Occupation and the risk of bothersome tinnitus: results from a prospective cohort study (HUNT)

Abstract

Objectives

Estimates of occupation-specific tinnitus prevalence may help identify high-risk occupations where interventions are warranted. The authors studied the effect of occupation on prevalence of bothersome tinnitus and estimated the attributable fraction due to occupation. The authors also studied how much of the effect remained after adjusting for noise exposure, education income, hearing thresholds and other risk factors.

Design

A prospective cohort study.

Setting

A health survey of the Nord-Trøndelag county of Norway.

Participants

A sample of the general adult population (n=49 948).

Primary outcome measure

The primary outcome measure is bothersome tinnitus.

Results

Occupation had a marked effect on tinnitus prevalence. The effect of occupation on tinnitus was reduced in men by controlling for self-reported occupational noise exposure and in women by controlling for education and income. Adding hearing loss as a predictor increased the effect of occupation somewhat. In men, age-adjusted prevalence ratios of tinnitus ranged from 1.5 (workshop mechanics) to 2.1 (crane and hoist operators) in the 10 occupations with highest tinnitus prevalence. In women, the most important contribution to the tinnitus prevalence was from the large group of occupationally inactive persons, with a prevalence ratio of 1.5.

Conclusion

This study found a moderate association between occupation and bothersome tinnitus.

Article summary

Article focus

• We studied the effect of occupation on prevalence of bothersome tinnitus and estimated the attributable fraction due to occupation.

• We also studied if the effect remained after adjustment for noise exposure, education and income, other risk factors and hearing threshold.

Key messages

• There are very few epidemiological studies quantifying work-related tinnitus risk, and our large and representative sample gives precise estimates of occupational risk.

• This study shows moderate effects of occupation on bothersome tinnitus and presents prevalence estimates of 122 different occupations in 49 948 subjects.

• Noisy occupations were associated with an increased risk of bothersome tinnitus in men, but in women, occupations with the highest risk for tinnitus were not typically noisy ones, and the attributable fraction was determined mainly by the group of occupationally inactive.

Strengths and limitations of this study

• The major advantages of the present study are the prospective design and that the study population is representative of the general working population.

• The occupations are not classified by risk factors for tinnitus, but according to the tasks and duties undertaken in the job. Heterogeneity regarding exposure within occupational categories implies that occupation, as an explanatory variable, does not capture all effects of occupational exposures on tinnitus.