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NORA Symposium 2008: Public Market for Ideas and Partnerships

Poster #007

Hearing Difficulty Attributable to Employment by Industry and Occupation: United States, 1997-2003

SangWoo Tak, ScD; Geoffrey M. Calvert, MD

National Institute for Occupational Safety and Health, Division of Surveillance, Hazard Evaluations, and Field Studies, Cincinnati, OH, USA

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• Are you interested in this work; if not, is there a related type of work that would interest you more?
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Abstract

Objective: To estimate the national burden of hearing difficulty among workers in US industries and occupations. Methods: Data on 130,102 employed National Health Interview Survey respondents between the ages of 18–65 years who were interviewed between 1997 and 2003 were analyzed to estimate the population prevalence, adjusted prevalence ratios (PR), and fractions of hearing difficulty attributable to employment. Results: The estimated population prevalence of hearing difficulty was 11.4% (24% attributable to employment). The adjusted PRs of hearing difficulty were highest for railroads, mining, and primary metal manufacturing industry. Occupations with increased risk of hearing difficulty were mechanics/repairers; machine operators; and transportation equipment operators. Conclusions: Hearing difficulty was differentially distributed across various industries. In industries with high rates, employers and workers should take preventive action to reduce the risk of occupational hearing loss.

Background

Occupational Hearing Loss (OHL):

• Hearing impairment due to work-related exposures
• Caused by
  • Excessive sound levels or vibration
  • Heavy metals and solvent exposure
  • Physical damage to outer/middle ear
• Number with OHL in U.S. unknown
• World wide, 16% of hearing loss attributed to occupational noise
• 100% preventable, but once acquired, irreversible

Approach

Objectives

1. Estimate prevalence and attributable fractions for hearing difficulty by industry and occupation
2. Estimate magnitude of hearing difficulty due to work in U.S.
3. Identify high risk industries and occupations for OHL

National Health Interview Survey (NHIS)

• Annual cross-sectional and multistage probability area survey
• U.S. civilian, non-institutionalized population
• Face-to-face interviews
• Sampling unit = household
• Combined data for 1997-2003

Study Population

• Included
  • Adult survey respondents
  • Aged 18 – 65 years
• Excluded
  • Occupation and industry missing
  • Military
  • Deafness or hearing difficulty prior to current jobs

Industry and Occupation

• Industry – 41 sectors
  • Standard Industrial Classification (SIC)
  • Reference group: banking, insurance, and real estate industries
• Occupation – 40 groups
  
  • Standard Occupation Classification (SOC)
  • Reference group: finance, commodities, and sales occupations

Self-reported Hearing difficulty = ‘A little trouble’ OR ‘a lot of trouble’

Population Attributable Fraction

• Where,
• i = industry or occupation categories
• p = Workers with hearing difficulty in each category/ Workers with hearing difficulty in the total population
• PRR = adjusted prevalence rate ratio for hearing difficulty estimated for each group (i) compared to reference groups

Statistical Analysis

• SUDAAN v9.0 – Weights and complex survey design effect accounted
• Robust prevalence rate ratios, and 95% CIs -- using Poisson regression
• Adjusted for age, sex, race, smoking status, and education.

Results

Table. Estimated population prevalence and adjusted prevalence rate ratio (PRR) for hearing difficulty, United States, 1997-2003 (n=130,102)

		Weighted Prevalence (%)	Adjusted PRR	95% CI
Sex	Male	14.0	1.6	1.5, 1.7
	Female	8.5	1.0
Race	Caucasian	12.6	2.1	2.0, 2.3
	African American	5.4	1.0
	Other	7.2	1.4	1.2, 1.5
Age (years)	18-25	5.7	1.0
	25-34	7.1	1.3	1.2, 1.4
	35-44	10.8	1.9	1.8, 2.1
	45-54	16.8	2.9	2.7, 3.2
	55-64	21.9	3.7	3.4, 4.0
Smoking Status	Current smoker	13.4	1.3	1.3, 1.4
	Former smoker	16.3	1.3	1.3, 1.4
	Never smoker	8.9	1.0
Education	16 yrs or more	9.6	1.0
	Less than 16 yrs	12.2	1.3	1.3, 1.4
Total		11.4

Chart 1. Estimated proportion of workers with hearing difficulty

Chart 2. Population estimates by industry	Chart 3. Population estimates by occupation

Conclusions

• First study of national prevalence of hearing difficulty due to work
• 24% of hearing difficulty attributable to employment
• High risk industries and occupations identified
• Attributable fraction > 50% for certain occupations
• Research should target high risk industries and occupations for hearing loss prevention programs

Future Directions

• Establish and enhance workplace hearing loss prevention programs
• Focus interventions at high risk industries and occupations
• Establish better surveillance systems

Disclaimer

The findings and conclusions in this poster are those of the author(s) and do not necessarily represent the views of the National Institute for Occupational Safety and Health. Citations to Web sites external to NIOSH do not constitute NIOSH endorsement of the sponsoring organizations or their programs or products. Furthermore, NIOSH is not responsible for the content of these Web sites.