Abstract
INTRODUCTION: Although conventional cigarette smoking has been linked to an increased risk of hearing loss, the association between heated tobacco products (HTPs) and hearing loss is unknown. The objective of this study was to investigate the association between cigarette and HTP use and hearing loss. METHODS: This cross-sectional study examined the data of 7769 employees from five companies (Study I) and 34404 employees from a large company (Study II), all participants in the Japan Epidemiology Collaboration on Occupational Health Study. The participants were categorized into five groups based on their self-reported tobacco use: never smokers, former smokers, exclusive cigarette smokers, exclusive users of HTPs, and those who used both cigarettes and HTPs. Hearing levels were measured using pure-tone audiometry at 1 and 4 kHz frequencies. Separate analyses were carried out for each study, and the results were then combined using fixed-effect models to pool the estimates. RESULTS: The analysis included 42173 participants, with a prevalence of 12.9% for exclusive cigarette smoking, 9.8% for exclusive HTP use, and 5.5% for dual use. The pooled adjusted odds ratios with 95% confidence intervals for unilateral hearing loss at 4 kHz were 1.21 (95% CI: 1.10-1.33) for former smokers, 1.83 (95% CI: 1.64-2.05) for exclusive cigarette smokers,1.46 (95% CI: 1.28-1.67) for exclusive HTP users, and 1.66 (95% CI: 1.41-1.96) for dual users, compared to never smokers. Additionally, the adjusted odds ratios for hearing loss at 4 kHz among exclusive cigarette smokers, exclusive HTP users, and dual users increased with the intensity of cigarette/HTP consumption (all p for trend <0.001). No significant associations were found between exclusive HTP use, dual use, and hearing loss at 1 kHz, apart from exclusive cigarette smoking. CONCLUSIONS: In this cross-sectional study, associations were found between exclusive cigarette smoking, exclusive HTP use, dual use, and hearing loss, particularly at 4 kHz. Further research is needed to confirm these findings.