We assessed socioeconomic position and hearing loss in a Norwegian population of 17 593 men and women aged 30–54 years in 1984–1986 who were followed for 11 years. We used analysis of variance, logistic regression, and population-attributable fraction analyses to examine associations. Significant socioeconomic inequalities in hearing loss were found among men. Adjusted odds ratios for hearing loss were approximately 1.3 to 1.9 for semi- and unskilled manual workers compared with participants with high occupational class; the population-attributable fraction of the prevalence of hearing loss over the cutpoint in the high-frequency (3, 4, 6, and 8 kHz) range was 35%.

Hearing impairment in adults is 1 of the most common chronic health problems in the Western world.1 In Norway, the estimated prevalence of permanent hearing loss in the adult population is approximately 15%,2 similar to that in other countries.35 This prevalence is expected to increase to 25% by 2020 along with increased life expectancy.3,6 A relatively stable occurrence of noise-induced hearing loss despite reduced occupational noise exposure7 might be explained by increased exposure to noise during leisure activities.8 Additional risk factors for hearing loss are heritage, infection, trauma, toxicity, and disease.9

Few reports have documented the relation between hearing loss and socioeconomic position as measured by education level and occupational class.4,1015 The total-population–based Nord-Trøndelag Health Study (HUNT) and its Nord-Trøndelag Hearing Loss Study component offered a unique opportunity to study the relation between socioeconomic position and hearing loss with a prospective study design.

The HUNT Study was performed as 2 cross-sectional surveys, HUNT 1 (1984–1986) and HUNT 2 (1995–1997). All residents of Norway who were 20 years and older in 1984–1986 were invited to participate.1618

Our sample included only men and women aged 30 to 54 years in HUNT 1. Altogether, 28 930 persons from HUNT 1 were invited to participate in HUNT 2 and the hearing loss study, of whom 8330 (57.0%) men and 9263 (64.7%) women, then aged 41 to 65 years, participated. Because of missing information, the total sample varied from 7849 to 8032 men and from 7513 to 8986 women.

Air-conductive hearing thresholds were obtained by pure tone audiometry with Interacoustics AD25 automatic, self-administered audiometers (Interacoustics A/S, Assens, Denmark) with TDH-39 earphones (Telephonics, Farmingdale, NY) linked to a personal computer.16 Thresholds were determined in accordance with ISO 8253-1 (1989).19 The audiometers were calibrated (ISO 389, 1991)20 every 6 months. Semiportable, dismountable sound-attenuation booths were used in rooms especially selected to avoid background noise. Background noise was measured and met the recommended standard (ISO 8253-1, 1989).19,21 Socioeconomic position was measured as education level and occupational class reported in the HUNT 1 questionnaire.2226

SPSS version 14.0 (SPSS Inc, Chicago, IL) was used to perform analyses. Possible associations were examined with 2-way analysis of variance with adjustment for age. The main outcomes were studied by using logistic regression analysis. Because the upper part of the hearing thresholds were of particular interest, we chose cutpoints that corresponded with the 10th percentile in all frequency ranges. The population-attributable fraction of the prevalence of hearing loss over the cutoff in the high frequency (3, 4, 6, and 8 kHz) range was calculated as the difference between the overall prevalence and the prevalence for the highest socioeconomic group, expressed as a percentage of the overall prevalence.27 For men, the chosen age group had high socioeconomic stability from HUNT 1 to HUNT 2; socioeconomic stability was lower among women in this age group.

The measured mean hearing threshold over 3 frequency ranges, by education level, in men and women is shown in Figure 1 and Table 1. The increases in thresholds from the highest to the lowest education level for the low-, middle-, and high-frequency ranges were statistically significant.

Table

TABLE 1 Age-Adjusted Mean Hearing Thresholds at 3 Frequency Ranges in 1995–1997, by Gender and 1984–1986 Educational Level: Hunt 1 and Hunt 2

TABLE 1 Age-Adjusted Mean Hearing Thresholds at 3 Frequency Ranges in 1995–1997, by Gender and 1984–1986 Educational Level: Hunt 1 and Hunt 2

Education LevelLow, dB (95% CI)Middle, dB (95% CI)High, dB (95% CI)
Men
College and university13.6 (13.2, 14.0)11.2 (10.7, 11.8)27.7 (26.8, 28.5)
Vocational or high school14.8 (14.5, 15.1)13.0 (12.6, 13.4)32.0 (31.4, 32.6)
≤ 10 years of public school15.3 (15.0, 15.5)14.0 (13.6, 14.3)33.6 (33.1, 34.1)
Women
College and university15.0 (14.4, 15.5)11.6 (11.1, 12.2)29.0 (18.3, 19.7)
Vocational or high school16.3 (16.0, 16.7)12.2 (11.8, 12.6)29.7 (19.2, 20.2)
≤ 10 years of public school16.7 (16.5, 16.9)12.8 (12.6, 13.1)20.9 (20.5, 21.2)

Note. HUNT = Nord-Trøndelag Health Study. CI = confidence interval; dB = decibels. Education level was categorized according to a standardized scheme developed by the Organisation for Economic Co-operation and Development.22 Actual frequencies used were 0.250 and 0.500 kHz (low), 1 and 2 kHz (middle), and 3, 4, 6, and 8 kHz (high).

In men, education level and occupational class showed clear effects on hearing loss in a multiple logistic regression model with occupational class, education level, and age as regressors (Table 2). In women, a logistic regression analysis showed no significant effects of education level or occupational class.

Table

TABLE 2 Odds Ratios (95% CI) for Education and Occupational Class in 1984–1986 and Prevalence of Mean Bilateral Hearing Loss at 3 Frequency Ranges Among Men (n = 7849) Aged 41–65 Years in 1995–1997: Hunt 1 and Hunt 2

TABLE 2 Odds Ratios (95% CI) for Education and Occupational Class in 1984–1986 and Prevalence of Mean Bilateral Hearing Loss at 3 Frequency Ranges Among Men (n = 7849) Aged 41–65 Years in 1995–1997: Hunt 1 and Hunt 2

Low Frequency, OR (95% CI)Middle Frequency, OR (95% CI)High Frequency, OR (95% CI)
Educational level in 1984–1986
    College and university (Ref)1.001.001.00
    Vocational or high school1.22 (0.94, 1.59)1.47 (1.10, 1,95)1.42 (1.03, 1.95)
    ≤ 10 years public school1.49 (1.12, 1.98)1.55 (1.14, 2.10)1.58 (1.13, 2.20)
Position in the labor market in 1984–1986
    I: Higher grade administrators and professionals (Ref)1.001.001.00
    II: Lower administrators and professionals1.28 (0.95, 1,72)1.03 (0.75, 1.41)1.43 (1.01, 2.04)
    III: Routine nonmanual employees1.06 (0.74, 1.51)0.79 (0.54, 1.17)0.97 (0.63, 1.49)
    IV: Self-employed, farmers and fishermen1.21 (0.93, 1.59)1.08 (0.82, 1.41)1.55 (1.14, 2.11)
    V+VI: Lower-grade technicians, supervisors of manual work1.13 (0.85, 1.52)1.15 (0.85, 1.54)1.78 (1.28, 2.47)
    VII: Semi- and unskilled manual workers1.46 (1.07, 1.98)1.27 (0.92, 1.74)1.88 (1.33, 2.67)

Note. HUNT = Nord-Trøndelag Health Study; CI = confidence interval. Educational level was categorized according to a standardized scheme developed by the Organisation for Economic Co-operation and Development.22 The occupational classification in HUNT ranged from high to low social position according to the Erikson Goldthorpe Portocarero social class scheme.26 The cutpoints for the upper 10% were 23 dB for low (0.250 and 0.500 kHz), 27 dB for middle (1 and 2 kHz), and 60 dB for high (3, 4, 6, and 8 kHz) frequencies. In the integrated model, effect variables were adjusted for each other and age.

On the basis of the observed numbers of participants with hearing loss in each occupational class, the population-attributable fraction of the prevalence of hearing loss over the high frequency (3, 4, 6, and 8 kHz) range cutpoint was calculated at 35%.

Socioeconomic position, as indicated by education level and occupational class, was associated with hearing loss in this Norwegian population of men aged 41 to 65 years at follow-up. Our results demonstrated a clear relation between occupational class and high-frequency hearing loss that was consistent with the results of comparable studies.4,10,13 These relations probably, in full or in part, reflect the effects of harmful occupational noise,4,10,11,1315 but also less healthy lifestyles (including exposure to smoke, exposure to noise during leisure activities, and so on) among poorly educated persons. We question, as other researchers have, whether women's occupational class is a suitable indicator for socioeconomic position in health matters.28,29

Future studies are needed to fully establish mechanisms behind the association between socioeconomic position and hearing loss. Regardless of the mechanism, the social patterning of hearing loss clearly has public health implications. Education level might also be of importance and should be taken into consideration when new hearing prevention programs are generated.30,31

Acknowledgments

The Nord-Trøndelag Health Study (The HUNT Study) is a collaboration between HUNT Research Centre, Faculty of Medicine, Norwegian University of Science and Technology, Norwegian Institute of Public Health, and Nord-Trøndelag County Council. The Nord-Trøndelag Hearing Loss Study, which is a part of HUNT, was funded by the National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD (research contract no. N01-DC-6-2104).

The authors also thank the Nord-Trøndelag Hearing Loss Study team for their diligence and Pål Romundstad for statistical advice.

Human Participant Protection

The study was approved by the Norwegian Regional Committee of Medical Research Ethics and the Data Inspectorate.

References

1. WHO. Prevention and noise-induced hearing loss. Report of an informal consultation. Paper presented at: World Health Organization; 1997; Geneva, Switzerland. Google Scholar
2. Tambs K. Utbredelse av hørselstap [Prevalence of hearing impairment]. Nytt fra Miljø og Samfunnsmedisin. 1998;2:1. Google Scholar
3. Sorri M, Brorsson B, Davis A, et al.. Hearing Impairment Among Adults. Report of a Joint (Nordic-British) Project. Helsinki, Finland: Edita Oyj; 2001. Google Scholar
4. Davis AC. The prevalence of hearing impairment and reported hearing disability among adults in Great Britain. Int J Epidemiol. 1989;18:911917. Crossref, MedlineGoogle Scholar
5. Wilson DH, Walsh PG, Sanchez L, et al.. The epidemiology of hearing impairment in an Australian adult population. Int J Epidemiol. 1999;28:247252. Crossref, MedlineGoogle Scholar
6. Rosenhall U, Jönsson R, Söderlind O. Self-assessed hearing problems in Sweden: a demographic study. Audiology. 1999;38:328334. Crossref, MedlineGoogle Scholar
7. Barrenäs M-L, Hellström P-A, Starck J. Hearing conservation. In: , Prasher D, Luxon L, Pyykkö I, eds. Advances in Noise Research. Volume II. Protection Against Noise. London, United Kingdom: Whurr Publishers Ltd; 1998:211218. Google Scholar
8. Borchgrevink HM. Does health promotion work in relation to noise? Noise Health. 2003;5:2530. MedlineGoogle Scholar
9. Yeoh LH. Causes of hearing disorders. In: , Kerr AG, ed. Scott-Brown's Otolaryngology. Oxford, United Kingdom: Reed Educational and Professional Publishing Ltd; 1997:2/10/1–2/10/128. Google Scholar
10. Quaranta A, Assennato G, Sallustio V. Epidemiology of hearing problems among adults in Italy. Scand Audiol Suppl. 1996;42:913. MedlineGoogle Scholar
11. Cruickshanks KJ, Wiley TL, Tweed TS, et al.. Prevalence of hearing loss in older adults in Beaver Dam, Wisconsin. The Epidemiology of Hearing Loss Study. Am J Epidemiol. 1998;148:879886. Crossref, MedlineGoogle Scholar
12. Meyer JD, Chen Y, McDonald JC, Cherry NM. Surveillance for work-related hearing loss in the UK: OSSA and OPRA 1997-2000. Occup Med. 2002;52:7579. CrossrefGoogle Scholar
13. Palmer KT, Griffin MJ, Syddall HE, Davis A, Pannett B, Coggon D. Occupational exposure to noise and the attributable burden of hearing difficulties in Great Britain. Occup Environ Med. 2002;59:634639. Crossref, MedlineGoogle Scholar
14. Cruickshanks KJ, Tweed TS, Wiley TL, et al.. The 5-year incidence and progression of hearing loss: the epidemiology of hearing loss study. Arch Otolaryngol Head Neck Surg. 2003;129:10411046. Crossref, MedlineGoogle Scholar
15. Hannaford PC, Simpson JA, Bisset AF, Davis A, McKerrow W, Mills R. The prevalence of ear, nose and throat problems in the community: results from a national cross-sectional postal survey in Scotland. Fam Pract. 2005;22:227233. Crossref, MedlineGoogle Scholar
16. Tambs K, Hoffman HJ, Borchgrevink HM, Holmen J, Samuelsen SO. Hearing loss induced by noise, ear infections, and head injuries: results from the Nord-Trøndelag Hearing Loss Study. Int J Audiol. 2003;42:89105. Crossref, MedlineGoogle Scholar
17. Holmen J, Midthjell K, Bjartveit K, et al.. The Nord-Trøndelag Health Survey 1984-86. Purpose, background and methods. Participation, non-participation and frequency distributions. Helsetjenesteforskning, Norway: Senter for samfunnsmedisinsk forskning; 1990. Report 4. Google Scholar
18. Holmen J, Midthjell K, Krüger Ø, et al.. The Nord-Trøndelag Health Study 1995-97 (HUNT 2): objectives, contents, methods and participation. Norsk Epidemiologi. 2003;13:1932. Google Scholar
19. ISO 8253-1. Acoustics—Audiometric test methods. Part I: Basic pure-tone air and bone conduction threshold audiometry. Geneva, Switzerland: International Organisation for Standardization; 1989. Google Scholar
20. ISO 389. Acoustics—Standard reference zero for the calibration of pure-tone air-conduction audiometers. Geneva, Switzerland: International Organisation for Standardization; 1991. Google Scholar
21. Tambs K, Hoffman HJ, Engdahl B, Borchgrevink HM. Hearing loss associated with ear infections in Nord-Trøndelag, Norway. Ear Hear. 2004;25:388396. Crossref, MedlineGoogle Scholar
22. Organisation for Economic Co-operation and Development. Education in OECD countries, 1988/89, 1989/90. A compendium if statistical information. Paris, France: OECD; 1993. Google Scholar
23. Lahelma E, Manderbacka K, Rahkonen O, Karisto A. Comparisons of inequalities in helath: evidence from national surveys in Finland, Norway and Sweden. Soc Sci Med. 1994;38:517524. Crossref, MedlineGoogle Scholar
24. Krokstad S, Westin S. Health inequalities by socioeconomic status among men in the Nord-Trøndelag Health Study, Norway. Scand J Public Health. 2002;30:113124. MedlineGoogle Scholar
25. Krokstad S, Rindal K, Westin S. Classifying people by social class in population based health surveys: two methods compared. Norsk Epidemiologi. 2002;12:1925. Google Scholar
26. Erikson R, Goldtorpe J. The Constant Flux. A Study of Class Mobility in Industrial Societies. Oxford, United Kingdom: Clarendon Press; 1992. Google Scholar
27. Mackenbach JP, Kunst AE. Measuring the magnitude of socio-economic inequalities in health: an overview of available measures illustrated with two examples from Europe. Soc Sci Med. 1997;44:757771. Crossref, MedlineGoogle Scholar
28. Vagero D. Health inequalities in women and men. BMJ. 2000;320:12861287. Crossref, MedlineGoogle Scholar
29. Sacker A, Firth D, Fitzpatrick R, Lynch K, Bartley M. Comparing health inequality in men and women: prospective study of mortality 1986-96. BMJ. 2000;320:13031307. Crossref, MedlineGoogle Scholar
30. Nondahl DM, Cruickshanks KJ, Dalton DS, et al.. The use of hearing protection devices by older adults during recreational noise exposure. Noise Health. 2006;8:147153. Crossref, MedlineGoogle Scholar
31. Beckett WS, Chamberlain D, Hallman E, et al.. Hearing conservation for farmers: source apportionment of occupational and environmental factors contributing to hearing loss. J Occup Environ Med. 2000;42:806813. Crossref, MedlineGoogle Scholar

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Anne-Sofie Helvik, PhD, Steinar Krokstad, PhD, and Kristian Tambs, PhDAnne-Sofie Helvik is with the Department of Public Health and General Practice, Faculty of Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway; Innlandet Hospital Trust, Division Tynset, Norway; and the Ear, Nose and Throat Department, St Olav's University Hospital, Trondheim, Norway. Steinar Krokstad is with the Department of Public Health and General Practice, Faculty of Medicine, NTNU, Trondheim; HUNT Research Centre, Department of Public Health and General Practice, Faculty of Medicine, NTNU, Verdal, Norway; and Levanger Hospital, Nord-Trøndelag Health Trust, Levanger, Norway. Kristian Tambs is with the Norwegian Institute of Public Health, Division of Mental Health, Oslo, Norway, and The Virginia Institute for Psychiatric and Behavioral Genetics, Medical College of Virginia, Virginia Commonwealth University, Richmond. “Socioeconomic Inequalities in Hearing Loss in a Healthy Population Sample: The HUNT Study”, American Journal of Public Health 99, no. 8 (August 1, 2009): pp. 1376-1378.

https://doi.org/10.2105/AJPH.2007.133215

PMID: 19542048