Hearing loss-an

underestimated public health problem

David Wilson Behuvioural Epidemiology Unit, Public and Environmental Health Sewice, Adelaide

Sun Xibin Henan Tumor Institute, Zheng Zhou, China

Pamela Read Better Hearing Australia, Adelaide

Paul Walsh East Adelaide Medical Centre

Adrian Esterman Health Statistics Unit, Public and Environmental Health Sewice, Adelaide Abstract: Estimates of hearing loss in Australia, collected over the last decade and a half, have reported a prevalence rate ranging from 0.1 to 7 per cent. This survey of a random sample of South Australians provides, depending upon definition, two estimates of 15 and 19 per cent. These data suggest that hearing loss has been underestimated as a public health problem. The need for an epidemiological study which measures actual hearing impairment, which can be used to develop an appropriate public health response, is discussed. (AustJ Public Health 1992; 16: 282-6)


earing loss has been identified as the most common of all physical impairments.' It is a problem which strikes at the very core of human existence-our relationships.' It is suffered by a large number of Australians, costs a great deal in economic and social terms, and has demonstrable opportunities for primary and secondary prevention initiative^.^.^ In spite of this, hearing loss does not feature as a public health p r i ~ r i t y .It~ . ~ has been identified as an occupational health priority,' largely because of its economic cost to industry, but the problem has many causes and consequences other than its occupational factors. If we are to adopt a comprehensive approach to hearing loss, it is therefore important that it be recognised as a public health as well as an occupational health problem. In 1989 Australia paid out $70 million in workers' compensation costs alone for hearing loss. This may be only the tip of the iceberg when it is considered the hearing-impaired occupy more hospital bed days, incur more doctor visits and have greater limitation of activity due to chronic conditions than the normal population.' They also suffer clinically significant psychological disturbance three times more than the general population,s and experience greater levels of anxiety, stress and fatigue which may predispose them to other health problems.g The fact that hearing loss does not feature as an important public health objective may, in part, be Correspondence to Mr David Wilson, Head, Behavioural Epidemiology Unit, Public and Environmental Health Service, PO Box 6, Rundle Mall, Adelaide SA 5000


due to the sufferers' own reluctance to promote their problem. Hetu and others have shown that stigmatisation of the hearing impaired is a very real issue and those who are impaired will often go to considerable lengths to conceal or deny the problem.gJo Such reluctance on the part of those who suffer from hearing loss obstructs its promotion as a public health priority. There are also data limitations which impede the promotion of hearing loss as a public health issue. The three major epidemiological studies conducted in Australia in recent years have assessed hearing loss from quite different perspectives and as expected produced varying estimates of prevalence ranging from 0.1 per cent to 7.4 per cent.".12.'Y More importantly, these studies relied largely on self report and did not measure actual hearing loss. Recent studies from overseas have suggested that without an audiometric assessment of hearing loss the extent of the problem may be ~nderestimated.'~ Even with the important issue of noise-induced hearing loss, there has never been a systematic study of occupational noise exposure in A~stra1ia.l~Without clear epidemiological information on hearing loss it is not possible to specify accurately its prevalence and severity or the underlying causes. Nor is it possible to assess the relative contributions of the risk factors, the characteristics of the groups with hearing loss, or the conditions in which they live and work, which may contribute to or modify the problem. Where good epidemiological data are available for prevalent diseases with modifiable components, they are likely to rate as public health priorities.



VOL. 16 NO. 3


In the recent British Epidemiological Study, where hearing loss was actually measured, Davis estimated that about 25 per cent of the population had a ‘significant’ unilateral or bilateral hearing loss occurring at 25 dBHTL (decibel hearing threshold level) averaged over the four frequencies of 0.5, 1, 2, and 4kHz.I4 In this British study people were asked ‘DO you usually have difficulty hearing what people say to you in a quiet room, a) if they speak loudly to you, b) if they speak normally to you, or c) if they whisper to you?’ Twenty-five per cent of the British population reported a hearing difficulty based on this question. Thus, the hearing in a quiet room question would appear to be a reasonable proxy estimate for measured hearing loss in the British study. This question from the British study was included, with other questions about hearing loss, in the South Australian Health Omnibus Survey. It was considered that as resources were not available to measure actual hearing thresholds it was at least prudent to use a question which had already given some indication of its validity elsewhere. It was also considered that short of measuring actual hearing loss, this question would provide a surrogate measure, help to upgrade data from previous Australian surveys and, in addition, provide some comparisons with the British study where hearing loss was actually measured. It is likely that some people who have a diagnosed hearing loss and have had it treated or who have learned new coping skills since diagnosis would say that they had no difficulty hearing in a quiet room. For this reason a second estimate of hearing loss was derived by adding to the response from the British question any person who reported a diagnosed hearing loss but said they had no difficulty hearing in a quiet room.

Methodology The South Australian Health Omnibus surveyI6used the Australian Bureau of Statistics to collect data on a range of health issues, including hearing loss. A representative sample of 0.43 per cent of the Adelaide metropolitan and 0.24 per cent of the country population was selected. The sample was a clustered, selfweighting, multistage, systematic area sample of people aged 15 years or older, with a constant sampling fraction for both Adelaide metropolitan and South Australian country regions. The household response rate in the Omnibus survey was 72 per cent which yielded 2 559 respondents throughout South Australia. With an expected 25 per cent of the sample admitting to a hearing loss, the sample size of 2 559 subjects would provide a 95 per cent confidence interval of 23 to 27 per cent. The information obtained was collected by personal interview from occupants, aged 15 years and over, of private dwellings. Hotels, motels, nursing homes and hospitals, etc., were excluded. The data collected were weighted by sex, five-year age groups and geographic area, so that findings would apply to the demographic profile of South Australia. Respondents were first asked whether or not they had a hearing loss or had trouble hearing in some

situations. They were then asked, ‘Do you usually have difficulty hearing what people say to you in a quiet room if they, a) speak loudly to you, b) speak normally to you, c) whisper to you, or d) none of the above?’. Respondents who said they had difficulty in any of the first three categories were considered to have a hearing loss. Further information was obtained from respondents on whether the hearing loss had been diagnosed by a doctor, if so, the diagnosed cause of the hearing problem, and on a range of sociodemographic variables. In order to test reliability of this question, 101 subjects were selected at random from the Health Omnibus Sample and the hearing in quiet question was asked again. The results were compared with the previous response. Of the 101 people re-interviewed, 99 gave exactly the same answer as they had done initially. Clearly this degree of test-retest reliability is excellent. It was also possible from data collected in the Omnibus study to describe the general medical profile of the hearing-impaired from data collected on asthma, diabetes and elevated blood pressure. The statistical package Epi Info Version 5.01 was used to calculate relative risks with their 95 per cent confidence intervals and level of statistical significance for variables thought to be associated with hearing loss. SPSS-PC Version 4 was used for a logistic regression analysis to determine the bestjoint predictors of hearing loss. Because of the multi-stage sampling in this study, it is possible that some variables would have clustered by household. However, for the purpose of this analysis, independence of observations was assumed. People in this sample were classified as working in a quiet or noisy industry according to the type of work they had done for most of their working lives, using the ASCO classification of occupations developed for Australia covering 1079 distinct categories of employment.18This was performed ‘blind’in relation to the hearing assessment. For comparison with the prevalence question about hearing in a quiet room asked in the British study, both sets of data were weighted by age and sex to the general South Australian population.

Results In this survey 17.8 per cent of males and 11.9 per cent of females (14.6 per cent overall) reported a hearing difficulty when asked the British Epidemiological Survey question assessing level of hearing loss in a quiet room. The age- and sexstandardised rate for South Australia on this question was 15 per cent compared with 25 per cent for the United Kingdom. Table 1 shows that if those who reported no hearing difficulty in answer to this question but said they had a diagnosed hearing loss were also included then the estimate of hearing loss increased to 24.0 per cent of males, and 15 per cent of females (19.4 per cent overall). Table 1 also shows that more males than females at each age reported a hearing loss. Table 2 shows that for those who were able to report a diagnosed cause of their hearing loss, exposure to loud noise was the



VOL. 16 NO.



Table 1 : Reported hearing loss by validated question or previous diagnosis Male Yes


Age 15 to 29 years

30 to 44 years 45 to 59 years












90 81 66 60




67 85 105


34 40

355 25 1 260

100 100 100 100


288 166 155

379 219 232





1 201


1 153


most important cause for men, and illness the most common cause for women. Analysis of data showed that overall 41 per cent of females and 24 per cent of males who reported a hearing loss in this study said that it had not been diagnosed by an appropriate health professional. Figure 1 shows that this difference between the sexes was greatest in the working years of life and appears to narrow in the 60 plus age group. Table 3 shows the relationship between hearing loss and various other potential risk factors for those who reported difficulty hearing in a quiet room or who had a diagnosed loss. Older age, male sex, lower educational level, working in a noisy industry, a history of diabetes and elevated blood pressure were all associated with hearing loss (P < 0.05). The variables which were found to be statistically significant at the univariate stage of analysis were entered into a logistic regression analysis. A model containing three predictor variables provided a good fit to the data (P < 0.0001) and explained 39 per cent of the variance. The adjusted odds ratios derived from the model are shown in Table 4. When these data were age-standardised using only the question data relating to hearing a whisper, a normal conversation or a loud noise in a quiet room, the prevalence of hearing loss for South Australia was 15.4 per cent compared with the British estimate on the same question of 25 per cent.

Discussion The estimates of hearing loss provided in this paper greatly exceed any estimate provided in previous Australian surveys. The lower sex- and agestandardised rate of 15 per cent compared with 25 Table 2: Diagnosed cause of hearing loss reported by South Australians Male







Age Other

114 17 17 12 14 53

7.6 7.6 5.1 6.3 23.3

16 24 9 19 42

4.1 14.0 21.0 7.4 16.5 36.9






Congenital Illness Accident








29 42 37 97

8 10 14 29


90 86 71

42 1 256 329

100 100 100 100






I -Males - -Females 1 50




\...... \ \







a a,





per cent in England may reflect a true difference between the two countries in the prevalence of hearing loss. There is however some evidence in this study to support the belief that the South Australian rate is higher at around 19 per cent. If either of these rates can be substantiated audiometrically, then the argument to declare hearing loss a public health priority is strengthened. N o opportunity was available to test the validity of the British question in an Australian context. The question was used in a self-completion questionnaire in the British study, but in the South Australian study was administered by trained interviewers. In the British study there was no substantial difference between reported hearing disability and measured hearing impairment. About 25 per cent of the British population had a unilateral or bilateral hearing deficit at 25dBHTL. We cannot, however, assume that the question is similarly valid in the Australian and British contexts. The only way to establish validity is to measure actual hearing loss. As measurement of hearing loss was not possible in this study, the next best option was to use a question which had established validity elsewhere.I4



Exposure to loud noise

Female Yes








0 15-29




Age group Figure 1 : Percentoges of those having o reported hearing loss who had not hod it diognosed.



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Table 3: Univariate analysis of data for variables associated with hearing loss

Vorioble Sex Female Mole Age in years (moles) I5 to 29 30 to 44 45 to 5 9


Relotive risk

95% confidence interval


1 358 1201

1 .o 1 .80

1.47 to 2.21

< 0.000

1.29 to 3.29 1.05 to 3.12 3.34 to 10.44

< 0.000 < 0.000


335 355 25 1 260

1 .o 2.05 1 .81 5.9

Age in yeors (females) I5 to 29 30 to 44 45 to 59 > 60

352 421 256 329

1 .o 1.23 1.88 4.66

0.73 to 2.09 1.04 to 3.25 2.91 to 7.48

856 694 568

1 .o 1.59 1.01

1.36 to 1.90 0.91 to 1.36

0.003 0.9



0.96 to 1.47



1 .o

819 374

1.05 1.56

0.74 to 1.50 1.12 to 2.14

0.8 0.006



1.12 to 2.05


129 1 456

1 .o 1.29

0.74 to 2.28




0.49 to 0.74

< 0.001

2 003 344

1 .o 1.34

1.02 to 1.77


2 233

1 .o

0.79 to 1.44


1.32 to 3.59



0.5 0.02

Hearing loss--an underestimated public health problem.

Estimates of hearing loss in Australia, collected over the last decade and a half, have reported a prevalence rate ranging from 0.1 to 7 per cent. Thi...
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