Obesity and risk of hearing loss: A prospective cohort study

Abstract

The existing yet limited prospective studies reported conflicting results about obesity and hearing loss. We investigated the prospective association between obesity and hearing loss in a large-scale Japanese working population, as well as the association between metabolic phenotype and hearing loss. The study included 48,549 employees aged 20-64 years and free of hearing loss at baseline. Pure-tone audiometric testing was performed annually to identify hearing loss at 1 and 4kHz. Cox proportional hazards regression was used to investigate the risk of hearing loss associated with body mass index (BMI) and metabolic phenotype (based on a BMI of ≥25.0/<25.0kg/m2 and presence/absence of ≥2 components of metabolic syndrome, except waist circumference). Baseline and updated information were obtained from annual health checkups. With a median follow-up of 7 years, 1595 and 3625 individuals developed unilateral hearing loss at 1 and 4kHz, respectively. The adjusted hazard ratios (HR) for hearing loss at 1kHz were 1.21 (1.08, 1.36) and 1.66 (1.33, 2.08) for those with BMI 25.0-29.9kg/m2 and BMI ≥30.0kg/m2, respectively, compared to individuals with BMI <25.0kg/m2. For hearing loss at 4kHz, the corresponding HRs were 1.14 (1.05, 1.23) and 1.29 (1.09, 1.52). Compared with metabolically healthy non-obese individuals, the adjusted HRs for hearing loss at 1kHz were 1.19 (1.03, 1.39), 1.27 (1.01, 1.61), and 1.48 (1.25, 1.76) for unhealthy non-obese, healthy obese, and unhealthy obese individuals, respectively. For hearing loss at 4kHz, the corresponding HRs were 1.13 (1.04, 1.25), 1.21 (1.04, 1.41), and 1.26 (1.12, 1.41). Overweight and obesity are associated with an increased risk of hearing loss, and metabolically unhealthy obesity may confer additional risk.