 0.11–1.64; P = 0.025), but not with overall, low-, or high-frequency PTA. Conclusions Carotid atherosclerotic burden and poorer hearing co-occurred strongly in unadjusted analyses, but their association was largely explained by age, suggesting that the two conditions predominantly represent parallel manifestations of aging rather than a strong independent macrovascular relationship. The exploratory association between greater TPA and poorer mid-frequency hearing requires prospective validation.