Relationship Between Hearing Impairment And Hypertension Among The Workers Exposure To Occupational Noise:A Longitudinal Study

Objective: This study investigated the association between the noise induced hearing impairment and hypertension and blood pressure levels.Methods: From March 2009 to March 2016,regular audiometry,physical examination,and demographical questionnaire were carried out among a auto-body factory workers.Hypertension was determined accordingly to the diagnostic criteria of Chinese hypertension guidelines(2018).The hearing threshold level and hearing impairment were used to evaluate the noise exposure.The present study was divided into two parts:Part one: This part of data was derived from the physical examination center database in a hospital.We recruited 3659 employees from a auto-body factory who were exposed to occupational noise.Among them,628 subjects with missing data of audiometry examination and 3 participants with missing data on blood pressure were excluded.Finally a total of 3028 subjects were included in the cross-sectional study.The Logistic regression model were used to analyze the association between hearing threshold level and hearing impairment and hypertension.Part two: Based on the subjects enrolled in Part one,753 subjects with hypertension and other cardiovascular diseases within baseline were further excluded.Those with physical examinations less than five times were further excluded.Finally,1090 individuals were selected for the prospective study.The Cox regression model was used to analyze the relationship between bilateral high-frequency hearing threshold,high frequency hearing threshold in the better ear,and low frequency hearing threshold in the better ear and hypertension.Based on the longitudinal repeated measurementsdata,the linear mixed effect model was used to examine the relationship between the change of noise exposure index and the change of blood pressure levels.Results:Part one: In the analysis of hearing threshold level and hearing impairment and hypertension risk at baseline,after adjusting for confounding factors,there was no significant correlation between hearing impairment and hypertension.No statistically significant relationship was found between hearing threshold level and the risk of hypertension according to the continuous variables of hearing threshold level(/10dB)and grades of hearing loss(P>0.05).Part two: In the longitudinal study with repeated measurements data,the linear mixed effect model analysis showed that after adjusting for potential confounding factors,high-levels of high-frequency hearing threshold in the better ear was related to the increase of systolic blood pressure(SBP)compared with those with low-levels of high-frequency hearing threshold.The SBP increased by 0.49%(95%CI: 0.15%,0.82%)for each 10 dB increase of high frequency hearing threshold in the better ear.The bilateral average high-frequency hearing threshold was associated with increased SBP.With each 10 dB increase of the bilateral high-frequency hearing threshold,the SBP increased by 0.42%(95%CI: 0.10%,0.74%).No statistically significant relationship was found between low-level low-frequency hearing threshold in the better ear and SBP.No statistically significant relationship was found between hearing thresholds and diastolic blood pressure(DBP).Similarly,no significant relationship was found between hearing impairment and hypertension risk.Conclusion: High-frequency hearing threshold in the better ear and bilateral high-frequency hearing threshold are related to the levels of SBP but not with DBP.No statistically significant relationship was found between low-frequency hearing threshold and SBP.Similarly,no significant relationship was found between hearing impairment and hypertension risk.