Comparison of the risk of noise-induced hearing loss between male police officers and male non-police officers: a nationwide cohort study using propensity score matching in South Korea

Abstract

Background: Police officers are at a high risk of noise-induced hearing loss (NIHL) owing to the nature of their work. Therefore, this study aimed to compare the risk of NIHL in police officers and controls.

Methods: This study used the National Health Insurance claims data of workers aged 25-65 years obtained from 2005 to 2015. The case group comprised police officers, while the control group comprised general workers and public officers. The study followed a three-phase cohort design. The standardized incidence ratio (SIR) was calculated using an indirect standardization method based on age. Propensity score matching was performed using the greedy matching method, with a police officer-to-control group ratio of 1:3. Cox regression analysis was performed for each matched control group. Statistical significance was determined by a lower limit of greater than 1, based on the 95% confidence interval (CI).

Results: The SIR values for police officers were 1.62 (95% CI: 1.44-1.82) compared with general workers and 1.78 (95% CI: 1.66-1.73) compared with public officers. Police officers exhibited an increased risk of NIHL compared with general workers (hazard ratio (HR): 1.71, 95% CI: 1.49-1.98) and public officers (HR: 2.19, 95% CI: 1.88-2.56).

Conclusions: It is necessary to prevent NIHL by reducing occupational noise exposure through measures such as wearing earplugs, improving shooting training methods, and improving the shift work system.