Noise-induced hearing loss and high blood pressure among city bus drivers

Abstract

To estimate the prevalence of occupational noise-induced hearing loss and arterial hypertension among city bus drivers. A cross-sectional study was carried out on a probability random sample of 108 city bus drivers taken out of a total of 1,529 estimated professionals in the city of Campinas, Brazil, in 1991. Drivers were interviewed using questionnaires on job history, shift work and vacation schedules and underwent clinical and laboratory examinations including measures of blood pressure, pure-tone audiometry, speech audiometry, and anthropometric data analysis after an informed consent was obtained. The prevalence of noise-induced hearing loss was 32.7%. According to Merluzzi's classification, 91.2% (31 cases) were classified as first and second-degree losses and the most affected frequencies were 6 kHz in 61.3%, and 4 kHz in 38.7%. There were no differences in the laterality of the first affected ear. The prevalence of arterial hypertension was 13.2% (PAD > or =90 mmHg; PAS > or =140 mmHg). The risk of noise-induced hearing loss was greater for drivers in job for more than 6 years, after controlling for age-related hearing loss. An odds ratio of 19.25 was found for those aged 45 or more (1.59<OR<386.75; p<0.01).