The Prevalence and Correlates of Hearing Loss in Drivers in Isfahan, Iran

Background: There are no data on the prevalence of occupational noise-induced hearing loss in drivers using standard audiometric testing. The aim of this study was to estimate the prevalence and risk factors of occupational noise-induced hearing loss in drivers.

Methods: A cross-sectional study was conducted on a random sample of 4300 long-distance drivers age > or =20 years taken out of a total of 10,000 estimated professionals in the city of Isfahan, Iran, from February 2006 through March 2007. The drivers were interviewed and underwent clinical and laboratory examinations including measurement of blood pressure, anthropometric data, and pure-tone audiometry in a sound-treated booths. The mean (SD) age of the participants was 40.8 (11.0) years with a mean (SD) duration of professional driving of 14.7 (9.6) years.

Results: The prevalence of bilateral noise-induced hearing loss was 18.1% [95% confidence interval (CI) 17.0~19.3]. The prevalence rates were higher in the left ear only 6.5% (95% CI: 5.8~7.3) than the right ear only 3.0 percent; (95% CI: 2.5~3.9). Using a stepwise binary logistic regression model for the right and left ear only and for both ears separately, age was a significant independent predictor of bilateral noise-induced hearing loss and for the left or right ear only. When bilateral noise-induced hearing loss was entered in the model, fasting blood glucose was a significant predictor of noise-induced hearing loss. Blood pressure, cholesterol, triglyceride, body mass index, and marital status had no significant independent association with noise-induced hearing loss when other covariates were considered.

Conclusion: These findings indicate that noise-induced hearing loss among the long-distance drivers appears to be similar to the world's population endures noise-induced hearing loss caused by occupational exposure to noise, with higher prevalence in the left ear only.